JP2013122328A - Refrigeration device for container - Google Patents

Abstract

In a configuration in which an inverter circuit is housed in an electrical component box disposed outside a marine container, compressor capacity control can be appropriately performed while suppressing a rise in temperature of the inverter circuit.
The temperature inside the electrical component box 15 arranged outside the container of the marine container is estimated from the current value flowing through the inverter circuit 5 and the outside air temperature, and the temperature inside the electrical component box 15 exceeds the reference temperature. The frequency of the inverter circuit 5 is controlled by the controller so as not to be present.
[Selection] Figure 3

Description

  The present invention relates to a container refrigeration apparatus for cooling the inside of a container used for marine transportation and the like, and in particular, a compressor that is based on the temperature of an electrical component box in which an inverter for variable capacity control of a compressor is accommodated. It is related to the control technology.

  2. Description of the Related Art Conventionally, shipping containers for transporting cargo such as foods on land or sea while keeping the temperature low are known. This transport container is provided with a container refrigeration apparatus as disclosed in Patent Document 1. This refrigeration apparatus includes a refrigerant circuit to which a compressor, a condenser, an expansion valve, and a cooling heat exchanger (evaporator) are connected. In the refrigerant circuit of this refrigeration apparatus, the refrigerant circulates to perform a vapor compression refrigeration cycle. As a result, the refrigerant flowing through the cooling heat exchanger absorbs heat from the internal air and evaporates, whereby the internal air is cooled. In this refrigeration apparatus, a freezing operation in which the air inside the container is lowered to less than zero degrees Celsius and the stored items in the container are frozen, and a refrigerated operation in which the air in the chamber is raised to less than zero degrees Celsius and the stored items in the container are refrigerated. Is possible.

  In this type of refrigeration apparatus, an electrical component box is fixed to the frame of the container, and is disposed outside the box together with equipment such as a compressor. When the compressor is an inverter-driven variable capacity compressor, the circuit board of the inverter is also housed in the electrical component box.

JP-A-9-203578

  For variable capacity compressors using inverters, it is necessary to control the frequency so that the capacity of the compressor can be matched to the refrigeration load while managing the temperature inside the electrical component box so that the inverter does not become higher than the reference temperature. is there.

  Here, when the inverter circuit is arranged in the electrical component box provided outside the container, the electrical component box is easily affected by the outside air temperature. Further, since the shipping container is transported from the low temperature region to the high temperature region, it is difficult to accurately measure the temperature of the inverter circuit even if a temperature sensor is provided in the electrical component box. Furthermore, since the temperature in the electrical component box and the circuit board of the inverter do not always become the same temperature, it is difficult to accurately measure the inverter temperature even if a temperature sensor is provided in the electrical component box.

  Therefore, it has been difficult to operate a refrigeration apparatus that cools the interior of a container used for marine transportation or the like so as to obtain sufficient capacity of the refrigeration apparatus while preventing the inverter temperature from rising excessively.

  The present invention has been made in view of such problems, and an object of the present invention is to suppress an increase in the temperature of the inverter in the configuration in which the inverter circuit is housed in an electrical component box disposed outside the container of the sea container. It is to be able to appropriately control the capacity of the compressor.

  The first invention is connected to the container body (1a), the refrigerant circuit (20) for adjusting the internal temperature of the container body (1a), and the variable capacity compressor (30) provided in the refrigerant circuit (20). The container refrigeration apparatus including the inverter circuit (5) and the electrical component box (15) for storing the inverter circuit (5) is assumed.

  The container refrigeration apparatus estimates the temperature in the electrical component box (15) from the current value flowing through the inverter circuit (5) and the outside air temperature, and the temperature in the electrical component box (15) It is characterized by comprising control means (100) for controlling the frequency of the inverter circuit (5) so as not to exceed the reference temperature.

  In the first invention, the frequency of the inverter circuit (5) is set so that the temperature in the electrical component box (15) estimated from the current value flowing through the inverter circuit (5) and the outside air temperature does not exceed the reference temperature. The compressor (30) is controlled and rotates within a range not exceeding the upper limit frequency of the inverter circuit (5).

  In the second invention, in the first invention, when it is determined that the temperature in the electrical component box (15) is higher than a reference temperature, the control means (100) controls the maximum frequency of the inverter circuit (5). It is characterized by being comprised so that it may fall.

  In the second aspect of the invention, when the temperature of the electrical component box (15) tends to rise, the operation is performed with the upper limit frequency of the inverter circuit (5) lowered. As a result, it is possible to suppress the temperature of the electronic component in the electrical component box (15) from rising too much and to prevent the temperature of the compressor (30) from rising too much.

  According to a third aspect, in the first aspect, when it is determined that the temperature in the electrical component box (15) has become lower than a reference temperature, the control means (100) controls the maximum frequency of the inverter circuit (5). It is characterized by being configured to raise.

  In the third aspect of the invention, when the temperature of the electrical component box (15) is lower than the reference temperature and there is a margin for temperature rise, the inverter circuit (5) is operated with the upper limit frequency increased. Thus, an operation for increasing the capacity of the container refrigeration apparatus is performed until the temperature of the electrical component box (15) reaches the reference temperature.

  According to the present invention, the temperature in the electrical component box (15) is prevented from excessively rising, and while protecting the circuit board and electronic components of the inverter circuit (5), the largest container refrigeration apparatus in that range Can gain the ability. For this reason, it is possible to perform an operation in which both the stability of the device and the capacity of the system are compatible.

  Moreover, since the temperature inside the electrical component box (15) is estimated from the current value flowing through the inverter circuit (5) and the outside air temperature, a temperature sensor is not provided in the electrical component box (15). Good. Therefore, since the number of parts can be suppressed, the increase in cost can also be suppressed. Also, when installing a temperature sensor in the electrical component box (15), the detection value of the temperature in the box may vary depending on the installation location, and the detection value may be inaccurate. In the invention, since the temperature is obtained from the current value of the inverter circuit (5), the temperature of the inverter circuit (5) can be obtained accurately, and the control accuracy can be increased.

  According to the second aspect of the invention, when the temperature of the electrical component box (15) tends to rise, the operation is performed with the upper limit frequency of the inverter circuit (5) lowered. As a result, it is possible to suppress the temperature of the electronic component in the electrical component box (15) from rising too much and to prevent the temperature of the compressor (30) from rising too much. Therefore, it is possible to perform an operation with an emphasis on protecting the electronic components in the electrical component box (15) and the compressor (30).

  According to the third aspect of the invention, when the temperature of the electrical component box (15) is lower than the reference temperature and there is a margin for the temperature increase, the operation is performed by increasing the upper limit frequency of the inverter circuit (5). Thus, it is possible to perform an operation with an emphasis on the capacity of the container refrigeration apparatus until the temperature of the electrical component box (15) reaches the reference temperature.

FIG. 1 is a longitudinal sectional view of a container refrigeration apparatus and a container body according to an embodiment of the present invention. 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. 4 is a flowchart showing control of the compressor based on the temperature in the electrical component box.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG.1 and FIG.2, the container refrigeration apparatus (10) of this embodiment cools the inside of the container used for marine transportation. The container refrigeration apparatus (10) includes a refrigerant circuit having a compressor (30), a condenser (31), and an evaporator (33), and constitutes a refrigeration cycle. The container refrigeration apparatus (10) also serves as a lid that closes the opening surface on the side of the container body (1a).

  The casing (13) of the container refrigeration apparatus (10) is provided on the casing main body (11) and the back surface (inside of the box) of the casing (13) that partitions the outside of the box outside the container and the inside of the box inside the container. Provided with a partition plate (14) and the like.

  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. The evaporator (33) and the internal 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) includes a compressor (30), a condenser (31), a main expansion valve (32), and an evaporator (33) connected in series by a refrigerant pipe in order.

  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).

  Both the condenser (31) and the evaporator (33) are constituted by 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). The inflow temperature sensor (67) detects the temperature 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). The outflow temperature sensor (68) detects the temperature 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 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) (the 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), an engine speed control unit (102) for controlling the operation 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 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. Note that the target temperature SP of the blown air constitutes a predetermined blown temperature according to the present invention. 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 operating speed N of the compressor (30) is lowered while the blown air temperature SS is the target. If it is higher than the temperature (SP), the operating speed N of the compressor (30) is increased.

  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) by a predetermined value A. It is adjusted by lowering. 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. If it carries out like this, the flow volume of the refrigerant | coolant which circulates through a refrigerant circuit (20) will fall by the driving | operation rotation (NA) of a compressor (30), and the cooling capacity of the container refrigeration apparatus (10) will fall. For this reason, the cooling capacity of the container refrigeration apparatus (10) and the cooling load in the container warehouse are balanced.

  The compressor control unit (101) of the controller (100) is configured to detect a current value flowing through the inverter circuit. The container refrigeration apparatus (10) is provided with the above-described outside temperature sensor (69) for detecting the outside temperature, and the detected value (outside temperature) of the outside temperature sensor (69) is input to the controller. It has become so.

  The compressor control unit (101) estimates the temperature in the electrical component box (15) from the current value flowing through the inverter circuit and the outside air temperature, and the temperature in the electrical component box (15) determines the reference temperature. Control means for controlling the frequency of the inverter so as not to exceed. Specifically, the compressor control unit (101) of the controller (100) reduces the maximum frequency of the inverter when it is determined that the temperature in the electrical component box (15) is higher than the reference temperature. On the other hand, when it is determined that the temperature in the electrical component box (15) has become lower than the reference temperature, the maximum frequency of the inverter is increased.

-Driving action-
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”, and “dehumidification 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) accommodated 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). 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 ends.

  In this embodiment, the operations of the defrosting operation and the dehumidifying operation are omitted, and the basic operation of the cooling 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 depressurized by the main expansion valve (32), and then 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).

  Next, control for preventing the temperature in the electrical component box (15) from exceeding the reference temperature will be described. As described above, the controller (100) estimates the temperature in the electrical component box (15) from the current value flowing through the inverter circuit and the outside air temperature, and the temperature in the electrical component box (15) is the reference. The frequency of the inverter is controlled so as not to exceed the temperature. Therefore, the compressor control unit (101) of the controller (100) reduces the maximum frequency of the inverter when it is determined that the temperature in the electrical component box (15) is higher than the reference temperature, When it is determined that the temperature in the electrical component box (15) has become lower than the reference temperature, control is performed to increase the maximum frequency of the inverter.

  Specific control will be described with reference to the flowchart of FIG.

  Step ST1 represents an initial state. In the initial state, the capacity of the compressor (30) is controlled according to the load of the refrigeration apparatus (10) without limiting the frequency of the inverter, and control is performed with priority on the capacity of the refrigeration apparatus (10). To do. Next, in step ST2, the frequency of the power source is 50 Hz, the outside temperature detected by the outside temperature sensor (69) is equal to or higher than the reference outside temperature T (° C.) (for example, 25 ° C. or higher), And it is discriminate | determined whether the calculated value of the temperature of an electrical component box (15) is more than reference | standard box temperature T1 (degreeC) (for example, it is 73 degreeC or more), and three conditions are satisfy | filled. The outside air temperature in step ST2 is a value obtained by correcting the detected value of the outside air temperature sensor (69) so as to be close to the actual outside air temperature. The temperature inside the electrical component box (15) is the primary current of the inverter. The value obtained by multiplying the squared value by a coefficient and taking the outside air temperature into consideration.

  When the condition of step ST2 is satisfied, the outside air temperature is a value equal to or higher than the reference outside air temperature, and the temperature in the electrical component box (15) is also equal to or higher than the reference box temperature. That is, the outside air temperature and the box temperature are high. In this state, the process proceeds to step ST3, and the current inverter frequency step driving the compressor (30) is set to the upper limit frequency step (INV_BOX). That is, during the control for limiting the frequency of the inverter, the frequency step of the inverter is prevented from becoming higher than the current level. In step ST4, the upper limit frequency step of the inverter is maintained at the current value.

  In step ST5, whether or not the calculated value of the temperature of the electrical component box (15) is equal to or lower than the set temperature T2 (° C.) and the state continues for t1 (seconds) (for example, calculation of the temperature of the electrical component box (15)) Whether or not a value of 68 ° C. or lower continues for 120 seconds) is determined. When the condition of step ST5 is satisfied, the temperature of the electrical component box (15) is lowered, so the process proceeds to step ST6. When the condition of step ST5 is not satisfied, the temperature of the electrical component box (15) is Since it is not lowered, the set value of step ST4 is maintained.

  In step ST6, since the temperature of the electrical component box (15) has decreased and there is room for the temperature of the electrical component box (15) to increase, the current upper limit frequency step of the inverter is one step. And set it to the new upper frequency step. Then, while maintaining the upper limit frequency step set in step ST6 in step ST4, control is performed with the frequency step as the upper limit. In the state where the control is performed with the frequency step set as the upper limit in this way, and it is determined in step ST5 that the temperature of the electrical component box (15) is sufficient, the upper limit value of the frequency step is determined in step ST6. Is further raised by one step to perform control. As described above, in steps ST4, 5, and 6, as long as there is room in the temperature of the electrical component box (15), the upper limit frequency step of the inverter is increased to perform control giving priority to the capacity of the refrigeration apparatus (10). .

  In step ST7, whether the temperature of the electrical component box (15) is equal to or higher than the reference box temperature T1 (° C.) and the state continues for t2 seconds (for example, the calculated value of the temperature of the electrical component box (15) is 73 ° C. Whether or not the above state continues for 20 seconds). If the condition of step ST7 is satisfied, the temperature of the electrical component box (15) is still high, so the process proceeds to step ST8. If the condition of step ST7 is not satisfied, the temperature of the electrical component box (15) is the reference. Since the temperature does not rise above the box temperature, the set value of step ST4 is maintained.

  In step ST8, since the temperature of the electrical component box (15) tends to rise, the current upper limit frequency step of the inverter is lowered by one step and set as a new upper limit frequency step. And control which makes the frequency step an upper limit is performed, maintaining the upper limit frequency step set by step ST8 by step ST4. When it is determined that the temperature of the electrical component box (15) has a tendency to increase in step ST7 while the control is performed with the frequency step set in this way as the upper limit, the upper limit of the frequency step is determined in step ST8. The value is further lowered by one step for control. As described above, in steps ST4, 7, and 8, the temperature of the electrical component box (15) tends to rise too much, so the upper limit frequency step of the inverter is lowered to reduce the capacity of the refrigeration apparatus (10). Take control.

  When control for limiting the upper limit frequency step of the inverter is performed in step ST3 to step ST8, it is determined in step ST9 whether to cancel the limitation. Specifically, in step ST9, when the compressor (30) is stopped or the upper limit frequency step of the inverter reaches the maximum frequency Nmax of the inverter, the control returns to the initial control state in step ST1.

  When the operation of the flowchart of FIG. 4 is performed, the upper limit frequency step of the inverter is set to be equal to or higher than the minimum frequency Nmin of the inverter. Further, when it is determined that the outside air temperature is abnormal, the control of the flowchart is not performed.

-Effect of Embodiment 1-
As described above, according to the present embodiment, the controller (100) estimates the temperature in the electrical component box (15) from the current value flowing through the inverter circuit and the outside air temperature, and the electrical component box (15 The frequency of the inverter is controlled so that the temperature in () does not exceed the reference temperature. In particular, if it is determined that the temperature in the electrical component box (15) is higher than the reference temperature, the inverter On the other hand, when it is determined that the temperature in the electrical component box (15) has become lower than the reference temperature, control is performed to increase the maximum frequency of the inverter.

  Therefore, the maximum capacity of the refrigeration apparatus (10) in the range can be obtained while protecting the circuit board and electronic parts of the inverter while preventing the temperature in the electrical component box (15) from rising excessively. . For this reason, it is possible to perform an operation in which both the stability of the device and the capacity of the system are compatible.

  In particular, when the temperature of the electrical component box (15) tends to rise, lower the upper limit frequency of the inverter and operate with emphasis on protecting the electronic components in the electrical component box (15) and the compressor (30). It can be performed. Also, when the temperature of the electrical component box (15) is lower than the reference temperature and there is room for temperature rise, increase the upper limit frequency of the inverter to operate with emphasis on the capacity of the refrigeration system (10). Can do.

  Moreover, since the temperature in the electrical component box (15) is estimated from the current value flowing through the inverter circuit and the outside air temperature, it is not necessary to provide a temperature sensor in the electrical component box (15). Therefore, since the number of parts can be suppressed, the increase in cost can also be suppressed. In addition, even when a temperature sensor is installed in the electrical component box (15), the detection value of the temperature in the box may vary depending on the installation location, and the detection value may be inaccurate. In this embodiment, since the temperature is obtained from the current value of the inverter, the temperature of the inverter can be obtained accurately, the control accuracy is improved, and the temperature of the inverter itself is prevented from rising excessively. You can also.

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

  For example, the refrigerant circuit of the container refrigeration apparatus is an example, and may be appropriately changed according to the specific configuration of the apparatus.

  Moreover, the specific numerical value of the temperature at the time of controlling a compressor so that the temperature in an electrical component box does not exceed reference | standard temperature is an example, and can be changed according to an operating condition.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a refrigeration apparatus that includes a variable capacity compressor and cools the inside of a container used for marine transportation or the like.

1a Container body
10 Refrigeration equipment
5 Inverter circuit
15 Electrical component box
20 Refrigerant circuit
30 Compressor (variable capacity compressor)
100 controller (control means)

Claims (3)

A container body (1a), a refrigerant circuit (20) for adjusting the internal temperature of the container body (1a), and an inverter circuit (5) connected to a variable capacity compressor (30) provided in the refrigerant circuit (20) ) And an electrical component box (15) for storing the inverter circuit (5),
The temperature inside the electrical component box (15) is estimated from the current value flowing through the inverter circuit (5) and the outside air temperature, and the temperature inside the electrical component box (15) is controlled so as not to exceed the reference temperature. A container refrigeration apparatus comprising a control means (100). In claim 1,
The control means (100) is configured to reduce the maximum frequency of the inverter circuit (5) when it is determined that the temperature in the electrical component box (15) is higher than the reference temperature. The container refrigeration equipment. In claim 1,
The control means (100) is configured to increase the maximum frequency of the inverter circuit (5) when it is determined that the temperature in the electrical component box (15) has become lower than the reference temperature. The container refrigeration equipment.

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