JP2016151410A - Transport refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transport refrigeration unit capable of preventing a refrigerator temperature from being reduced during defrosting operation, defrosting within a short period of time, appropriately adjusting a condensing capability during cooling operation, restricting a frequent starting or stopping operation of a compressor at the time of thermo-on or -off and assuring its reliability in operation.SOLUTION: This invention relates to a transport refrigeration unit 1 having a heat-pump type heating function constituted in such a way that when a heat pump heating operation is carried out under an arrangement that two heat exchangers in a plurality of heat exchangers 8A to 8C are arranged in parallel outside a refrigerator as outside heat exchangers 8A, 8B of the refrigerator, one heat exchanger is arranged in the refrigerator as an inside heat exchanger 8C. The outside heat exchangers 8A, 8B are applied as evaporators and the inside heat exchanger 8C is applied as a condenser, if the outside heat exchangers 8A, 8B are frosted, a flow of refrigerant against the inside heat exchanger 8C is stopped, a defrosting operation is carried out while one of the outside heat exchangers 8A, 8B being applied as a condenser and the other being applied as an evaporator.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transport refrigeration unit equipped with a heat pump heating function mounted on a refrigerated vehicle, a trailer or the like.

  In recent years, a transport refrigeration unit having a heat pump heating function has been provided, and examples thereof are shown in Patent Documents 1 and 2. These are connected to one end side of a plurality of heat exchangers via a high pressure gas pipe and a high pressure on-off valve on the discharge side of the compressor, respectively, and one end side of the plurality of heat exchangers is respectively connected to a low pressure gas pipe and a low pressure Connected to the suction side of the compressor via an on-off valve, and a pressure reducing means with an on-off valve function on each other end of each heat exchanger (having an on-off valve and an expansion valve connected in series, or having an on-off valve function A liquid side pipe provided with a parallel circuit of a check valve and the like is connected, and the liquid side pipes are connected in communication with each other to constitute a refrigerant circuit.

  In addition, one of the plurality of heat exchangers is disposed outside the cold storage as an outside heat exchanger, and one or more heat exchangers are respectively disposed in the cold storage as inside heat exchangers. Open and close the open / close valve function of each high pressure open / close valve provided in the high pressure gas pipe, each low pressure open / close valve provided in the low pressure gas pipe, and each pressure reducing means with open / close valve function provided in the liquid side pipe. The refrigerant flow to the heat exchanger is switched, the outside heat exchanger functions as a condenser, and the inside heat exchanger functions as an evaporator to perform a cooling operation, and the inside heat exchanger is a condenser and outside heat exchange. The heater functions as an evaporator and heat pump heating operation is performed.

  On the other hand, in a multi-type air conditioner that employs a refrigerant circuit similar to the above and is capable of simultaneous cooling and heating operations, a so-called cooling / heating-free multi-type air conditioner, comprising a plurality of outdoor heat exchangers When the outdoor heat exchanger is frosted during heating operation, one of the outdoor heat exchangers is evaporated while flowing the hot gas refrigerant through the indoor heat exchanger and continuing the heating operation. Patent Documents 3 and 4 disclose that the other unit functions as a condenser and a plurality of frosted outdoor heat exchangers are alternately defrosted.

Japanese Patent No. 5535510 JP 2013-234784 A JP-A-3-55474 JP-A-9-26219

  However, in the transport refrigeration unit, when an efficient heat pump heating method is adopted, there are many operating conditions for frosting the outside heat exchanger that functions as an evaporator during heating operation, especially in cold regions Since there are many opportunities for heating operation, the number of cases where the outside heat exchanger is frosted inevitably increases. In this case, the reverse cycle, that is, the defrost operation is performed by switching the heat pump heating cycle to the cooling cycle, but in the cooling cycle, the internal heat exchanger acts as an evaporator and absorbs heat from the internal air. In addition, there is a problem that the temperature inside the cabinet is lowered during the defrosting operation and the cargo may be damaged.

  On the other hand, as shown in Patent Documents 3 and 4, by adopting a configuration in which a plurality of outdoor heat exchangers are arranged in parallel, even when frosting occurs in the outdoor heat exchanger during heating operation, The frosted outdoor heat exchanger can be alternately defrosted while continuing the heat pump heating. However, in this case, since the defrosting is performed while flowing the hot gas refrigerant to the indoor heat exchanger side and continuing the heating operation, it is not possible to use all the refrigerant for defrosting, and the defrost time is increased accordingly. Therefore, there is a problem in applying this technique as it is to a transport refrigeration unit.

  In other words, in the case of an air conditioner that air-conditions a space where people are present, rather than interrupting the heating operation in order to avoid a situation in which the sudden temperature change caused by the interruption of the heating operation due to the defrost operation causes the person to feel uncomfortable Priority is given to continuing heating operation even if it takes some time to defrost. However, in the case of a transport refrigeration unit, it cools and heats the inside of the cool box with high heat insulation, so it is temporarily Even if the cooling operation or heating operation is interrupted, the internal temperature does not change abruptly, and defrosting in a short period of time and returning to a state in which heating operation can be performed provide better temperature controllability for the load. This is because it is desirable in securing.

  The present invention has been made in view of such circumstances, and it is possible to prevent a decrease in the internal temperature during defrosting, to defrost in a short time, and to appropriately adjust the condensation capacity during cooling operation, It is an object of the present invention to provide a transport refrigeration unit that employs a heat pump heating system that can ensure reliability by suppressing frequent start / stop of a compressor during on / off.

In order to solve the above-described problems, the transport refrigeration unit of the present invention employs the following means.
That is, the transport refrigeration unit according to the present invention includes a compressor, a plurality of heat exchangers each having one end connected to a discharge side of the compressor via a high-pressure gas pipe and a high-pressure on-off valve, and the plurality of units. A low-pressure gas pipe that connects one end side of each of the heat exchangers to the suction side of the compressor via a low-pressure on-off valve; Liquid-side piping connecting the other ends of the parallel circuit of the means and the check valve to each other, and at least two of the plurality of heat exchangers are connected to the outside heat. As an exchanger, it is arranged in parallel outside the cold storage, and at least one heat exchanger is arranged as an internal heat exchanger in the cold storage, and the external heat exchanger is an evaporator, the internal heat During the heat pump heating operation with the exchanger functioning as a condenser, When the exchanger is frosted, the refrigerant flow to the inside heat exchanger is stopped, and at least one of the plurality of outside heat exchangers is a condenser and the other one is a defrost operation. It is characterized by having a configuration.

  According to the present invention, one end side of a plurality of heat exchangers, one end side of which is connected to the discharge side of the compressor via a high-pressure gas pipe and a high-pressure on-off valve, respectively, is connected via a low-pressure gas pipe and a low-pressure on-off valve, respectively. Connected to the suction side of the compressor, and connected to the other end of each of the plurality of heat exchangers is a liquid side pipe provided with a parallel circuit of a pressure reducing means with an on-off valve function and a check valve. A refrigerant circuit is configured by connecting the other end sides of the pipes to each other, and at least two of the heat exchangers are arranged in parallel outside the cool box as external storage heat exchangers. Since at least one heat exchanger is arranged in the cold storage as an internal heat exchanger, the two external heat exchangers outside the storage function as condensers, By functioning one internal heat exchanger as an evaporator By performing a cooling operation to cool the inside of the cabinet, one inside heat exchanger inside the warehouse functions as a condenser, and two outside heat exchangers outside the warehouse function as evaporators, It is possible to perform a heat pump heating operation for heating Therefore, it is possible to perform a high-performance and efficient heating operation by the heat pump method. On the other hand, when the outside heat exchanger is frosted during the heat pump heating operation, the circulation of the refrigerant to the inside heat exchanger is stopped, and at least one of the plurality of outside heat exchangers is a condenser, Since one unit is configured to perform defrost operation as an evaporator, all the hot gas refrigerant discharged from the compressor is supplied to at least one of the frosted outside heat exchangers, and the other one of the outside heats The exchanger can function as an evaporator, and defrost operation can be performed while absorbing heat by the evaporator. Therefore, the defrosting of the outside heat exchanger can be performed using the full capacity of the heat pump (all refrigerants) without absorbing heat from the inside air, and the defrosting operation time can be shortened and the defrosting operation can be performed. The change in the inside temperature can be reduced.

  Furthermore, the transport refrigeration unit of the present invention is the above transport refrigeration unit, wherein at least one of the plurality of frosted outside heat exchangers is sequentially switched as a condenser and the other one as an evaporator, A plurality of the outside heat exchangers are sequentially defrosted.

  According to the present invention, at least one of a plurality of frosted outside heat exchangers is sequentially switched as a condenser and the other one as an evaporator, and the plurality of outside heat exchangers are sequentially defrosted. Therefore, the high-pressure on-off valve in the high-pressure gas pipe connected to each outside heat exchanger, the low-pressure on-off valve in the low-pressure gas pipe, and the opening / closing of the decompression means with the on-off valve function in the parallel circuit on the liquid side pipe side By opening and closing the valve function and switching the flow of the refrigerant between the plurality of outside heat exchangers, the plurality of outside heat exchangers can be sequentially defrosted. Therefore, a plurality of outside heat exchangers can be alternately defrosted using the full capacity (all refrigerants) of the heat pump, and can be defrosted in a short time.

  Furthermore, the transport refrigeration unit according to the present invention is characterized in that, in any of the transport refrigeration units described above, a blower system including an outside fan for the plurality of outside heat exchangers is provided independently. And

  According to this invention, since it is set as the structure which provided the ventilation system containing the warehouse outer side fan with respect to the several warehouse outer side heat exchanger each independently, it is for the warehouse outer side heat exchanger which functions as a condenser at the time of a defrost operation. While the outside fan is stopped, the outside fan for the outside heat exchanger functioning as an evaporator can be operated and defrosted. Accordingly, the amount of heat absorbed in the outside heat exchanger functioning as an evaporator is increased, and the heat can be defrosted efficiently and in a short time by radiating the heat with the outside heat exchanger that defrosts.

  Furthermore, the transport refrigeration unit of the present invention is the above-described internal heat exchanger when any of the above transport refrigeration units has a difference between the internal temperature and the set temperature equal to or higher than a specified value during the defrost operation. The high-pressure on-off valve in the high-pressure gas pipe connected to is opened, the high-pressure gas refrigerant is circulated through the internal heat exchanger, and a heating operation is performed.

  According to the present invention, during the defrost operation, when the difference between the internal temperature and the set temperature becomes equal to or greater than the specified value, the high pressure on-off valve in the high pressure gas pipe connected to the internal heat exchanger is opened. Since the high-temperature gas refrigerant is circulated through the inner heat exchanger and heated, the internal temperature suddenly changes for some reason during the defrost operation, and the difference from the set temperature exceeds the specified value. Even if there is, a part of the hot gas refrigerant from the compressor is introduced into the internal heat exchanger just by opening the high pressure on-off valve, and the heating operation can be performed while continuing the defrost operation. Therefore, the internal temperature does not drop below the specified value during the defrost operation, the temperature controllability can be maintained even during the defrost, and the quality of the cargo can be ensured, and the reliability of the transport refrigeration unit can be improved.

  Furthermore, in the transport refrigeration unit of the present invention, in any one of the transport refrigeration units described above, during the cooling operation in which the outside heat exchanger functions as a condenser, the condensation capacity becomes excessive and the high pressure decreases. When it passes, it is set as the structure which adjusts a condensation capacity | capacitance by reducing the number of operation | movement of a plurality of said outside heat exchangers.

  According to the present invention, during the cooling operation in which the outside heat exchanger functions as a condenser, when the condensing capacity is excessive and the high pressure is excessively lowered, the number of operating units of the plurality of outside heat exchangers is reduced. For example, when the cooling operation is performed under a condition where the outside air temperature is relatively low, if the operation is performed using all the plurality of outside heat exchangers, the inside heat exchange is performed. Compressor capacity is excessive due to excessive heat condensing capacity and the pressure in the high-pressure side circuit decreases, causing the differential pressure between the high and low pressures to become too small and deviate from the flow controllable range of the expansion valve. However, it is possible to adjust the condensation capacity by reducing the number of operating external heat exchangers and maintain the high / low pressure differential pressure within an appropriate range. Therefore, the transport refrigeration unit can be stably operated by appropriately adjusting the capacity on the outside heat exchanger side corresponding to the heat exchange amount in the inside heat exchanger and maintaining the operation balance.

  Furthermore, the transport refrigeration unit according to the present invention is characterized in that, in any of the transport refrigeration units described above, the plurality of outside heat exchangers are heat exchangers having different capacities.

  According to the present invention, since the plurality of outside heat exchangers are heat exchangers having different capacities, the condensation capacity in the outside heat exchanger is determined by selecting the operation of the plurality of heat exchangers. It is possible to adjust in many more stages. Therefore, under various outdoor air temperature and internal set temperature conditions, the condensing capacity is finely adjusted to maintain the high / low pressure difference within the appropriate range, so that more stable operation can be performed. Reliability can be improved.

  The transport refrigeration unit according to the present invention includes a compressor, a plurality of heat exchangers each having one end connected to a discharge side of the compressor via a high-pressure gas pipe and a high-pressure on-off valve, and the plurality of units. A low-pressure gas pipe connecting one end side of each of the heat exchangers to the suction side of the compressor via a low-pressure on-off valve, and a pressure-reducing valve with an on-off valve function connected to the other end side of the plurality of heat exchangers Liquid-side piping connecting the other ends of the parallel circuit of the means and the check valve to each other, and at least two of the plurality of heat exchangers are connected to the outside heat. As an exchanger, it is arranged in parallel outside the cold storage, and at least one heat exchanger is arranged in the cold storage as an internal heat exchanger, and when the thermostat is turned off after the internal temperature reaches the set temperature, If the compressor operating time is less than the specified time, The circulation of the refrigerant is stopped, and the compressor is continuously operated until the operation time exceeds the specified time by using one of the plurality of outside heat exchangers as a condenser and the other as an evaporator. It is characterized by that.

  According to the present invention, one end side of a plurality of heat exchangers, one end side of which is connected to the discharge side of the compressor via a high-pressure gas pipe and a high-pressure on-off valve, respectively, is connected via a low-pressure gas pipe and a low-pressure on-off valve, respectively. Connected to the suction side of the compressor, and connected to the other end of each of the plurality of heat exchangers is a liquid side pipe provided with a parallel circuit of a pressure reducing means with an on-off valve function and a check valve. A refrigerant circuit is configured by connecting the other end sides of the pipes to each other, and at least two of the heat exchangers are arranged in parallel outside the cool box as external storage heat exchangers. Since at least one heat exchanger is arranged in the cold storage as an internal heat exchanger, the two external heat exchangers outside the storage function as condensers, By functioning one internal heat exchanger as an evaporator By performing a cooling operation to cool the inside of the cabinet, one inside heat exchanger inside the warehouse functions as a condenser, and two outside heat exchangers outside the warehouse function as evaporators, It is possible to perform a heat pump heating operation for heating Therefore, it is possible to perform a high-performance and efficient heating operation by the heat pump method. On the other hand, after the inside temperature reaches the set temperature by the cooling operation or the heating operation, the thermo-ON / OFF is normally repeated. In this case, if the thermo is turned on / off in a short time, the compressor will frequently start and stop, which may cause failure and reduced life. However, if the compressor's operating time is less than the specified time when the thermo is off, The refrigerant flow to the exchanger is stopped, and the compressor is continuously operated until the operating time exceeds a specified time by using one of the plurality of outside heat exchangers as a condenser and the other as an evaporator. Therefore, for example, even when thermo-ON / OFF is repeated in a short time due to temperature interference between multiple chambers (inside the room), when the thermo-off is performed, the compressor is continuously operated until the operating time of the compressor exceeds a specified time. Frequent start / stop of the compressor can be prevented by idling the refrigeration unit using one of the outside heat exchangers as a condenser and the other as an evaporator. Therefore, the start / stop frequency of the compressor can be suppressed and its reliability can be ensured.

  According to the present invention, the cooling operation for cooling the interior by causing the two outside heat exchangers on the outside of the warehouse to function as condensers, and the one inside heat exchanger on the inside of the warehouse to function as an evaporator. Heat pump heating that heats the inside of the warehouse by causing one inside heat exchanger inside the warehouse to function as a condenser and two outside heat exchangers outside the warehouse to function as evaporators Since the operation can be performed, a high-capacity and efficient heating operation by a heat pump method can be performed, while at least one of the outside heat exchangers that has frosted all of the hot gas refrigerant discharged from the compressor. Since it can be supplied to the stand and the other one outside heat exchanger functions as an evaporator, and defrost operation can be performed while absorbing heat by the evaporator, the heat pump does not absorb heat from the inside air. Full capacity All refrigerant) can perform defrosting of the refrigerator outer heat exchanger with, it is possible to shorten the defrosting operation time, it is possible to reduce the change in the internal temperature during the defrosting operation.

  According to the present invention, even when thermo-ON / OFF is repeated in a short time, when the thermo-off is performed, the compressor is continuously operated until the operating time of the compressor exceeds the specified time, and one of the plurality of outside heat exchangers is connected to the condenser. By operating the refrigeration unit idly with the other one as an evaporator, frequent start / stop of the compressor can be prevented, so the start / stop frequency of the compressor is suppressed and its reliability is ensured. Can do.

It is a refrigerant circuit figure of the refrigerating unit for transportation concerning a 1st embodiment of the present invention. It is a refrigerant circuit block diagram at the time of the defrost driving | operation on the external heat exchanger (A) side of the said transport refrigeration unit. It is a refrigerant circuit block diagram at the time of the defrost driving | operation on the external heat exchanger (B) side of the said transport refrigeration unit. It is a control flowchart figure at the time of the defrost driving | operation of the said transport refrigeration unit. It is a refrigerant circuit block diagram at the time of condensation capacity adjustment at the time of the cooling operation of the transport refrigeration unit concerning a 2nd embodiment of the present invention. It is a flowchart figure at the time of the compressor start / stop frequency reduction control of the transport refrigeration unit according to the third embodiment of the present invention.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
FIG. 1 is a refrigerant circuit diagram of the transport refrigeration unit according to the first embodiment of the present invention. FIGS. 2 and 3 are refrigerant circuit configuration diagrams during the defrost operation, and FIG. 4 is a defrost operation. A control flowchart diagram of the hour is shown.
In this embodiment, an example will be described in which the present invention is applied to an integrated transport refrigeration unit 1 that cools or heats the inside of a cool box called a van body mounted on the loading platform side of a refrigerated vehicle or the like. Of course, the present invention is not limited to the body-type transport refrigeration unit, and can be widely applied to all transport refrigeration units.

  As shown in FIG. 1, the refrigerant circuit 2 of the transport refrigeration unit 1 includes a compressor 3 (here, an electric compressor), and a high-pressure gas port 5 connected to a discharge pipe 4 of the compressor 3. , A plurality (three in this example) of high-pressure gas pipes 6A, 6B, 6C branched from the high-pressure gas port 5, and high-pressure on-off valves (solenoid valves) provided in the respective high-pressure gas pipes 6A, 6B, 6C 7A, 7B, 7C, and a plurality of heat exchangers 8A, 8B, 8C having one end connected to each of the high-pressure gas pipes 6A, 6B, 6C.

  Two of the heat exchangers 8A, 8B, and 8C among the plurality of heat exchangers 8A, 8B, and 8C are respectively an outside heat exchanger (A) 8A and an outside heat exchanger (B) 8B. The other one is arranged in the cold storage as the inside heat exchanger 8C.

  Further, at one end side of the plurality of heat exchangers 8A, 8B, 8C, which are the outside heat exchanger (A) 8A, the outside heat exchanger (B) 8B, and the inside heat exchanger 8C, A plurality of (three) low-pressure gas pipes 9A, 9B, 9C connected so as to branch off from the respective high-pressure gas pipes 6A, 6B, 6C, and low-pressure opening / closing provided in the low-pressure gas pipes 9A, 9B, 9C Valves (solenoid valves) 10A, 10B, and 10C and low-pressure gas ports 11 to which the low-pressure gas pipes 9A, 9B, and 9C are connected are provided. The low-pressure gas port 11 is connected to the compressor 3 via the suction pipe 12. It is configured to be connected to.

  Similarly, on the other end side of the outside heat exchanger (A) 8A, the outside heat exchanger (B) 8B, and the inside heat exchanger 8C, an expansion valve 15A is provided for each of the check valves 14A, 14B, and 14C. , 15B, 15C and open / close valves (solenoid valves) 16A, 16B, 16C are connected in parallel to one end of parallel circuits 13A, 13B, 13C, and other parallel circuits 13A, 13B, 13C are connected. By connecting the ends to the high-pressure liquid port 17, liquid-side pipes 18 </ b> A, 18 </ b> B, and 18 </ b> C that are connected in communication with each other are provided, thereby forming a closed-cycle heat pump refrigerant circuit 2.

  In the present invention, the series circuit of the expansion valves 15A, 15B, 15C and the on-off valves (solenoid valves) 16A, 16B, 16C is referred to as pressure reducing means with on-off valve function. Here, a separate expansion valve and an on-off valve (solenoid valve) are connected in series, but may be an integrated valve, or may be replaced by an electric expansion valve having an on-off valve function, In the meaning including these, it is a collective term of “a pressure reducing means with an on-off valve function”.

  On the other hand, in the integrated transport refrigeration unit 1, the internal heat exchanger 8C is disposed in the internal air circulation path on the unit side so that the internal heat exchanger 8C faces the internal, and other equipment is mounted outside the internal storage. It will be arranged on the unit main body side. The internal heat exchanger 8C is provided with an internal fan 19 so that the internal air can be circulated through the internal heat exchanger 8C, and the external heat exchanger (A) 8A and the external side With respect to the heat exchanger (B) 8B, the outside fans 20A and 20B are respectively attached, so that outside air is supplied to the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B. An independent blower system for blowing air is configured.

  In the refrigerant circuit 2, the high pressure gas port 5, the low pressure gas port 11 and the high pressure liquid port 17 are respectively connected to the discharge pipe 4 and the high pressure gas pipes 6A, 6B and 6C, and the suction pipe 12 and the low pressure gas pipes 9A and 9B. 9C and the liquid side pipes 18A, 18B, 18C may be omitted, and the high pressure liquid port 17 may be replaced by a receiver.

In the transport refrigeration unit 1 including the heat pump refrigerant circuit 2 described above, the cooling operation and the heat pump heating operation are performed as follows.
[Cooling operation]
The cooling operation is an operation performed by causing the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B to function as a condenser and the inside heat exchanger 8C as an evaporator, respectively. In this case, the high-pressure on-off valves 7A and 7B in the high-pressure gas pipes 6A, 6B and 6C are opened, the high-pressure on-off valve 7C is closed, and the low-pressure on-off valves 10A and 10B in the low-pressure gas pipes 9A, 9B and 9C are closed. The valve 10C is opened, the on-off valves 16A, 16B in the parallel circuits 13A, 13B, 13C of the liquid side pipes 18A, 18B, 18C are closed, and the on-off valve 16C is opened.

  As a result, the high-temperature and high-pressure refrigerant gas discharged from the compressor 4 passes through the discharge pipe 4, the high-pressure gas port 5, and the high-pressure gas pipes 6A and 6B, and the outside heat exchanger (A) 8A and the outside heat exchanger ( B) After being led to 8B and condensed, it is led to the high pressure liquid port 17 through the check valves 14A and 14B and the liquid side pipes 18A and 18B of the parallel circuits 13A and 13B. The high-pressure liquid refrigerant merged at the high-pressure liquid port 17 is adiabatically expanded through the liquid side pipe 18C, the on-off valve 16C and the expansion valve 15C in the parallel circuit 13C, and then led to the internal heat exchanger 8C, The air evaporates by cooling and circulates in the return cycle of the compressor 3 through the low-pressure on-off valve 10C, the low-pressure gas pipe 9C, the low-pressure gas port 11, and the suction pipe 12. As a result, the interior is cooled.

[Heat pump heating operation]
The heat pump heating operation is an operation performed by causing the inside heat exchanger 8C to function as a condenser, and the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B to function as an evaporator, respectively. In this case, the high pressure on / off valves 7A and 7B in the high pressure gas pipes 6A, 6B and 6C are closed, the high pressure on / off valve 7C is opened, the low pressure on / off valves 10A and 10B in the low pressure gas pipes 9A, 9B and 9C are opened, and the low pressure on / off The valve 10C is closed, the on-off valves 16A, 16B in the parallel circuits 13A, 13B, 13C of the liquid side pipes 18A, 18B, 18C are opened, and the on-off valve 16C is closed.

  As a result, the high-temperature and high-pressure refrigerant gas discharged from the compressor 4 is guided to the internal heat exchanger 8C through the discharge pipe 4, the high-pressure gas port 5, and the high-pressure gas pipe 6C, and radiates heat to warm the interior. Then, the liquid is condensed and then led to the high pressure liquid port 17 through the check valve 14C and the liquid side pipe 18C of the parallel circuit 13C. The high-pressure liquid refrigerant introduced into the high-pressure liquid port 17 is adiabatically expanded via the liquid side pipes 18A and 18B, the on-off valves 16A and 16B and the expansion valves 15A and 15B in the parallel circuits 13A and 13B, and then the outside heat It is led to the exchanger (A) 8A and the outside heat exchanger (B) 8B and absorbs heat from the outside air to be evaporated and gasified, and the low pressure on-off valves 10A and 10B, the low pressure gas pipes 9A and 9B, the low pressure gas port 11 and the suction pipe 12 and circulates in the return cycle of the compressor 3. As a result, the interior is heated.

  During this heat pump heating operation, if the outside air temperature is low, frost is formed on the surfaces of the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B functioning as an evaporator, and the capacity is reduced. . For this reason, it is necessary to defrost (defrost) when frost formation is detected. In this embodiment, in order to defrost the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B, the following configuration is adopted.

When frost formation on the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B is detected,
(1) The high pressure on-off valve 7C and the on-off valve 16C of the parallel circuit 13C are closed, the refrigerant flow to the internal heat exchanger 8C is stopped, and the heating operation is interrupted.
(2) Defrosting is sequentially performed by causing one of the two outside heat exchangers (A) 8A and the outside heat exchanger (B) 8B to function as a condenser and the other as an evaporator.

  That is, as shown in FIG. 2, for the two outside heat exchangers (A) 8A and the outside heat exchanger (B) 8B, first, the high pressure on-off valve 7A and the parallel circuit 13B in the high pressure gas pipe 6A are used. The on-off valve 16B in the inside and the low-pressure on-off valve 10B in the low-pressure gas pipe 9B are opened, the high-pressure on-off valve 7B in the high-pressure gas pipe 6B, the on-off valve 16A in the parallel circuit 13A, and the low-pressure on-off valve 10A in the low-pressure gas pipe 9A. The hot gas refrigerant discharged from the compressor 3 is introduced into the external heat exchanger (A) 8A to dissipate heat, and the frost in the external heat exchanger (A) 8A is melted.

  The refrigerant condensed and liquefied by being subjected to defrosting of the outside heat exchanger (A) 8A is adiabatically expanded by the expansion valve 15B in the parallel circuit 13B and introduced into the outside heat exchanger (B) 8B. After the heat is absorbed from the outside air and evaporated, the cycle of sucking into the compressor 3 through the low pressure gas pipe 9A, the low pressure gas port 11 and the suction pipe 12 is circulated. In this way, a refrigeration cycle is configured with one of the plurality of outside heat exchangers (A) 8A and outside heat exchanger (B) 8B disposed outside the refrigerator as a condenser and the other as an evaporator. The frosted outside heat exchanger (A) 8A can be defrosted. At this time, the outside fan 20A for the outside heat exchanger (A) 8A is stopped, and the outside fan 20B for the outside heat exchanger (B) 8B is operated.

  When the defrosting of the outside heat exchanger (A) 8A is completed, as shown in FIG. 3, the high-pressure on-off valve 7B in the high-pressure gas pipe 6B, the on-off valve 16A in the parallel circuit 13A, and the low-pressure gas pipe 9A Hot gas discharged from the compressor 3 is opened by opening the low-pressure on-off valve 10A, closing the high-pressure on-off valve 7A in the high-pressure gas pipe 6A, the on-off valve 16B in the parallel circuit 13B, and the low-pressure on-off valve 10B in the low-pressure gas pipe 9B. A refrigerant is introduced into the outside heat exchanger (B) 8B to dissipate heat, thereby defrosting the outside heat exchanger (B) 8B. In this case, the outside fan 20B for the outside heat exchanger (B) 8B serving as a condenser is stopped, and the outside fan 20A for the outside heat exchanger (A) 8A serving as an evaporator is operated. Become.

FIG. 4 shows a control flowchart during the above-described defrost operation.
When the control is started, in step S1, it is determined whether or not the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B satisfy the defrost start condition. If not satisfied, it is determined as NO and the process proceeds to the end. On the other hand, if it determines with YES, it will progress to step S2 and will be switched to the circuit (cycle) for defrosting the outside heat exchanger (A) 8A here. This switching is the switching of (2) above, and the on-off valve (solenoid valve) and the outside fan are opened / closed and stopped as described above.

  When the switching operation in step S2 is completed, the process proceeds to step S3, where the supply of refrigerant to the internal heat exchanger 8C is stopped. This is the control of (1) above, and the heating operation in the cabinet is stopped. When the supply stop process of the refrigerant is completed in step S3, the process proceeds to step S4, and it is determined whether or not the defrosting of the outside heat exchanger (A) 8A is completed. Whether or not the defrosting is completed may be determined by a known method such as detecting the temperature of the outside heat exchanger.

  When it is determined in step S4 that the defrosting of the outside heat exchanger (A) 8A has been completed, the process proceeds to step S5, and subsequently, in accordance with step S2 in order to defrost the outside heat exchanger (B) 8B. A switching operation of opening / closing and stopping the operation of each on-off valve (solenoid valve) and each outside fan is executed. Thus, when defrosting of the outside heat exchanger (B) 8B is started, the process proceeds to step S6, and it is determined whether or not the defrosting of the outside heat exchanger (B) 8B is finished. If it is determined in step S6 that the defrost end condition is satisfied, the process proceeds to step S7, and the internal temperature adjustment operation is resumed.

  As described above, in the present embodiment, in the heat pump type refrigerant circuit 2, the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B are arranged in parallel (two units). The inside heat exchanger (A) 8A and the outside heat exchanger (B) 8B function as an evaporator, and the inside heat exchanger 8C functions as a condenser, so that the inside of the warehouse is a heat pump. Heating operation is possible. Therefore, it is possible to perform a high-performance and efficient heating operation by the heat pump method.

  On the other hand, when the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B are frosted by the heat pump heating operation under a low outside air temperature, supply of the refrigerant to the inside heat exchanger 8C In a state where the heating operation is interrupted and the defrost cycle is configured with one of the multiple outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B as a condenser and the other as an evaporator. However, it is possible to defrost alternately and sequentially while absorbing heat from the outside air with one of the outside heat exchanger (A) 8A or the outside heat exchanger (B) 8B.

Therefore, defrosting of the plurality of outside heat exchangers (A) 8A and outside heat exchangers (B) 8B is performed using the full capacity of the heat pump (all refrigerants) without absorbing heat from the inside air. The defrosting operation time can be shortened, and the change in the internal temperature during the defrosting operation can be reduced.
In addition, when defrosting the two outside heat exchangers (A) 8A and the outside heat exchanger (B) 8B, which of the outside heat exchangers is to be defrosted first may be arbitrarily determined, By defrosting a plurality of storage-side heat exchangers 8A and 8B alternately in sequence, each storage-side heat exchanger 8A and 8B can be defrosted using the full capacity of the heat pump (all refrigerants) and defrosted in a short time. Can do.

  Moreover, in this embodiment, it is set as the structure which provided independently the ventilation system containing the outer side fans 20A and 20B with respect to the multiple unit outer side heat exchangers 8A and 8B. For this reason, at the time of defrost operation, the outside fan 20A or 20B for the outside heat exchanger 8A or 8B that functions as a condenser is stopped, and the outside for the outside heat exchanger 8A or 8B that functions as an evaporator. The fan 20A or 20B can be operated and defrosted. Therefore, the amount of heat absorbed by the outside heat exchanger 8A or 8B functioning as an evaporator is increased, and the heat is released by the outside heat exchanger 8A or 8B that defrosts the heat efficiently and in a short time. can do.

In addition, it can be set as the following structures by having arrange | positioned multiple units | sets (2 units | sets) in parallel with the outside heat exchanger (A) 8A and the outside heat exchanger (B) 8B.
[Modification 1]
During the cooling operation, the two outside heat exchangers (A) 8A and the outside heat exchanger (B) 8B are operated as condensers. However, when the outside air temperature is low, the condensation capacity becomes excessive. High pressure may drop too much. For this reason, when the high pressure is monitored and the high pressure falls too much, either the outside heat exchanger (A) 8A or the outside heat exchanger (B) 8B is stopped (see FIG. 5). In this case, the outside heat exchanger (B) 8B may be stopped), and the condensation capacity may be adjusted by reducing the number of operating units.

  That is, when the cooling operation is performed under a condition where the outside air temperature is relatively low, when all of the plurality of outside heat exchangers 8A and 8B are operated, the heat exchange amount of the inside heat exchanger 8C is The condensation pressure becomes excessive, the pressure in the high-pressure side circuit decreases, the differential pressure between the high and low pressures becomes too small, and deviates from the flow rate adjustable range of the expansion valve 15C. It may become.

  In this case, as shown in FIG. 5, the high-pressure on-off valve 7B in the high-pressure gas pipe 6B connected to the outside heat exchanger (B) 8B is closed, the low-pressure on-off valve 10B is opened, and the outside fan 20B is stopped and the outside heat exchanger (B) 8B is stopped, and the condensation capacity is adjusted (decreased) by reducing the number of operating outside heat exchangers 8A and 8B, thereby reducing the pressure difference between high and low pressures. It can be maintained within an appropriate range. Therefore, the transport refrigeration unit 1 is stably operated by appropriately adjusting the capacity of the outside heat exchangers 8A and 8B in accordance with the amount of heat exchange in the inside heat exchanger 8C and maintaining the operation balance. can do.

  Moreover, when employ | adopting the said modification 1, the multiple unit outside heat exchangers 8A and 8B can be made into the heat exchanger of a respectively different capability. By configuring the outside heat exchangers 8A and 8B using heat exchangers having different capacities as described above, the condensation capacity of the two outside heat exchangers 8A and 8B can be determined by selecting the operation of the heat exchanger. , It is possible to adjust to three stages more than the number. For this reason, under various outdoor air temperatures and internal set temperature conditions, the condensing capacity can be finely adjusted accordingly, and a more stable operation can be performed while keeping the high-low pressure difference within an appropriate range. Reliability can be improved.

[Modification 2]
In the above embodiment, during the defrost operation of the outside heat exchangers 8A and 8B, as shown in FIGS. 2 and 3, the refrigerant flow to the inside heat exchanger 8C is stopped. When the difference between the temperature and the set temperature exceeds the specified value, from the viewpoint of protecting the cargo, the high-pressure on-off valve 7C in the high-pressure gas pipe 6C connected to the internal heat exchanger 8C is opened, and the internal heat exchange is performed. It is good also as a structure which distribute | circulates a high pressure gas refrigerant | coolant to the container 8C, and performs a heating operation.

  That is, if a situation occurs in which the internal temperature suddenly changes for some reason during the defrost operation and the difference from the set temperature exceeds a specified value, the quality of the load may not be guaranteed. For this reason, when the difference between the internal temperature and the set temperature exceeds a specified value, the high pressure on-off valve 7C in the high pressure gas pipe 6C connected to the internal heat exchanger 8C is opened, and the internal heat exchange is performed. By supplying a part of the high-pressure gas refrigerant to the vessel 8C, the heating operation can be performed while continuing the defrost operation. Accordingly, the internal temperature does not drop below the specified value during the defrost operation, the temperature controllability can be maintained even during the defrost, and the quality of the cargo can be ensured, and the reliability of the transport refrigeration unit 1 can be improved. .

[Modification 3]
In the above-described embodiment and modification, the embodiment has been described in which two outside heat exchangers 8A and 8B and one inside heat exchanger 8C are arranged in parallel. The outer heat exchangers 8A and 8B are not limited to two, and three or more outside heat exchangers may be arranged in parallel. Moreover, about the warehouse inner side heat exchanger 8C, it is good also as a structure which arrange | positioned multiple units | sets in parallel and arrange | positioned each warehouse inner side heat exchanger separately to the some chamber divided in the cold storage. In this case, it is possible not only to cool or warm a plurality of partitioned rooms at the same time, but also to perform simultaneous cooling and heating operations such as cooling one room and heating another room. .

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
The present embodiment is different from the first embodiment described above in that the frequency of starting and stopping of the compressor 3 can be reduced by using a plurality of outside heat exchangers 8A and 8B. Since other points are the same as those in the first embodiment, description thereof will be omitted.
In the present embodiment, the transport refrigeration unit 1 is thermo-on / off after the inside temperature reaches the set temperature by the cooling operation or the heating operation. It is intended to suppress outages.

  When the internal temperature reaches the set temperature, the transport refrigeration unit 1 is turned on / off (thermo on / off) with a predetermined differential. When the thermo-on time is short, the compressor 3 is turned on. Repeated start and stop frequently, which causes failure and reduced life, impairing reliability. Therefore, when the thermo-off condition is established, a plurality of storage-side heat exchangers 8A arranged in parallel with the refrigerant flowing to the storage-side heat exchanger 8C stopped and the cooling operation or heating operation stopped. , 8B is used to constitute a refrigeration cycle, and the compressor 3 is continuously operated for a specified time and then stopped to prevent frequent start and stop.

Below, the specific structure is demonstrated based on the control flowchart figure shown in FIG.
When the control is started, it is determined in step S11 whether or not the thermo-off condition is satisfied. If NO, the control is immediately terminated, and if YES, the process proceeds to step S12. In step S12, it is determined whether or not the ON time (operation time) of the compressor 3 exceeds a preset specified time. If YES, the process proceeds to step S17 and the compressor 3 is operated as it is. Stop and turn off the thermo.

  On the other hand, if the prescribed time has not been reached and it is determined as NO, the process proceeds to step S13 to switch to the following operation circuit (idle operation circuit), and the compressor 3 is continuously operated. The operation circuit here is one of a plurality (two) of the outside heat exchangers 8A and 8B, for example, the outside heat exchanger (A) 8A is a condenser, and the other outside heat exchanger (B ) Opening the high-pressure on-off valve 7A, the on-off valve 16B, and the low-pressure on-off valve 10B, and opening and closing the high-pressure on-off valve 7B in order to form a refrigeration cycle in which 8B is an evaporator and both the outside fans 20A, 20B are operated. The valve 16A and the low pressure on-off valve 10A are closed, and the outside fans 20A and 20B are switched on, the refrigerant from the compressor 3 is supplied to the high pressure gas port 5, the outside heat exchanger (A) 8A, the high pressure liquid port 17, A circuit that circulates in the order of the expansion valve 16B, the outside heat exchanger (B) 8B, and the low-pressure gas port 11 is configured. Note that the outside heat exchangers 8A and 8B may be switched so that their functions are reversed.

  After the switching in step S13, the process proceeds to step S14, the high pressure on-off valve 7C, the on-off valve 16C, and the low-pressure on-off valve 10C are closed, the refrigerant flow to the internal heat exchanger 8C is stopped, and the thermo-off state is established. To do. At this time, the compressor 3 constitutes the refrigeration cycle and is continuously operated. In this state, the process proceeds to step S15, where it is determined whether or not the condition for returning to thermo-on is satisfied. If it is determined YES, the process proceeds to step S18, and the refrigerant supply start process to the internal heat exchanger 8C is performed. Then, the process proceeds to step S19.

  In step S19, the high pressure on / off valves 7A to 7C, the on / off valves 16A to 16C, and the low pressure on / off valves 10A to 10C are switched, and the refrigerant circuit 2 is switched to the original cooling operation or heating operation cycle, that is, the internal heat exchanger 8C. Cooling operation cycle using evaporator and outside heat exchangers 8A and 8B as condensers, or heat pump heating operation cycle using inside heat exchanger 8C as condenser and outside heat exchangers 8A and 8B as evaporator Perform switching and thermo-on operation. Thereafter, the same operation is repeated.

  When it is determined in step S15 that the thermo-on return condition is not satisfied, the process proceeds to step S16, where it is determined whether or not the ON time (operating time) of the compressor 3 exceeds the specified time. Returning to step S15, the operations of steps S15 and S16 are repeated. If it is determined in step S16 that the operation time of the compressor 3 exceeds the specified time (YES), the process proceeds to step S17, where the compressor 3 is turned off and the operation is stopped. Repeat the same operation.

  Thus, even if the thermo-off state is established under the thermo-on / off operation, the refrigeration cycle is configured by using the plurality of outside heat exchangers 8A and 8B, and the refrigeration unit 1 is operated idly, thereby the compressor 3 can always be operated for a specified time or more, and the compressor 3 can be prevented from frequently starting and stopping. Therefore, the start / stop frequency of the compressor 3 can be suppressed and its reliability can be ensured. In particular, in the case of a cold storage compartment that is divided into multiple chambers, thermo-ON / OFF may be repeated in a short time due to temperature interference between the chambers. By continuing the operation until the time is exceeded, frequent start / stop of the compressor can be prevented.

  In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, in the above-described embodiment, an example in which the compressor 3 is applied to the integrated transportation refrigeration unit 1 using an electric compressor has been described. However, the present invention is not limited thereto, and the present invention is not limited to an open compressor. Needless to say, the present invention can also be applied to a direct-coupled transport refrigeration unit driven by a traveling engine via an electromagnetic clutch or a sub-engine type transport refrigeration unit having a dedicated sub-engine for driving the refrigeration unit. .

  Moreover, not only the integrated transport refrigeration unit 1, but also the separation transport refrigeration unit of the type in which the internal unit installed inside the storage and the external unit installed outside the storage are separated are similarly applied. Of course you can.

DESCRIPTION OF SYMBOLS 1 Refrigeration unit for transport 2 Refrigerant circuit 3 Compressor 6A, 6B, 6C High pressure gas piping 7A, 7B, 7C High pressure on-off valve 8A, 8B Outside heat exchanger (A), (B) (heat exchanger)
8C Inside heat exchanger (heat exchanger)
9A, 9B, 9C Low pressure gas piping 10A, 10B, 10C Low pressure on-off valve 13A, 13B, 13C Parallel circuit 14A, 14B, 14C Check valve 15A, 15B, 15C Expansion valve 16A, 16B, 16C On-off valve 18A, 18B, 18C Liquid side piping 19 Inside fan 20A, 20B Outside fan

Claims (7)

A compressor,
A plurality of heat exchangers, one end of which is connected to the discharge side of the compressor via a high-pressure gas pipe and a high-pressure on-off valve,
Low-pressure gas pipes each connecting one end side of the plurality of heat exchangers to the suction side of the compressor via a low-pressure on-off valve;
A liquid side pipe that connects the other end sides of the parallel circuit of the decompression means with check valve function and the check valve respectively connected to the other end side of the plurality of heat exchangers,
At least two heat exchangers among the plurality of heat exchangers are arranged in parallel outside the cold storage as external storage heat exchangers, and at least one heat exchanger is a cold storage as internal storage heat exchangers. In the inside,
During heat pump heating operation in which the outside heat exchanger functions as an evaporator and the inside heat exchanger functions as a condenser, when the outside heat exchanger is frosted, the refrigerant with respect to the inside heat exchanger A transport refrigeration unit characterized in that the circulation is stopped and at least one of the plurality of outside heat exchangers is configured as a condenser and the other one as an evaporator.   A configuration in which at least one of the plurality of frosted outside heat exchangers is sequentially switched as a condenser and the other one as an evaporator, and the plurality of outside heat exchangers are sequentially defrosted. The transport refrigeration unit according to claim 1, wherein   The transport refrigeration unit according to claim 1 or 2, wherein an air blowing system including an outside fan for the plurality of outside heat exchangers is provided independently.   During the defrost operation, when the difference between the internal temperature and the set temperature becomes a specified value or more, the high-pressure on-off valve in the high-pressure gas pipe connected to the internal heat exchanger is opened and the internal heat The transport refrigeration unit according to any one of claims 1 to 3, wherein a high-pressure gas refrigerant is circulated through the exchanger and a heating operation is performed.   During cooling operation with the outside heat exchanger functioning as a condenser, if the condensation capacity is excessive and the high pressure is too low, the condensation capacity can be reduced by reducing the number of operating multiple outside heat exchangers. The transport refrigeration unit according to any one of claims 1 to 4, wherein the refrigeration unit for transport according to any one of claims 1 to 4 is configured.   The transport refrigeration unit according to any one of claims 1 to 5, wherein the plurality of the outside heat exchangers are heat exchangers having different capacities. A compressor,
A plurality of heat exchangers, one end of which is connected to the discharge side of the compressor via a high-pressure gas pipe and a high-pressure on-off valve,
Low-pressure gas pipes each connecting one end side of the plurality of heat exchangers to the suction side of the compressor via a low-pressure on-off valve;
A liquid side pipe that connects the other end sides of the parallel circuit of the decompression means with check valve function and the check valve respectively connected to the other end side of the plurality of heat exchangers,
At least two heat exchangers among the plurality of heat exchangers are arranged in parallel outside the cold storage as external storage heat exchangers, and at least one heat exchanger is a cold storage as internal storage heat exchangers. In the inside,
At the time of thermo-off after the internal temperature reaches the set temperature, when the operation time of the compressor is not more than a specified time, the refrigerant flow to the internal heat exchanger is stopped, and a plurality of the external heat exchangers A transport refrigeration unit characterized in that one compressor serves as a condenser and the other serves as an evaporator, and the compressor is continuously operated until the operating time exceeds the specified time.

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