JP2015232411A - Freezing device system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezing device system for executing a pull-down operation in which a freezer temperature control, a reliability assurance of a freezing device system and a reduction of operation consumption power are attained.SOLUTION: A control means described above divides a pull-down operation C into three segments, i.e. a preferential cooling operation area C1 in which a temperature range reaching a thermo-off set temperature Tis cooled until a freezer temperature T becomes a frequency shift set temperature Tor less and an intake pressure P becomes a frequency shift set suction pressure Por less with a driving frequency (f) of a compressor being applied as the first driving frequency f; a preferential stable suction pressure operation area C2 in which the driving frequency (f) of the compressor is being decreased in speed while the frequency shift set suction pressure Pis being kept; and a preferential high COP operation area C3 in which cooling is carried out to get the thermo-off set temperature Twith the driving frequency (f) of the compressor being applied as the second driving frequency fthat is an efficient driving frequency set on the basis of the pre-input compressor information, and then the compressor driving frequency (f) is updated in correspondence with each of the temperature ranges.

Description

  The present invention relates to a refrigeration system, and more particularly, to a drive frequency control of a compressor during pull-down operation in a refrigeration system having a compressor capable of changing a drive frequency.

  The refrigeration system includes a refrigeration cycle configured by connecting a compressor, a condenser, an expansion valve, and an evaporator with refrigerant piping, and is cooled by exchanging heat with the refrigerant in the evaporator (cooled medium ( Supply the air in the refrigerator) to the refrigerator. The refrigeration system is roughly divided into a condensing unit having a compressor and a condenser, a cooler disposed in the refrigerator and having an expansion valve and an evaporator, and a controller for controlling the operation thereof. ing.

  The controller stores a thermo-on set temperature and a thermo-off set temperature in advance. The controller compares the refrigerator internal temperature detected by the internal temperature sensor with the thermo-on set temperature and thermo-off set temperature, and outputs an operation command signal to the condensing unit or cooler according to the result. The refrigeration system is controlled. That is, when the internal temperature becomes equal to or higher than the thermo-on set temperature, the controller outputs a command signal for starting the operation of the refrigeration cycle to the condensing unit and the cooler. Thus, the condensing unit control device drives and controls the compressor and drives the condenser fan, and the cooler control device drives the evaporator fan and cools the internal air cooled by the evaporator to the refrigerator. Circulate within. When the internal temperature becomes lower than the thermo-off set temperature, the controller outputs a command signal for stopping the operation of the refrigeration cycle to the condensing unit or the cooler. As a result, the condensing unit controller stops the compressor and condenser fans, and the cooler controller stops the evaporator fans.

  An index of the refrigerator cooling load is the compressor suction pressure. That is, when the internal cooling load is large, such as when the internal temperature is high, the suction pressure increases due to the characteristics of the refrigerant. In addition, when the internal cooling load is small, such as when the internal temperature is low, the suction pressure is low. Using this characteristic, during normal operation of the condensing unit, the drive frequency is increased or decreased according to the suction pressure of the compressor (cooling load in the refrigerator). Note that if the drive frequency is decelerated without following the actual internal cooling load (compressor suction pressure), the amount of refrigerant circulating decreases, resulting in an increase in the apparent internal cooling load, resulting in a reduction in intake pressure. To rise. When the suction pressure exceeds the specification range of the refrigeration system, the compressor becomes abnormally hot, and if the state continues for a long time, the compressor is damaged and the reliability is lowered.

  Due to reasons such as intrusion heat when the outside temperature is high, frequent replacement of stored items in the refrigerator, etc. The temperature may be higher than a certain temperature above the thermo-on temperature. In this case, the compressor is operated at a high rotational speed (relatively high driving frequency) in order to prevent damage to the stored articles in the refrigerator and further to keep the suction pressure of the compressor within the specification range of the refrigeration system. Perform pull-down operation to cool the refrigerator rapidly.

  Here, in order to suppress the power consumption of the refrigeration system, attention is paid to the control of the compressor that occupies most of the power consumption, and a control method is known in which the compressor drive frequency during the pull-down operation is gradually reduced.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2013-152040), each set rotational speed of the cooling compressor is set to a constant rotational speed corresponding to each temperature range allocated until reaching the target temperature, In the cooling compressor control device that gradually decreases the set rotational speed in the process of pull-down cooling to the target temperature, at least one temperature range among the temperature ranges is a cooling performance parameter corresponding to each of the set rotational speeds. A cooling compressor control device is disclosed which is assigned by a function formed based on a ratio between them (see claim 1).

JP2013-152040A

  In general, the COP (Coefficient Of Performance) of the refrigeration system reaches a maximum value in a specific rotation speed range (for example, a range of 1500 rpm to 2500 rpm) of the compressor rotation speed (drive frequency).

  For this reason, when the compressor is operated at a high rotation speed (for example, 4500 rpm) in the initial stage of the pull-down operation, the COP of the refrigeration system decreases according to the operation time. On the other hand, if the compressor is not operated at a high rotational speed, the cooling rate of the internal temperature decreases, and the required time from the start of operation until the target internal temperature is reached is facilitated. This will cause damage to the goods. As described above, the COP and the required time in the cooling technology are in a trade-off relationship, and it is practically impossible to maximize both merits at the same time.

  On the other hand, in the cooling compressor control device disclosed in Patent Literature 1, in order to achieve both COP and required time (cooling speed), each set rotational speed (drive) of the compressor based on information on the compressor set in advance. Frequency) is provided with a superiority, so that operation at a high rotation speed (relatively high driving frequency) is reduced. For this reason, nothing is mentioned about the cooling time to the allowable upper limit of the internal temperature which a user asks, and there is a possibility that the stored article in the refrigerator may be damaged.

  Moreover, in the cooling compressor control apparatus disclosed in Patent Document 1, nothing is mentioned about the specification range of the suction pressure of the compressor, and when the operation is performed according to the control content, the state outside the specification range of the refrigeration apparatus system may be lost. There is a possibility of continuing for a long time, and there is a risk of impairing reliability.

  Furthermore, in the cooling compressor control apparatus disclosed in Patent Document 1, the cooling time and the COP superiority are determined by the outside (inside) temperature of the initial pull-down operation, but the inside temperature actually decreases. In fact, it is difficult to obtain a temperature difference from the evaporator, and due to the aging of the refrigeration system, the cooling time and the rotational speed of the compressor, which is the extreme value of COP, cannot be determined.

  Then, this invention makes it a subject to provide the refrigeration apparatus system which implements pull-down driving | operation which aimed at the internal temperature management, ensuring the reliability of a refrigeration apparatus system, and reducing the operating power consumption.

  In order to solve such a problem, the present invention provides a refrigeration cycle comprising a compressor, a condenser, an expansion valve, and an evaporator having a variable driving frequency, and a medium to be cooled cooled by the evaporator. A refrigerator to be supplied, an internal temperature sensor for detecting an internal temperature of the refrigerator, an intake pressure sensor for detecting an intake pressure of the compressor, and when the internal temperature is equal to or higher than a thermo-on set temperature, Control means for instructing the start of operation of the refrigeration cycle, and instructing to stop the operation of the refrigeration cycle when the internal temperature becomes equal to or lower than the thermo-off set temperature, and the control means includes the compression input in advance Based on the machine information, the frequency shift set temperature provided until the thermo-off set temperature is reached, and the preset frequency shift set suction pressure, the drive frequency of the compressor is optimized. A refrigeration system characterized in that it comprises the operation mode to be changed.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerator temperature system which implements the pull-down driving | operation which aimed at the internal temperature management, the ensuring of the reliability of a freezing apparatus system, and reduction of driving | operation power consumption can be provided.

1 is a schematic configuration diagram of a refrigeration system according to a first embodiment. It is a figure which shows the magnitude relationship with the saturation pressure in each setting temperature, and each setting pressure. It is the schematic of the driving | running behavior of the freezing apparatus system which concerns on a reference example. It is the schematic of the driving | running behavior in the pull-down driving | operation of the refrigeration apparatus system which concerns on 1st Embodiment. It is a control flow of the compressor in the cooling priority operation | movement of the refrigeration apparatus system which concerns on 1st Embodiment. It is a control flow of the compressor in the suction pressure stability priority operation of the refrigeration system according to the first embodiment. It is a control flow of the compressor in the high COP priority operation of the refrigeration system according to the first embodiment. It is a control flow until it issues an internal temperature high temperature abnormality alarm in the pull-down operation of the refrigeration system according to the second embodiment. It is a control flow until it issues an apparatus abnormality alarm in the pull-down operation of the refrigeration system according to the second embodiment. It is a block diagram of the structure of the freezing apparatus system which concerns on 3rd Embodiment. It is a control flow of the electronic expansion valve in the cooling priority operation of the refrigeration system according to the third embodiment. It is a control flow of the electronic expansion valve in the suction pressure stability priority operation of the refrigeration system according to the third embodiment. It is a control flow of the electronic expansion valve in the high COP priority operation of the refrigeration system according to the third embodiment.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

<< First Embodiment >>
<Refrigeration system>
First, the refrigeration system S according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a refrigeration system S according to the first embodiment.

  The refrigeration system S such as a refrigerator, a freezer, a refrigeration case, and a refrigeration case includes a condensing unit 11, a cooler 13 disposed inside the refrigerator 12, and a controller 8. Air (cooled medium) can be cooled by a cooler 13 (evaporator 5 described later). As a result, the refrigeration system S can cool the stored articles (not shown) stored in the refrigerator 12.

  Specifically, the refrigeration system S includes a compressor 1, a condenser 2, an electromagnetic valve 3 for refrigerant liquid, an expansion valve 4, and an evaporator 5. A refrigeration cycle connected in an annular shape with a refrigerant pipe so as to circulate is provided. Although not shown, the refrigeration system S includes a condensing unit fan (not shown) for taking outside air into the condensing unit 11 and exchanging heat with the refrigerant flowing through the condenser 2, and a refrigerator 12. Cooling for taking the internal air (cooled medium) into the cooler 13 and exchanging heat with the refrigerant flowing through the evaporator 5 and circulating the internal air (cooled medium) cooled by the evaporator 5 to the refrigerator 12 And a fan (not shown).

  The compressor 1, the condenser 2, and the condensing unit fan (not shown) are arranged in the condensing unit 11. Further, the refrigerant liquid solenoid valve 3, the expansion valve 4, the evaporator 5, and the cooler fan (not shown) are arranged in the cooler 13 of the refrigerator 12.

  Each configuration of the refrigeration system S will be described along the flow of the refrigerant circulating in the refrigeration cycle.

  The compressor 1 compresses the refrigerant gas from the cooler 13 (evaporator 5) and discharges the high-temperature and high-pressure refrigerant gas to the condenser 2. The compressor 1 is driven and controlled by a condensing unit control device 10 described later via an inverter (not shown).

  The condenser 2 is an air-refrigerant heat exchanger, and heat-exchanges high-temperature and high-pressure refrigerant gas from the compressor 1 with air (outside air), thereby cooling and condensing the refrigerant into a refrigerant liquid. The refrigerant liquid from the condenser 2 flows into the expansion valve 4 via the refrigerant liquid electromagnetic valve 3.

  The solenoid valve 3 for refrigerant liquid is opened during the operation of the refrigeration cycle, that is, during the operation of the compressor 1, so that the refrigerant can flow therethrough. On the other hand, when the operation of the refrigeration cycle is stopped, that is, when the operation of the compressor 1 is stopped, the valve is closed, so that the refrigerant is prevented from flowing and so-called refrigerant stagnation is prevented. The refrigerant liquid solenoid valve 3 is controlled to be opened and closed by a cooler control device 9 described later.

  The expansion valve 4 depressurizes (adiabatic expansion) the high-pressure refrigerant from the condenser 2 to obtain a low-temperature low-pressure refrigerant. Note that a temperature type automatic expansion valve can be used as the expansion valve 4 of the refrigeration system S according to the first embodiment. The low-temperature and low-pressure refrigerant from the expansion valve 4 flows into the evaporator 5.

  The evaporator 5 is a refrigerant-heat medium heat exchanger, and heat is exchanged between the low-temperature and low-pressure refrigerant from the expansion valve 4 and the internal air (cooled medium) of the refrigerator 12, whereby the internal air (cooled medium). And the refrigerant is evaporated. The refrigerant from the evaporator 5 flows into the compressor 1.

  Thus, the refrigerating machine system S cools the internal air (cooled medium) of the refrigerator 12 by operating the compressor 1 and circulating the refrigerant through the refrigeration cycle.

  The refrigeration system S includes an internal temperature sensor 6 that detects the internal temperature T, an intake pressure sensor 7 that detects the intake pressure P, a controller 8 that controls the entire refrigeration system S, and a cooler 13. And a condensing unit control device 10 for controlling the condensing unit 11.

  The internal temperature sensor 6 is disposed in the refrigerator 12 and can detect the internal temperature T of the refrigerator 12. A detection signal of the internal temperature T detected by the internal temperature sensor 6 is output to the controller 8 via the communication line, and further output from the controller 8 to the condensing unit control device 10.

  The suction pressure sensor 7 is provided in the condensing unit 11 and can detect the suction pressure P that is the pressure of the refrigerant gas on the suction side of the compressor 1. A detection signal of the suction pressure P detected by the suction pressure sensor 7 is output to the condensing unit control device 10 via a communication line.

  The controller 8 is communicably connected to the internal temperature sensor 6, the cooler control device 9 and the condensing unit control device 10 through a communication line.

In addition, a thermo-on set temperature T _ON and a thermo-off set temperature T _OFF with respect to the internal temperature T are stored in the storage unit 8a of the controller 8 in advance. Here, the thermo-on set temperature T _ON is a temperature at which cooling of the internal air (cooled medium) by the refrigeration cycle is started in a normal operation of the refrigeration system S described later (see FIG. 3 described later). The set temperature T _OFF is a temperature at which cooling of the internal air (cooled medium) by the refrigeration cycle is stopped in a normal operation (see FIG. 3) of the refrigeration system S described later.

Further, the controller 8 is provided with an operation unit (set temperature changing unit) 8b composed of a switch, a monitor, and the like, and when the user operates the operation unit 8b, the thermo-on stored in the storage unit 8a. The set temperature T _ON and the thermo-off set temperature T _OFF can be changed. Specifically, the operation unit (set temperature changing unit) 8b is adapted to be able to set a target temperature T _P of the internal temperature T of the refrigerator 12. From the set target temperature T _P and the preset temperature change allowable value T _a , the thermo-on set temperature T _ON “T _ON = T _P + T _a ” and the thermo-off set temperature T _OFF “T _OFF = T _P −T _a Is set and stored in the storage unit 8a. It may be adapted to be able to change the temperature change tolerance T _a be the operation section 8b. The operation unit 8b may directly set the thermo-on set temperature T _ON and the thermo-off set temperature T _OFF and store it in the storage unit 8a.

The controller 8 compares the internal temperature T detected by the internal temperature sensor 6 with the thermo-on set temperature T _ON and the thermo-off set temperature T _OFF and outputs an operation command signal according to the result. Yes. That is, when the internal temperature T is equal to or higher than the thermo-on set temperature T _ON , the controller 8 outputs an operation start command signal for instructing the cooler control device 9 and the condensing unit control device 10 to start the operation of the refrigeration cycle. . When the internal temperature T is lower than the thermo-off set temperature T _OFF , the controller 8 outputs an operation stop command signal that instructs the cooler control device 9 and the condensing unit control device 10 to stop the operation of the refrigeration cycle. . Thus, the controller 8 controls the condensing unit 11 and the cooler 13 by outputting an operation command signal (operation start command signal, operation stop command signal), in other words, the entire refrigeration system S. Can be controlled.

  The cooler control device 9 is provided in the cooler 13 and is connected to the controller 8 through a communication line so as to be communicable.

  The cooler control device 9 controls the cooler 13 based on the operation command signal of the controller 8. That is, the cooler control device 9 opens the refrigerant liquid electromagnetic valve 3 and drives a cooler fan (not shown) in response to the operation start command signal. Further, the cooler control device 9 closes the refrigerant liquid electromagnetic valve 3 and stops the cooler fan (not shown) in response to the operation stop command signal.

  The condensing unit control device 10 is provided in the condensing unit 11, and is connected to the suction pressure sensor 7 and the controller 8 so as to communicate with each other through a communication line.

The storage unit 10a of the condensing unit control device 10 stores in advance an upper limit set pressure (start set pressure) P _H , a lower limit set pressure P _L and a stop set pressure P _S with respect to the suction pressure P. Here, the upper limit set pressure P _H is the upper limit pressure in the specification range with respect to the suction pressure P of the compressor 1 in the refrigeration system S, and the lower limit set pressure P _L is the suction of the compressor 1 in the refrigeration system S. This is the lower limit pressure of the specification range for the pressure P. Further, the stop set pressure P _S is a pressure indicating a threshold for determining whether or not to stop the operation of the compressor 1. These set pressures are determined by the characteristics of the compressor 1 and the like.

Here, the relationship between each set temperature (thermo-on set temperature T _ON , thermo-off set temperature T _OFF ) and each set pressure (upper limit set pressure (start set pressure) P _H , lower limit set pressure P _L , stop set pressure P _S ) Will be described with reference to FIG. FIG. 2 is a diagram showing the magnitude relationship between the saturation pressure at each set temperature and each set pressure.

First, the thermo-on set temperature T _ON is set to be higher than the thermo-off set temperature T _OFF . Further, the upper limit set pressure (start set pressure) P _H is set to be higher than the lower limit set pressure P _L , and the stop set pressure P _S is set to be lower than the lower limit set pressure P _L.

Then, as shown in FIG. 2, the upper limit set pressure (starting set pressure) P _H is set to be smaller than the saturation pressure of the refrigerant at the thermo-on set temperature T _ON, the lower limit set pressure P _L is the thermo-off set temperature T _OFF is set to be larger than the saturation pressure of the refrigerant, stop setting pressure P _S is set to be smaller than the saturation pressure of the refrigerant in the thermo-off set temperature T _OFF.

  Returning to FIG. 1, the condensing unit control device 10 controls the condensing unit 11 based on the operation command signal of the controller 8. That is, the condensing unit control device 10 controls the drive of the compressor 1 through an inverter (not shown) provided in the condensing unit 11 in response to the operation start command signal, and also performs a condensing unit fan (see FIG. Drive (not shown). Further, the condensing unit control device 10 stops the compressor 1 and stops the condensing unit fan (not shown) via an inverter (not shown) in response to the operation stop command signal.

Further, the condensing unit control device 10 compares the suction pressure P detected by the suction pressure sensor 7 with the upper limit set pressure (start set pressure) P _H , the lower limit set pressure P _L and the stop set pressure P _S , The compressor 1 is driven and controlled through an inverter (not shown) according to the result. That is, the condensing unit controller 10 determines the operation start command signal from the controller 8 is input, whether a suction pressure P starts set pressure (upper limit set pressure) P _H or more, the suction pressure P There start set pressure when it is determined that the (upper set pressure) P _H or more, to start driving the compressor 1.

Then, during operation of the compressor 1, if the suction pressure P is an upper limit set pressure P _H or more, condensing unit controller 10 increases the rotational speed of the compressor 1, i.e., the compressor 1 drive frequency f To raise. As a result, the suction pressure P is reduced, and the suction pressure P of the compressor 1 falls within the specification range (P _{L to} P _H ). Further, when the compressor 1 is being driven, when the suction pressure P is less than the upper limit set pressure P _H and greater than or equal to the lower limit set pressure P _L , the condensing unit control device 10 maintains the rotation speed of the compressor 1, that is, The drive frequency f of the compressor 1 is maintained. Further, when the compressor 1 is driven, when the suction pressure P is less than the lower limit set pressure P _{L and} equal to or higher than the stop set pressure P _S , the condensing unit control device 10 decreases the rotation speed of the compressor 1, that is, The drive frequency f of the compressor 1 is decreased. As a result, the suction pressure P is reduced, and the suction pressure P of the compressor 1 falls within the specification range (P _{L to} P _H ). Furthermore, during operation of the compressor 1, if the suction pressure P is less than the stop set pressure P _S, and stops the compressor 1.

<Operational behavior of the refrigeration system according to the reference example>
Next, the operation behavior of a general refrigeration system (according to a reference example) will be described with reference to FIG. FIG. 3 is a schematic diagram of the operation behavior of the refrigeration system according to the reference example. Here, the horizontal axis of FIG. 3 represents time, and the vertical axis represents time variation of the driving frequency f of the compressor 1, the internal temperature T of the refrigerator 12, and the suction pressure P of the compressor 1. The configuration of the refrigeration system according to the reference example is the same as that of the refrigeration system S according to the first embodiment shown in FIG. Incidentally, the refrigerating apparatus system S according to the first embodiment and the refrigerating apparatus system according to the reference example are different in control in the pull-down operation described later. Control in the pull-down operation of the refrigeration system _{S according} to the first embodiment will be described later with reference to FIG.

As shown in FIG. 3, the refrigeration system according to the reference example includes a normal operation A for cooling the internal temperature T from the thermo-on set temperature T _ON to the thermo-off set temperature T _OFF, and defrosting for defrosting the evaporator 5. The operation B and the pull-down operation C that cools the internal temperature T to the thermo-off set temperature T _OFF immediately after the start of the refrigeration system or after the defrosting operation can be performed.

The normal operation A is an operation for cooling so that the internal temperature T of the refrigerator 12 becomes the target temperature T _P (within _a range of T _P ± T _a ). That is, first, when the internal temperature T is lower than the thermo-on set temperature T _ON , the compressor 1 is stopped. Thereafter, when the internal temperature T becomes equal to or higher than the thermo-on set temperature T _ON , the compressor 1 is driven, and the inside of the refrigerator 12 is increased or decreased while increasing or decreasing the drive frequency f of the compressor 1 according to the suction pressure P as described above. Cool down. When the internal temperature T reaches the thermo-off set temperature T _OFF or less, the compressor 1 is stopped. Thereafter, the internal temperature T rises due to the intrusion heat from the outside of the refrigerator 12 into the inside of the refrigerator 12 or the heat of the stored articles (not shown) stored in the refrigerator 12, When the temperature T becomes equal to or higher than the thermo-on set temperature T _ON , the compressor 1 is driven again, and the same operation is repeated thereafter.

  Here, in the normal operation A of the refrigeration system, the cooler 13 of the refrigeration system cools the internal temperature T of the refrigerator 12 to below freezing or near freezing. For this reason, the vapor | steam in the air in a store | warehouse | chamber (cooled medium) sublimates, and frost may adhere to the evaporator 5 arrange | positioned inside the refrigerator 12. FIG. If frost forms on the evaporator 5, heat exchange between the refrigerant and the internal air (cooled medium) is hindered, and the performance of the evaporator 5 is significantly impaired. For this reason, the refrigeration system can perform a defrosting operation B that melts the frost attached to the evaporator 5. In the defrosting operation B, the compressor 1 is stopped regardless of the internal temperature T and the suction pressure P, and the electric heater (not shown) provided in the evaporator 5 is energized to reach the evaporator 5. Melt the frost.

After completion of the defrosting operation B, depending on the outside temperature, the inside temperature T is often higher than the thermo-on set temperature T _ON by a certain temperature T _b or more (T ≧ T _ON + T _b ). In this case, in order to prevent damage to stored articles (not shown) stored in the refrigerator 12, the suction pressure P of the compressor 1 is further within the specification range of the refrigeration system S (P _L ~ (P _H ), the pull-down operation C for operating the compressor 1 at full speed (or a relatively high driving frequency) is performed to rapidly cool the internal temperature T of the refrigerator 12.

It should be noted that the internal temperature T is higher than the thermo-on set temperature T _ON by a certain temperature T _b or more (T _ON + T _b ) is not limited to only after the defrosting operation B is completed. It is also conceivable that the internal temperature T greatly increases due to intrusion heat from the outside of the warehouse, heat of the storage article itself, or the like during trial operation when the apparatus system is introduced or when the storage article (not shown) is replaced. Even in such a case, the pull-down operation C is performed, and the internal temperature T of the refrigerator 12 is rapidly cooled.

When the internal temperature T of the refrigerator 12 is cooled to the thermo-off set temperature T _OFF by the pull-down operation C, the compressor 1 is stopped and the normal operation A is repeated until the next pull-down operation C is reached.

<Operational behavior of the refrigeration system according to the first embodiment (pull-down operation)>
Next, the operation behavior of the refrigeration system S according to the first embodiment will be described. Here, the refrigeration system S according to the first embodiment can perform the normal operation A, the defrosting operation B, and the pull-down operation C, similarly to the refrigeration system according to the reference example. ing. And the refrigerating apparatus system S which concerns on 1st Embodiment differs in the control in the pull-down operation C compared with the refrigerating apparatus system which concerns on a reference example.

The pull-down operation C of the refrigeration system S according to the first embodiment will be described with reference to FIGS. FIG. 4 is a schematic diagram of the operation behavior in the pull-down operation C of the refrigeration system _{S according} to the first embodiment. Here, the horizontal axis of FIG. 4 represents time, and the vertical axis represents time variation of the driving frequency f of the compressor 1, the internal temperature T of the refrigerator 12, and the suction pressure P of the compressor 1.

As shown in FIG. 4, the pull-down operation C of the refrigeration system S according to the first embodiment is a temperature range until the internal temperature T reaches the thermo-off set temperature T _OFF, and a cooling priority operation region, which will be described later in detail. And the suction frequency stability priority operation region and the high COP priority operation region, and the drive frequency f of the compressor 1 is changed corresponding to each temperature range. That is, as shown in FIG. 4, in the pull-down operation C of the refrigeration system S according to the first embodiment, there are three stages of the cooling priority operation C1, the suction pressure stability priority operation C2, and the high COP priority operation C3. You can drive.

<Cooling priority operation>
First, the cooling priority operation C1 will be described with reference to FIG. 5 and FIG. FIG. 5 is a control flowchart in the cooling priority operation C1. In the cooling priority operation C1, the internal temperature T is a frequency shift set temperature (hereinafter referred to as a shift temperature) T _shift or less, and the suction pressure P is a frequency shift set intake pressure (hereinafter referred to as a shift pressure) P. _The operation is to cool the compressor 1 at a full speed (maximum drive frequency f _max ) until the _shift becomes lower than the _shift .

  When receiving the operation start command signal from the controller 8, the condensing unit control device 10 starts the following processing.

In step S1, the condensing unit controller 10 determines whether or not the internal temperature T is higher than the thermo-on set temperature T _ON by a certain temperature (T _b ) or more (T ≧ T _ON + T _b ?). Here, the certain constant temperature Tb is a threshold value for determining whether cooling by the normal operation A or cooling by the pull-down operation C is performed, and is stored in advance in the storage unit 10a of the condensing unit control device 10. ing.

When the internal temperature T is higher than the thermo-on set temperature T _ON by a certain temperature or more (S1 · Yes), the processing of the condensing unit control device 10 proceeds to step S2. When the internal temperature T is not higher than the thermo-on set temperature T _ON by a certain temperature (S1 · No), the processing of the condensing unit control device 10 proceeds to step S8, and the normal operation A (see FIG. 3) is performed.

In step S2, the condensing unit control device 10 determines whether or not the internal temperature T is _{equal to} or higher than the shift temperature T _shift (T ≧ T _shift ?). Here, the shift temperature T _shift can be arbitrarily set by the user. For example, the shift temperature T _shift is set to a temperature at which an alarm of a high temperature abnormality in the cabinet is generated. Preferably, the stored article ( (Not shown) is set to a temperature in a range that does not damage, more preferably, the maximum temperature is set to a range that does not damage stored articles (not shown) stored in the refrigerator 12. For this reason, the shift temperature T _shift is set to a temperature higher than the thermo-on set temperature T _ON .

When the internal temperature T is equal to or higher than the shift temperature T _shift (S2 · Yes), the processing of the condensing unit control device 10 proceeds to step S3. When the internal temperature T is not equal to or higher than the shift temperature T _shift (S2 · No), the processing of the condensing unit control device 10 proceeds to step S9, and the pull-down operation is performed according to the determination of other sections. That is, the process proceeds to step S11 in FIG.

In step S3, the condensing unit control apparatus 10 has the suction pressure P outside the specification range (lower limit set pressure P _L to upper limit set pressure P _H ) of the compressor 1 of the refrigeration system S. (P <P _L or P> P _H ?). Here, the specification range of the suction pressure P of the compressor 1 of the refrigeration system S refers to a range that is not less than the aforementioned lower limit set pressure P _{L and not} greater than the aforementioned upper limit set pressure P _H.

  When the suction pressure P is out of the specification range (S3 / Yes), the processing of the condensing unit control device 10 proceeds to step S4. When the suction pressure P is not out of the specification range (S3 / No), the processing of the condensing unit control device 10 proceeds to step S9, and the pull-down operation is performed according to the determination of other sections.

In step S4, the condensing unit control apparatus 10 starts the cooling priority operation C1 (pull-down operation C). Specifically, the condensing unit control device 10 drives the compressor 1 at the full drive speed (maximum drive frequency f _max ) via an inverter (not shown). And the process of the condensing unit control apparatus 10 progresses to step S5.

In step S5, the condensing unit control device 10 determines whether or not the internal temperature T is equal to or lower than the shift temperature T _shift (T ≦ T _shift ?). When the internal temperature T is not equal to or lower than the shift temperature T _shift (S5 · No), the processing of the condensing unit control device 10 returns to step S5, and the operation is performed with the drive frequency f of the compressor 1 being the maximum drive frequency f _max. continue. When the internal temperature T is equal to or lower than the shift temperature T _shift (S5 / Yes), the processing of the condensing unit control device 10 proceeds to step S6.

In step S6, the condensing unit controller 10 determines whether or not the suction pressure P is equal to or lower than the shift pressure P _shift (P ≦ P _shift ?). Here, the shift pressure P _shift is set based on information of the refrigeration system S (information of the condensing unit 11, such as the upper limit set pressure P _H and the lower limit set pressure P _L ). For example, the refrigeration system It may be 80% of the upper limit of the specification range of the suction pressure P of the S compressor 1 (P _shift = 0.8 × P _H ). By setting the shift pressure P _shift in this way, a margin can be provided from the upper limit of the specification range of the suction pressure P, and the suction pressure P increases by decelerating the drive frequency f of the compressor 1 as will be described later. Even if it is within the specification range of the suction pressure P of the compressor 1 of the refrigeration system S, the reliability of the refrigeration system S can be ensured. For this reason, the shift pressure P _shift is set within a range that is greater than or _equal to the lower limit set pressure P _L and less than the upper limit set pressure P _H.

If the suction pressure P is not less than or equal to the shift pressure P _shift (S6, No), the processing of the condensing unit control device 10 returns to step S5, and the operation is continued with the drive frequency f of the compressor 1 kept at the maximum drive frequency _fmax. To do. When the suction pressure P is equal to or lower than the shift pressure P _shift (S6 / Yes), the processing of the condensing unit control device 10 proceeds to step S7.

  In step S7, the condensing unit control device 10 ends the cooling priority operation C1, decelerates the drive frequency f of the compressor 1, and shifts to the suction pressure stability priority operation C2. Here, the deceleration amount of the drive frequency f is the same as the deceleration amount of the suction pressure stability priority operation C2 described later (see step S16 of FIG. 6 described later).

<Suction pressure stability priority operation>
Next, the suction pressure stability priority operation C2 will be described using FIG. 6 with reference to FIG. FIG. 6 is a control flowchart in the suction pressure stability priority operation C2. The suction pressure stability priority operation C2 means that the suction pressure P is within the specification range of the refrigeration system S (lower limit set pressure P _L to upper limit set pressure P _H ) and the shift pressure P _shift or more is maintained while the compressor 1 In this operation, the drive frequency f is gradually decelerated to a high COP frequency f _COP described later.

Here, as shown in FIG. 4, generally, when the drive frequency f of the compressor 1 is decelerated, the suction pressure P increases, and then the suction temperature P decreases as the internal temperature T decreases. . That is, in the suction pressure stability priority operation C2, if the suction pressure P is equal to or lower than the shift pressure _{Pshift, the} drive frequency f is decelerated. Immediately after deceleration of the drive frequency f, the amount of refrigerant circulation decreases, and the apparent internal cooling load increases, so the suction pressure P increases. Thereafter, the suction pressure P decreases as the internal temperature T decreases. If the suction pressure P becomes equal to or lower than the shift pressure _Pshift , the drive frequency f is similarly reduced.

In step S11, the condensing unit controller 10 determines whether or not the suction pressure P is _{equal to} or higher than the shift pressure P _shift (P ≧ P _shift ?). When the suction pressure P is equal to or higher than the shift pressure P _shift (S11 / Yes), the processing of the condensing unit control device 10 proceeds to step S12. When the suction pressure P is not equal to or higher than the shift pressure P _shift (S11 / No), the processing of the condensing unit control device 10 proceeds to step S19, and the pull-down operation is performed according to the determination of other sections.

In step S12, the condensing unit controller 10 determines whether or not the internal temperature T is equal to or lower than the shift temperature T _shift (T ≦ T _shift ?). When the internal temperature T is equal to or lower than the shift temperature T _shift (S12 / Yes), the processing of the condensing unit control device 10 proceeds to step S13. If the internal temperature T is not equal to or lower than the shift temperature T _shift (S12, No), the processing of the condensing unit control device 10 proceeds to step S19, and the pull-down operation is performed according to the determination of other sections.

In step S13, the condensing unit control device 10 has the suction pressure P within the specification range (lower limit set pressure P _L to upper limit set pressure P _H ) of the compressor 1 of the refrigeration system S. (P _L ≦ P ≦ P _H ?). When the suction pressure P is within the specification range (S13 / Yes), the processing of the condensing unit control device 10 proceeds to step S14. If the suction pressure P is not within the specification range (S13 / No), the processing of the condensing unit control device 10 proceeds to step S19, and pull-down operation is carried out based on the determination of another category.

  In step S14, the condensing unit control device 10 starts the suction pressure stability priority operation C2 (pull-down operation C). Specifically, the condensing unit control device 10 drives the compressor 1 while maintaining the drive frequency f (not decelerating) via an inverter (not shown). And the process of the condensing unit control apparatus 10 progresses to step S15.

In step S15, the condensing unit controller 10 determines whether or not the suction pressure P is equal to or lower than the shift pressure P _shift (P ≦ P _shift ?). When the suction pressure P is not equal to or lower than the shift pressure P _shift (S15, No), the processing of the condensing unit control device 10 returns to step S12, and the operation is continued while the drive frequency f of the compressor 1 is maintained. When the suction pressure P is equal to or lower than the shift pressure P _shift (S15 / Yes), the processing of the condensing unit control device 10 proceeds to step S16.

In step S16, the condensing unit controller 10 decelerates the drive frequency f. Here, as shown in FIG. 4, the decrease amount Δf of the drive frequency f that decelerates at once is the specification of the suction pressure P of the compressor 1 of the refrigeration system S, where the suction pressure P that rises after the drive frequency f is decelerated. It is desirable to set so as to fall within the range (lower limit set pressure P _L to upper limit set pressure P _H ), and specifically, 10 Hz is preferably maximized. Further, after the drive frequency f is decelerated, it is desirable to maintain the operation maintenance time Δt at the decelerated drive frequency f for at least 30 seconds. Thereby, it is possible to prevent the suction pressure P from rapidly increasing by decelerating the drive frequency f rapidly, and to ensure the reliability of the refrigeration system S. And the process of the condensing unit control apparatus 10 progresses to step S17.

In step S17, the condensing unit controller 10 determines whether or not the drive frequency f has reached the high COP frequency f _COP (f = f _COP ?). Here, the high COP frequency f _COP is a drive frequency at which the _COP of the compressor 1 (refrigeration system S) becomes high (preferably a maximum value), and is determined by the characteristics of the compressor 1 and the like. It is stored in the storage unit 10 a of the unit controller 10. If the drive frequency f is not the high COP frequency f _COP (S17, No), the processing of the condensing unit control device 10 returns to step S15. When the drive frequency f is the high COP frequency f _COP (S17 / Yes), the processing of the condensing unit control device 10 proceeds to step S18.

  In step S18, the condensing unit control device 10 ends the suction pressure stability priority operation C2, and shifts to the high COP priority operation C3.

<High COP priority operation>
Next, the high COP priority operation C3 will be described with reference to FIG. 7 and FIG. FIG. 7 is a control flowchart in the high COP priority operation C3. The high COP priority operation C3 drives the compressor 1 at a high COP frequency f _COP at which the _COP of the compressor 1 (refrigeration system S) increases, and cools until the internal temperature T becomes the thermo-off set temperature T _OFF. Driving.

  In step S21, the condensing unit controller 10 determines whether or not the suction pressure priority operation C2 (see FIG. 6) has been performed. If the suction pressure priority operation C2 has been performed (S21 / Yes), the processing of the condensing unit control device 10 proceeds to step S22. When the suction pressure priority operation C2 has not been performed (S21 / No), the processing of the condensing unit control device 10 proceeds to step S27, and the pull-down operation is performed according to the determination of another category.

In step S22, the condensing unit controller 10 determines whether or not the internal temperature T is equal to or lower than the shift temperature T _shift (T ≦ T _shift ?). When the internal temperature T is equal to or lower than the shift temperature T _shift (S22 / Yes), the processing of the condensing unit control device 10 proceeds to step S23. When the internal temperature T is not equal to or lower than the shift temperature T _shift (S22 / No), the processing of the condensing unit control device 10 proceeds to step S27, and performs pull-down operation according to the determination of other sections.

In step S23, the condensing unit control apparatus 10 has the suction pressure P within the specification range (lower limit set pressure P _L to upper limit set pressure P _H ) of the compressor 1 of the refrigeration system S. (P _L ≦ P ≦ P _H ?). When the suction pressure P is within the specification range (S23 / Yes), the processing of the condensing unit control device 10 proceeds to step S24. When the suction pressure P is not within the specification range (S23, No), the processing of the condensing unit control device 10 proceeds to step S27, and the pull-down operation is performed according to the determination of other sections.

In step S24, the condensing unit controller 10 starts the high COP priority operation C3 (pull-down operation C). Specifically, the condensing unit control device 10 drives the compressor 1 at a high COP frequency f _COP through an inverter (not shown). And the process of the condensing unit control apparatus 10 progresses to step S25.

In step S25, the condensing unit controller 10 determines whether or not the internal temperature T is equal to or lower than the thermo-off set temperature T _OFF (T ≦ T _OFF ?). When the internal temperature T is not equal to or lower than the thermo-off set temperature T _OFF (No in S25), the processing of the condensing unit control device 10 returns to Step S22 and operates with the drive frequency f of the compressor 1 being set to the high COP frequency f _COP. Continue. When the internal temperature T is equal to or lower than the thermo-off set temperature T _OFF (S25 / Yes), the processing of the condensing unit control device 10 proceeds to step S26.

  In step S26, the condensing unit control device 10 ends the high COP priority operation C3 (pull-down operation C) and stops the compressor 1.

In the pull-down operation C of the refrigeration system S according to the first embodiment configured as described above, first, while ensuring the reliability of the refrigeration system S by the cooling priority operation C1, the minimum required storage space is maintained. Responding to temperature (shift temperature T _shift ), next, request COP improvement while ensuring reliability of refrigeration system S by suction pressure stability priority operation C2, and finally improve COP by high COP priority operation By satisfying the internal temperature (thermo-off set temperature T _OFF ), it is possible to carry out pull-down operation for managing internal temperature, ensuring the reliability of the refrigeration system, and reducing operating power consumption.

<< Second Embodiment >>
Next, the refrigeration system S according to the second embodiment will be described. The refrigeration apparatus system S according to the second embodiment has the same configuration (see FIG. 1) as the refrigeration apparatus system S according to the first embodiment, and pulls down similarly to the refrigeration apparatus system S according to the first embodiment. In operation, based on the internal temperature T and the suction pressure P, the compressor 1 is divided into three categories of a cooling priority operation region, a suction pressure stability priority operation region, and a high COP priority operation region. The drive frequency f is changed.

As described above, in the cooling priority operation C1, cooling is performed until the internal temperature T is equal to or lower than the shift temperature T _shift and the suction pressure P is equal to or lower than the shift pressure P _shift, and the heat is stored in the internal storage article (not shown). When the damage is prevented, the operation shifts to the suction pressure stability priority operation C2, and the drive frequency f of the compressor 1 is sequentially decelerated to the high COP frequency f _COP while maintaining the shift pressure P _shift .

Here, in the suction pressure stability priority operation C2 (see FIG. 6) of the refrigeration system S according to the first embodiment, the internal temperature T is not included in the deceleration condition of the drive frequency f, so that the drive is sometimes performed. By decelerating the frequency f, the cooling capacity of the refrigeration cycle is insufficient, and there is a possibility that cooling to the thermo-off set temperature T _OFF becomes impossible. In addition, such a state of being unable to cool may be caused by a malfunction of the device or by a setting failure such as the shift temperature T _shift or the shift pressure P _shift .

  Therefore, the refrigeration system S according to the second embodiment can issue a high temperature alarm. FIG. 8 is a control flow until the inside temperature high temperature abnormality alarm is issued in the pull-down operation of the refrigeration system S according to the second embodiment.

  In step S31, the condensing unit control device 10 determines whether or not a pull-down operation is being performed. When the pull-down operation is being performed (S31 / Yes), the processing of the condensing unit control device 10 proceeds to step S32. When the pull-down operation is not being performed (No in S31), the process of the condensing unit control device 10 proceeds to Step S38, and the process illustrated in FIG. 8 is terminated while the normal operation is being performed or the operation is stopped (Step S38).

  In step S32, the condensing unit control device 10 measures the operation time of each section (cooling priority operation C1, suction pressure stability priority operation C2, and high COP priority operation C3), and calculates the total pull-down operation time that is the sum of them. To do.

  In step S33, the condensing unit controller 10 determines whether or not the total pull-down operation time calculated in step S32 is longer than a preset pull-down time. When the total pull-down operation time is shorter than the set pull-down time (S33, No), the processing of the condensing unit control device 10 returns to step S32. When the total pull-down operation time is longer than the set pull-down time (S33 / Yes), the processing of the condensing unit control device 10 proceeds to step S34.

In step S34, the driving frequency f Hayashi sequentially increased until the maximum drive frequency f _max, the process proceeds to preferential cooling operation. However, while the normal cooling priority operation C1 shown in FIG. 5 cools to the shift temperature T _shift , the cooling priority operation in step S34 aims at cooling to the thermo-off set temperature T _OFF .

In step S35, the condensing unit controller 10 determines whether or not the internal temperature T is equal to or lower than the thermo-off set temperature T _OFF (T ≦ T _OFF ?). If the internal temperature T is not equal to or lower than the thermo-off set temperature T _OFF (S35, No), the processing of the condensing unit control device 10 proceeds to step S36. When the internal temperature T is equal to or lower than the thermo-off set temperature T _OFF (S35 / Yes), the processing of the condensing unit control device 10 proceeds to Step S39, ends the pull-down operation C, and stops the compressor 1 (Step S39). ).

  In step S36, the condensing unit control device 10 determines whether or not the operation time of the cooling priority operation is longer than a preset time limit. When the operation time of the cooling priority operation is shorter than the preset time limit (S36, No), the processing of the condensing unit control device 10 returns to step S35. When the operation time of the cooling priority operation is longer than the preset time limit (S36 / Yes), the processing of the condensing unit control device 10 proceeds to step S37.

  In step S <b> 37, the condensing unit control device 10 issues an internal temperature high temperature abnormality alarm by an alarm means (not shown) such as an alarm or a lamp.

As described above, when the operation time of the pull-down operation exceeds the set pull-down operation time, the refrigeration apparatus system S according to the second embodiment shifts to the cooling priority operation, and the internal temperature T becomes the thermo-off set temperature T _OFF . The drive frequency f of the compressor 1 is operated at full speed (maximum drive frequency f _max ) until When the cooling priority operation time, which is the operation time after shifting to the cooling priority operation, exceeds the limit time, an internal temperature high temperature abnormality alarm is issued. Thereby, while preventing damage of the stored article in a warehouse, an apparatus abnormality can be detected and a user can be warned by an alarm.

  In addition, the controller 8 of the refrigeration system S according to the second embodiment sets the operation time in each of the above-described sections (cooling priority operation C1, suction pressure stability priority operation C2, and high COP priority operation C3) in a predetermined cycle ( For example, when the pull-down operation is performed, the latest operation time is compared with the accumulated data at the end of the operation of each section. Generally, if the device has been used for a long time, the operation time becomes longer due to deterioration over time, but if it is a short cycle such as one month, there should be no deviation. Here, when the deviation appears extremely, the controller 8 determines that the device is more than the device, issues a device abnormality alarm, and warns the user.

  FIG. 9 is a control flow until a device abnormality alarm is issued in the pull-down operation of the refrigeration system S according to the second embodiment.

  In step S41, the controller 8 measures the operation time of each section (cooling priority operation C1, suction pressure stability priority operation C2, high COP priority operation C3).

  In step S42, the controller 8 compares the current operation time with the past operation time for each section, and calculates the deviation (calculated each section operation time deviation).

  In step S43, the controller 8 determines whether or not the deviation of the operation time for each section calculated in step S42 (calculated each section operation time deviation) is larger than a preset deviation upper limit. When the calculated operation time deviation for each section is larger than the deviation upper limit (S43 / Yes), the process of the controller 8 proceeds to step S44, and an apparatus abnormality alarm is issued by an alarm means (not shown) such as an alarm or a lamp. (Step S44). When the calculated operation time deviation of each section is smaller than the deviation upper limit (S43, No), the process of the controller 8 proceeds to step S45, and the operation time of each section measured in step S41 is stored as accumulated data (step S45).

  As described above, the refrigeration system S according to the second embodiment measures the operation time in each section (cooling priority operation C1, suction pressure stability priority operation C2, and high COP priority operation C3), and the past in each section. By comparing with the operation time, an abnormality of the device can be detected, and a warning can be given to the user.

The controller 8 stores a table (not shown) showing the relationship between each drive frequency f and power consumption when the electric motor 1 is driven at the drive frequency f. Based on the driving frequency f of the electric motor 1 in each section, the power consumption in each section can be calculated, and the total power consumption that is the sum of the power consumption in each section can be calculated and stored as accumulated data. The accumulated data can be output arbitrarily.

Thereby, the user can suitably change the setting of the shift temperature T _shift and the shift pressure P _shift based on the accumulated data. In addition, the same information can be used as demand control or peak cut control.

«Third embodiment»
Next, the refrigeration system S according to the third embodiment will be described. While the refrigeration system S (see FIG. 1) according to the first embodiment has been described as having a temperature type automatic expansion valve as the expansion valve 4, the refrigeration system S according to the third embodiment is The electronic expansion valve 4E is provided, and the valve opening degree of the electronic expansion valve 4E can be controlled by the cooler control device 9. Other configurations are the same, and detailed description thereof is omitted.

  Further, the refrigeration system S according to the third embodiment is similar to the refrigeration system S according to the first embodiment, in the pull-down operation, based on the internal temperature T and the suction pressure P, the cooling priority operation region, The driving frequency f of the compressor 1 is changed in accordance with each of the three operation ranges, namely, the suction pressure stability priority operation region and the high COP priority operation region.

  The refrigeration apparatus system S according to the third embodiment controls the valve opening degree of the electronic expansion valve 4E, and thereby cooler overheating, which is a temperature difference between the refrigerant outlet temperature of the cooler 13 and the refrigerant inlet temperature of the cooler 13. Control the degree. Generally, when the valve opening degree of the electronic expansion valve 4E is decreased, the cooler superheat degree is increased, and when the valve opening degree of the electronic expansion valve 4E is increased, the cooler superheat degree is decreased.

  As the opening degree of the electronic expansion valve 4E is increased, more refrigerant flows through the cooler 13 (evaporator 5), and heat exchange in the evaporator 5 is promoted, so that the system capacity is improved and contributes to energy saving. . On the other hand, if the valve opening degree of the electronic expansion valve 4E is made too large, the so-called “liquid back phenomenon”, in which heat is not exchanged in the cooler 13 and returns to the compressor 1 while being in a liquid state, is likely to occur. There is a risk of lowering reliability. For this reason, it is desirable for the electronic expansion valve 4E to control the valve opening so as to reduce the degree of superheater of the cooler within a range in which the liquid back phenomenon does not occur.

  The user can set the set value (superheat degree set value) of the cooler superheat degree by operating the operation unit 8 b of the controller 8. When the operation start command signal is input from the controller 8, the cooler control device 9 calculates the cooler superheat degree as needed, and determines whether the calculated value is equal to or greater than a set value. If it is equal to or greater than the set value, the cooler control device 9 opens the valve opening of the electronic expansion valve 4E by a preset amount. If it is determined that the value is less than the set value, the cooler control device 9 By closing the valve opening of the expansion valve 4E by a preset amount, the valve opening is adjusted so that the cooler superheat degree becomes the superheat degree set value.

  As described above, since the cooling load and the suction pressure P are interrelated, the suction pressure P can be adjusted by controlling the valve opening degree of the electronic expansion valve 4E that adjusts the flow rate of the refrigerant directly connected to the cooling load. .

  Here, for example, if the valve opening degree of the electronic expansion valve 4E is decreased in order to reduce the suction pressure P, the degree of superheater of the cooler also increases. Therefore, the cooler control device 9 then sets the degree of superheater of the cooler. In order to make the degree of superheat, control is performed to increase the valve opening degree of the electronic expansion valve 4E. In such control, a so-called hunting phenomenon occurs in which the degree of superheat of the cooler is not stable, and the suction pressure P of the compressor 1 becomes unstable. Since the stability and control of the suction pressure P are directly related to the COP and reliability of the refrigeration system S, the electronic expansion valve 4E is also appropriately controlled in each section of the pull-down operation C, so that higher COP and higher reliability can be achieved. Can be planned.

  Therefore, in each section of the pull-down operation C of the refrigeration system S according to the third embodiment, the control of the electronic expansion valve 4E is changed from the conventional control for controlling the cooler superheat degree so as to become the superheat degree set value, The control is changed to the control shown in FIG. 11 to FIG. 13 below.

  FIG. 11 is a control flow of the electronic expansion valve 4E in the cooling priority operation C1 of the refrigeration system S according to the third embodiment.

  In step S51, the cooler control device 9 opens the valve opening degree of the electronic expansion valve 4E to the maximum system.

  In step S <b> 52, the cooler control device 9 detects a refrigerant outlet temperature detected by a temperature sensor (not shown) that detects a refrigerant outlet temperature of the cooler 13 and a temperature sensor that detects a refrigerant inlet temperature of the cooler 13 (FIG. The degree of superheat of the cooler is calculated from the refrigerant inlet temperature detected in (not shown). And it is determined whether the calculated cooler superheat degree is more than the lower limit of the range of the cooler superheat degree in which the liquid back phenomenon does not occur.

  If the cooler superheat degree is not equal to or greater than the lower limit (S52, No), the process of the cooler control device 9 proceeds to step S53, and the valve opening degree of the electronic expansion valve 4E is decreased (step S53). And the process of the cooler control apparatus 9 returns to step S52.

  When the cooler superheat degree is equal to or higher than the lower limit (S52 / Yes), the process of the cooler control device 9 proceeds to Step S54 and maintains the valve opening degree of the electronic expansion valve 4E (Step S54).

  FIG. 12 is a control flow of the electronic expansion valve 4E in the suction pressure stability priority operation of the refrigeration system S according to the third embodiment.

  In step S <b> 61, the cooler control device 9 detects the refrigerant outlet temperature detected by a temperature sensor (not shown) that detects the refrigerant outlet temperature of the cooler 13, and the temperature sensor that detects the refrigerant inlet temperature of the cooler 13 (FIG. The degree of superheat of the cooler is calculated from the refrigerant inlet temperature detected in (not shown). And it is determined whether the calculated cooler superheat degree is more than the lower limit of the range of the cooler superheat degree in which the liquid back phenomenon does not occur.

  When the degree of superheater of the cooler is not equal to or lower than the lower limit (S61 / No), the process of the cooler control device 9 proceeds to step S62, and the valve opening degree of the electronic expansion valve 4E is decreased (step S62). In addition, the decreasing rate (valve closing speed) of the valve opening degree in step S62 is set lower than the increasing speed (valve opening speed) of the valve opening degree in step S63 described later. And the process of the cooler control apparatus 9 returns to step S61.

  When the cooler superheat degree is equal to or greater than the lower limit value (S61 / Yes), the process of the cooler control device 9 proceeds to step S63 and increases the valve opening degree of the electronic expansion valve 4E (step S63). And the process of the cooler control apparatus 9 returns to step S61.

  FIG. 13 is a control flow of the electronic expansion valve 4E in the high COP priority operation of the refrigeration system S according to the third embodiment.

  In step S <b> 71, the cooler control device 9 detects the refrigerant outlet temperature detected by a temperature sensor (not shown) that detects the refrigerant outlet temperature of the cooler 13, and the temperature sensor that detects the refrigerant inlet temperature of the cooler 13 (FIG. The degree of superheat of the cooler is calculated from the refrigerant inlet temperature detected in (not shown). And it is determined whether the calculated cooler superheat degree is more than the lower limit of the range of the cooler superheat degree in which the liquid back phenomenon does not occur.

  If the cooler superheat degree is not equal to or greater than the lower limit (S71, No), the process of the cooler control device 9 proceeds to step S72, and the valve opening degree of the electronic expansion valve 4E is decreased (step S72). In addition, the decreasing rate (valve closing speed) of the valve opening degree in step S72 is set lower than the increasing speed (valve opening speed) of the valve opening degree in step S73 described later. And the process of the cooler control apparatus 9 returns to step S71.

  When the cooler superheat degree is equal to or higher than the lower limit (S71 / Yes), the process of the cooler control device 9 proceeds to Step S73, and the valve opening degree of the electronic expansion valve 4E is increased (Step S73). And the process of the cooler control apparatus 9 progresses to step S74.

  In step S74, the cooler control device 9 determines whether or not the valve opening degree of the electronic expansion valve 4E is the maximum in the system and the suction pressure P is equal to or lower than the shift pressure. When the valve opening degree of the electronic expansion valve 4E is not the maximum in the system or the suction pressure P is not equal to or lower than the shift pressure (No in S74), the process of the cooler control device 9 returns to Step S71. When the valve opening degree of the electronic expansion valve 4E is the maximum in the system and the suction pressure P is equal to or lower than the shift pressure (S74 / Yes), the process of the cooler control device 9 proceeds to step S75.

  In step S75, the cooler control device 9 controls the valve opening degree of the electronic expansion valve 4E according to a preset set value of the cooler superheat degree.

  That is, as shown in FIG. 11, in the cooling priority operation C1, in order to quickly reduce the internal temperature T and the suction pressure P, a large amount of refrigerant is flowed at a relatively large valve opening, and the valve is set to ensure reliability. The opening speed is set high, and the response of flow rate adjustment is accelerated so that liquid back does not occur.

Further, as shown in FIG. 12, also in the suction pressure stability priority operation C2, the suction pressure P is decreased within the specification range (P _{L to} P _H ) of the refrigeration system S, and the operation immediately shifts to the high COP priority operation C3. Therefore, the valve opening is increased or decreased within a range where the suction pressure P is less than the upper limit of the specification.

In addition, as shown in FIG. 13, in the high COP priority operation C3, the suction pressure P is maintained within the specification range (P _{L to} P _H ) of the refrigeration system S, so that the shift pressure P _shift or more is maintained. Increase or decrease the degree.

Here, in the pull-down operation C (cooling priority operation C1, suction pressure stability priority operation C2, high COP priority operation C3), the above-described superheat degree set value is temporarily ignored and within the specification range of the refrigeration system S (P _L to The target superheat degree and the valve opening speed are adjusted so that the shift pressure P _shift or more is _reached at P _H ). If the suction pressure P cannot be maintained at the shift pressure P _shift or more even when the valve opening is opened to the upper limit (Yes in S74), the valve opening of the electronic expansion valve 4E is set in accordance with the superheat setting value described above. adjust.

  Further, as in the case of the drive frequency control of the compressor 1, in order to prevent the suction pressure P from rapidly increasing due to a sudden decrease in the valve opening, the valve opening speed is restricted (however, the valve opening speed> Valve closing speed).

  In order to prevent the liquid back phenomenon, a lower limit value of the cooler superheat degree is set, and when the cooler superheat degree is less than the lower limit value, the opening degree of the electronic expansion valve 4E is controlled to be closed.

  In the present embodiment configured as described above, after the reliability of the refrigeration system is ensured and the minimum required internal temperature control is satisfied, an operation with a higher COP than the above-described embodiment is performed. I can do it.

<Modification>
Note that the refrigeration system S according to this embodiment is not limited to the configuration of the above embodiment, and various modifications can be made without departing from the spirit of the invention.

  The pull-down operation control of the refrigeration system S according to the present embodiment may be set to one cooling mode so that the user can easily select and switch with a dip switch or the like.

Various setting values (T _b , T _shift , P _shift , f _COP , Δf, Δt, etc.) have been described as being set in advance and stored in the storage unit, but by operating the operation unit 8 b of the controller 8 The user may be able to set.

  Although the controller 8 has been described as being provided separately from the condensing unit 11 and the refrigerator 12, it is not limited thereto. For example, the controller 8 may be provided in the casing of the condensing unit 11, and the controller 8 may be provided in the casing of the refrigerator 12. Moreover, although it demonstrated as what controls the refrigeration system S by the controller 8, the cooler control apparatus 9, and the condensing unit control apparatus 10, it is not restricted to this, One control means is refrigeration system S whole. It may be one that controls.

S Refrigeration system 1 Compressor 2 Condenser 3 Refrigerant liquid solenoid valve 4 Expansion valve 4E Electronic expansion valve 5 Evaporator 6 Internal temperature sensor 7 Suction pressure sensor 8 Controller (control means)
9 Cooler control device (control means)
10 Condensing unit control device (control means)
11 Condensing unit 12 Refrigerator 13 Cooler T Chamber temperature T _ON Thermo-on set temperature T _OFF Thermo-off set temperature T _P Target temperature T _shift shift temperature (frequency shift set temperature)
P _shift shift pressure (frequency shift setting suction pressure)
f Drive frequency f _max Maximum drive frequency (first drive frequency)
f _COP high COP frequency (second drive frequency)

Claims (9)

A refrigeration cycle consisting of a compressor, a condenser, an expansion valve, and an evaporator whose driving frequency is variable;
A refrigerator to which a medium to be cooled cooled by the evaporator is supplied;
An internal temperature sensor for detecting the internal temperature of the refrigerator;
A suction pressure sensor for detecting the suction pressure of the compressor;
Control means for instructing operation start of the refrigeration cycle when the internal temperature is equal to or higher than a thermo-on set temperature, and instructing to stop operation of the refrigeration cycle when the internal temperature is equal to or lower than a thermo-off set temperature; With
The control means includes
Information on the compressor input in advance;
A frequency shift set temperature provided until the thermo-off set temperature is reached;
Based on the preset frequency shift set suction pressure,
A refrigeration system comprising an operation mode for appropriately changing the drive frequency of the compressor. The control means includes
In the pull-down operation in which the internal temperature is higher than the thermo-on set temperature by a certain temperature or more, the temperature range until the thermo-off set temperature is reached in the pull-down operation for cooling to the thermo-off set temperature,
A cooling priority operation region in which the compressor is driven until the internal temperature is equal to or lower than the frequency shift set temperature and the suction pressure is equal to or lower than the frequency shift set suction pressure, with the drive frequency of the compressor as the first drive frequency;
A suction pressure stable priority operation region in which the drive frequency of the compressor is decelerated while maintaining the frequency shift set suction pressure;
A high COP priority operation range for cooling to the thermo-off set temperature as a second drive frequency that is an efficient drive frequency set based on the compressor information inputted in advance as the drive frequency of the compressor; Divided into 3 categories
The refrigeration system according to claim 1, wherein a driving frequency of the compressor is changed corresponding to each temperature range. The suction pressure stability priority operation range is
Each time the suction pressure falls below the frequency shift set suction pressure, the drive frequency of the compressor is reduced by one step,
The refrigeration system according to claim 2, wherein when the drive frequency of the compressor is decelerated to the second drive frequency, the compressor shifts to the high COP priority operation range. The frequency shift set temperature is
The refrigeration system according to claim 2, wherein the temperature is a maximum temperature within a range that does not damage the stored articles stored in the refrigerator. The frequency shift set suction pressure is
The compressor is set so as to be within a specification range of the refrigeration cycle even when the suction pressure increases when the drive frequency of the compressor is decelerated by one step in the suction pressure stability priority operation region. 4. The refrigeration system according to 3. When the drive frequency of the compressor is decelerated by one step in the suction pressure stability priority operation range,
The drive frequency of the compressor is reduced to 10 Hz or less,
4. The refrigeration system according to claim 3, wherein an interval of 30 seconds or more is provided from the previous deceleration to the next deceleration. The control means includes
Measure each operation time of the cooling priority operation region, the suction pressure stability priority operation region, and the high COP priority operation region,
When the measured operation time, which is the sum of all, exceeds a preset operation time,
3. The refrigeration system according to claim 2, wherein the compressor is switched to a cooling priority operation in which cooling is performed until the internal temperature becomes equal to or lower than the thermo-off set temperature with the driving frequency of the compressor as a first driving frequency. The control means includes
As one of the information of the compressor, the power consumption amount of the compressor at each driving frequency is stored as power consumption amount information,
From each operation time, each drive frequency of the compressor and the power consumption information, to calculate the total power consumption,
The refrigeration system according to claim 2, wherein the state of the refrigeration system is determined based on the calculated total power consumption and the past total power consumption. The expansion valve is
An electronic expansion valve capable of controlling the valve opening and the valve opening speed by the control means,
The control means includes
In the pull-down operation,
Controlling the valve opening and the valve opening speed so as to maintain the suction pressure at or above the frequency shift set suction pressure within the specification range of the refrigeration cycle;
Even if the upper limit of the opening degree of the expansion valve is reached, if it becomes impossible to maintain the frequency shift set suction pressure or higher, the valve opening degree is controlled based on a preset outlet superheat degree of the evaporator. The refrigeration system according to claim 2, wherein

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