WO2016088379A1

WO2016088379A1 - Refrigeration device

Info

Publication number: WO2016088379A1
Application number: PCT/JP2015/006008
Authority: WO
Inventors: 秀徳松井; 滋人田中
Original assignee: ダイキン工業株式会社
Priority date: 2014-12-05
Filing date: 2015-12-03
Publication date: 2016-06-09
Also published as: JP2016109419A; JP6149921B2

Abstract

A refrigeration device (10) wherein: a defrosting operation control unit (106) is provided, said defrosting operation control unit beginning a defrosting operation when it is determined that the temperature difference (SS-EOS) between the discharge temperature (SS) or the suction temperature (RS) of air and the outlet temperature (EOS) of a coolant in an evaporator (33) is equal to or greater than a prescribed threshold value; frosting of the evaporator (33) can be detected quickly; and thus, the defrosting operation can be completed quickly.

Description

Refrigeration equipment

The present invention relates to a container refrigeration apparatus for cooling the inside of a container used for marine transportation or the like, a cooling apparatus for cooling the inside of a refrigerator or a freezer, and a refrigeration apparatus such as an air conditioner capable of heating a room. In particular, the present invention relates to a technique for shortening the time required for detecting the frost formation of the evaporator and quickly ending the defrost operation.

Conventionally, for example, containers used for marine transportation or the like are generally configured by attaching a container refrigeration apparatus to a container body (see, for example, Patent Document 1). The container refrigeration apparatus includes a refrigerant circuit configured by sequentially connecting a compressor, a condenser, an expansion mechanism, and an evaporator, and the operation of a refrigeration cycle performed by circulating the refrigerant through the refrigerant circuit. Cool the container.

The refrigeration apparatus of Patent Document 1 has a controller including pull-down operation means and defrost operation means. And a controller is comprised so that a defrost operation may be performed for every fixed time with a timer during a pull-down operation.

JP 09-096475 A

However, in the above configuration, even if the cooling capacity is reduced due to frost formation on the evaporator, and the interior cannot be cooled to the set temperature, defrosting is performed only with a timer. There was a case where the time when defrosting was not performed even though frosting occurred. In such a case, the pull-down operation has been performed for a long time in a frosting state in which the inside of the refrigerator is difficult to cool. Thus, in the conventional technology, the time required for frost detection and defrost operation may be longer than necessary.

Conventionally, when pulling down the refrigeration operation (operation where the suction temperature is -20 ° C or lower) or the like, if the detected value of the suction temperature sensor does not drop more than 0.2 ° C in one hour, the evaporator forms frost. However, in this case, it takes a long time to detect frost and to defrost in order to perform control to prevent erroneous detection.

In addition, the problem that the time required for defrosting from detection of frost formation is not limited to the pull-down operation, but may occur in the normal cooling operation as well. In addition, the problem that the time required for frost detection and defrosting becomes longer is not limited to the container refrigeration apparatus, but also in the cooling apparatus that cools the inside of a refrigerator or a freezer or the air conditioning apparatus that can heat a room. May occur.

The present invention has been made in view of such problems, and an object of the present invention is to provide an evaporator in a refrigeration apparatus such as a container refrigeration apparatus, a refrigerator such as a refrigerator, and a refrigeration apparatus such as an air conditioner. It is possible to quickly detect the frost formation of the water, prevent the start of the defrost operation from being delayed unnecessarily, and end the defrost operation quickly.

In the first aspect of the present disclosure, a temperature control target chamber (1a), a compressor (30), a condenser (31), an expansion mechanism (32), and an evaporator (33) are connected in order to perform a refrigeration cycle operation. And a refrigeration apparatus including a refrigerant circuit (20) for controlling the temperature of the inside of the temperature control target chamber (1a) and a control device (100) for controlling the refrigerant circuit (20).

In the refrigeration apparatus, the control device (100) includes a defrosting operation control unit (106) for controlling the defrosting operation, and the air blowing temperature or the suction temperature and the refrigerant outlet temperature in the evaporator (33) are controlled. When it is determined that the temperature difference is equal to or greater than a predetermined threshold value, it is detected that the evaporator (33) has formed frost, and the defrost operation control for starting the defrost operation is performed by the defrost operation control unit (106). It is said.

In the first aspect, the temperature difference between the air blowing temperature or the suction temperature and the refrigerant outlet temperature in the evaporator (33) is a predetermined threshold (for example, the outlet temperature of the evaporator (33) and the refrigerant outlet temperature). The temperature difference threshold of 5 ° C. and the temperature difference threshold between the suction temperature of the evaporator (33) and the outlet temperature of the refrigerant is 10 ° C.) or more. Detected frost formation. This is because the heat transfer rate is reduced due to frost formation on the evaporator (33), the refrigerant does not evaporate to the outlet of the evaporator (33), and the outlet temperature of the refrigerant is lowered. It is possible. And it becomes possible to detect rapidly that the evaporator (33) frosted by doing in this way.

According to a second aspect of the present disclosure, in the first aspect, the control device (100) includes a pull-down operation control unit (105) that performs a pull-down operation for rapidly cooling the temperature control target chamber (1a). The defrost operation control is performed during operation.

In the second aspect, when the defrost operation is performed during the pull-down operation in the container refrigeration apparatus and the refrigerator or refrigerator cooling apparatus, it is possible to quickly detect that the evaporator (33) is frosted. Become.

According to a third aspect of the present disclosure, in the first or second aspect, the control device (100) is configured according to the air volume of the evaporator fan (36) disposed in the vicinity of the evaporator (33). The threshold value is changed, and the threshold value is increased when the air volume becomes larger than the current value.

In the third aspect, the threshold value is changed according to the air volume of the evaporator fan (36), frost formation is detected based on the threshold value, and defrosting operation is controlled.

According to a fourth aspect of the present disclosure, in any one of the first to third aspects, when the control device (100) detects frost formation within a predetermined time after performing the defrost operation, thereafter, The defrosting operation is prohibited until the power is turned off.

In the fourth aspect, when defrosting is detected again within a predetermined time after the defrosting is completed, the control is performed such that the defrosting is not performed. This is because the possibility of false detection is high, such as the evaporator (33) being dirty.

According to the first aspect of the present disclosure, when it is determined that the temperature difference between the air blowing temperature or the suction temperature and the refrigerant outlet temperature in the evaporator (33) is equal to or greater than a predetermined threshold, the evaporator (33 The defrost operation control for starting the defrost operation is performed by the defrost operation control unit (106). In this way, defrosting operation is not performed based on the set time of the timer, but by using the above temperature difference, frost formation can be detected quickly and defrost operation can be started. The operation time in the lowered state can be minimized. That is, the defrosting operation can be completed quickly.

In particular, the temperature difference between the air blowing temperature or the suction temperature and the refrigerant outlet temperature in the evaporator (33) is not affected by factors such as intrusion heat, cargo heat capacity, and cooling capacity, which are short. Highly effective in detecting frost formation over time.

Furthermore, since defrosting can be started earlier than before, defrosting can be started with a small amount of frost formation. As a result, the defrosting operation time itself can be shortened, so that the time required for defrosting can be shortened more reliably, and the defrosting completion temperature can be lowered, so that the cooling operation can be resumed smoothly.

According to the second aspect of the present disclosure, when the defrost operation is performed during the pull-down operation in the container refrigeration apparatus and the refrigerator or refrigerator cooling apparatus, it is quickly detected that the evaporator (33) has formed frost. Therefore, the defrosting operation can be completed quickly during pull-down, and the pull-down time can be shortened.

According to the third aspect of the present disclosure, for example, when the air volume of the evaporator fan (36) is larger than the current value, the temperature difference between the air blowing temperature and the refrigerant outlet temperature in the evaporator (33) increases. On the other hand, by setting a threshold value corresponding to the air volume, frost detection can be quickly performed even when the air volume changes, and the defrosting operation can be completed quickly.

According to the fourth aspect of the present disclosure, when frost formation is detected again within a predetermined time after the defrosting is completed, there is a high possibility of erroneous detection. This can prevent useless defrost operation.

FIG. 1 is a longitudinal sectional view of a state in which a container refrigeration apparatus according to an embodiment of the present invention is mounted on a container body. FIG. 2 is a schematic perspective view of the container refrigeration apparatus of FIG. 1 viewed from the outside. FIG. 3 is a refrigerant circuit diagram of the container refrigeration apparatus of FIG. FIG. 4A is a graph showing the operations of the pull-down operation and the defrost operation of the present embodiment, and FIG. 4B is a graph showing the operations of the pull-down operation and the defrost operation of the comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. This embodiment relates to a container refrigeration apparatus.

As shown in FIGS. 1 and 2, the container refrigeration apparatus (10) of the present embodiment cools (temperature control) the inside of a container used for marine transportation or the like. The container refrigeration apparatus (10) includes a refrigerant circuit having a compressor (30), a condenser (31), and an evaporator (33). Moreover, the container refrigeration apparatus (10) also serves as a lid that closes the side opening surface of the container main body (temperature control target chamber) (1a).

The casing (13) of the container refrigeration apparatus (10) includes a casing body (11) and a casing (13) that partition the outside of the container outside the container and the inside of the container (inside the temperature control target chamber). ) And a partition plate (14) provided on the back (inside of the cabinet).

The casing body (11) is formed in a double structure of an aluminum inner casing (11a) and an FRP outer casing (11b). And the heat insulation layer (11c) which consists of a foaming agent is formed between the said inner casing (11a) and the outer casing (11b).

Furthermore, a bulging portion (12) bulging to the inside of the cabinet is formed at the lower part of the casing body (11). And while the inside of the said bulging part (12) is comprised by the storage space outside a store | warehouse | chamber (S1), the upper part of the back surface of the said casing (13) has the inside located in the upper part of the bulging part (12) A storage space (S2) is formed.

In the external storage space (S1), the compressor (30), the condenser (31), and the external fan (35) are stored, and the electrical component box (15) is stored. An evaporator (33) and an internal fan (evaporator fan) (36) are attached to the space (S2). Moreover, it is comprised between the said bulging part (12) and a partition plate (14) by the air path (S3) through which internal air flows. The upper end of the air passage (S3) communicates with the internal storage space (S2), while the lower end communicates with the interior.

As shown in FIG. 3, the container refrigeration apparatus (10) includes a refrigerant circuit (20) that performs a cooling cycle by circulating the refrigerant. The refrigerant circuit (20) includes a main circuit (21), a hot gas bypass circuit (22), a reheat circuit (80), and a supercooling circuit (23).

The main circuit (21) is configured by connecting a compressor (30), a condenser (31), a main expansion valve (32), and an evaporator (33) in series by a refrigerant pipe in order. Perform cycle operation.

The compressor (30) has a motor (not shown) that drives the compression mechanism. The rotation speed of the motor of the compressor (30) is controlled in multiple stages by an inverter. In other words, the compressor (30) is a variable capacity compressor that is configured to have a variable operating rotational speed. The inverter circuit board connected to the compressor (30) is housed in the electrical component box (15).

The condenser (31) and the evaporator (33) are both fin-and-tube heat exchangers. The condenser (31) is arranged outside the warehouse as described above. In the condenser (31), heat is exchanged between the outside air and the refrigerant. The evaporator (33) is arranged in the cabinet as described above. In the evaporator (33), the air in the warehouse and the refrigerant exchange heat. Further, a drain pan (37) (not shown in FIG. 1) is provided below the evaporator (33). The drain pan (37) is formed in a flat container shape whose upper side is open. Inside the drain pan (37), frost and ice blocks that have fallen off from the evaporator (33), condensed water condensed from the air, and the like are collected.

The main expansion valve (32) is configured such that the opening degree can be adjusted in multiple stages by a pulse motor. The condenser (31) is provided with an external fan (35), while the evaporator (33) is provided with an internal fan (36). The internal fan (36) is configured to supply the cooling air cooled by the evaporator (33) into the internal space. The external fan (35) and the internal fan (36) are provided with an external fan motor (35a) and an internal fan motor (36a), respectively.

The high pressure gas pipe (24) between the compressor (30) and the condenser (31) is provided with a fourth open / close valve (38) and a check valve (CV) in this order. The fourth on-off valve (38) is configured such that the opening degree can be adjusted in multiple stages by a pulse motor. The check valve (CV) allows the refrigerant to flow in the direction of the arrow shown in FIG. 3 and prohibits the reverse flow.

The high pressure liquid pipe (25) between the condenser (31) and the main expansion valve (32) includes a receiver (41), a second on-off valve (49), a dryer (43), and a supercooling heat exchanger ( 44) and so on. The receiver (41) is provided on the downstream side of the condenser (31), and is configured to allow the refrigerant that has flowed through the condenser (31) to flow into the saturated liquid and the saturated gas. The second on-off valve (49) is an openable / closable solenoid valve. The dryer (43) is configured to capture moisture in the liquid refrigerant that has flowed through the condenser (31). A liquid seal prevention pipe (90) connected to the downstream side of the main expansion valve (32) is connected to the upstream side of the condenser (31). The liquid seal prevention pipe (90) is provided with a liquid seal on-off valve (91).

The supercooling heat exchanger (44) cools the liquid refrigerant that has flowed through the condenser (31). The supercooling heat exchanger (44) has a primary side passage (45) and a secondary side passage (46). That is, in the supercooling heat exchanger (44), the refrigerant flowing through the primary side passage (45) and the refrigerant flowing through the secondary side passage exchange heat. The primary side passage (45) is connected to the high-pressure liquid pipe (25) of the main circuit (21), and the secondary side passage (46) is connected to the supercooling branch pipe (26) of the supercooling circuit (23). Has been. The inflow end of the supercooling branch pipe (26) is connected between the receiver (41) and the second on-off valve (49) in the high-pressure liquid pipe (25). The outflow end of the supercooling branch pipe (26) is connected to a compression chamber (intermediate compression chamber) in the middle of compression (intermediate pressure state) of the compressor (30). That is, the subcooling branch pipe (26) is a passage through which a part of the liquid refrigerant in the high-pressure liquid pipe (25) is divided and flows into the intermediate compression chamber of the compressor (30). A first on-off valve (47) and a supercooling expansion valve (48) are provided on the inflow side of the secondary passage (46) in the supercooling branch pipe (26). The first on-off valve (47) is an openable / closable solenoid valve. The supercooling expansion valve (48) can be adjusted in multiple stages by a pulse motor, and constitutes a decompression mechanism for decompressing the refrigerant.

The hot gas bypass circuit (22) has one main passage (50) and two branch passages (51, 52) branched from the main passage (50). The two branch passages (51, 52) are referred to as a first branch passage (51) and a second branch passage (52). The inflow end of the main passage (50) is connected between the fourth on-off valve (38) in the high-pressure gas pipe (24) and the discharge side of the compressor (30). A third on-off valve (53) is provided in the main passage (50). The third on-off valve (53) is an openable / closable solenoid valve.

The first branch passage (51) has one end connected to the outflow end of the main passage (50) and the other end connected to the low-pressure liquid pipe (27) between the main expansion valve (32) and the evaporator (33). It is connected. Similarly, the second branch passage (52) has one end connected to the outflow end of the main passage (50) and the other end connected to the low-pressure liquid pipe (27). The second branch passage (52) is composed of a refrigerant pipe that is longer than the first branch passage (51). The second branch passage (52) has a drain pan heater (54) arranged meandering along the bottom of the drain pan (37). The drain pan heater (54) is configured to heat the inside of the drain pan (37) with a refrigerant. As described above, the hot gas bypass circuit (22) supplies the refrigerant compressed by the compressor (30) (the high-temperature gas refrigerant discharged from the compressor (30)) to the evaporator (33). A bypass circuit is configured.

The reheat circuit (80) has a reheat passage (82). The inflow end of the reheat passage (82) is connected between the fourth on-off valve (38) in the high-pressure gas pipe (24) and the discharge side of the compressor (30). The reheat passage (82) is provided with a fifth on-off valve (81). The fifth on-off valve (81) is an openable / closable solenoid valve. The reheat passage (82) has a reheat heat exchanger (83) and a capillary tube. In the dehumidifying operation, the reheat heat exchanger (83) exchanges heat between the discharged refrigerant that has flowed in and the air that has been cooled and dehumidified by the evaporator (33), and heats the air. . The reheat heat exchanger (83) is a fin-and-tube heat exchanger. The capillary tube decompresses the refrigerant that has flowed out of the reheat heat exchanger (83). As described above, the reheat circuit (80) supplies a part of the refrigerant (high-temperature gas refrigerant discharged from the compressor (30)) compressed by the compressor (30) to the reheat heat exchanger (83). The circuit for doing is comprised.

The refrigerant circuit (20) is also provided with various sensors. Specifically, the high pressure gas pipe (24) is provided with a high pressure sensor (60), a high pressure switch (61), and a discharge temperature sensor (62). The high pressure sensor (60) detects the pressure of the high pressure gas refrigerant discharged from the compressor (30). The discharge temperature sensor (62) detects the temperature of the high-pressure gas refrigerant discharged from the compressor (30). The low pressure gas pipe (28) between the evaporator (33) and the compressor (30) is provided with a low pressure sensor (63) and a suction temperature sensor (64). The low pressure sensor (63) detects the pressure of the low pressure gas refrigerant sucked into the compressor (30). The suction temperature sensor (64) detects the temperature of the low-pressure gas refrigerant sucked into the compressor (30).

The subcooling branch pipe (26) is provided with an inflow temperature sensor (65) on the inflow side of the secondary side passage (46) and an outflow temperature sensor (66) on the outflow side of the secondary side passage (46). It has been. The inflow temperature sensor (65) detects the temperature of the refrigerant immediately before flowing into the secondary side passage (46). The outflow temperature sensor (66) detects the temperature of the refrigerant immediately after flowing out of the secondary side passage (46).

The low-pressure liquid pipe (27) is provided with an inflow temperature sensor (67) on the inflow side of the evaporator (33). This inflow temperature sensor (67) detects the temperature (EIS) of the refrigerant immediately before flowing into the evaporator (33). The low pressure gas pipe (28) is provided with an outflow temperature sensor (68) on the outflow side of the evaporator (33). This outflow temperature sensor (68) detects the temperature (EOS) of the refrigerant immediately after flowing out of the evaporator (33).

Outside the container, an outside air temperature sensor (69) is provided on the suction side of the condenser (31). The outside air temperature sensor (69) detects the temperature of the outside air just before being sucked into the condenser (31) (that is, the temperature of the outside air). Inside the container, a suction temperature sensor (70) is provided on the suction side of the evaporator (33), and an outlet temperature sensor (71) is provided on the outlet side of the evaporator (33). The suction temperature sensor (70) detects the temperature (RS) of the internal air immediately before passing through the evaporator (33). The blowing temperature sensor (71) detects the temperature of the internal air immediately after passing through the evaporator (33) (blowing air temperature (SS)).

The container refrigeration apparatus (10) is provided with a controller (100) as a control unit for controlling the refrigerant circuit (20). The controller (100) includes a compressor control unit (101) for controlling the frequency N of the inverter that drives the compressor (30), and a compressor (100) according to the operating state of the internal fan (36). 30), a rotation speed control unit (102) for controlling the operation rotation speed N, a valve control unit (103) for controlling various valves (32, 38, 47 to 49, 53, 81), and each fan ( 35, 36) and a fan control unit (104) is provided. The controller (100) also includes a pull-down operation control unit (105) that performs pull-down operation for rapidly cooling the inside of the container, and defrosting when it detects that the evaporator (33) is frosted during the pull-down operation. A defrost operation control unit (106) that performs operation is provided.

The compressor control unit (101) is for controlling the operation speed (inverter operation frequency) (N) of the compressor (30) in the cooling operation. The compressor control unit (101) controls the operation speed (N) of the compressor (30) so that the blown air temperature (SS) becomes the target temperature (SP) of the blown air. In the present embodiment, the target temperature (SP) is appropriately set between −30 ° C. and + 30 ° C.

Specifically, if the temperature of the blown-out air blown into the container warehouse (the blown air temperature (SS)) is lower than the target temperature (SP), the operation speed N of the compressor (30) is lowered while the blown air If the temperature (SS) is higher than the target temperature (SP), control for increasing the operation speed (N) of the compressor (30) is performed.

When the fan control unit (104) switches the rotation of the internal fan (36) from the high state to the low state, the rotation number control unit (102) sets the operation rotation number (N) of the compressor (30) to a predetermined value. It is adjusted by lowering by A. Specifically, when the cooling load in the container store decreases, the fan control unit (104) switches the rotation of the store fan (36) from the high state to the low state. If it carries out like this, since the cooling capacity of the container refrigeration apparatus (10) will become excess, a rotation speed control part (102) will reduce the driving | running rotation speed (N) of a compressor (30) by the predetermined value A. As a result, the flow rate of the refrigerant circulating in the refrigerant circuit (20) is reduced by the operating speed (NA) of the compressor (30), and the cooling capacity of the container refrigeration apparatus (10) is reduced. For this reason, the cooling capacity of the container refrigeration apparatus (10) and the cooling load in the container warehouse are balanced.

The controller (100) detects the detection value of the outlet temperature sensor (71) and the detection of the outflow temperature sensor (68) during the pull-down operation performed by the pull-down operation control unit (105) with higher cooling capacity than during normal operation. The temperature difference (SS−EOS) between the air blowing temperature (SS) and the refrigerant outlet temperature (EOS) in the evaporator (33) is a predetermined threshold value (a specific value in this embodiment is 5 ° C.). ) If it is determined that it is above, it is determined that the evaporator (33) is frosted. The reason for this is that when the evaporator (33) is not frosted, the air and the refrigerant efficiently exchange heat, so the temperature difference between the air and the refrigerant is small. When frost is formed, the heat transfer rate decreases, so the air temperature does not drop much even when the evaporation temperature is low, and the temperature difference between the air blowing temperature (SS) and the refrigerant outlet temperature (EOS) is large. It is to become. And when this temperature difference becomes more than said threshold value, the said defrost operation control part (106) performs control which starts a defrost operation.

The controller (100) changes the threshold value according to the air volume of the internal fan (36) disposed in the vicinity of the evaporator (33), and increases the threshold value when the air volume exceeds the current value. Take control. This is because when the air volume is larger than the current value, the temperature difference (SS-EOS) between the outlet temperature (SS) of the evaporator (33) and the outlet temperature (EOS) of the refrigerant increases. The threshold value is increased in order to perform appropriate defrost detection while the temperature difference (SS-EOS) increases.

Further, when the controller (100) detects frost formation within a predetermined time after the defrost operation, the defrost operation control unit (106) controls the defrost operation until the power is turned off thereafter. Do. This is because if frost formation is detected again within a predetermined time (for example, 1 hour) after the defrost operation has been completed normally, frost formation is detected when the evaporator is dirty. Since the possibility is high, in this case, the defrost operation is not performed.

Moreover, in this embodiment, the reheat heat exchanger (83) is provided, and while the refrigerant is flowing through the reheat heat exchanger (83), the blowing temperature of the evaporator (3) rises and the blowing temperature Although the temperature difference (SS-EOS) between (SS) and the refrigerant outlet temperature (EOS) increases, it is determined that frost is not formed and defrost operation is not performed.

Furthermore, in this embodiment, the abnormality of the outflow temperature sensor (68) and the outlet temperature sensor (71) is checked, and the temperature difference between the outlet temperature (SS) of the evaporator (33) and the outlet temperature (EOS) of the refrigerant. Even if (SS-EOS) exceeds the above threshold, defrost operation is not performed unless the outflow temperature sensor (68) and the blowout temperature sensor (71) are normal. Specifically, when the detection value of the blowout temperature sensor (71) shifts high or when the detection value of the outflow temperature sensor (68) shifts low, the temperature difference is actually smaller than the threshold value. Since it may be determined that the threshold value is exceeded, the defrost operation is not performed in that case. Therefore, although not illustrated in the present embodiment, one sensor for checking the detection values of the outflow temperature sensor (68) and the blowout temperature sensor (71) is provided.

In addition, when the refrigerant state of the evaporator (33) is alternately changed between wet and dry, the controller (100) is configured such that the temperature of the outlet temperature (SS) of the evaporator (33) and the outlet temperature (EOS) of the refrigerant. An average value of the difference for 10 minutes is obtained, and if this average value is equal to or greater than the threshold value, defrost operation is performed. For example, in the wet operation, the refrigerant temperature at the outlet of the evaporator (33) decreases, so the temperature difference between the outlet temperature (SS) and the refrigerant outlet temperature (EOS) increases, resulting in a dry operation. If so, the refrigerant at the outlet of the evaporator (33) is warmed by air, so that the temperature difference between the blowing temperature (SS) and the refrigerant outlet temperature (EOS) becomes small. Therefore, an average value of the temperature difference for 10 minutes is obtained, and it is determined whether or not the defrost operation is performed based on the obtained value. This prevents false detection of frost formation when the evaporator (33) is not frosted, and false detection of frost formation when it is frosted. it can.

In addition, after starting the defrost operation, the defrost is terminated when the outlet temperature (EOS) of the refrigerant in the evaporator (33) rises above a predetermined temperature. Specifically, the controller (100) determines that there is no undissolved when the outlet temperature (EOS) is 5 ° C. or higher, and ends the defrost.

In this embodiment, the time elapsed after the defrost operation is completed is measured by a timer, and even when the frost detection is not detected, the defrost operation is performed if the set time of the timer elapses. Further, in addition to the control of the frost detection, when the detection value of the suction temperature sensor (70) does not decrease more than 0.2 ° C. per hour (this value is an example) at the time of the pull-down, the evaporator is frosted. It may be determined that the control is performed, and the same control as in the prior art for starting defrosting may be performed.

-Driving operation-
Next, the operation of the container refrigeration apparatus (10) will be described. The operation of the container refrigeration apparatus (10) is roughly classified into “cooling operation”, “defrost operation”, “dehumidification operation”, and “pull-down operation”. The cooling operation is an operation for cooling the interior of the container to a relatively low temperature. That is, the cooling operation is an operation for refrigeration / cooling the interior of the container in order to preserve the transported goods (for example, fresh food) stored in the container body (1a). In the defrost operation, the refrigerant discharged from the compressor (30) is passed through the hot gas bypass circuit (22) to melt the frost adhering to the surface of the heat transfer tube of the evaporator (33) (defrosting). Driving). In general, the defrost operation is executed, for example, every time a predetermined set time elapses from the start of the cooling operation, and the cooling operation is resumed after the defrost operation is completed. The pull-down operation is an operation for rapidly cooling the interior to a set temperature, and the defrost operation is also performed when the evaporator is frosted during the pull-down operation.

In this embodiment, the basic operation of the cooling operation and the defrost operation performed during the pull-down operation and the pull-down operation will be described.

In the basic cooling operation in the cooling operation, the first on-off valve (47) and the second on-off valve (49) are opened, and the third on-off valve (53) and the fifth on-off valve (81) are closed. . The fourth on-off valve (38) is fully opened, and the opening degrees of the supercooling expansion valve (48) and the main expansion valve (32) are adjusted as appropriate. Further, the compressor (30), the outside fan (35) and the inside fan (36) are operated.

The refrigerant compressed by the compressor (30) is condensed by the condenser (31) and then passes through the receiver (41). A part of the refrigerant that has passed through the receiver (41) flows through the low-pressure liquid pipe (27) as it is, and the rest is divided into the supercooling branch pipe (26). The refrigerant that has flowed through the low-pressure liquid pipe (27) is supercooled by the supercooling heat exchanger (44), then depressurized by the main expansion valve (32), and flows through the evaporator (33). In the evaporator (33), the refrigerant absorbs heat from the internal air and evaporates. Thereby, the air in a warehouse is cooled. The refrigerant evaporated in the evaporator (33) is sucked into the compressor (30) and compressed again.

The refrigerant divided into the supercooling branch pipe (26) passes through the supercooling expansion valve (48) and is reduced to an intermediate pressure, and then passes through the secondary passage (46) of the supercooling heat exchanger (44). Flowing. In the supercooling heat exchanger (44), heat is exchanged between the refrigerant flowing through the primary passage (45) and the refrigerant flowing through the secondary passage (46). As a result, the refrigerant in the primary passage (45) is subcooled, while the refrigerant in the secondary passage (46) evaporates. The refrigerant that has flowed out of the secondary passage (46) is sucked into the compression chamber in the intermediate pressure state from the intermediate port of the compressor (30).

During the pull-down operation, the capacity of the compressor (30) is increased and the interior is rapidly cooled. At that time, if the evaporator (33) is frosted, the defrost operation is also performed. The following is the difference between the air blowing temperature (SS) and the refrigerant outlet temperature (EOS) in the evaporator (33) (SS-EOS) for the pull-down operation and the frost detection and defrosting operations performed at that time. ) And the control of the comparative example performed using only the timer will be described.

FIG. 4A shows the control of this embodiment, and FIG. 4B shows the control of the comparative example. 4A and 4B, the vertical axis represents temperature and the horizontal axis represents time. The operating conditions are an outside air temperature of 30 ° C. and a set temperature (SP) in the cabinet of −25 ° C.

First, the control of this embodiment will be described with reference to FIG. Time (T1) is the time when the pre-cooling is finished in the absence of cargo. In this state, the internal air is cooled to −25 ° C. Next, from time (T1) to time (T2), the refrigeration apparatus (10) is turned off, the container door is opened, and the loading operation is performed. During this time, the inside temperature rises, and accordingly, the air suction temperature (RS) and the outlet side refrigerant temperature (EOS) in the evaporator (33) also rise to almost the outside air temperature.

Pull-down operation starts from time (T2). When the pull-down operation is started, the temperature in the warehouse is lowered, and the air temperature (RS) and the refrigerant temperature (EOS) are also lowered. On the other hand, when the evaporator (33) is gradually frosted, the heat transfer coefficient of the evaporator (33) is lowered, so that the blown air temperature (SS) is hardly lowered. At this time, since the refrigerant temperature (EOS) at the outlet of the evaporator (33) decreases, the temperature difference (SS−) between the air blowing temperature (SS) and the refrigerant outlet temperature (EOS) in the evaporator (33). EOS) is getting bigger. The temperature difference (SS-EOS) is represented by a broken line as an average value every 10 minutes.

When the temperature difference (SS-EOS) is 5 ° C. or higher, the defrost operation start condition of the present embodiment is satisfied, so the defrost operation is started at time (T3). In the example shown in the figure, it is the time when 4 hours have elapsed since the start of the pull-down operation.

When the defrost operation is started, hot gas flows through the evaporator (33), so that the outlet temperature (EOS) rises and the internal temperature rises, and the suction temperature (RS) rises accordingly. When the outlet temperature (EOS) reaches 5 ° C., it is determined that the frost has melted, and the defrost operation is terminated (time (T4)). In the example of the figure, 20 minutes have passed from time (T3) to time (T4).

When the defrost is completed, the pull-down operation is resumed and the interior is cooled. At time (T5), the pull-down is completed, and the inside of the refrigerator is cooled to -25 ° C. In the example shown in the figure, the pull-down operation is completed in 3 hours from the end of the defrost.

On the other hand, also in the comparative example shown in FIG. 4B, the pre-cooling ends at time (T1), the loading operation ends at time (T2), and the pull-down operation starts.

When pull-down operation is started, defrost operation is not performed until the time set by the timer has elapsed (until time (T3 ')). In FIG. 4A, since frost formation is detected at time (T3), at this time T3, the heat transfer coefficient of the evaporator (33) has already decreased compared to the state where frost formation has not occurred. Thus, the refrigerant outlet temperature (EOS) in the evaporator (33) decreases from time (T3) to time (T3 ′). On the other hand, in the frosted state, it is difficult for the blowing temperature (SS) and the internal temperature to decrease, and the suction temperature (RS) is also difficult to decrease. The temperature difference (SS−EOS) greatly exceeds 5 ° C., but the defrosting start time (T3 ′) is reached with the cooling capacity being lowered. After that, the temperature difference (SS-EOS) increases from 5 ° C.

In the comparative example of FIG. 4B, when the defrost operation is started at time (T3 ′), compared to the state in which the defrost operation is started at time (T3) by the control of the present embodiment shown in FIG. 4A. The amount of frost formation is increasing. Therefore, in this comparative example, in order to sufficiently melt frost, the outlet temperature (EOS) is set to 20 ° C. or more as a defrost termination condition, and inevitably the time from the start of the defrost operation to the termination. (T4′−T3 ′) also becomes longer. In this example, 30 minutes have passed from the defrost start time (T3 ') to the end time (T4').

When the defrost is completed at time (T4 '), the pull-down operation is started again, and the interior is cooled. Then, at time (T5 '), the pull-down ends and the interior is cooled to -25 ° C. In the example shown in the figure, the pull-down operation is completed in 3 hours from the end of the defrost.

-Effects of the embodiment-
According to the present embodiment, when it is determined that the temperature difference between the air blowing temperature and the refrigerant outlet temperature in the evaporator (33) is equal to or greater than a predetermined threshold, it is detected that the evaporator (33) has formed frost. Then, by performing defrost operation control for starting the defrost operation by the defrost operation control unit (106), frost formation can be detected quickly in a short time, and the defrost operation can be started. The driving time at the can be minimized. Therefore, the defrosting operation during pull-down can be completed quickly, and consequently the pull-down operation can be completed quickly.

In particular, the temperature difference between the air blowing temperature and the refrigerant outlet temperature in the evaporator (33) is not affected by factors such as intrusion heat, cargo heat capacity, and cooling capacity, so it is reliable in a short time. Frost can be detected.

Furthermore, since defrosting can be started earlier than before, defrosting can be started with a small amount of frost formation. As a result, the defrosting operation time itself can be shortened, the time required for defrosting can be shortened more reliably, and the defrosting completion temperature can be lowered, so that the pull-down can be restarted smoothly.

In the air conditioner, the outdoor heat exchanger is a defrost target during heating operation, but generally the outdoor temperature exchanger (evaporator) outlet temperature sensor is not provided. Therefore, the control of the present embodiment is not generally performed by the air conditioner. On the other hand, in this embodiment, since the sensor normally provided in the container refrigeration apparatus (10) is used, a new sensor is unnecessary and the configuration is not complicated. However, even if it is an air conditioning apparatus, if the blowing temperature sensor which detects the blowing air temperature of the evaporator at the time of heating is provided, it is possible to perform control similar to this embodiment.

In addition, when the air volume of the internal fan (36) increases, the temperature difference between the air blowing temperature and the refrigerant outlet temperature in the evaporator (33) increases, whereas a threshold value corresponding to the air volume is set. As a result, even if the air volume changes, frost formation can be detected quickly, so that the defrost operation can be completed quickly.

Further, in the present embodiment, when frost formation is detected again within a predetermined time after the defrosting is completed, there is a high possibility that the evaporator (33) is erroneously detected due to contamination or the like. It is trying to become. This can prevent useless defrost operation.

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

For example, the frost detection and the defrost operation of the above embodiment may be performed not only during the pull-down operation but also during the normal cooling operation.

In the above embodiment, when it is determined that the temperature difference (SS−EOS) between the air blowing temperature (SS) and the refrigerant outlet temperature (EOS) in the evaporator (33) is equal to or greater than a predetermined threshold value, Although it has been detected that the evaporator (33) is frosted and the hot gas defrost is performed by supplying the discharge gas refrigerant of the compressor (30) to the evaporator (33) to remove the frost, the defrost operation is The operation may be performed using an electric heater.

In the above embodiment, the temperature difference (SS−EOS) between the air blowing temperature (SS) and the refrigerant outlet temperature (EOS) in the evaporator (33) is determined to be 5 ° C. or more as a predetermined threshold. In this case, it is determined that the evaporator (33) is frosted, but the above threshold value is merely an example, and may be set to an appropriate value according to the apparatus.

Further, in the above embodiment, the threshold value is made constant, and when the temperature difference becomes abnormal within one hour from the defrost operation, the defrost operation is stopped as a false detection, but after the defrost operation, You may make it perform learning control which correct | amends the said threshold value on the basis of the said temperature difference.

Moreover, although the said embodiment demonstrated the example which applied this invention to the container refrigeration apparatus for cooling the inside of the container of the container used for marine transportation etc., this invention cools the inside of the refrigerator and the freezer. The present invention is also applicable to a cooling device that performs heating and an air conditioner that can heat a room. That is, the present invention can be applied to a refrigeration apparatus in a broad sense including refrigeration and air conditioning. In the case of an air conditioner, the present invention can be applied to defrost during heating operation.

Further, in the above embodiment, when it is determined that the temperature difference (SS−EOS) between the air blowing temperature (SS) and the refrigerant outlet temperature (EOS) in the evaporator (33) is equal to or greater than a predetermined threshold value, It detects that the evaporator (33) has formed frost and starts defrosting. However, the suction temperature (RS) is used instead of the outlet temperature (SS) of the evaporator (33), and the evaporator (33 ) Detects that the evaporator (33) has formed frost when it is determined that the temperature difference (RS-EOS) between the air suction temperature (RS) and the refrigerant outlet temperature (EOS) is equal to or greater than a predetermined threshold. Then, the defrost operation may be started.

In that case, although the suction temperature (RS) is slightly higher than the blowout temperature (SS), it changes in almost the same way as the blowout temperature (SS). Therefore, the suction temperature (RS) of the air in the evaporator (33) When the defrost operation is started when it is determined that the temperature difference (RS−EOS) with respect to the refrigerant outlet temperature (EOS) is equal to or greater than a predetermined threshold, it is possible to achieve the same effect as the above embodiment. When the control of this modification is performed, the suction temperature (RS) is generally higher than the blowing temperature (SS) as described above. Therefore, in the embodiment using the blowing temperature (SS), The threshold value may be changed as appropriate, for example, a value set to 5 ° C. as the predetermined threshold value is set to 10 ° C., for example.

In the case of an air conditioner, since an intake temperature sensor is generally provided for detecting the intake temperature of the evaporator during heating, the air intake temperature (RS) and the refrigerant outlet temperature (EOS) in the evaporator (33) When it is determined that the temperature difference (RS-EOS) is greater than or equal to a predetermined threshold, the control to detect that the evaporator (33) has formed frost and start the defrost operation is performed by using a dedicated sensor for the air conditioner. It is possible to carry out without providing.

In addition, the above embodiment is an essentially preferable example, and is not intended to limit the scope of the present invention, its application, or its use.

As described above, the present invention relates to a container refrigeration apparatus for cooling the interior of a container used for marine transportation or the like, a cooling apparatus for cooling the interior of a refrigerator or a freezer, and an air conditioner capable of heating a room. In a refrigeration apparatus such as an apparatus, it is useful for a technique for shortening the time required to detect frost formation in an internal heat exchanger (evaporator) and quickly ending defrost operation.

1a Container body (temperature controlled room)
10 Refrigeration equipment for containers 20 Refrigerant circuit 30 Compressor 31 Condenser 32 Main expansion valve (expansion mechanism)
33 Evaporator 36 Internal fan (evaporator fan)
100 controller (control device)
105 Pull-down operation control unit 106 Defrost operation control unit

Claims

The temperature control target chamber (1a), the compressor (30), the condenser (31), the expansion mechanism (32), and the evaporator (33) are connected in order to perform the refrigeration cycle operation. ) A refrigeration apparatus comprising a refrigerant circuit (20) for controlling the temperature inside, and a control device (100) for controlling the refrigerant circuit (20),
The control device (100) includes a defrost operation control unit (106) for controlling the defrost operation, and a temperature difference between the air blowing temperature or the suction temperature and the refrigerant outlet temperature in the evaporator (33) is a predetermined threshold value or more. The refrigeration apparatus is characterized in that when it is determined that the evaporator (33) is frosted, the defrost operation control is performed by the defrost operation control unit (106) to start the defrost operation.
In claim 1,
The control device (100) includes a pull-down operation control unit (105) that performs a pull-down operation for rapidly cooling the temperature control target chamber (1a), and performs the defrost operation control during the pull-down operation. apparatus.
In claim 1 or 2,
The said control apparatus (100) changes the said threshold value according to the air volume of the evaporator fan (36) arrange | positioned in the vicinity of the said evaporator (33), and when the air volume becomes larger than the present value, the said threshold value is enlarged. A refrigeration apparatus characterized by that.
In any one of Claims 1-3,
When the control device (100) detects frost formation within a predetermined time after performing the defrost operation, the control device (100) thereafter prohibits the defrost operation until the power is turned off.