JP5602519B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus that controls equipment using an outside air temperature sensor, and particularly to control when the outside air temperature sensor is abnormal.

  Conventionally, this kind of refrigeration apparatus has a refrigeration cycle composed of a compression means, a condenser (gas cooler), a throttle means, an evaporator, etc., and the refrigerant compressed by the compression means radiates heat in the condenser (gas cooler), and the throttle means Then, the refrigerant is evaporated by an evaporator, and the surrounding air is cooled by evaporation of the refrigerant at this time.

  At this time, the outside air temperature sensor is used for energization control of a dew condensation prevention frame heater provided at an opening edge of a cooling storage in which the refrigeration apparatus is employed, operation control of a gas cooler blower, and the like.

  Specifically, the energization control of the frame heater is a dew condensation prevention control that increases the energization rate as the temperature difference between the inside temperature detected by the inside temperature sensor and the outside air temperature detected by the outside air temperature sensor increases. I do. The operation control of the gas cooler blower performs blower operation control that increases the rotation speed of the blower as the outside air temperature detected by the outside air temperature sensor is higher.

  When the outside temperature sensor fails, the control means determines that the outside temperature is a predetermined temperature, for example, 35 ° C. in any case as a backup operation at the time of the sensor failure, and energizes the frame heater. And the blower was operated continuously.

  On the other hand, in recent years, chlorofluorocarbon refrigerants cannot be used in this type of refrigeration apparatus due to natural environmental problems. For this reason, the thing using the carbon dioxide which is a natural refrigerant | coolant is developed as a substitute of a fluorocarbon refrigerant | coolant. The carbon dioxide refrigerant is a refrigerant having a high and low pressure difference, and has a low critical pressure. It is known that the high pressure side of the refrigerant cycle is brought into a supercritical state by compression (see, for example, Patent Document 1).

  In such a supercritical refrigerant cycle, under conditions where the refrigerant temperature at the gas cooler outlet becomes high due to a high heat source temperature on the gas cooler side (for example, the outside air temperature as a heat medium that exchanges heat with the gas cooler), the evaporator inlet Since the specific enthalpy of the slag increased, there was a problem that the refrigeration effect was significantly reduced. In this case, in order to ensure the refrigerating capacity, it is necessary to increase the high-pressure pressure, which causes a disadvantage that the compression power increases and the coefficient of performance also decreases.

  For this reason, the refrigerant cooled by the gas cooler is divided into two refrigerant flows, one of the divided refrigerant flows (first refrigerant flow) is throttled by the auxiliary throttle means, and then one of the passages of the intermediate heat exchanger (first passage) 1) and the other refrigerant flow (second refrigerant flow) is exchanged with the first flow channel of the intermediate heat exchanger in a heat exchange manner (second flow channel). ), And a so-called split-cycle (two-stage compression, one-stage expansion intermediate refrigeration cycle) refrigeration apparatus that evaporates in an evaporator via a main throttle means has been proposed.

  In the split cycle apparatus described above, the refrigerant after radiating heat from the gas cooler is diverted, and the second refrigerant flow can be cooled by the first refrigerant flow that has been decompressed and expanded. Can be reduced. As a result, the refrigeration effect can be increased and the performance can be effectively improved as compared with the conventional apparatus.

  However, the cooling effect of the first refrigerant flow for cooling the second refrigerant flow before depressurization depends on the amount of the first refrigerant flow and the second refrigerant flow flowing through the intermediate heat exchanger. That is, if the amount of the first refrigerant flow is too large, the amount of the second refrigerant flow that finally evaporates in the evaporator will be insufficient. Conversely, if the amount of the first refrigerant flow is too small, The cooling effect (that is, the effect of the split cycle) due to the refrigerant flow 1 is reduced.

  Therefore, the opening degree control of the auxiliary throttle means is controlled so that the inlet side temperature of the first refrigerant flow flowing into the intermediate heat exchanger becomes a predetermined target value. At this time, the inlet side temperature correlates with the intermediate pressure of the two-stage compression, and the optimum intermediate pressure differs depending on the high pressure that changes for each outside air temperature. Therefore, it is necessary to use a target value corresponding to the state change.

  Therefore, an outside temperature sensor that detects the outside temperature is used. However, if the outside temperature sensor fails, the control unit cannot detect the outside temperature. As a backup operation, the outside air temperature is determined to be a predetermined temperature, for example, 20 ° C., and the opening control of the auxiliary throttle means as described above is performed.

Japanese Patent Publication No. 7-18602

  However, in the above case, when the outside air temperature sensor fails, even when the outside air temperature is actually low, higher energization rate control of the frame heater and high rotation speed control of the blower are performed. There was a problem from the viewpoint of energy saving, and proper control could not be performed.

  In the case of the opening control of the auxiliary throttle means, when the outside air temperature sensor fails, it is determined that the outside air temperature is a predetermined temperature, for example, 20 ° C., and the opening degree of the auxiliary throttle means is controlled as described above. For this reason, it becomes impossible to set a target value of the inlet side temperature of the intermediate heat exchanger corresponding to the actual outside air temperature. As a result, there is a problem that the amount of the first refrigerant flow cannot be optimized and efficient cooling control cannot be realized.

  The present invention has been made to solve the conventional technical problem, and is suitable for backup operation, such as frame heater control, gas cooler blower control, and auxiliary throttle means, even when the outside air temperature sensor fails. It aims at realizing the opening degree control of.

In order to solve the above-described problems, a refrigeration apparatus according to the present invention includes a refrigerant circuit including a compression unit, a gas cooler, a throttling unit, and an evaporator, and includes a blowing unit that cools the gas cooler, and an evaporation unit. Condensation prevention heating means for heating a portion where condensation occurs due to cooling by the vessel, control means for controlling the compression means, the throttle means, the air blowing means and the condensation prevention heating means, and for detecting the outside air temperature AT An outside air temperature detecting means, a gas cooler outlet side temperature detecting means for detecting the refrigerant outlet side temperature GT of the gas cooler, and a cooled space temperature detecting means for detecting the temperature PT of the cooled space cooled by the evaporator. , the control means, the difference e between the outside air temperature AT detected by the refrigerant outlet side temperature GT1 and the outside air temperature detection means of the gas cooler to be detected gas cooler outlet side temperature detection means, a gas cooler cold It has a database constructed by storing each temperature zone outlet side temperature GT1, based on the temperature PT of the cooling space for detecting the target cooling space temperature detection means, a predetermined upper limit temperature HST of the the cooled space The compression means is started, the thermocycle is stopped at the lower limit temperature LST, the blower means and / or the dew condensation prevention heating means are controlled based on the outside air temperature AT detected by the outside air temperature detecting means, and the outside temperature When the detection means is abnormal, the difference e corresponding to the temperature zone to which the refrigerant outlet side temperature GT1 of the gas cooler detected by the gas cooler outlet side temperature detection means belongs is read from the database, and the refrigerant outlet side temperature GT1 and the temperature having the difference e are It is characterized by substituting as temperature AT .

In the refrigeration apparatus according to the second aspect of the present invention, a refrigerant circuit is constituted by the compression means, the gas cooler, the auxiliary throttle means, the intermediate heat exchanger, the main throttle means, and the evaporator, and two refrigerants are discharged from the gas cooler. The first refrigerant flow is passed through the auxiliary throttle means to the first flow path of the intermediate heat exchanger, and the second refrigerant flow is flowed to the second flow path of the intermediate heat exchanger. Thereafter, the first refrigerant flow and the second refrigerant flow are exchanged in the intermediate heat exchanger by flowing into the evaporator through the main throttle means, and the refrigerant discharged from the evaporator is transferred to the low pressure portion of the compression means. The first refrigerant flow from the intermediate heat exchanger is sucked into the intermediate pressure portion of the compression means, the control means for controlling the compression means, the auxiliary throttle means and the main throttle means, and the outside air temperature AT For detecting the outside air temperature detecting means for detecting the refrigerant and the refrigerant outlet side temperature GT of the gas cooler A gas cooler outlet side temperature detection means, and a target cooling space temperature detection means for detecting a temperature PT of the cooling space to be cooled by the evaporator, the control means, the refrigerant of the gas cooler to be detected gas cooler outlet side temperature detection means It has a database constructed by storing the difference e between the outlet side temperature GT1 and the outside air temperature AT detected by the outside air temperature detecting means for each temperature zone of the refrigerant outlet side temperature GT1 of the gas cooler, and detects the temperature of the cooled space Based on the temperature PT of the cooled space detected by the means, the compression means is started at a predetermined upper limit temperature HST of the cooled space, and the thermocycle is stopped at the lower limit temperature LST. It controls the auxiliary throttle means on the basis of the outside air temperature AT for detecting, at the time of abnormality of the outdoor air temperature detecting means detects the gas cooler outlet side temperature detection means Reads the difference e of the refrigerant outlet side temperature GT1 of Sukura corresponds to the temperature range belonging to the database, characterized by substituting the temperature with a refrigerant outlet side temperature GT1 and the difference e as the outside air temperature AT.

In the invention of claim 3 , in each of the above inventions , the difference e stored in the database is an average value obtained at each timing immediately before starting the compression means, or an average obtained by weighting the latest value. It is a value.

According to a fourth aspect of the present invention, in each of the above inventions, when both the outside air temperature detecting means and the gas cooler outlet side temperature detecting means are abnormal, the control means is a throttling means to a value that ensures a predetermined refrigerant flow rate, or The opening degree of the main throttle means and the auxiliary throttle means is maintained.

The invention of claim 5 is characterized in that, in each of the above inventions, the control means comprises an alarm means for notifying abnormality of the temperature detection means.

The invention of claim 6 is characterized in that, in each of the above inventions, carbon dioxide is used as a refrigerant.

According to the first aspect of the present invention, the control means determines the difference e between the refrigerant outlet side temperature GT1 of the gas cooler detected by the gas cooler outlet side temperature detecting means and the outside air temperature AT detected by the outside air temperature detecting means, as the refrigerant outlet of the gas cooler. It has a database constructed by storing for each temperature zone of the side temperature GT1, and based on the temperature PT of the cooled space, starts the compression means at a predetermined upper limit temperature HST of the cooled space, and sets the lower limit temperature LST The control unit controls the air blowing means and / or the dew condensation prevention heating means based on the outside air temperature AT detected by the outside air temperature detecting means, and when the outside air temperature detecting means is abnormal, the gas cooler outlet side temperature is controlled. The difference e corresponding to the temperature zone to which the refrigerant outlet side temperature GT1 of the gas cooler detected by the detection means belongs is read from the database, and the refrigerant outlet side temperature GT1 is read out. Since substitute temperature with the difference e as the outside air temperature AT, and the outside air temperature AT reads a difference e between the outside air temperature AT for each temperature zone refrigerant outlet side temperature GT1 of the gas cooler from the database, the blowing means and / or condensation It becomes possible to execute control of the heating means for prevention.

Therefore, as in the conventional case, when the outside air temperature detecting means is abnormal, more accurate control is realized as compared with the case where the control of the air blowing means and / or the dew condensation preventing heating means is performed as a predetermined outside air temperature set in advance. It becomes possible to do. Accordingly, it is possible to easily realize appropriate backup control based on the refrigerant outlet side temperature GT1 of the gas cooler until the outside air temperature detecting means is repaired or replaced.

According to the invention of claim 2, in the refrigeration apparatus adopting a so-called two-stage compression / one-stage expansion intermediate cooling cycle, the control means for controlling the compression means, the auxiliary throttle means and the main throttle means, and for detecting the outside air temperature AT An outside air temperature detecting means, a gas cooler outlet side temperature detecting means for detecting the refrigerant outlet side temperature GT of the gas cooler, and a cooled space temperature detecting means for detecting the temperature PT of the cooled space cooled by the evaporator. The control means determines the difference e between the refrigerant outlet side temperature GT1 of the gas cooler detected by the gas cooler outlet side temperature detecting means and the outside air temperature AT detected by the outside air temperature detecting means for each temperature zone of the refrigerant outlet side temperature GT1 of the gas cooler. has a database constructed by storing, based on the temperature PT of the cooling space, starting compression means at a predetermined upper limit temperature HST of the object to be cooled space Executes thermo cycle and stops at the lower limit temperature LST, with outside air temperature detecting means for controlling the auxiliary throttle means on the basis of the outside air temperature AT for detecting, at the time of abnormality of the outdoor air temperature detection means, the gas cooler outlet side temperature detection means Since the difference e corresponding to the temperature zone to which the refrigerant outlet temperature GT1 of the gas cooler to be detected belongs is read from the database and the temperature having the difference e and the temperature having the difference e is substituted as the outside air temperature AT, the refrigerant outlet temperature of the gas cooler The difference e between the GT1 and the outside air temperature AT for each temperature zone is read from the database to obtain the outside air temperature AT, and the auxiliary throttle means can be controlled.

Therefore, it is possible to realize control with higher accuracy than in the conventional case where the control of the auxiliary throttle means is performed at a preset predetermined outside air temperature when the outside air temperature detecting means is abnormal. Therefore, appropriate backup control based on the refrigerant outlet side temperature GT1 of the gas cooler can be easily realized until the outside air temperature detecting means is repaired or replaced.

According to the invention of claim 3 , in each of the above-mentioned inventions , the difference e stored in the database is weighted to the average value or the latest value obtained at each timing immediately before starting the compression means. By using the average value, it becomes possible to realize backup control with higher accuracy.

According to the invention of claim 4 , in each of the above inventions, when both the outside air temperature detection means and the gas cooler outlet side temperature detection means are abnormal, the control means is a throttle means to a value that ensures a predetermined refrigerant flow rate, Alternatively, by maintaining the opening degree of the main throttle means and the auxiliary throttle means, it is possible to ensure oil return, avoid overload operation, and cool by the evaporator.

According to the invention of claim 5 , in each of the above-mentioned inventions, the control means includes an alarm means for notifying the abnormality of the temperature detection means, so that the user can detect an abnormality in the outside air temperature detection means or the gas cooler outlet side temperature detection means. It is possible to notify the fact that there has been, and to promptly perform maintenance work such as repair and replacement.

In particular, when carbon dioxide is used as the refrigerant as in the invention of claim 6 , in each of the above-described inventions, the refrigerant circuit becomes complicated, the number of detection means used for control increases, and the abnormality occurrence rate of the sensor increases. As described above, effective backup control can be realized against abnormality of the detecting means, and the cooling failure to the cooled space can be minimized.

It is a vertical side view of the freezer as an example which applies the present invention. It is a schematic perspective view of the freezing apparatus of this invention. It is a refrigerant circuit figure of the freezing apparatus of this invention. It is an electrical block diagram of a control apparatus. It is a figure which shows the relationship with target value ST with respect to outside temperature AT. It is a flowchart at the time of outside temperature sensor abnormality. (First estimation method) It is a flowchart at the time of outside temperature sensor abnormality. (Second estimation method) It is a figure which shows the database in FIG. It is a flowchart at the time of abnormality in a discharge gas temperature sensor. It is a flowchart at the time of the outlet side temperature sensor abnormality of an intermediate heat exchanger. (Second estimation method) It is a figure which shows the database in FIG. It is a flowchart at the time of the outlet side temperature sensor abnormality of an intermediate heat exchanger. (Third estimation method) It is a figure which shows the database in FIG. It is a flowchart which shows the opening degree Q1 determination method at the time of the inlet side temperature sensor abnormality of an intermediate heat exchanger. It is a figure which shows the database in FIG. It is a flowchart which shows the opening degree Q1 determination method at the time of the inlet side temperature sensor abnormality of an intermediate heat exchanger. It is a figure which shows the database in FIG. It is a flowchart at the time of the inlet side temperature sensor abnormality of an intermediate heat exchanger.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a longitudinal side view of a commercial freezer (low temperature storage) R as an embodiment to which a refrigeration apparatus 10 of the present invention is applied, FIG. 2 is a schematic perspective view of a refrigerator side unit of the refrigeration apparatus 10, and FIG. 3 is a refrigeration apparatus. 10 refrigerant circuit diagrams are respectively shown. The freezer R according to the embodiment is installed in a kitchen of a hotel or a restaurant, for example, and a main body is constituted by a heat insulating box 1 whose front opening 22 is closed by a door 6 so as to be freely opened and closed.

  The heat insulating box 1 is filled in an in-situ foaming manner between an outer box 2 made of a steel plate such as stainless steel, an inner box 3 incorporated in the outer box 2, and both inner and outer boxes 2, 3. It is made of polyurethane heat insulating material 4. And the inside of this heat insulation box 1 (inner box 3) is made into the storage room (space to be cooled) 5. A frame heater 15 as a dew condensation prevention heating means is disposed in contact with the surface of the outer box 2 on the side of the heat insulating material 4 around the edge of the front opening 22 of the heat insulating box 1.

  In addition, a cooling chamber 14 to which the evaporator 11 of the refrigeration apparatus 10 according to the present invention and the blower 12 for circulating cold air are attached is partitioned by a partition plate 13 in the upper portion of the storage chamber 5. The cold air sucked into the cooling chamber 14 from the storage chamber 5 by the cool air circulation blower 12 is exchanged with the evaporator 11 and then discharged from the opening at the rear of the cooling chamber 14 so that the inside of the storage chamber 5 has a predetermined temperature. To be cooled.

  On the other hand, a machine room 17 is defined on the top surface of the heat insulation box 1 by a front panel 16 and panels constituting both side surfaces and a rear surface. An opening 1A is formed on the top surface of the heat insulating box 1, and the opening 1A is closed by a unit plate 21 constituted by a heat insulating plate.

  On the upper surface of the unit plate 21, a compressor 18, a gas cooler 19, and a gas cooler for cooling the gas cooler 19 are located in the machine room 17 and constitute a well-known refrigeration cycle of the refrigeration apparatus 10 together with the evaporator 11. A blower (blower unit) 20, an electrical box 25, and the like are installed. On the lower surface of the unit plate 21, an evaporator 11 located in the cooling chamber 14 located in the upper part of the storage chamber 5 is provided.

  Here, the refrigerant circuit 7 of the refrigeration apparatus 10 in the present embodiment will be described with reference to the refrigerant circuit diagrams of FIGS. 2 and 3. In the refrigeration cycle of the refrigeration apparatus 10 in the present embodiment, carbon dioxide is enclosed as a refrigerant, and a split cycle (two-stage compression one stage) in which the refrigerant pressure (high pressure) on the high pressure side is equal to or higher than the critical pressure (supercritical). Adopt expansion intercooling cycle).

  The refrigerating apparatus 10 of the present embodiment includes a low-stage compression element (low-stage compression means) 18A that constitutes a compressor (compression means) 18 and a high-stage compression element (high-stage) that also constitutes a compression means. Side compression means) 18B, gas cooler 19, flow divider 37, merger 38, auxiliary expansion valve 39 as auxiliary throttle means, intermediate heat exchanger 40, internal heat exchanger 41, and main throttle means The refrigerant circuit 7 is composed of the expansion valve 8 and the evaporator 11.

  The gas cooler 19 dissipates heat from the high-temperature and high-pressure refrigerant discharged from the high-stage compression element 18B, thereby cooling the refrigerant discharged from the high-stage compression element 18B. The flow divider 37 divides the refrigerant from the gas cooler 19 into a first refrigerant flow and a second refrigerant flow, flows the first refrigerant flow to the sub circuit 42, and sends the second refrigerant flow to the main circuit 43. Shed.

  In the main circuit 43 through which the second refrigerant flow flows, the refrigerant diverted by the flow divider 37 includes an inner pipe (second flow path) 40B of the intermediate heat exchanger 40, an inner pipe 41B of the internal heat exchanger 41, The low-stage compression means is constructed by sequentially passing through the strainer 44, the expansion valve 8, the evaporator 11, the outer pipe 41A of the internal heat exchanger 41, the refrigerant introduction pipe 23 provided with the check valve 45, and the strainer 46. It is connected so as to be supplied to the suction side (low pressure part) of the compression element 18A.

  In the sub-circuit 42 through which the first refrigerant flow flows, the refrigerant diverted by the flow divider 37 sequentially passes through the strainer 47, the auxiliary expansion valve 39, and the outer pipe (first flow path) 40A of the intermediate heat exchanger 40. The high-stage side compression means is connected so as to be supplied to the suction side (intermediate pressure part) of the compression element 18B.

  The compressor 18 in the present embodiment includes an internal intermediate pressure two-stage compression in which a compression element 18A as a low-stage compression means and a compression element 18B as a high-stage compression means are accommodated in a single sealed container. A rotary compressor is used. These compression elements 18A and 18B are driven by a compressor motor (electric element, DC motor) housed in the same sealed container.

  Next, the control device (control means) 9 of the refrigeration apparatus 10 in the present embodiment will be described with reference to FIG. The control device 9 is composed of a general-purpose microcomputer and incorporates a timer 32 as a time limit means, an arithmetic processing unit 33, and a memory 34 as a storage means.

  A control panel 35 having various setting switches and a display unit is connected to the control device 9. The various setting switches include an LCD panel (setting means) 36 that can arbitrarily set each setting value as will be described in detail later.

  Further, on the input side of the control device 9, an internal temperature sensor (cooled space temperature detecting means) 31 for detecting a current temperature (internal temperature) PT in the storage chamber 5 (cooled space), an evaporator 11. An evaporator inlet-side temperature sensor 29 for detecting the refrigerant inlet-side temperature, an evaporator outlet-side temperature sensor 30 for detecting the refrigerant outlet-side temperature of the evaporator 11, and an outer pipe of the intermediate heat exchanger 40 (first Of the inlet side temperature sensor (inlet side temperature detecting means) 49 for detecting the inlet side temperature IMTI of 40A and the outlet side temperature IMTO of the outer pipe (first channel) 40A of the intermediate heat exchanger 40. An outlet side temperature sensor (outlet side temperature detecting means) 50 for detecting, a gas cooler outlet side temperature sensor (gas cooler outlet side temperature detecting means) 51 for detecting the refrigerant outlet side temperature GT of the gas cooler 19, and a high stage side compression Element 18B (compressed Discharge gas temperature discharge gas temperature sensor (discharge gas temperature sensing means DT for detecting a) 52, the outside air temperature sensor (outside air temperature detecting means for detecting the outside air temperature AT) 48, etc. of the step) is connected. In the present embodiment, the outside air temperature sensor 48 is disposed on the outer surface of the electrical equipment box 25 disposed in the machine room 17.

  On the other hand, on the output side of the control device 9, a compressor motor (DC motor) 18M that drives the compressor 18, a blower motor 12M that drives the blower 12 for circulating cold air, a blower motor 20M that drives the blower 20 for gas cooler, An expansion valve 8, an auxiliary expansion valve 39, a frame heater (condensation preventing heating means) 15, an alarm lamp 53 and the like are connected as alarm means. The alarm means may employ a buzzer in addition to the alarm lamp 53, and may display the alarm content on the display unit of the control panel 35.

  The compressor motor 18M is connected via an inverter device 25, whereby the operating frequency of the compressor motor 18M can be arbitrarily changed. The blower motors 12M and 20M are connected to each other via drive circuits 26 and 27 such as a chopper circuit, whereby the rotational speed can be arbitrarily changed.

  Further, the expansion valve 8 and the auxiliary expansion valve 39 respectively rotate the built-in stepping motor by an arbitrary angle according to the number of pulses of the drive voltage output from the control device 9, and this rotation amount is adjusted to the valve body valve. The valve opening is adjusted by converting the amount of advancement / retraction relative to the seat.

  With the above configuration, when the refrigeration apparatus 10 is operated by the control device 9, the refrigerant taken into the suction side (low pressure portion) of the low-stage compression element 18A of the compressor 18 is increased to the intermediate pressure here. . The refrigerant compressed by the low-stage compression element 18A is discharged into a sealed container through a communication pipe (not shown).

  The refrigerant introduction pipe whose one end is opened in the closed container is provided on the suction side of the high-stage compression element 18B, and the refrigerant whose pressure has been increased to the intermediate pressure by the low-stage compression element 18A The refrigerant mixed with the intermediate pressure refrigerant from the circuit 42 flows into the high-stage compression element 18B (intermediate pressure portion) from the refrigerant introduction pipe, and is further pressurized to a predetermined high pressure.

  At this time, the pressure of the refrigerant compressed by the high-stage compression element 18B (high-pressure side pressure HP) is set to a supercritical pressure, and the refrigerant in the supercritical state is passed through the refrigerant discharge pipe 24 to the gas cooler 19. Is flowed into. In the present embodiment, the compression elements 18A and 18B constituting the compressor 18 are integrally coupled by a single motor, but the present invention is not limited to this.

  The refrigerant that has exited the gas cooler 19 is cooled in the process of passing, and then enters the flow divider 37 and is divided into the sub circuit 42 through which the first refrigerant flow flows and the main circuit 43 through which the second refrigerant flow flows. The first refrigerant flow that has flowed into the sub-circuit 42 reaches the intermediate pressure (that is, the discharge pressure of the low-stage compression element 18A and substantially the same pressure as the suction pressure of the high-stage compression element 18B) at the auxiliary expansion valve 39. Depressurized.

  Then, in the process of passing through the outer pipe (first flow path) 40A of the intermediate heat exchanger 40 and passing through the outer pipe (first flow path) 40A, the flow divider 37 passes through the inner pipe 40B. Evaporates by exchanging heat with the second refrigerant flow, which is the other refrigerant flow after being divided in step (b). After that, the merger 38 joins the second refrigerant flow after being compressed by the low-stage compression element 18A, and is sucked into the high-stage compression element 18B (intermediate pressure part).

  On the other hand, the second refrigerant flow flowing into the main circuit 43 passes through the inner pipe (second flow path) 40B of the intermediate heat exchanger 40, and the first refrigerant is decompressed by the auxiliary expansion valve 39. After being cooled by exchanging heat with the flow, it passes through the inner pipe (second flow path) 41B of the internal heat exchanger 41. In the process of passing through the inner pipe (second flow path) 41B, the refrigerant is cooled by exchanging heat with the refrigerant discharged from the evaporator 11 flowing in the outer pipe (first flow path) 41A.

  The first refrigerant flow that has flowed out of the internal heat exchanger 41 is decompressed to the evaporation pressure by the expansion valve 8, and then flows into the evaporator 11 and uses the inside of the storage chamber 5 (cooled space) as a heat source. It evaporates and is sucked into the lower stage compression element 18 (low pressure part) through the outer tube 41A of the internal heat exchanger 41. Here, the refrigerant that flows into the expansion valve 8 is heat-exchanged with the low-temperature refrigerant that has flowed out of the evaporator 11 by the internal heat exchanger 41, so that the cooling performance can be improved.

  As described above, the refrigeration apparatus 10 of this embodiment is a natural refrigerant as a refrigerant, and uses carbon dioxide having a low critical pressure and a supercritical state of the high pressure of the refrigerant cycle. For this reason, it is possible to reduce the load on the environment and to secure the cooling capacity. Also, the second refrigerant flow that flows through the other divided main circuit 43 is cooled by the first refrigerant flow that flows through one of the sub-circuits 42 that has been cooled and separated by the gas cooler 19 and decompressed and expanded. Thus, by using a so-called split cycle cooling device, the specific enthalpy at the inlet of the evaporator 11 can be reduced and the refrigeration effect can be increased.

  As described above, when the refrigeration apparatus 10 is operated, the cold air exchanged with the evaporator 11 in the cooling chamber 14 is discharged to the storage chamber 5 by the cool air circulation blower 12 and circulated in the storage chamber 5. Thereafter, circulation is performed to return to the cooling chamber 14 by the blower 12 again.

(A-1) Operation Control of Compressor 18 At this time, the control device 9 operates the compressor motor 18M so that the temperature PT in the storage chamber 5 detected by the internal temperature sensor 31 is set as the cooling target temperature. Perform frequency control. That is, when the temperature PT is lower than the cooling target temperature, the operating frequency of the compressor motor 18M is decreased, and when it is higher, the operating frequency is increased.

  In addition to the frequency control of the compressor 18, the control device 9 has reached the predetermined upper limit temperature HST at which the current temperature PT in the storage chamber 5 detected by the internal temperature sensor 31 is higher than the cooling target temperature by a predetermined temperature. In this case, the compressor motor 18M is started, and when a predetermined lower limit temperature LST lower than the cooling target temperature is reached, a thermocycle for stopping the compressor motor 18M is executed, and the current temperature PT in the refrigerator is set as the cooling target. Control to temperature.

  In addition to the frequency control of the compressor 18, the control device 9 determines that the discharge gas temperature DT is equal to or higher than a predetermined value (abnormal value) based on the discharge gas temperature DT of the compressor 18 detected by the discharge gas temperature sensor 52. Is increased in the direction of decreasing the discharge gas temperature DT, that is, in the direction of decreasing the operating frequency of the compressor 18. This ensures safety.

(A-2) Opening Control of Expansion Valve 8 The control device 9 is configured such that the opening of the expansion valve 8 is detected by the evaporator inlet side temperature sensor 29, the refrigerant inlet side temperature of the evaporator 11, and the evaporator outlet side. Usually, the superheat degree is controlled by the refrigerant outlet side temperature of the evaporator 11 detected by the temperature sensor 30. When the temperature difference between the inlet side temperature and the outlet side temperature of the evaporator 11 is smaller than a predetermined temperature difference, the opening degree of the expansion valve 8 is reduced, and when it is larger, the opening degree is increased.

(A-3) Judgment determination of expansion valve 8 When the opening degree control of the expansion valve 8 is performed, when the control is performed near the valve closing point of the main throttle means by the device, the expansion valve is used to take the degree of superheat. If the opening degree of 8 is reduced too much, the valve closes, the degree of superheat is lost, and the opening degree may be further reduced. When the expansion valve 8 is closed, the refrigerant does not flow into the evaporator 11, and as a result, the refrigerant as the second refrigerant flow suddenly flows into the first refrigerant flow side in large quantities, so that intermediate heat exchange is performed. The outlet side temperature IMTO of the first refrigerant flow in the vessel 40 rapidly decreases.

  Therefore, the control device 9 detects that the outlet side temperature IMTO is detected at a predetermined sampling cycle by the intermediate heat exchanger outlet side temperature sensor 50, and the expansion valve 8 is closed when the temperature falls below a predetermined temperature. to decide.

  When the blockage of the expansion valve 8 is detected, the control device 9 performs control to forcibly expand the expansion valve 8 to a predetermined opening.

(A-4) Operation Control of Gas Cooler Blower 20 The control device 9 determines the rotation speed of the gas cooler blower 20 based on the outside air temperature AT detected by the outside air temperature sensor 48 provided in the electrical box 25 in the machine room 17. Control. That is, the higher the outside air temperature AT detected by the outside air temperature sensor 48, the higher the rotation speed of the gas cooler blower 20, and the lower the outside air temperature AT, the lower the rotation speed of the blower 20 is controlled. Thereby, energy saving operation is realized while improving the cooling efficiency in the gas cooler 19.

(A-5) Energization control of the frame heater 15 The control device 9 is a temperature between the current temperature PT in the storage chamber 5 detected by the internal temperature sensor 31 and the outside air temperature AT detected by the outside air temperature sensor 48. The difference is calculated, and energization control is performed such that the energization rate of the frame heater 15 is increased as the temperature difference is larger, and the energization rate of the frame heater 15 is decreased as the temperature difference is smaller. For example, when the temperature difference is 20 ° C., the current ratio is 57%, when the temperature difference is 25 ° C., the current ratio is 72%, when the temperature difference is 30 ° C., the current ratio is 84%, and when the temperature difference is 35 ° C., the current ratio is 96%. And Thereby, the energization rate of the frame heater 15 is increased at the time of high outside air temperature at which condensation is likely to occur, and condensation that occurs near the front opening 22 of the main body can be effectively prevented. Further, at a low outside temperature at which dew condensation is unlikely to occur, it is possible to save energy while effectively preventing the occurrence of dew condensation by reducing the energization rate of the frame heater 15.

(A-6) Opening Control of Auxiliary Expansion Valve 39 When controlling the opening of the auxiliary expansion valve 39, the control device 9 first detects the outside air temperature AT by the outside air temperature sensor 48 at a predetermined sampling period. To the storage unit 34.

  Then, the target value IMTI1 of the inlet side temperature IMTI of the outer pipe 40A of the intermediate heat exchanger 40 is calculated from the current outside air temperature AT acquired as described above. At this time, the control device 9 calculates the inlet side temperature target value IMTI1 using a predetermined function formula based on the outside air temperature AT.

  In the present embodiment, as shown in the diagram showing the relationship between the outside air temperature AT and the target value ST in FIG. 5, the control device 9 uses the outside air temperature AT as x and the inlet side temperature target value IMTI1 as y. The target value IMTI1 is calculated using the function. The function formula is stored in advance in the storage unit 34 of the control device 9.

  In this embodiment, carbon dioxide whose high-pressure side pressure HP is in the supercritical region is used as the refrigerant. Therefore, the linear function (function formula) is saturated when the high-pressure side pressure HP of the refrigerant circuit is in the supercritical region. The slope is different depending on the area. Specifically, as shown in FIG. 5, the slope of the functional expression becomes larger when the ambient temperature AT is around 30 ° C. or higher, for example, near the supercritical temperature of the carbon dioxide, compared to when it is lower than 30 ° C.

  This is because, when carbon dioxide is used as the refrigerant, the high pressure side pressure HP is in the supercritical region when the outside air temperature AT is 30 ° C. or higher, and therefore the outside air temperature AT in which the high pressure side pressure HP is in the saturation region is less than 30 ° C. Compared to the case, the fluctuation of the appropriate intermediate pressure due to the increase in the outside air temperature AT becomes larger. Therefore, the inlet-side temperature target value IMTI1 is changed so that the intermediate pressure is appropriate following the state of the high-pressure side pressure.

  As described above, the control device 9 acquires the inlet side temperature target value IMTI1 of the intermediate heat exchanger 40 for the outside air temperature AT from the taken outside air temperature AT using the linear function. Then, the control device 9 compares the acquired target value IMTI1 with the inlet side temperature IMTI detected and taken in earlier, and sets the opening of the auxiliary expansion valve 39 so that the inlet side temperature IMTI becomes the target value IMTI1. Control. At this time, the pulse control of the operation amount is performed in such a direction that the valve opening degree of the auxiliary expansion valve 39 is further narrowed as the inlet side temperature IMTI is higher than the target value IMTI1, and the valve opening degree is further opened as the inlet side temperature IMTI is lower.

  In the opening degree control of the auxiliary expansion valve 39, the control device 9 detects the discharge gas temperature DT of the compressor 18 detected by the discharge gas temperature sensor 52 at a predetermined sampling period, and the discharge gas temperature DT is predetermined. When it rises above the value (abnormal value), the opening degree of the auxiliary expansion valve 39 is controlled in the direction of decreasing the discharge gas temperature DT, that is, in the direction of expanding the auxiliary expansion valve 39. This ensures safety.

(A-7) Temperature difference control of the auxiliary expansion valve 39 The opening degree control of the auxiliary expansion valve 39 is not limited to the control based on the inlet side temperature IMTI, but detects the outlet side temperature IMTO as in this embodiment. In the refrigeration apparatus 10 including the intermediate heat exchanger outlet side temperature sensor 50, the difference IMTe between the outlet side temperature IMTO and the inlet side temperature IMTI of the intermediate heat exchanger 40 of the first refrigerant flow is a predetermined temperature difference target value. You may control an opening degree so that it may become.

  In this case, when the detected temperature difference IMTe is smaller than the temperature difference target value, the opening degree of the auxiliary expansion valve 39 is reduced, and when it is larger, the opening degree is enlarged. Thereby, by optimizing the flow rate of the first refrigerant flow, optimal flow rate control between the first refrigerant flow and the second refrigerant flow divided thereby is realized, and the efficiency improvement effect by the split cycle is achieved. Can be demonstrated.

  As described above, each temperature sensor (outside air temperature sensor 48, gas cooler outlet side temperature sensor 51, intermediate heat exchanger 40 inlet side temperature sensor 49, outlet side temperature sensor 50, compressor discharge gas temperature sensor 52) When it functions normally, the above control is performed. On the other hand, a case where an abnormality occurs due to a failure of each temperature sensor will be described in detail below.

(B) Control when the outside air temperature sensor 48 is abnormal As shown in the above (A-4), (A-5), and (A-6), the outside air temperature AT detected by the outside air temperature sensor 48 is a gas cooler. It is used for operation control of the air blower 20, energization control of the frame heater 15, and opening degree control of the auxiliary expansion valve 39. When an abnormality occurs due to a failure or the like in the outside air temperature sensor 48 used for each control, the control device 9 detects the gas cooler detected by the gas cooler outlet side temperature sensor 51 immediately before starting the compressor 18 executing the thermocircle. The outside air temperature AT is estimated on the basis of the refrigerant outlet side temperature GT1, and backup control of each control is executed. There are a plurality of methods for estimating the outside air temperature AT based on the refrigerant outlet side temperature GT1 of the gas cooler, which will be described in detail below. Note that the control device 9 determines whether or not the resistance value of the outside air temperature sensor 48 is an abnormal value (too small or too large) at a predetermined sampling period, and thereby detects the occurrence of an abnormality.

(B-1) First Estimation Method of Outside Air Temperature AT In the first estimation method, the control device 9 detects the refrigerant outlet side temperature of the gas cooler 19 detected by the gas cooler outlet side temperature sensor 51 when the outside air temperature sensor 48 is abnormal. GT1 or a temperature (GT1-e1) having a certain difference e1 (for example, −2 deg) from the refrigerant outlet side temperature GT1 is used as the outside air temperature AT.

  Therefore, as shown in the flowchart of FIG. 6, when the control device 9 detects an abnormality in the outside air temperature sensor 48 in step S <b> 1, the outside air is turned on by the lighting of the alarm lamp (alarm means) 53 and the display unit of the control panel 35. While notifying the abnormality of the temperature sensor 48, the process proceeds to step S2, and as an outside air temperature AT used for operation control of each gas cooler blower 20, energization control of the frame heater 15, and opening control of the auxiliary expansion valve 39, provisionally, The refrigerant outlet side temperature GT1 of the gas cooler 19 detected by the gas cooler outlet side temperature sensor 51 is used. If it is known in advance that the refrigerant outlet side temperature GT1 of the gas cooler 19 immediately before the compressor 18 and the actual outside air temperature AT have a predetermined temperature difference (for example, -2 deg), the refrigerant outlet side temperature A temperature (GT1−e1) having a certain difference e1 (in this case −2 deg) from GT1 may be used as the outside air temperature AT used for each control.

  Then, the control device 9 proceeds to step S3, determines whether or not the compressor 18 is currently operating the compressor 18 in the thermocycle, and detects the current in the storage chamber 5 detected by the internal temperature sensor 31. When the temperature PT reaches a predetermined lower limit temperature LST that is a predetermined temperature lower than the cooling target temperature and the compressor motor 18M is stopped (thermo-off), the process proceeds to step S4.

  In step S4, the control device 9 detects the refrigerant outlet side temperature GT1 of the gas cooler 19 with the gas cooler outlet side temperature sensor 51, and is constant with the refrigerant outlet side temperature GT1 or the refrigerant outlet side temperature GT1 as described above. The temperature having the difference e1 (GT1-e1) is stored in the memory 34 as the outside air temperature AT.

  Then, the control device 9 proceeds to step S5, where the current temperature PT in the storage chamber 5 detected by the internal temperature sensor 31 reaches a predetermined upper limit temperature HST that is higher than the cooling target temperature by a predetermined temperature, and the compressor motor 18M. Whether or not is activated (thermo-on) is determined. When the compressor 18 is not started, the process returns to step S4, and the refrigerant outlet side temperature GT1 of the gas cooler 19 is detected again by the gas cooler outlet side temperature sensor 51, and the refrigerant outlet side temperature GT1 or the refrigerant outlet is detected. The temperature (GT1-e1) having a certain difference e1 from the side temperature GT1 is rewritten in the memory 34 as the outside air temperature AT.

  In step S5, when the compressor 18 is started, at this time, the refrigerant outlet side temperature GT1 of the gas cooler immediately before starting the compressor 18 stored in the memory 34 or a constant difference e1 from this is set. The temperature (GT1-e1) that is included is adopted as the outside air temperature AT, and the operation control of each gas cooler blower 20, the energization control of the frame heater 15, and the opening degree control of the auxiliary expansion valve 39 are performed.

  Specifically, the operation control of the gas cooler blower 20 when the outside air temperature sensor 48 is abnormal has a refrigerant outlet side temperature GT1 of the gas cooler immediately before starting the substituted compressor 18 or a certain difference e1 from this. The higher the temperature (GT1-e1), the higher the rotation speed of the gas cooler blower 20, and the lower the refrigerant outlet side temperature GT1 or (GT1-e1) of the gas cooler immediately before starting the compressor, the lower the rotation speed of the blower 20. Take control.

  The energization control of the frame heater 15 when the outside air temperature sensor 48 is abnormal includes the current temperature PT in the storage chamber 5 detected by the internal temperature sensor 31 and the refrigerant outlet of the gas cooler immediately before starting the substituted compressor 18. The temperature difference between the side temperature GT1 or the temperature having a certain difference e1 (GT1-e1) is calculated, and the larger the temperature difference, the larger the energization rate of the frame heater 15, and the smaller the temperature difference, Energization control for reducing the energization rate of the frame heater 15 is performed.

  The opening degree control of the auxiliary expansion valve 39 when the outside air temperature sensor 48 is abnormal has a refrigerant outlet side temperature GT1 of the gas cooler immediately before starting the compressor 18 substituted for the outside air temperature AT or a constant difference e1 therewith. Based on the temperature (GT1-e1), a target value IMTI1 of the inlet side temperature of the outer pipe 40A of the intermediate heat exchanger 40 is calculated using a predetermined relational expression. Then, the opening degree of the auxiliary expansion valve 39 is controlled so that the inlet side temperature IMTI detected by the intermediate heat exchanger inlet side temperature sensor 49 becomes the inlet side temperature target value IMTI1.

  Thereafter, the control device 9 returns from step 5 to step S3, and rewrites the estimated outside air temperature AT each time the compressor 18 is started by the thermocycle control of the compressor 18, and thereafter, similarly for each gas cooler. Operation control of the blower 20, energization control of the frame heater 15, and opening control of the auxiliary expansion valve 39 are performed. Therefore, since the estimated outside air temperature AT is not changed except at the timing when the compressor 18 is started, the refrigerant outlet side temperature GT1 of the gas cooler detected immediately before the start of the previous compressor 18 or until it is changed. Then, the temperature (GT1-e1) having a certain difference e1 from this is continuously estimated as the outside air temperature AT and each control is performed.

  As a result, the compressor 19 has a temperature approximate to the ambient temperature AT, which is the ambient temperature, between the time when the compressor 18 is stopped and the next time it is started by the execution of the thermocycle control of the compressor 18. The outside air temperature AT is estimated from the refrigerant outlet side temperature GT1 of the gas cooler 19 immediately before starting, and the rotational speed control of the gas cooler blower 20, the energization control of the frame heater 15, and the opening degree control of the auxiliary expansion valve 39 are executed. It becomes possible.

  Therefore, as usual, when the outside air temperature sensor 48 is abnormal, the rotational speed control of the gas cooler blower 20, the energization control of the frame heater 15, and the opening degree control of the auxiliary expansion valve 39 are set as a predetermined outside air temperature AT set in advance. Compared with the case where it performs, it becomes possible to implement | achieve control with higher precision. Therefore, appropriate backup control can be realized until the outside temperature sensor 48 is repaired or replaced.

  In the present embodiment, the refrigerant outlet side temperature GT1 of the gas cooler 19 immediately before starting the compressor 18 is the gas cooler at a predetermined sampling period from the stop of the compressor 18 in the thermocycle control of the compressor 18 until the start. 19 refrigerant outlet side temperatures GT1 are detected and sequentially rewritten in the memory 34, and the refrigerant outlet side temperature GT1 or GT1-e1 stored in the memory 34 immediately before starting the compressor 18 is used as the outside air temperature AT. . However, the present invention is not limited to this. For example, when a predetermined delay time is provided from the stop to the start of the compressor 18, the control device 9 detects the gas cooler outlet side temperature sensor just before the end of the delay time. 51, the refrigerant outlet side temperature GT1 of the gas cooler 19 is detected, and the refrigerant outlet side temperature GT1 of the gas cooler 19 immediately before starting the compressor 18 or GT1-e1 having a certain difference with this is substituted for the outside air temperature AT. Also good.

  In the estimation method of the outside air temperature AT, when the outside air temperature sensor 48 is abnormal, the refrigerant outlet side temperature GT1 of the gas cooler 19 detected by the gas cooler outlet side temperature sensor 51 or a temperature having a certain difference from the refrigerant outlet side temperature GT. Since GT1-e1 is set to the outside air temperature AT, backup control can be easily realized.

(B-2) Second Estimation Method of Outside Air Temperature AT In the second estimation method, the control device 9 detects the refrigerant outlet side temperature of the gas cooler 19 detected by the gas cooler outlet side temperature sensor 51 when the outside air temperature sensor 48 is abnormal. It has a database constructed by storing the difference e between GT1 and the outside air temperature AT detected by the outside air temperature sensor for each temperature zone of the refrigerant outlet side temperature GT1 of the gas cooler 19, and when the outside air temperature sensor 48 is abnormal, The difference e corresponding to the temperature zone to which the refrigerant outlet side temperature GT1 of the gas cooler 19 detected by the gas cooler outlet side temperature sensor 51 belongs is read from the database, and the refrigerant outlet side temperature GT1 and the temperature having the difference e are substituted as the outside air temperature AT. .

  Therefore, as shown in the flowchart of FIG. 7, first, the control device 9 proceeds to step S7 when the outside air temperature sensor 48 and the gas cooler outlet side temperature sensor 51 are normal (step S6), and in the thermocycle of the compressor 18. The refrigerant outlet temperature GT1 of the gas cooler 19 immediately before the compressor is started (thermo-on) is detected by the gas cooler outlet temperature sensor 51, and the outside air temperature AT is detected by the outside air temperature sensor 48 at the same time as or before or after the detection timing. The method for detecting the refrigerant outlet temperature GT1 may be the same as the estimation method 1.

  Then, the control device 9 calculates a difference e between the refrigerant outlet side temperature GT1 of the gas cooler 19 immediately before the compressor start and the outside air temperature AT detected by the normally functioning outside air temperature sensor 48, and the refrigerant of the gas cooler 19 is calculated. The data is stored in the memory 34 for each temperature zone of the outlet side temperature GT1, and a database is constructed.

  For example, as shown in FIG. 8, the database divides the refrigerant outlet side temperature GT1 of the gas cooler 19 into temperature zones of 10 ° C. or lower, 10 to 20 ° C., 20 to 30 ° C., 30 ° C. or higher, respectively. The difference e between the temperature GT1 and the outside air temperature AT is stored as A1, A2, A3, A4.

  Then, the control device 9 proceeds to step S8, and the difference e between the refrigerant outlet side temperature GT1 and the outside air temperature AT is a value obtained at each timing immediately before the compressor 18 is started (thermo-on) for each temperature zone. The average value or the average value Ave in which the weight is placed on the latest value, for example, the average value of the previous average value Ave and the latest value e ((AVe + e) / 2) is stored in the database.

  If an abnormality of the outside air temperature sensor 48 is detected in step S9, the abnormality of the outside air temperature sensor 48 is notified by turning on the alarm lamp (alarm means) 53 and the display part of the control panel 35, and in step S10. move on. As in the first estimation method, the gas cooler outlet side temperature sensor 51 detects the refrigerant outlet side temperature GT1 of the gas cooler 19 just before the compressor 18 is started, and the temperature range to which the refrigerant outlet side temperature GT1 belongs is detected. The difference e between the corresponding refrigerant outlet side temperature GT1 and the outside air temperature AT is read from the database stored in the memory 34.

  The control device 9 estimates the temperature having the detected refrigerant outlet side temperature GT1 and the read difference e as the outside air temperature AT, and controls the operation of each gas cooler blower 20, the energization control of the frame heater 15, and the auxiliary expansion valve. 39 is controlled.

  More specifically, the operation control of the gas cooler blower 20 when the outside air temperature sensor 48 is abnormal is based on the difference e read from the refrigerant outlet side temperature GT1 of the gas cooler immediately before starting the substituted compressor 18 and the database. The higher the temperature, the higher the rotational speed of the gas cooler blower 20, and the lower the temperature having the difference e read from the refrigerant outlet side temperature GT1 of the gas cooler immediately before starting the compressor, the lower the rotational speed of the blower 20 is. Control to lower.

  The energization control of the frame heater 15 when the outside air temperature sensor 48 is abnormal includes the current temperature PT in the storage chamber 5 detected by the internal temperature sensor 31 and the refrigerant outlet of the gas cooler immediately before starting the substituted compressor 18. The temperature difference between the side temperature GT1 and the temperature having the difference e read from the database is calculated. The larger the temperature difference is, the larger the energization rate of the frame heater 15 is. Energization control is performed to reduce the energization rate.

  The opening degree control of the auxiliary expansion valve 39 when the outside air temperature sensor 48 is abnormal is based on the difference e read from the refrigerant outlet side temperature GT1 of the gas cooler immediately before starting the compressor 18 substituted for the outside air temperature AT and the database e. Based on the temperature, the target value IMTI1 of the inlet side temperature of the outer pipe 40A of the intermediate heat exchanger 40 is calculated using a predetermined relational expression. Then, the opening degree of the auxiliary expansion valve 39 is controlled so that the inlet side temperature IMTI detected by the intermediate heat exchanger inlet side temperature sensor 49 becomes the inlet side temperature target value IMTI1.

  Also in the case of the second estimation method, the estimated outside air temperature AT is rewritten every time the compressor 18 is started by the thermocycle control of the compressor 18 as in the first estimation method, and thereafter the same. In addition, operation control of each gas cooler blower 20, energization control of the frame heater 15, and opening control of the auxiliary expansion valve 39 are performed.

  Also by this, usually, by executing the thermocycle control of the compressor 18, the outside air temperature AT is estimated based on the refrigerant outlet side temperature GT1 of the gas cooler 19 immediately before the start of the compressor 18 which becomes an approximate temperature, and the gas cooler It is possible to execute the rotational speed control of the blower 20 and the energization control of the frame heater 15, and further the opening degree control of the auxiliary expansion valve 39.

  Therefore, as usual, when the outside air temperature sensor 48 is abnormal, the rotational speed control of the gas cooler blower 20, the energization control of the frame heater 15, and the opening degree control of the auxiliary expansion valve 39 are set as a predetermined outside air temperature AT set in advance. Compared with the case where it performs, it becomes possible to implement | achieve control with higher precision. Therefore, appropriate backup control can be realized until the outside temperature sensor 48 is repaired or replaced.

  Further, in the estimation method of the outside air temperature AT, when the outside air temperature sensor 48 and the refrigerant outlet side temperature sensor 51 are normal, the outside air temperature AT and the compressor 18 immediately before starting the compressor 18 for each temperature zone of the refrigerant outlet side temperature GT1. The difference e between the refrigerant outlet side temperature GT1 is constructed as a database, and when the outside air temperature sensor 48 is abnormal, the temperature having the difference e constructed in the database and the gas cooler outlet side temperature GT1 immediately before starting the compressor is set as the outside air temperature AT. As a result, it is possible to easily implement backup control with higher accuracy.

  In particular, in this embodiment, the difference e between the outside air temperature AT constructed in the database and the refrigerant outlet side temperature GT1 immediately before the compressor 18 is started is a value obtained at each timing immediately before the compressor 18 is started (thermo-on). By adopting the average value, it becomes possible to realize backup control with higher accuracy. At this time, when an average value in which the weight is placed on the latest value is adopted, the difference e can be calculated in consideration of the aging of the device, and the accuracy can be further improved.

  Further, in the backup control employing the first and second estimation methods, when the occurrence of an abnormality in the outside air temperature sensor 48 is detected, the control device uses the alarm lamp 53 or the display unit of the control panel 35 to display the outside air temperature. By notifying the sensor 48 of an abnormality, it is possible to promptly perform maintenance work such as repair and replacement.

(B-3) Control at the time of abnormality of both the outside air temperature sensor 48 and the gas cooler outlet side temperature sensor 51 In addition to the abnormality of the outside air temperature sensor 48, the control device 9 also detects the abnormality of the gas cooler outlet side temperature sensor 51. In this case, the outside air temperature AT as described above cannot be estimated using the gas cooler outlet side temperature sensor 51. For this reason, the control device 9 controls the gas cooler blower 20 with the rotation speed fixed to a predetermined rotation speed, and controls the power supply with the energization rate of the frame heater 15 fixed to a predetermined value.

  Further, the control device 9 maintains the opening degree of the expansion valve 8 and the auxiliary expansion valve 39 at a value (a specified opening degree of opening) that ensures a predetermined refrigerant flow rate. In the case of the auxiliary expansion valve 39, the value at which the predetermined refrigerant flow rate is ensured is an opening larger than the average value in the normal control range in which oil return can be ensured. The opening degree is larger than the average value in the normal control range in which cooling by the evaporator 11 can be ensured.

  As a result, it is possible to ensure smooth oil return, avoid overload operation, and ensure cooling by the evaporator 11.

  In addition to the abnormality of the outside air temperature sensor 48, the control device 9 also detects the abnormality of the gas cooler outlet side temperature sensor 51 and the alarm lamp 53 and the display part of the control panel 35. Notifies that the gas cooler outlet side temperature sensor 51 is abnormal. This makes it possible to promptly perform maintenance work such as repair and replacement.

  As described above, when the outside air temperature sensor is abnormal, the control is performed in the split cycle (two-stage compression / one-stage expansion intermediate) in which the refrigerant pressure (high pressure) on the high pressure side is higher than the critical pressure (supercritical) as in this embodiment. The refrigeration apparatus is not limited to the refrigeration apparatus 10, and the same effect can be obtained even with a refrigeration apparatus that constitutes a normal refrigeration cycle.

(C) Control at the time of abnormality of the discharge gas temperature sensor 52 As shown in the above (A-1) and (A-6), the discharge gas temperature DT detected by the discharge gas temperature sensor 52 is determined by the compressor 18. It is used for operating frequency control and opening control of the auxiliary expansion valve 39. When an abnormality occurs due to a failure or the like in the discharge gas temperature sensor 52 used for each control, the control device 9 detects that the outside air temperature AT detected by the outside air temperature sensor 48 is higher than the predetermined outside air temperature AT1. The opening frequency of the auxiliary expansion valve 39 is controlled by setting the operating frequency to a constant low value that is assumed to prevent the discharge gas temperature DT from rising, and increasing the inlet temperature target value IMTI1 so that the discharge gas temperature does not rise. Perform backup control. Note that the control device 9 determines whether or not the resistance value of the discharge gas temperature sensor 52 is an abnormal value (too small or too large) at a predetermined sampling period, and thereby detects the occurrence of an abnormality.

  Hereinafter, specific control when the discharge gas temperature sensor 52 is abnormal will be described with reference to the flowchart of FIG. First, when the controller 9 detects an abnormality in the discharge gas temperature sensor 52 in step S11, the alarm lamp (alarm means) 53 is turned on and the display unit of the control panel 35 displays the discharge gas temperature sensor 52. While notifying abnormality, it progresses to step S12 and it is judged whether backup frequency control of the operation frequency control of each compressor 18 and the opening degree control of the auxiliary expansion valve 39 is performed. If the control panel 35 is set in advance to execute backup control when the discharge gas temperature sensor 52 is abnormal, the process proceeds to step S13. If not set, the process proceeds to step S18, and the compressor 18 is operated. Or the auxiliary expansion valve 39 is changed to a sufficiently large valve opening determined for each outside air temperature AT.

  If execution of the backup control is set in step S12, the outside temperature AT detected by the outside temperature sensor 48 in step S13 is a predetermined outside temperature AT1 stored in the memory 34, for example, 25 ° C. or more. Determine whether or not. Here, when the outside air temperature AT is 25 ° C. or more, the control device 9 proceeds to step S14, and the operation frequency of the compressor 18 is assumed to be a constant low value that is assumed that the discharge gas temperature DT does not rise, that is, Then, it is set to a value that has been confirmed beforehand that the increase in the discharge gas temperature DT is within the allowable value, for example, 40 Hz, which is a lower frequency in the operable frequency range.

  Thereafter, the control device 9 proceeds to step S15, and sets the inlet side temperature target value IMTI1 used for opening control of the auxiliary expansion valve 39 by a predetermined value, for example, by 5 ° C. That is, in the opening degree control of the auxiliary expansion valve 39, the inlet side temperature target value IMTI1 of the intermediate heat exchanger 40 for the outside air temperature AT is acquired from the taken outside air temperature AT using the predetermined linear function described above, and the In step S15, this inlet side target value is added by 5 ° C. to obtain the inlet side target value IMTI2, and compared with the inlet side temperature IMTI detected and taken in earlier, the inlet side temperature IMTI becomes the corrected target value IMTI2. The opening degree of the auxiliary expansion valve 39 is controlled.

  Therefore, in this situation where the outside air temperature AT is high, the inlet side temperature IMTI is controlled to be higher than the target value IMTI2 compared to the case where the outside air temperature AT is equal to or lower than the predetermined temperature. The opening is controlled to be more open.

  On the other hand, in step S13, when the outside air temperature AT detected by the outside air temperature sensor 48 is less than a predetermined outside air temperature AT1, for example, 25 ° C., the process proceeds to step S16 without executing the backup control, and the compressor The process proceeds to step S17 without changing the operation frequency 18 and the target value IMTI1 of the inlet side temperature of the intermediate heat exchanger.

  In this manner, even when the outside gas temperature DT is estimated to rise by using the outside air temperature AT that is normally in a causal relationship with the rise in the discharged gas temperature DT, the outside air temperature AT becomes a predetermined high outside air temperature AT1. The compressor 18 can be continuously operated at a low operating frequency that is assumed to prevent the discharge gas temperature DT from rising without stopping the compressor 18.

  When the outside air temperature AT is higher than the predetermined outside air temperature AT1, the opening degree control of the auxiliary expansion valve 39 is performed using the corrected target value IMTI2 obtained by increasing the inlet side temperature target value IMTI1 so as to ensure a predetermined refrigerant flow rate. Therefore, the flow rate of the refrigerant flowing through the first refrigerant flow that cools the second refrigerant flow toward the evaporator 11 in the intermediate heat exchanger 40 can be appropriately ensured, and the rise in the discharge gas temperature can be suppressed. In addition, it is possible to ensure oil return and cooling by the evaporator 11.

  Therefore, appropriate backup control can be realized until the discharge gas temperature sensor 52 is repaired or replaced.

  In particular, the predetermined outside air temperature AT1 for estimating whether or not the discharge gas temperature DT is abnormally high is a value that is confirmed in advance that the increase in the discharge gas temperature DT is within an allowable value. By doing so, it is possible to further ensure safety.

  Further, the predetermined outside air temperature AT1 is the state in which the discharge gas temperature sensor 52 is functioning normally and the outside air temperature AT detected by the outside air temperature sensor 48 is equal to or lower than the predetermined outside air temperature AT1. When the opening degree of the auxiliary expansion valve 39 is expanded and changed by the increase in the discharge gas temperature DT detected by the discharge gas temperature sensor 52, the discharge gas temperature DT becomes abnormally high at the outside air temperature. The memory 34 is rewritten and changed to the new outdoor temperature AT1 as the new outdoor temperature AT1. Then, in the backup control when the discharge gas temperature sensor 52 is abnormal, the changed predetermined outside air temperature AT1 is employed. Thereby, it is possible to realize backup control with higher accuracy.

  Thereafter, the control device 9 proceeds to step S16, and determines whether or not the intermediate heat exchanger inlet side temperature sensor 49 is abnormal. If there is no abnormality, the process returns to step S11 to continue the backup control. On the other hand, if there is an abnormality, the process proceeds to step S18, and the abnormality of the inlet side temperature sensor 49 is notified in addition to the discharge gas temperature sensor 52 by the lighting of the alarm lamp (alarm means) 53 and the display part of the control panel 35. Then, the compressor 18 is stopped or the auxiliary expansion valve 39 is changed to a sufficiently large valve opening determined for each temperature of the outside air temperature AT.

  Thus, in addition to the abnormality of the discharge gas temperature sensor 52, when the abnormality occurs in the inlet side temperature sensor 49, the opening degree control of the suitable auxiliary expansion valve 39 cannot be performed. By stopping, safety can be ensured.

  In the backup control, when the occurrence of abnormality in the discharge gas temperature sensor 52 or the inlet side temperature sensor 49 is detected, the control device 9 causes the alarm lamp 53 or the display unit of the control panel 35 to display the discharge gas temperature sensor 52 or By notifying that there is an abnormality in the inlet side temperature sensor 49, it is possible to promptly perform maintenance work such as repair and replacement.

(D) Control at the time of abnormality of the outlet side temperature sensor 50 As shown in the above (A-3) and (A-7), the first refrigerant of the intermediate heat exchanger 40 detected by the outlet side temperature sensor 50 The outlet side temperature IMTO of the flow is used for blockage determination of the expansion valve 8 and temperature difference control of the auxiliary expansion valve 39. When an abnormality occurs due to a failure or the like in the outlet side temperature sensor 50 used for each control, the control device 9 performs backup control of each control based on the inlet side temperature IMTI detected by the inlet side temperature sensor 49. To do. The blockage determination of the expansion valve 8 is performed by estimating the outlet side temperature IMTO based on the inlet side temperature IMTI detected by the inlet side temperature sensor 49, and the outlet side temperature IMTO based on the inlet side temperature IMTI is determined. There are a plurality of estimation methods, which will be described in detail below. Note that the control device 9 determines whether or not the resistance value of the outlet side temperature sensor 50 is an abnormal value (too small or too large) at a predetermined sampling period, and thereby detects the occurrence of an abnormality.

(D-1) First Estimating Method for the Outlet Side Temperature IMTO In the first estimating method, the control device 9 uses the first intermediate heat exchanger 40 detected by the inlet side temperature sensor 49 when the outlet side temperature sensor 50 is abnormal. The temperature (IMTI + IMTe1) having a certain difference IMTe1 (for example, +10 deg) from the inlet side temperature IMTI of one flow path is used as the outlet side temperature IMTO.

  Therefore, when the controller 9 detects an abnormality in the outlet side temperature sensor 50, the controller 9 notifies the abnormality of the outlet side temperature sensor 50 by lighting the alarm lamp (alarm means) 53 and the display unit of the control panel 35, and the expansion. As the outlet side temperature IMTO used for determining the closing of the valve 8, a temperature (IMTI + IMTe1) having a certain difference IMTe1 from the inlet side temperature IMTI detected by the inlet side temperature sensor 49 is used.

  When the estimated outlet side temperature IMTO (in this case, IMTI + IMTe1) falls below a predetermined temperature, it is determined that the expansion valve 8 is closed. When the control device 9 detects the blockage of the expansion valve 8, the control device 9 performs control to forcibly expand the expansion valve 8 by a predetermined opening degree.

  As a result, it is possible to determine whether or not the expansion valve 8 is blocked by using the inlet side temperature IMTI that is normally controlled to have a predetermined temperature difference from the outlet side temperature IMTO. Therefore, as in the conventional case, when the outlet side temperature sensor 50 is abnormal, the main throttle means expansion valve is more accurate than when the expansion valve 8 is fixed at a predetermined opening. 8 control can be realized. Therefore, appropriate backup control can be realized until the outlet side temperature sensor 50 is repaired or replaced.

  In particular, in the first estimation method, by performing expansion valve blockage determination in which the temperature having a certain difference IMTe1 from the inlet side temperature IMTI is used as the outlet side temperature IMTO, the inlet side when the outlet side temperature sensor 50 is abnormal is determined. Backup control based on the temperature IMTI can be easily realized.

(D-2) Second estimation method of outlet side temperature IMTO In the second estimation method, the control device 9 calculates the difference IMTe between the inlet side temperature IMTI and the outlet side temperature IMTO for each temperature zone of the outside air temperature AT. When the outlet side temperature sensor 50 is abnormal, the difference IMTe corresponding to the temperature zone to which the outside temperature AT detected by the outside temperature sensor 48 belongs is read from the database, and the inlet side temperature IMTI is stored. The temperature having the difference IMTe is used as the outlet side temperature IMTO.

  Therefore, as shown in the flowchart of FIG. 10, first, the control device 9 proceeds to step S21 when the outlet side temperature sensor 50 and the inlet side temperature sensor 49 are normal (step S20), and at a predetermined sampling cycle, The outlet side temperature IMTO is detected by the outlet side temperature sensor 50, the inlet side temperature IMTI is detected by the inlet side temperature sensor 49, and the outside air temperature sensor 48 detects the outside air temperature AT at the same time as or before or after the detection timing. To do.

  Then, when the control device 9 is stable during operation of the compressor 18, for example, when the opening degree control of the auxiliary expansion valve 39 is performed by the method (A-6), the inlet side temperature sensor 49 is used. Is in a range close to the target value IMTI1, for example, the absolute value of the difference between the inlet side temperature IMTI and the target value IMTI1 is less than a predetermined value KF (IMTI-IMTI1 <± KF), the difference IMTe between the outlet side temperature IMTO detected by the outlet side temperature sensor 50 functioning normally and the inlet side temperature IMTI detected by the inlet side temperature sensor 49 at that time is calculated. The data is stored in the memory 34 for each temperature zone of the outside air temperature AT detected by the outside air temperature sensor 48, and a database is constructed.

  For example, as shown in FIG. 11, the database divides the outdoor air temperature AT into temperature zones of 10 ° C. or lower, 10-20 ° C., 20-30 ° C., 30 ° C. or higher, and the outlet side temperature IMTO and the inlet side temperature, respectively. The difference IMTe from IMTI is stored as B1, B2, B3, B4.

  Then, the control device 9 proceeds to step S22, and the difference IMTe between the outlet side temperature IMTO and the inlet side temperature IMTI is an average value for each temperature zone of the values obtained for each predetermined sampling period, or the latest The value is stored in the database as an average value AVIMTe with weights placed thereon, for example, an average value of the previous average value AVIMTe and the latest value IMTe ((AVMTe + IMTe) / 2).

  In step S23, when an abnormality of the outlet side temperature sensor 50 is detected, the abnormality of the outlet side temperature sensor 50 is notified by turning on the alarm lamp (alarm means) 53 and the display part of the control panel 35. Proceed to S24. Then, the outside air temperature AT is detected by the outside air temperature sensor 48, and the difference IMTe between the outlet side temperature IMTO and the inlet side temperature IMTI corresponding to the temperature zone to which the outside air temperature AT belongs is read from the database stored in the memory 34.

  The control device 9 detects the inlet-side temperature IMTI at that time by the inlet-side temperature sensor 49, and outputs the temperature (IMTI + IMTe) having the difference IMTe read from the inlet-side temperature IMTI and the outside air temperature AT to the outlet-side temperature IMTO. It is estimated that the expansion valve 8 is closed.

  That is, when the estimated outlet side temperature IMTO (in this case, IMTI + IMTe) falls below a predetermined temperature, it is determined that the expansion valve 8 is closed. When the control device 9 detects the blockage of the expansion valve 8, the control device 9 performs control to forcibly expand the expansion valve 8 by a predetermined opening degree.

  Also in the case of the second estimation method, as with the first estimation method, the expansion valve 8 is normally controlled using the inlet side temperature IMTI that is controlled to be a predetermined temperature difference from the outlet side temperature IMTO. It becomes possible to determine occlusion. Therefore, the control of the expansion valve 8 can be performed with higher accuracy than in the conventional case where the opening of the expansion valve 8 is fixed at a predetermined opening when the outlet side temperature sensor 50 is abnormal. Can be realized. Therefore, appropriate backup control can be realized until the outlet side temperature sensor 50 is repaired or replaced.

  Further, in the estimation method of the outlet side temperature IMTO, when the outlet side temperature sensor 50 and the inlet side temperature sensor 49 are normal, the outlet side temperature IMTO and the inlet side temperature IMTI are set for each temperature zone of the outside air temperature AT. The difference IMTe is constructed as a database, and when the outlet side temperature sensor 50 is abnormal, the difference IMTe corresponding to the outside air temperature AT at that time is added to the detected inlet side temperature IMTI to obtain the outlet side temperature IMTO. By using the estimation, backup control based on the inlet side temperature IMTI when the outlet side temperature sensor 50 is abnormal can be easily realized with higher accuracy.

(D-3) Third estimation method of the outlet side temperature IMTO In the third estimation method, the control device 9 calculates the difference IMTe between the inlet side temperature IMTI and the outlet side temperature IMTO for each temperature zone of the inlet side temperature IMTI. When the outlet side temperature sensor 50 is abnormal, the difference IMTe corresponding to the temperature zone to which the inlet side temperature IMTI detected by the inlet side temperature sensor 49 belongs is read from the database. The temperature having the temperature IMTI and the difference IMTe is used as the outlet side temperature IMTO.

  Therefore, as shown in the flowchart of FIG. 12, first, the control device 9 proceeds to step S26 when the outlet side temperature sensor 50 and the inlet side temperature sensor 49 are normal (step S25), and at a predetermined sampling period, The outlet side temperature IMTO is detected by the outlet side temperature sensor 50, and the inlet side temperature IMTI is detected by the inlet side temperature sensor 49.

  Then, when the control device 9 is stable during operation of the compressor 18, for example, when the opening degree control of the auxiliary expansion valve 39 is performed by the method (A-6), the inlet side temperature sensor 49 is used. Is in a range close to the target value IMTI1, for example, the absolute value of the difference between the inlet side temperature IMTI and the target value IMTI1 is less than a predetermined value KF (IMTI-IMTI1 <± KF), the difference IMTe between the outlet side temperature IMTO detected by the outlet side temperature sensor 50 functioning normally and the inlet side temperature IMTI detected by the inlet side temperature sensor 49 at that time is calculated. The data is stored in the memory 34 for each temperature zone of the inlet side temperature IMTI, and a database is constructed.

  For example, as shown in FIG. 13, the database divides the inlet side temperature IMTI into temperature zones of 10 ° C. or lower, 10-20 ° C., 20-30 ° C., 30 ° C. or higher. The difference IMTe from the temperature IMTI is stored as C1, C2, C3, C4.

  Then, the control device 9 proceeds to step S27, and the difference IMTe between the outlet side temperature IMTO and the inlet side temperature IMTI is an average value for each temperature zone of the values obtained for each predetermined sampling period, or the latest The value is stored in the database as an average value AVIMTe with weights placed thereon, for example, an average value of the previous average value AVIMTe and the latest value IMTe ((AVMTe + IMTe) / 2).

  In step S28, when an abnormality of the outlet side temperature sensor 50 is detected, the abnormality of the outlet side temperature sensor 50 is notified by turning on the alarm lamp (alarm means) 53 and the display part of the control panel 35. Proceed to S29. Then, the inlet side temperature sensor 49 detects the inlet side temperature IMTI, and a database in which the difference IMTe between the outlet side temperature IMTO corresponding to the temperature zone to which the inlet side temperature IMTI belongs and the inlet side temperature IMTI is stored in the memory 34 is stored. Read from.

  The control device 9 detects the inlet side temperature IMTI at that time by the inlet side temperature sensor 49, estimates the temperature having the difference IMTe read from the inlet side temperature IMTI (IMTI + IMTe) as the outlet side temperature IMTO, Judgment of the expansion valve 8 is performed.

  That is, when the estimated outlet side temperature IMTO (in this case, IMTI + IMTe) falls below a predetermined temperature, it is determined that the expansion valve 8 is closed. When the control device 9 detects the blockage of the expansion valve 8, the control device 9 performs control to forcibly expand the expansion valve 8 by a predetermined opening degree.

  Also in the case of the third estimation method, like the first and second estimation methods, the inlet side temperature IMTI that is normally controlled to be a predetermined temperature difference from the outlet side temperature IMTO is used. It is possible to determine whether the expansion valve 8 is blocked. Therefore, the control of the expansion valve 8 can be performed with higher accuracy than in the conventional case where the opening of the expansion valve 8 is fixed at a predetermined opening when the outlet side temperature sensor 50 is abnormal. Can be realized. Therefore, appropriate backup control can be realized until the outlet side temperature sensor 50 is repaired or replaced.

  Further, in the method of estimating the outlet side temperature IMTO, when the outlet side temperature sensor 50 and the inlet side temperature sensor 49 are normal, the outlet side temperature IMTO and the inlet side temperature IMTI for each temperature zone of the inlet side temperature IMTI. Difference IMTe is constructed as a database, and when the outlet side temperature sensor 50 is abnormal, the difference IMTe corresponding to the inlet side temperature IMTI at that time is added to the detected inlet side temperature IMTI. By estimating and using IMTO, backup control based on the inlet side temperature IMTI when the outlet side temperature sensor 50 is abnormal can be easily realized with higher accuracy.

  In particular, in the second and third estimation methods, the difference IMTe between the outlet side temperature IMTO and the inlet side temperature IMTI constructed in the database is obtained by adopting an average value obtained for each predetermined sampling period. Therefore, it becomes possible to realize backup control with higher accuracy. At this time, when an average value in which the weight is placed on the latest value is adopted, the difference e can be calculated in consideration of the aging of the device, and the accuracy can be further improved.

  Furthermore, each outlet side temperature IMTO and inlet side temperature IMTI used for the construction of the database can be obtained by adopting an average value of values obtained for each predetermined sampling period at the time of stable cooling during the operation of the compressor 18. Highly accurate control can be realized.

  In the backup control employing the first to third estimation methods, when the abnormality of the outlet-side temperature sensor 50 is detected, the control device uses the warning lamp 53 or the display unit of the control panel 35 to exit. By notifying that there is an abnormality in the side temperature sensor 50, it is possible to promptly prompt maintenance work such as repair and replacement.

(D-4) Control at the time of abnormality of both the outlet side temperature sensor 50 and the inlet side temperature sensor 49 The control device 9 detects the abnormality of the inlet side temperature sensor 49 in addition to the abnormality of the outlet side temperature sensor 50. In this case, it is impossible to determine whether or not the expansion valve 8 is closed by estimating the outlet side temperature IMTO based on the inlet side temperature sensor 49 as described above. Therefore, the control device 9 performs control in which the opening degree of the expansion valve 8 is maintained at a value (a specified opening degree that is open) that ensures a predetermined refrigerant flow rate. The value at which the predetermined refrigerant flow rate is ensured is an opening that is larger than an average value in a normal control range in which cooling by the evaporator 11 can be ensured.

  Thereby, obstruction | occlusion of the expansion valve 8 can be prevented and the overload driving | operation of the compressor 18 by excessive throttling can be avoided. Further, it is possible to ensure smooth oil return and cooling by the evaporator 11.

  In addition to the abnormality of the outlet side temperature sensor 50, the control device 9 detects the abnormality of the inlet side temperature sensor 49, and the outside air outlet side temperature sensor is displayed on the alarm lamp 53 or the display part of the control panel 35. 50 and the inlet side temperature sensor 49 are informed. This makes it possible to promptly perform maintenance work such as repair and replacement.

(D-5) Auxiliary expansion valve control when the outlet side temperature sensor is abnormal Next, a backup when the outlet side temperature sensor 50 is abnormal when the temperature difference control of the auxiliary expansion valve 39 shown in (A-7) is performed. Control will be described. First, when the control device 9 detects an abnormality of the outlet side temperature sensor 50 during the temperature difference control of the auxiliary expansion valve 39, the control device 9 turns on the alarm lamp (alarm means) 53 and controls the control panel 35. The abnormality of the outlet side temperature sensor 50 is notified by the display unit.

  Then, the control device 9 detects the inlet side temperature detected by the inlet side temperature sensor 49 as shown in (A-6) from the temperature difference control of the auxiliary expansion valve 39 in (A-7) which has been performed so far. The process proceeds to opening control of the auxiliary expansion valve 39 based on IMTI.

  Specifically, when controlling the valve opening degree of the auxiliary expansion valve 39, the control device 9 first detects the inlet side temperature IMTI with the inlet side temperature sensor 49 at a predetermined sampling period, and further detects the outside air temperature sensor. At 48, the outside air temperature AT is detected. A target value IMTI1 of the inlet side temperature IMTI is calculated from the current inlet side temperature IMTI and the outside air temperature AT.

  Then, the opening degree of the auxiliary expansion valve 39 is controlled so that the inlet temperature IMTI becomes the target value IMTI1. At this time, the pulse control of the operation amount is performed in such a direction that the valve opening degree of the auxiliary expansion valve 39 is further narrowed as the inlet side temperature IMTI is higher than the target value IMTI1, and the valve opening degree is further opened as the inlet side temperature IMTI is lower.

  As a result, when the outlet side temperature sensor 50 is abnormal as in the prior art, it is possible to achieve more accurate control than when the auxiliary expansion valve 39 is controlled at a predetermined opening degree. Become. Therefore, appropriate backup control can be realized until the outlet side temperature sensor 50 is repaired or replaced.

  Also in this case, the control device 9 informs that there is an abnormality in the outlet side temperature sensor 50 on the alarm lamp 53 or the display part of the control panel 35, so that maintenance work such as repair / replacement can be performed at an early stage. Can be encouraged.

(E) Control at the time of abnormality of the inlet side temperature sensor 49 As shown in the above (A-6) or (A-7), the first of the intermediate heat exchanger 40 detected by the inlet side temperature sensor 49 The outlet side temperature IMTI of the refrigerant flow is used for opening degree control of the auxiliary expansion valve 39. When an abnormality occurs due to a failure or the like in the inlet side temperature sensor 49 used for the control, the control device 9 sets the opening Q of the auxiliary expansion valve 39 to a predetermined opening Q1, and in that state, the discharge gas temperature sensor When the discharge gas temperature DT of the compressor 18 detected by 52 rises to a predetermined value or higher, backup control for expanding the opening Q of the auxiliary expansion valve 39 is executed. There are a plurality of methods for determining the predetermined opening Q1, which will be described in detail below. The control device 9 determines whether or not the resistance value of the inlet side temperature sensor 49 is an abnormal value (too small or too large) at a predetermined sampling period, thereby detecting the occurrence of an abnormality.

(E-1) First Determination Method of Predetermined Opening Q1 In the first determination method, the control device 9 stores the opening Q of the auxiliary expansion valve 39 for each temperature zone of the outside air temperature AT. When the inlet side temperature sensor 49 is abnormal, it has a built database, and the opening degree Q corresponding to the temperature zone to which the outside temperature AT detected by the outside temperature sensor 48 belongs is read from the database, and backup control is performed as a predetermined opening degree Q1. I do.

  Therefore, as shown in the flowchart of FIG. 14, first, the control device 9 proceeds to step S31 when the outside air temperature sensor 48 and the inlet side temperature sensor 49 are normal (step S30), and at a predetermined sampling period, the outside air temperature sensor 48 The temperature AT is detected by the outside air temperature sensor 48, and the opening Q of the auxiliary expansion valve 39 is detected (acquired) at the same time as the detection timing or before and after.

  And the control apparatus 9 is an inlet side temperature sensor when the opening degree control of the auxiliary | assistant expansion valve 39 is performed by the method of said (A-6) at the time of the cooling stable in the driving | operation of the compressor 18, for example. When the inlet side temperature IMTI detected at 49 is in a range close to the target value IMTI1, for example, when the absolute value of the difference between the inlet side temperature IMTI and the target value IMTI1 is less than the predetermined value KF (IMTI-IMTI1 < ± KF), the outside air temperature sensor 48 detects the outside air temperature AT, and the opening Q of the auxiliary expansion valve 39 at that time is stored in the memory 34 for each temperature zone of the outside air temperature AT at that time, and a database is constructed. To do.

  When the opening degree control of the auxiliary expansion valve 39 is performed by the temperature difference control (A-7), the outlet side temperature sensor 50 detects the cooling stability during the operation of the compressor 18. When the temperature difference IMTe between the outlet side temperature IMTO and the inlet side temperature IMTI detected by the inlet side temperature sensor 49 is in a range close to a predetermined temperature difference target value, for example, the temperature difference IMTe and the temperature difference target value The database is constructed when the absolute value of the difference is less than the predetermined value KG when the cooling is stable.

  For example, as shown in FIG. 15, the database divides the outside air temperature AT into temperature zones of 10 ° C. or lower, 10-20 ° C., 20-30 ° C., 30 ° C. or higher, and the opening Q of the auxiliary expansion valve 39, respectively. Are stored as D1, D2, D3, and D4.

  Then, the control device 9 proceeds to step S32, and the opening Q of the auxiliary expansion valve 39 is weighted to the average value for each temperature zone or the most recent value of the values obtained for each predetermined sampling period. The stored average value AVQ, for example, the average value of the previous average value AVQ and the latest value Q ((AVQ + Q) / 2) is stored in the database.

  In step S33, when an abnormality of the inlet side temperature sensor 49 is detected, the abnormality of the inlet side temperature sensor 49 is notified by turning on the alarm lamp (alarm means) 53 and the display part of the control panel 35. Proceed to S34. Then, the outside air temperature sensor 48 detects the outside air temperature AT, reads the opening degree Q of the auxiliary expansion valve 39 corresponding to the temperature zone to which the outside air temperature AT belongs, from the database stored in the memory 34, and the predetermined opening degree Q1. (Initial valve opening after correction at the time of backup control).

(E-2) Second Determination Method of Predetermined Opening Q1 In the second determination method, the control device 9 stores the opening Q of the auxiliary expansion valve 39 for each temperature zone of the outlet side temperature IMTO. When the inlet side temperature sensor 49 is abnormal, the opening degree Q corresponding to the temperature zone to which the outlet side temperature IMTO detected by the outlet side temperature sensor 50 belongs is read from the database, and the predetermined opening degree Q1 As a backup control. Since the backup control uses the outlet side temperature sensor 50 of the intermediate heat exchanger 40, the outlet side temperature sensor 50 is used for determining the closing of the expansion valve 8 as described above. This is particularly effective when the opening degree control of the auxiliary expansion valve 39 is performed by the temperature difference control shown in (A-7).

  Therefore, as shown in the flowchart of FIG. 16, first, the control device 9 proceeds to step S36 when the outlet side temperature sensor 50 and the inlet side temperature sensor 49 are normal (step S35), and at a predetermined sampling period, The outlet side temperature IMTO is detected by the outlet side temperature sensor 50, and the opening Q of the auxiliary expansion valve 39 is detected (acquired) at the same time as the detection timing or before and after.

  And the control apparatus 9 makes the exit side temperature sensor 50 into the outlet side temperature sensor 50, when the temperature difference control of the auxiliary | assistant expansion valve 39 is performed by the method of said (A-7) at the time of the cooling stable in the driving | operation of the compressor 18, for example. When the temperature difference IMTe between the outlet side temperature IMTO detected by the inlet side and the inlet side temperature IMTI detected by the inlet side temperature sensor 49 is in a range close to a predetermined temperature difference target value, for example, the temperature difference IMTe and the temperature difference When the absolute value of the difference from the target value is less than the predetermined value KG, when cooling is stable, the outlet side temperature sensor 50 detects the outlet side temperature IMTO, and the opening degree Q of the auxiliary expansion valve 39 at that time is Each time the outlet side temperature IMTO is stored in the memory 34, a database is constructed.

  For example, as shown in FIG. 17, the database divides the outlet side temperature IMTO into temperature zones of 10 ° C. or lower, 10-20 ° C., 20-30 ° C., 30 ° C. or higher, and the opening degree of the auxiliary expansion valve 39. Q is stored as E1, E2, E3, E4.

  Then, the control device 9 proceeds to step S37, and the opening degree Q of the auxiliary expansion valve 39 is weighted to the average value for each temperature zone of the values obtained for each predetermined sampling period or the latest value. The stored average value AVQ, for example, the average value of the previous average value AVQ and the latest value Q ((AVQ + Q) / 2) is stored in the database.

  In step S38, if an abnormality of the inlet side temperature sensor 49 is detected, the abnormality of the inlet side temperature sensor 49 is notified by turning on the alarm lamp (alarm means) 53 and the display part of the control panel 35. Proceed to S39. Then, the outlet side temperature sensor 50 detects the outlet side temperature IMTO, reads the opening degree Q of the auxiliary expansion valve 39 corresponding to the temperature zone to which the outlet side temperature IMTO belongs, from the database stored in the memory 34, Let it be an opening Q1 (initial valve opening after correction at the time of backup control).

(E-3) Backup control using the predetermined opening Q1 determined by the first or second determination method Here, the predetermined opening Q1 determined by the first or second determination method as described above The backup control using this will be described with reference to the flowchart of FIG. First, when the controller 9 detects an abnormality of the inlet side temperature sensor 49 in step S40, the controller 9 detects the abnormality of the inlet side temperature sensor 49 by lighting the alarm lamp (alarm means) 53 and the display unit of the control panel 35. While notifying, it progresses to step S41. Then, the opening degree Q of the auxiliary expansion valve 39 is changed from the current opening degree to the predetermined opening degree Q1 determined by the first or second determination method as described above as the retraction valve opening degree.

  Then, the control device 9 determines whether or not the compressor 18 is in operation (step S42), and is not in operation, that is, the compressor 18 is stopped (thermo-off) in the thermocycle operation of the compressor 18. If it is, the process returns to step S41, and again, the opening Q of the auxiliary expansion valve 39 is set to the predetermined opening Q1 determined by the first or second determination method, and the compressor 18 is started. (Thermo-ON) In the initial stage, the opening Q of the auxiliary expansion valve 39 is set to the opening of the retraction valve.

  In step S42, if the compressor 18 is in operation, the process proceeds to step S43, and the control device 9 performs a predetermined sampling on the discharge gas temperature DT of the compressor 18 detected by the discharge gas temperature sensor 52. When the discharge gas temperature DT is detected at a cycle and rises to a predetermined high temperature (predetermined value) or more, control is performed to expand the opening Q of the auxiliary expansion valve 39 by a predetermined opening.

  As a result, the compressor 18 in the thermocycle operation of the compressor 18 is compared with the case where the control of the auxiliary expansion valve 39 is fixed at a predetermined opening when the inlet side temperature sensor 49 is abnormal as in the prior art. At start-up (thermo-on), the opening degree Q1 determined by the first or second method is set as the retraction valve opening degree, and then the opening degree of the auxiliary expansion valve 39 is expanded in consideration of the discharge gas temperature DT. Therefore, it is possible to realize safer and more accurate control. Accordingly, appropriate backup control can be realized until the inlet side temperature sensor 49 is repaired or replaced.

  In particular, the initial opening degree Q1 of the auxiliary expansion valve 39 when an abnormality occurs in the inlet side temperature sensor 49 is stored for each temperature zone of the outside air temperature AT based on the database constructed in the normal state in the first determination method. In the second determination method, the opening degree is stored more normally for each temperature zone of the outlet side temperature IMTO by the database constructed at the normal time, and the opening degree at that time is set to a predetermined opening degree Q1, thereby making it more normal. It becomes possible to control using the opening degree Q of the auxiliary expansion valve 39 approximated to the control at the time. As a result, more accurate backup control can be realized.

  In particular, the opening Q1 (retraction valve opening) of the auxiliary expansion valve 39, which is changed when an abnormality occurs in the inlet side temperature sensor 49, is a value obtained at every predetermined sampling period in any of the determination methods. By adopting the average value, it becomes possible to realize backup control with higher accuracy. At this time, when an average value in which the weight is placed on the latest value is adopted, the opening degree Q1 can be set in consideration of aging of the device, and the accuracy can be further improved.

  Further, the opening degree of the auxiliary expansion valve 39 used for the construction of the database is more accurate by adopting an average value obtained at every predetermined sampling period when the cooling is stable during the operation of the compressor 18. Control can be realized.

  In the backup control, when the occurrence of an abnormality in the inlet side temperature sensor 49 is detected, the control device 9 confirms that there is an abnormality in the inlet side temperature sensor 49 on the alarm lamp 53 or the display part of the control panel 35. By notifying, it becomes possible to promptly perform maintenance work such as repair and replacement.

  In particular, in the present embodiment, in the refrigeration apparatus 10 using carbon dioxide as the refrigerant, a so-called two-stage compression single-stage expansion intercooling cycle in which the refrigerant pressure on the high-pressure side (high-pressure) is equal to or higher than the critical pressure as described above. By adopting it, the refrigerant circuit 7 becomes complicated, and the number of sensors (detection means) used for control increases. Therefore, the increase in the number of sensors also increases the sensor abnormality occurrence rate. However, as described above, each temperature sensor (outside air temperature sensor 48, gas cooler outlet side temperature sensor 51, intermediate heat exchanger 40 inlet side temperature sensor 49, Since effective backup control can be realized against abnormalities in the outlet side temperature sensor 50 and the discharge gas temperature sensor 52) of the compressor, the cooling failure to the storage chamber 5 (cooled space) is minimized. be able to.

R Commercial freezer (low temperature storage)
1 Insulation box 5 Storage room (cooled space)
7 Refrigerant circuit 8 Expansion valve (throttle means, main throttle means)
9 Control device (control means)
DESCRIPTION OF SYMBOLS 10 Refrigeration apparatus 11 Evaporator 12 Blower for cold air circulation 15 Frame heater (heating means for preventing condensation)
17 Machine room 18 Compressor (compression means)
18A Low stage side compression element 18B High stage side compression means 19 Gas cooler 20 Gas cooler blower (blower means)
22 Front opening 23 Refrigerant introduction pipe 29 Evaporator inlet side temperature sensor 30 Evaporator outlet side temperature sensor 31 Inside temperature sensor (cooled space temperature detecting means)
32 timer (time limit means)
33 arithmetic processing unit 34 memory (storage means)
35 Control panel 36 LCD panel (setting means)
37 Divider 38 Merger 39 Auxiliary expansion valve (auxiliary throttle means)
40 Intermediate heat exchanger 40A Outer pipe (first flow path through which the first refrigerant flow flows)
40B Inner pipe (second flow path through which second refrigerant flow flows)
41 Internal heat exchanger 41A Outer pipe 41B Inner pipe 42 Sub circuit 43 Main circuit 45 Check valve 48 Outside air temperature sensor (outside air temperature detecting means)
49 Intermediate heat exchanger inlet side temperature sensor (inlet side temperature detection means)
50 Intermediate heat exchanger outlet side temperature sensor (outlet side temperature detection means)
51 Gas cooler outlet side temperature sensor (gas cooler outlet side temperature detection means)
52 Discharge gas temperature sensor (discharge gas temperature detection means)
53 Alarm lamp (alarm means)

Claims (6)

In the refrigeration apparatus in which the refrigerant circuit is configured by the compression means, the gas cooler, the throttle means, and the evaporator,
A blowing means for cooling the gas cooler;
Heating means for preventing condensation for heating a portion where condensation occurs due to cooling by the evaporator;
Control means for controlling the compression means, the throttling means, the air blowing means, and the dew condensation preventing heating means;
An outside air temperature detecting means for detecting the outside air temperature AT;
A gas cooler outlet side temperature detecting means for detecting a refrigerant outlet side temperature GT of the gas cooler;
A cooled space temperature detecting means for detecting a temperature PT of the cooled space cooled by the evaporator,
The control means calculates the difference e between the refrigerant outlet side temperature GT1 of the gas cooler detected by the gas cooler outlet side temperature detecting means and the outside air temperature AT detected by the outside air temperature detecting means, from the refrigerant outlet side temperature GT1 of the gas cooler. It has a database constructed by storing each temperature zone, and based on the temperature PT of the cooled space detected by the cooled space temperature detecting means, the compression is performed at a predetermined upper limit temperature HST of the cooled space. And the thermocycle which starts at the lower limit temperature LST is executed, and the air blowing means and / or the dew condensation preventing heating means are controlled based on the outside air temperature AT detected by the outside air temperature detecting means,
When the outside air temperature detecting means is abnormal, the difference e corresponding to the temperature zone to which the refrigerant outlet side temperature GT1 of the gas cooler detected by the gas cooler outlet side temperature detecting means belongs is read from the database, and the refrigerant outlet side temperature GT1. And a temperature having the difference e as a substitute for the outside air temperature AT . The compression means, the gas cooler, the auxiliary throttle means, the intermediate heat exchanger, the main throttle means, and the evaporator constitute a refrigerant circuit, and the refrigerant discharged from the gas cooler is divided into two flows, and the first The refrigerant flow is passed through the auxiliary throttle means to the first flow path of the intermediate heat exchanger, the second refrigerant flow is flowed to the second flow path of the intermediate heat exchanger, and then the main throttle means The first refrigerant flow and the second refrigerant flow are exchanged in the intermediate heat exchanger, and the refrigerant discharged from the evaporator is transferred to the low pressure portion of the compression means. In the refrigerating apparatus for sucking and sucking the first refrigerant flow from the intermediate heat exchanger into the intermediate pressure part of the compression means,
Control means for controlling the compression means, the auxiliary throttle means and the main throttle means;
An outside air temperature detecting means for detecting the outside air temperature AT;
A gas cooler outlet side temperature detecting means for detecting a refrigerant outlet side temperature GT of the gas cooler;
A cooled space temperature detecting means for detecting a temperature PT of the cooled space cooled by the evaporator,
The control means calculates the difference e between the refrigerant outlet side temperature GT1 of the gas cooler detected by the gas cooler outlet side temperature detecting means and the outside air temperature AT detected by the outside air temperature detecting means, from the refrigerant outlet side temperature GT1 of the gas cooler. It has a database constructed by storing each temperature zone, and based on the temperature PT of the cooled space detected by the cooled space temperature detecting means, the compression is performed at a predetermined upper limit temperature HST of the cooled space. And the auxiliary throttle means is controlled based on the outside air temperature AT detected by the outside air temperature detecting means.
When the outside air temperature detecting means is abnormal, the difference e corresponding to the temperature zone to which the refrigerant outlet side temperature GT1 of the gas cooler detected by the gas cooler outlet side temperature detecting means belongs is read from the database, and the refrigerant outlet side temperature GT1. And a temperature having the difference e as a substitute for the outside air temperature AT . The difference e stored in the database is an average value obtained immediately before starting the compression means, or an average value obtained by weighting the latest value. Item 3. The refrigeration apparatus according to Item 2. When both the outside air temperature detecting means and the gas cooler outlet side temperature detecting means are abnormal, the control means sets the throttle means or the main throttle means and the auxiliary throttle means to a value that ensures a predetermined refrigerant flow rate. The refrigeration apparatus according to any one of claims 1 to 3, wherein the opening degree is maintained. The refrigerating apparatus according to any one of claims 1 to 4, wherein the control means includes alarm means for notifying abnormality of the temperature detection means. The refrigeration apparatus according to any one of claims 1 to 5, wherein carbon dioxide is used as the refrigerant.

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