JP2014128471A - Cooling system control method and cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling system control method and a cooling system capable of improving an energy-saving effect by greatly reducing power consumption while performing excellent temperature control.SOLUTION: The cooling system controls a temperature in a refrigerating/freezing showcase by executing a cooling cycle of repeating a former defrosting time to defrost frosting in the refrigerating/freezing showcase cooled by a refrigerant, and a later defrosting time to defrost frosting in the refrigerating/freezing showcase, produced by cooling after the former defrosting time. The operation time of a compressor is shortened to thereby suppress power consumption by alternately repeating cooling and defrosting so that a temperature in the refrigerating/freezing showcase reach a set lower limit temperature preset based on a rated ability of the refrigerating/freezing showcase when the later defrosting time is reached.

Description

  The present invention relates to a control method and a cooling system for a cooling system that cools and defrosts the inside of a refrigerated freezer showcase to control the temperature inside the refrigerated freezer showcase.

  A cooling system used in a commercial facility or the like mainly includes a refrigerated showcase that stores and cools food, beverages, and the like, and a compressor that compresses refrigerant supplied to the refrigerated showcase.

  In such a cooling system, when supplying a refrigerant to cool food in the refrigerated freezer showcase, the supply of the refrigerant is executed by opening the electromagnetic valve, and when the supply of the refrigerant is stopped, the electromagnetic The supply of the refrigerant is stopped by the closing operation of the valve (see, for example, Patent Document 1).

  By the way, the temperature control in the refrigerated freezer showcase in such a cooling system is generally a pull-down operation that continuously operates the compressor at the start of refrigeration or freezing, and the temperature in the refrigerated freezer showcase reaches the set temperature. At this stage, the operation is performed by a thermocycle operation in which the operation of the compressor is intermittently operated by turning it on / off.

  Various techniques have been proposed for temperature control in the refrigerated freezer showcase using such a cooling system from the viewpoint of reducing the power consumption and improving the energy saving effect.

  Patent Document 2 discloses a refrigeration apparatus that controls a variable speed compressor in accordance with an operating state. According to the refrigeration apparatus of Patent Document 2, in the initial stage of the pull-down operation, the compressor is rotated at a medium speed in order to perform the so-called break-in operation. From the end of the initial stage of the pull-down operation to the end of the thermocycle operation, the compressor is rotated at a high speed in order to quickly reach the set temperature.

  On the other hand, when the outside air temperature is low during the thermocycle operation, it reaches the set temperature relatively easily without increasing the refrigerating capacity, so the compressor is rotated at a low speed.

  In this way, the speed of the compressor is controlled by increasing or decreasing the speed according to the request in each operation state of pull-down operation or thermocycle operation, and the compressor is operated at a low speed or medium speed that is lower than the high speed rotation. The power consumption can be reduced during the deceleration control for rotation.

JP 2008-302004 A JP 11-270914 A

  In general, the cooling system operates intermittently by turning the compressor on and off in thermocycle operation, but in order to efficiently reduce power consumption, the compressor stop time is increased. It is preferable to make it.

  However, the refrigeration apparatus of Patent Document 2 controls the rotation speed of the compressor in response to a request in each operation state, and increases the stop time of the compressor during the thermocycle operation, that is, the operation of the compressor. It does not control the on / off timing.

  Therefore, according to the above-mentioned Patent Document 2, it is not considered to secure the stop time of the compressor. As a result, although a small energy saving effect can be obtained when the compressor is turned on during the thermocycle operation, a significant energy saving effect cannot be obtained in the refrigeration apparatus.

  The present invention has been made in view of the above problems, and its object is to provide a cooling system control method capable of significantly reducing power consumption and improving energy saving effect while performing good temperature control, and It is to provide a cooling system.

  In order to achieve the above object, the invention according to claim 1 is directed to a refrigerated freezer showcase in which the refrigerant is supplied on the low pressure side of the refrigerant pressure, and to the refrigerated freezer showcase downstream of the refrigerated freezer showcase. A compressor that compresses the supplied refrigerant, and a valve that adjusts the refrigerant pressure between the compressor and the refrigerated freezer showcase, and is configured to reduce frost in the refrigerated freezer showcase cooled by the refrigerant. Executing a cooling cycle that repeats a defrosting time before defrosting and a defrosting time after defrosting the frost in the refrigerated freezing showcase caused by cooling after the previous defrosting time, In the control method of the cooling system for controlling the temperature in the refrigerated freezing showcase, the valve is controlled to open and close between the previous defrost time and the subsequent defrost time, and the subsequent defrost time of The cooling and defrosting are repeated alternately so that the temperature in the refrigerated freezer showcase reaches a preset lower limit temperature based on the rated capacity of the refrigerated freezer showcase, and the valve is closed. The refrigerant in which the refrigerant pressure is preset based on the rated capacity of the refrigerated refrigeration showcase on the low pressure side by increasing the temperature in the refrigerated refrigeration showcase and increasing the compression rate of the refrigerant by the compressor When the pressure lower limit value is reached, the operation of the compressor is stopped.

  According to this configuration, the refrigerant pressure is adjusted between the refrigerated showcase and the compressor by the valve opening / closing control between the previous defrost time and the subsequent defrost time until the set lower limit temperature is reached. Control that alternately repeats cooling and defrosting is executed.

  Therefore, the temperature in the refrigerated freezer showcase is gradually lowered to reach the set lower limit temperature over a long period of time, so that the refrigerant pressure in the cooling system is suppressed and the inside of the refrigerated freezer showcase is cooled. The refrigerant requirement can be suppressed.

  Since the refrigerant required for cooling in the refrigerated refrigeration showcase is suppressed, the compression of the refrigerant by the compressor is also executed so as to be able to meet the suppressed refrigerant demand. Power consumption can be suppressed by shortening.

  According to a second aspect of the present invention, in the cooling system control method according to the first aspect, the operation of the compressor is stopped when the refrigerant pressure reaches a value immediately before reaching the lower limit value of the refrigerant pressure. It is characterized by

  Generally, when the compressor power consumption is stopped at the refrigerant pressure lower limit value, the load on the compressor motor increases and the power consumption is maximized. Since the operation of the compressor is stopped by the value, the power consumption is efficiently suppressed before the power consumption becomes maximum.

  According to a third aspect of the present invention, in the control method of the cooling system according to the second aspect, the control signal generated by the control unit in which a value immediately before the refrigerant pressure reaches the refrigerant pressure lower limit value is generated. On the basis of this, the operation of the compressor is stopped.

  According to this configuration, by setting the value immediately before reaching the refrigerant pressure lower limit value in the control unit, when the refrigerant pressure reaches the value immediately before reaching the refrigerant pressure lower limit value, the control unit The operation of the compressor can be easily stopped based on the generated signal.

  The invention according to claim 4 is the refrigerated freezer showcase produced by the defrosting time before defrosting the frost in the refrigerated freezing showcase cooled by the refrigerant and the cooling after the previous defrosting time. In the cooling system for controlling the temperature in the refrigerated refrigeration showcase by executing a cooling cycle that repeats the defrosting time after defrosting the inside frost, the refrigerant is supplied on the low pressure side of the refrigerant pressure of the refrigerant. Refrigerated main showcase, a compressor for compressing the refrigerant supplied to the refrigerated main showcase downstream of the refrigerated main showcase, and the refrigerant pressure between the compressor and the refrigerated main showcase A main cooling circuit having a valve for adjusting the temperature, a refrigerated refrigeration sub-showcase to which the refrigerant is supplied from the main refrigeration circuit, the refrigerated refrigeration sub-showcase and the comp of the main cooling circuit A sub-cooling circuit having a valve for adjusting the refrigerant pressure between the sub-cooling circuit and the opening / closing timing of the valve of the sub-cooling circuit between the previous defrosting time and the subsequent defrosting time. Control is performed in synchronization with the opening / closing timing of the valve of the main cooling circuit, and the temperature in the refrigerated freezer showcase is based on the rated capacity of the refrigerated freezer showcase when the subsequent defrosting time is reached. A controller that alternately repeats cooling and defrosting so as to reach a preset lower limit temperature, and the refrigeration refrigeration is performed by closing the valve of the main cooling circuit and the valve of the sub cooling circuit. As the temperature in the showcase rises and the compression rate of the refrigerant by the compressor increases, the refrigerant pressure on the low pressure side changes the refrigeration main showcase and the refrigeration subshowcase. It stops the operation of the compressor when it reaches the preset refrigerant pressure lower limit value based on the rated capacity, characterized in that.

  According to this configuration, by controlling the opening / closing timing of the valve of the sub cooling circuit so as to be synchronized with the opening / closing timing of the valve of the main cooling circuit, it is possible to suppress the refrigerant demand in the cooling system to be constant.

  Therefore, since the refrigerant requirements in the refrigeration main showcase of the main cooling circuit and the refrigeration subshowcase of the sub cooling circuit are constant, the refrigerant pressure in the cooling system is also constant.

  As a result, the compression of the refrigerant by the compressor of the main cooling circuit is also kept constant, so that the operation time of the compressor can be effectively shortened and the power consumption can be suppressed.

  According to a fifth aspect of the present invention, in the cooling system according to the fourth aspect, the control unit operates the compressor when the refrigerant pressure reaches a value immediately before reaching the refrigerant pressure lower limit value. It is characterized by controlling to stop.

  According to this configuration, by setting the value immediately before reaching the refrigerant pressure lower limit value in the control unit, when the refrigerant pressure reaches the value immediately before reaching the refrigerant pressure lower limit value, the control unit The operation of the compressor can be easily stopped based on the generated signal.

  A sixth aspect of the present invention is the cooling system according to the fourth or fifth aspect, wherein a plurality of the sub-cooling circuits are provided. According to this configuration, even when there are a plurality of sub-cooling circuits, the valve opening / closing timing of the sub-cooling circuit can be synchronized with the valve opening / closing timing of the main cooling circuit.

  Therefore, even when a plurality of sub-cooling circuits are provided, the refrigerant requirements in the refrigeration main showcase of the main cooling circuit and the refrigeration sub-showcase of the sub cooling circuit can be made constant, and the refrigerant pressure in the cooling system can also be Can be constant.

  According to this invention, the refrigerant pressure is adjusted between the refrigerated showcase and the compressor by the valve opening / closing control between the previous defrost time and the subsequent defrost time until the set lower limit temperature is reached. Control that alternately repeats cooling and defrosting is executed. Therefore, the temperature in the refrigerated freezer showcase is gradually lowered to reach the set lower limit temperature over a long period of time, so that the refrigerant pressure in the cooling system is suppressed and the inside of the refrigerated freezer showcase is cooled. The refrigerant requirement can be suppressed.

  Since the refrigerant required for cooling in the refrigerated refrigeration showcase is suppressed, the compression of the refrigerant by the compressor is also executed so as to be able to meet the suppressed refrigerant demand. Power consumption can be suppressed by shortening. As a result, the power consumption is greatly reduced and the energy saving effect is improved.

It is a block diagram explaining the outline of the cooling system which concerns on 1st Embodiment of this invention. Similarly, it is a control block diagram of the cooling system according to the present embodiment. Similarly, it is a flowchart showing the control steps of the cooling system according to the present embodiment. Similarly, it is a timing chart showing a control state of the cooling system according to the present embodiment. It is a figure showing the temperature transition state in the cooling system which concerns on this Embodiment, (a) is a figure showing the temperature transition state at the time of performing the existing control method, (b) is the control method which concerns on this Embodiment It is a figure showing the temperature transition state at the time of performing. It is a block diagram explaining the outline of the cooling system which concerns on 2nd Embodiment of this invention. It is a figure explaining the synchronous control of the opening / closing timing of the expansion valve in the cooling system which concerns on this Embodiment, (a) is a figure showing the temperature transition in the refrigerated freezer showcase before performing synchronous control, (b) is It is a figure showing the temperature transition in the refrigerated freezer showcase after performing synchronous control. It is a figure explaining the outline of the state where the cooling system concerning the present invention is arranged in a large-scale retail store.

(First embodiment)
Next, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a configuration diagram illustrating an outline of a cooling system according to the present embodiment. As shown in the figure, the cooling system 10 condenses the refrigerant compressed by the compressor 14, a refrigerated showcase 12 having an evaporator 12 a that vaporizes the refrigerant, a compressor 14 that compresses the refrigerant vaporized by the evaporator 12 a. A condenser 16 and an expansion valve 18 that decompresses the refrigerant condensed in the condenser 16 are provided as main components.

  In the cooling system 10, the refrigerated freezer showcase 12 and the expansion valve 18 are configured as a chamber 13 in which the inside of the refrigerated freezer showcase 12 is cooled by the refrigerant supplied via the expansion valve 18.

  A surge tank 19 for storing refrigerant is provided between the refrigerated freezer showcase 12 and the compressor 14. The surge tank 19 is provided with a pressure sensor 19 a that detects a refrigerant pressure that is the pressure of the refrigerant circulating in the cooling system 10.

  In this cooling system 10, a low-temperature and low-pressure liquid refrigerant is sent to the evaporator 12 a via the expansion valve 18. The low-temperature and low-pressure refrigerant sent to the evaporator 12a absorbs and vaporizes heat in the refrigerated freezer showcase 12, and cools the refrigerated freezer showcase 12.

  The low-temperature and low-pressure refrigerant that has been vaporized by cooling the refrigerated showcase 12 is drawn into the compressor 14 via the surge tank 19, and the drawn refrigerant is compressed by the compressor 14. The refrigerant compressed by the compressor 14 is sent to the condenser 16 in a high temperature / high pressure state.

  The high-temperature and high-pressure vaporized refrigerant sent to the condenser 16 is radiated and liquefied in the condenser 16, and the normal-temperature and high-pressure liquid refrigerant is sent to the expansion valve 18. The room-temperature / high-pressure liquid refrigerant sent to the expansion valve 18 is decompressed by the expansion valve 18 and sent again to the evaporator 12a.

  As described above, in the cooling system 10, when the refrigerant is vaporized by the evaporator 12 a to cool the refrigerated freezer showcase 12, the refrigerant vaporized by the evaporator 12 a is compressed by the compressor 14, and the refrigerant compressed by the compressor 14 is A cycle in which the refrigerant liquefied by the condenser 16 and the refrigerant liquefied by the condenser 16 is decompressed by the expansion valve 18 is executed.

  During execution of this cycle, the refrigerant pressure of the refrigerant circulating in the cooling system 10 is detected by a pressure sensor 19 a provided in the surge tank 19. In the present embodiment, the value (refrigerant pressure) immediately before the pressure sensor 19a reaches the lower limit (refrigerant pressure lower limit) of the refrigerant pressure in the cooling system 10 set in advance based on the rated capacity of the refrigerated freezer showcase 12. When the value immediately before the lower limit) is detected, the operation of the compressor 14 is stopped.

  On the other hand, the value immediately before the pressure sensor 19a reaches the upper limit (refrigerant pressure upper limit) of the refrigerant pressure in the cooling system 10 set in advance based on the rated capacity of the refrigerated freezer showcase 12 (the immediately preceding value of the refrigerant pressure upper limit). Is detected, the operation of the compressor 14 is started.

  In the cooling system 10, the refrigerant pressure is adjusted between the refrigerated freezer showcase 12 and the compressor 14 by controlling the opening / closing operation of the expansion valve 18. That is, the refrigerant pressure is adjusted to a low pressure on the refrigeration / freezer showcase 12 side in the cooling system 10, and the refrigerant pressure is adjusted to a high pressure on the condenser 16 side in the cooling system 10.

  In the cooling system 10 having the above-described configuration, the defrosting time (defrost time) of the destination that defrosts the frost that has formed in the refrigerated freezer showcase 12 cooled by the refrigerant (defrost time), and the time after the previous defrost time The cooling cycle which repeats the defrosting time (defrost time) after defrosting the frost in the refrigerated freezing showcase 12 produced by cooling is performed, and the temperature of the freezing freezing showcase 12 in the cooling system 10 is controlled. It is configured as follows.

  FIG. 2 is a control block diagram of the cooling system 10 according to the present embodiment. As illustrated, the cooling system 10 is controlled by a control mechanism 20. The control mechanism 20 includes a computer 22 as a control unit, a compressor control switch 24 connected to the computer 22, an expansion valve control switch 26, and a heater control switch 28 as main components.

  The compressor control switch 24, the expansion valve control switch 26, and the heater control switch 28 constitute a control device 21.

  A signal from a defrost timer 30 provided in the chamber 13 is input to the computer 22. The defrost timer 30 has a preset differential time, and an electric signal is input to the computer 22 when the set time is reached.

  In the present embodiment, the differential time is set to 2 minutes from the start to the end of the defrost, and the electrical signal for the start of the differential time and the electrical signal for the end of the differential time are respectively input to the computer 22. Is done.

  On the other hand, a signal from a pressure sensor 19 a provided in the surge tank 19 is input to the computer 22. When the pressure sensor 19a detects the value immediately before the refrigerant pressure upper limit or the value immediately before the refrigerant pressure lower limit preset in the computer 22, the computer 22 sends a compressor control signal for controlling the compressor 14 based on the signal input from the pressure sensor 19a. Generate.

  Further, the temperature in the refrigerated freezer showcase 12 measured by a thermometer 32 provided in the refrigerated freezer showcase 12 is input to the computer 22 as an electrical signal. When the thermometer 32 measures the temperature preset in the computer 22, the computer 22 generates a control signal for controlling the opening / closing of the expansion valve 18 based on the signal input from the thermometer 32.

  Regarding the temperature set in advance in the computer 22, in the present embodiment, the set upper limit temperature, which is the upper limit temperature in the refrigerated freezer showcase 12 set in advance based on the rated capacity of the refrigerated freezer showcase 12, the refrigerated freezer show. A preset lower limit temperature, which is a lower limit temperature in the refrigerated freezer showcase 12 set in advance based on the rated capacity of the case 12, is set in the computer 22 in advance.

  Furthermore, the expansion valve 18 is opened to relatively cool the expansion valve opening temperature that requires cooling in the refrigerated freezer showcase 12, and the expansion valve 18 is closed to defrost the refrigerated freezer showcase 12. A relatively low expansion valve closing temperature is preset in the computer 22.

  The compressor 14 is connected to the compressor control switch 24. In the present embodiment, the compressor 14 is a variable speed type that compresses the refrigerant by operating the motor, and the compressor control switch 24 is based on a control signal from the computer 22 and immediately before the refrigerant pressure upper limit and the refrigerant pressure lower limit. At the immediately preceding value, the compressor 14 is switched between the operating state and the stopped state.

  The expansion valve 18 is connected to the expansion valve control switch 26. In this embodiment, the expansion valve 18 is configured to be electromagnetically openable and closable, and the expansion valve control switch 26 switches the expansion valve 18 between an open state and a closed state based on a control signal from the computer 22. .

  A heater 32 provided in the evaporator 12a is connected to the heater control switch 28. The heater control switch 28 controls the heating of the evaporator 12a by the heater 32 based on a control signal from the computer 22. And switching to the heating stop state.

  Next, a method for controlling the cooling system 10 will be described.

  FIG. 3 is a flowchart showing control steps of cooling system 10 according to the present embodiment. As shown in the figure, if it is determined in step S1 that the def time preset in the defrost timer 30 has been reached, the defrost timer 30 inputs an electrical signal to the computer 22 and executes the defrost.

  When an electric signal for starting the def time is input from the defrost timer 30 to the computer 22, the computer 22 generates an expansion valve closing control signal based on the electric signal, and the expansion valve closing control signal is sent to the expansion valve control switch 26. In step S2, the expansion valve 18 is closed by operating the expansion valve control switch 26.

  On the other hand, when an electric signal is input from the defrost timer 30 to the computer 22, the computer 22 generates a heater operation signal based on the electric signal, and the heater operation signal is input to the heater control switch 28. In step S2, The heater 32 heats the evaporator 12 a by the operation of the heater control switch 28.

  By closing the expansion valve 18 and heating the evaporator 12a by the heater 32, the temperature in the refrigerated freezer showcase 12 rises rapidly, and frost in the refrigerated freezer showcase 12 is defrosted in a short time.

  Due to the closing of the expansion valve 18 and the heating of the evaporator 12a by the heater 32, the temperature in the refrigerated freezer showcase 12 rises in step S3. When the heat absorption rate by the refrigerant increases in the evaporator 12a due to the rise in temperature, the refrigerant compression rate by the compressor 14 also increases. Therefore, in step S4, the refrigerant pressure on the low pressure side of the cooling system 10 decreases.

  When the refrigerant pressure on the low pressure side of the cooling system 10 decreases and reaches a value immediately before the refrigerant pressure lower limit, the pressure sensor 19 a inputs an electric signal to the computer 22.

  The computer 22 inputs the compressor control signal generated based on the electrical signal input from the pressure sensor 19a to the compressor control switch 24, and the operation of the compressor 14 is stopped by the operation of the compressor control switch 24 in step S5.

  When power consumption of the compressor 14 stops at the refrigerant pressure lower limit value, the load on the motor of the compressor 14 increases and the power consumption becomes maximum, but the operation of the compressor 14 is stopped at the value immediately before the refrigerant pressure lower limit value (peak cut). For this reason, the power consumption is suppressed before the power consumption is maximized.

  If it is determined that the def time set in the defrost timer 30 has expired, the defrost timer 30 inputs an electrical signal to the computer 22 in step S6.

  When an electrical signal is input from the defrost timer 30 to the computer 22, the computer 22 generates a heater operation stop signal based on this signal, and the heater operation stop signal is input to the heater control switch 28. In step S7, the heater operation stop signal is input. The operation of the control switch 28 stops the heating of the evaporator 12a by the heater 32.

  On the other hand, when an electrical signal indicating the end of the differential time is input from the defrost timer 30 to the computer 22, the computer 22 generates an expansion valve opening control signal based on the electrical signal, and the expansion valve control switch 26 controls the expansion valve opening control signal. In step S8, the expansion valve 18 is opened by operating the expansion valve control switch 26.

  When the expansion valve 18 is opened, the temperature in the refrigerated freezer showcase 12 decreases in step S9. When the heat dissipation rate due to the refrigerant increases in the condenser 16 due to the decrease in temperature, the refrigerant compression rate by the compressor 14 also decreases, so that the refrigerant pressure on the low pressure side of the cooling system 10 increases in step S10.

  When the refrigerant pressure on the low pressure side of the cooling system 10 rises and reaches a value just before the refrigerant pressure upper limit, the pressure sensor 19 a inputs an electric signal to the computer 22.

  The computer 22 inputs the compressor control signal generated based on the electric signal input from the pressure sensor 19a to the compressor control switch 24. In step S11, the operation of the compressor 14 is started by the operation of the compressor control switch 24.

  When the refrigerant pressure on the low pressure side of the cooling system 10 is drawn into the compressor 14 and compressed by the operation of the compressor 14, the refrigerant pressure on the low pressure side of the cooling system 10 decreases in step S <b> 12.

  When the refrigerant pressure on the low pressure side of the cooling system 10 decreases and reaches a value immediately before the refrigerant pressure lower limit, the pressure sensor 19 a inputs an electric signal to the computer 22.

  The computer 22 inputs the compressor control signal generated based on the electric signal input from the pressure sensor 19a to the compressor control switch 24, and the operation of the compressor 14 is stopped by the operation of the compressor control switch 24 in step S13.

  On the other hand, when an electric signal for starting the def time is input from the defrost timer 30 to the computer 22, the computer 22 generates an expansion valve closing control signal based on this electric signal, and the expansion valve control switch 26 supplies this expansion valve closing control signal. In step S14, the expansion valve 18 is closed by operating the expansion valve control switch 26.

  By closing the expansion valve 18, the temperature in the refrigerated freezer showcase 12 rises, and the frost in the refrigerated freezer showcase 12 is gradually defrosted.

  Thereafter, in step 15, it is determined whether or not the temperature in the refrigerated freezer showcase 12 measured by the thermometer 32 has reached a set lower limit temperature preset in the computer 22.

  On the other hand, if it is determined in step S1 that the def time preset in the defrost timer 30 has not been reached, the temperature in the refrigerated freezer showcase 12 measured by the thermometer 32 in step S16 is It is determined whether or not a preset upper limit temperature preset in 22 has been reached. If it is determined that the set upper limit temperature has been reached, defrosting is performed even if the def time has not been reached.

  If it is determined in step S6 that the def time set in the defrost timer 30 has not ended, the process returns to step S3, and the expansion valve 18 is kept closed until the def time ends.

  Furthermore, when it is determined in step S15 that the temperature in the refrigerated freezer showcase 12 measured by the thermometer 32 has not reached the preset lower limit temperature preset in the computer 22, the process returns to step S8.

  That is, the expansion valve 18 is opened again to lower the temperature, while the refrigerant pressure rises and the operation of the compressor 14 starts to lower the refrigerant pressure. Therefore, the operation of the compressor 14 is stopped and the expansion valve 18 is stopped. Closes. Thus, the refrigerant pressure is adjusted between the refrigerated freezer showcase 12 and the compressor 14 by opening and closing the expansion valve 18, and cooling and defrosting are alternately repeated until the set lower limit temperature is reached.

  In the present embodiment, the opening / closing timing of the expansion valve 18 is set to be repeatedly executed every two minutes based on the def time preset in the defrost timer 30.

  FIG. 4 is a timing chart showing the control state of the cooling system 10 according to the present embodiment executed in the above steps. As illustrated, when the expansion valve 18 is closed, the temperature in the refrigerated freezer showcase 12 increases, and when the expansion valve 18 is opened, the temperature in the refrigerated freezer showcase 12 decreases.

  On the other hand, when the heat absorption rate by the refrigerant increases in the evaporator 12a due to the temperature rise in the refrigerated freezer showcase 12, the refrigerant compression rate by the compressor 14 also increases, so the refrigerant pressure on the low pressure side of the cooling system 10 decreases. When the refrigerant pressure on the low pressure side decreases and reaches the value just before the refrigerant pressure lower limit, the operation of the compressor 14 is stopped.

  When the compressor 14 stops at the refrigerant pressure lower limit value, the load on the motor of the compressor 14 increases and the power consumption becomes maximum. However, if the operation of the compressor 14 is stopped at the value just before the refrigerant pressure lower limit value, the power consumption becomes maximum. Before power consumption is suppressed.

  When the heat release rate by the refrigerant increases in the condenser 16 due to the temperature drop in the refrigerated freezer showcase 12, the refrigerant compression rate by the compressor 14 also decreases, so the refrigerant pressure on the low pressure side of the cooling system 10 increases. When the refrigerant pressure on the low pressure side rises and reaches the value just before the refrigerant pressure upper limit, the operation of the compressor 14 is started.

  FIG. 5 is a diagram illustrating a temperature transition state in the cooling system 10 according to the present embodiment, where (a) executes an existing control method, and (b) executes the control method according to the present embodiment. This is the case.

  As shown in FIG. 5A, in the case of the existing control method, the temperature in the refrigerated freezer showcase 12 rapidly rises to about 12 ° C. due to the arrival of the def time DT1, which is the previous defrost time. Is executed, until the next differential time DT2, which is the subsequent defrosting time, the temperature is rapidly lowered to the set lower limit temperature of −27 ° C. for a short time, approximately 1. Reach in 5 hours.

  On the other hand, as shown in FIG. 5B, in the case of the control method of the present embodiment, the temperature in the refrigerated freezer showcase 12 rapidly rises to about 10 ° C. by the arrival of the differential time DT1. After defrosting, until the next differential time DT2, the cooling and defrosting are alternately repeated to gradually decrease the temperature gradually to the set lower limit temperature of −27 ° C. for a long time. The form takes about 5.5 hours to reach.

  As described above, in the cooling system 10 according to the present embodiment, the refrigerant pressure between the refrigerated freezer showcase 12 and the compressor 14 is controlled by opening / closing the expansion valve 18 between the differential time DT1 and the next differential time DT2. Is adjusted, and cooling and defrosting are alternately controlled until the set lower limit temperature is reached.

  Therefore, since the temperature in the refrigerated freezer showcase 12 is gradually lowered to reach the set lower limit temperature over a long time, the refrigerant pressure in the cooling system 10 is suppressed, and the inside of the refrigerated freezer showcase 12 is The refrigerant | coolant request | requirement for cooling can be suppressed.

  Since the refrigerant required for cooling in the refrigerated refrigeration showcase 12 is suppressed, the compression of the refrigerant by the compressor 14 is also executed so as to meet the suppressed refrigerant demand. The operation time can be shortened to reduce power consumption.

  In addition, when the compressor 14 stops at the refrigerant pressure lower limit value, the load on the motor of the compressor 14 increases and the power consumption is maximized. However, in the cooling system 10 according to the present embodiment, the value immediately before the refrigerant pressure lower limit value. Since the operation of the compressor 14 is stopped, the power consumption is suppressed before the power consumption becomes maximum. As a result, the power consumption is greatly reduced and the energy saving effect is improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7, the same reference numerals are given to the same components as those in FIGS. 1 to 5, and detailed description thereof will be omitted.

  FIG. 6 is a configuration diagram illustrating an outline of the cooling system according to the present embodiment. As illustrated, the cooling system 40 includes a main cooling circuit 40-1 and a plurality of sub cooling circuits 40-2 to 40-n connected to the main cooling circuit 40-1.

  The main cooling circuit 40-1 includes a refrigerated main showcase 42-1 including an evaporator 12a, a compressor 14, a condenser 16, and an expansion valve 18 as main components. On the other hand, the sub-cooling circuits 40-2 to 40-n include the refrigeration / freezing sub-showcases 42-2 to 42-n and the expansion valve 18 as main components, respectively.

  In addition, the refrigeration main showcase 42-1 of the main cooling circuit 40-1 and the refrigeration sub-showcases 42-2 to 42-n of the sub-cooling circuits 40-2 to 40-n have the same configuration. Configured.

  In the main cooling circuit 40-1, a low-temperature and low-pressure liquid refrigerant is sent to the evaporator 12a of the main cooling circuit 40-1 via the expansion valve 18 of the main cooling circuit 40-1. The low-temperature and low-pressure refrigerant sent to the evaporator 12a absorbs and vaporizes the heat in the refrigerated main showcase 42-1 to cool the inside of the refrigerated main showcase 42-1.

  In the sub-cooling circuits 40-2 to 40-n, the low-temperature and low-pressure liquid refrigerant evaporates from the sub-cooling circuits 40-2 to 40-n via the expansion valve 18 of the sub-cooling circuits 40-2 to 40-n. To the device 12a. The low-temperature and low-pressure refrigerant sent to the evaporator 12a absorbs the heat in the refrigerated freezer sub-showcases 42-2 to 42-n and vaporizes to cool the refrigerated freezer showcases 42-2 to 42-n. To do.

  The low-temperature and low-pressure refrigerant that has been vaporized by cooling the inside of the refrigerated main showcase 42-1 and the refrigerated sub-showcases 42-2 to 42-n is mainly cooled via the surge tank 19 of the main cooling circuit 40-1. The refrigerant drawn into the compressor 14 of the circuit 40-1 is compressed by the compressor 14 of the main cooling circuit 40-1. The refrigerant compressed by the compressor 14 becomes a high temperature / high pressure state and is sent to the condenser 16 of the main cooling circuit 40-1.

  The high-temperature and high-pressure vaporized refrigerant sent to the condenser 16 of the main cooling circuit 40-1 is radiated and liquefied in the condenser 16, and the normal-temperature and high-pressure liquid refrigerant is converted into the main cooling circuit 40-1 and the sub-cooling. It is sent to each expansion valve 18 of the circuits 40-2 to 40-n. The room-temperature / high-pressure liquid refrigerant sent to each expansion valve 18 is decompressed by each expansion valve 18 and sent again to the evaporator 12a.

  As described above, in the cooling system 40, the refrigerant is vaporized by the evaporator 12a of the main cooling circuit 40-1 and the plurality of sub-cooling circuits 40-2 to 40-n, and the refrigerated main showcase of the main cooling circuit 40-1. In cooling the refrigerated sub-showcases 42-2 to 42-n of the 42-1 and the plurality of sub-cooling circuits 40-2 to 40-n, the main cooling circuit 40-1 and the plurality of sub-cooling circuits 40-2 to 40-n are cooled. The refrigerant vaporized by the evaporator 12a of 40-n is compressed by the compressor 14 of the main cooling circuit 40-1, the refrigerant compressed by the compressor 14 is liquefied by the condenser 16 of the main cooling circuit 40-1, and the condenser 16 A cycle is performed in which the refrigerant liquefied in step 1 is depressurized by each expansion valve 18.

  In the cooling system 10 configured as described above, the open / close operation of each expansion valve 18 of the main cooling circuit 40-1 and the plurality of sub-cooling circuits 40-2 to 40-n is controlled to perform the refrigeration main show of the main cooling circuit 40-1. The refrigerant pressure is adjusted between the case 42-1 and the refrigerated sub-showcases 42-2 to 42-n of the plurality of sub-cooling circuits 40-2 to 40-n and the compressor 14 of the main cooling circuit 40-1. That is, the refrigerant pressure is adjusted to a low pressure on the refrigeration main showcase 42-1 and the refrigeration sub-showcases 42-2 to 42-n side in the cooling system 40, and the refrigerant pressure is high on the condenser 16 side in the cooling system 40. Adjusted to

  By controlling the operating state of the compressor 14 of the main cooling circuit 40-1 based on the adjusted refrigerant pressure, the refrigeration main showcase 42-1 and the refrigeration sub-showcase 42-2 in the cooling system 40 are controlled. It is configured to control the temperature within 42-n.

  In particular, in the cooling system 40 of the present embodiment, control is performed so that the opening / closing timings of the expansion valve 18 of the main cooling circuit 40-1 and the expansion valves 18 of the plurality of sub cooling circuits 40-2 to 40-n are synchronized. Thus, the refrigeration / freezing main showcase 42-1 of the main cooling circuit 40-1 and the refrigeration / freezing sub-showcases 42-2 to 42-n of the plurality of sub-cooling circuits 40-2 to 40-n and the main The refrigerant pressure of the cooling system 40 is adjusted between the compressor 14 of the cooling circuit 40-1.

  In the present embodiment, the opening / closing timings of the expansion valves 18 of the sub cooling circuits 40-2 to 40-n are controlled to be synchronized with the opening / closing timings of the expansion valves 18 of the main cooling circuit 40-1.

  Next, a method for synchronously controlling the opening / closing timing of the expansion valve 18 of the main cooling circuit 40-1 and the expansion valves 18 of the plurality of sub-cooling circuits 40-2 to 40-n in the cooling system 40 will be described.

  FIG. 7 is a view for explaining the synchronous control of the opening / closing timing of each expansion valve 18 in the cooling system 40 according to the present embodiment. FIG. 7A shows each refrigerated freezer showcase 42-1 before performing the synchronous control. The figure showing the temperature transition in 42-2 to 42-n, (b) is a figure showing the temperature transition in each refrigerated showcase 42-1 and 42-2 to 42-n after performing synchronous control. is there.

  In the cooling system 40, the temperature in each of the refrigerated freezer showcases 42-1 to 42-n is increased or decreased by opening and closing the expansion valve 18. Therefore, in the present embodiment, as shown in FIG. 7, the temperature waveform representing the temperature transition indicating the rise and fall of the temperature in the refrigerated main showcase 42-1 of the main cooling circuit 40-1 is displayed on the secondary side. The subcooling is performed at the opening / closing timing of the expansion valve 18 of the main cooling circuit 40-1 by matching the temperature waveforms of the temperatures in the refrigeration / freezing subshowcases 42-2 to 42-n of the cooling circuits 40-2 to 40-n. Control is performed so that the opening and closing timings of the expansion valves 18 of the circuits 40-2 to 40-n are synchronized.

  Specifically, in the present embodiment, as shown in FIG. 7A, before the synchronous control is performed, the expansion valve 18 of the main cooling circuit 40-1 and the sub cooling circuits 40-2 to 40-. Since the opening / closing timings of the n expansion valves 18 are different, the temperature waveform in the refrigerated main showcase 42-1 of the main cooling circuit 40-1 and the refrigerated refrigeration subshowcase of the sub cooling circuits 40-2 to 40-n. The temperature rise and fall timings in the temperature waveforms in 42-2 to 42-n are different from each other.

  For example, if the temperature in the refrigerated sub-showcases 42-2 to 42-n of the sub-cooling circuits 40-2 to 40-n exceeds the set upper limit temperature or falls below the set lower limit temperature, the main cooling circuit 40-1 Timing of the arrival of the differential time of the refrigerated main showcase 42-1 and the arrival of the differential times of the refrigerated sub-showcases 42-2 to 42-n of the plurality of sub-cooling circuits 40-2 to 40-n are different. As a result, the differential time between the refrigerated main showcase 42-1 of the main cooling circuit 40-1 and the refrigerated subshowcases 42-2 to 42-n of the plurality of subcooling circuits 40-2 to 40-n. Will result in variations.

  Therefore, in the present embodiment, each expansion based on a signal input from the thermometer 32 provided in each of the refrigerated sub-showcases 42-2 to 42-n of the plurality of sub-cooling circuits 40-2 to 40-n. The opening / closing control of the valve 18 by the computer 22 is stopped. That is, each of the sub-cooling circuits 40-2 to 40-n is released from the opening / closing control of each expansion valve 18 based on the signal input from each thermometer 32.

  Specifically, the computer 22 is based on signals input from the thermometers 32 provided in the refrigerated sub-showcases 42-2 to 42-n of the plurality of sub-cooling circuits 40-2 to 40-n, respectively. The control signal for controlling the opening and closing of the expansion valve 18 is not generated, and the expansion valve 18 based on a signal input from the thermometer 32 provided in the refrigerated main showcase 42-1 of the main cooling circuit 40-1. Only the generation of a control signal for controlling the opening and closing is executed.

  On the other hand, as shown in FIG. 7B, the temperature waveforms in the refrigeration / freezing sub-showcases 42-2 to 42-n of the sub-cooling circuits 40-2 to 40-n are converted into the refrigeration / freezing of the main cooling circuit 40-1. Control is performed to match the temperature waveform in the main showcase 42-1.

  Thereby, the temperature waveform in the refrigeration freezer main showcase 42-1 of the main cooling circuit 40-1 and the temperature waveform in the refrigeration freezing subshowcases 42-2 to 42-n of the subcooling circuits 40-2 to 40-n. Are considered to have a temperature transition at the same temperature rise and fall timing.

  Therefore, based on the control signal for controlling the opening and closing of the expansion valve 18 based on the signal input from the thermometer 32 provided in the refrigerated freezer main showcase 42-1 of the main cooling circuit 40-1, the sub cooling circuit 40- Opening and closing of the expansion valves 18 of 2 to 40-n is controlled. As a result, the opening / closing timings of the expansion valves 18 of the sub cooling circuits 40-2 to 40-n are controlled to be synchronized with the opening / closing timings of the main cooling circuit 40-1.

  Thus, in the cooling system 40 according to the present embodiment, the refrigeration / freezer main showcase 42-1 of the main cooling circuit 40-1 and the refrigeration / freezer subshowcase 42 of the plurality of sub-cooling circuits 40-2 to 40-n. Even when there is a variation in the differential time with −2 to 42-n, the opening / closing timing of each expansion valve 18 of the sub cooling circuits 40-2 to 40-n is set to the expansion valve 18 of the main cooling circuit 40-1. By controlling so as to synchronize with the opening / closing timing of the refrigerant, the refrigerant demand in the cooling system 40 can be kept constant.

  Therefore, the refrigerant requirements in the refrigeration / freezer showcase 42-1 of the main cooling circuit 40-1 and the refrigeration / freezer sub-showcases 42-2 to 42-n of the sub-cooling circuits 40-2 to 40-n are constant. The refrigerant pressure in the cooling system 40 is also constant. As a result, the compression of the refrigerant by the compressor 14 is also kept constant, so that the operation time of the compressor 14 can be shortened and power consumption can be suppressed.

(Application example)
Next, an application example of the cooling system 10 (40) according to the present invention will be described based on FIG.

  In FIG. 8, the same components as those in FIGS. 1 to 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 8 is a diagram for explaining the outline of the food section of the large-scale retail store 100 to which the cooling system 10 (40) is applied. As illustrated, the large-scale retail store 100 includes a sales floor 102, an office 104, and a machine room 106. The cooling system 10 (40) is applied to cool a plurality of refrigerated freezer showcases 12 (42-1 to 42-n) arranged in the sales floor 102.

  In this application example, the refrigerated freezer showcase 12 (42-1 to 42-n) stores a meat case 12A for storing and storing refrigerated meat, a fresh fish case 12B for storing and storing fresh fish, and a vegetable. A refrigerated vegetable case 12C, a frozen confectionery case 12D for storing and freezing frozen confectionery such as ice cream, and a frozen food case 12E for storing and freezing other frozen foods are provided.

  These refrigerated case 12A, fresh fish case 12B, vegetable case 12C, frozen dessert case 12D and frozen food case 12E are refrigerated and frozen. Since the defrost cycle can be set almost similarly, the present application example is configured to control these showcases simultaneously.

  Each of the meat case 12A, the fresh fish case 12B, the vegetable case 12C, the frozen dessert case 12D, and the frozen food case 12E includes a refrigerated freezer showcase 12 (42-1 to 42-n). In the application example, a thermometer 32 connected by a wireless LAN is provided.

  Further, the sales floor 102 is provided with a router 50, which is connected to the thermometer 32 via a wireless LAN.

  The office 104 is provided with a computer 22. The computer 22 is connected to a router 50 provided in the sales floor 102 and a control device 21 disposed in the machine room 106. The control device 21 includes a compressor control switch 24, an expansion valve control switch 26, and a heater control switch 28, and is connected to a router 50 provided in the sales floor 102.

  In this application example, the cooling system 10 (40) configured in the large-scale retail store 100 with the above configuration is configured as a main cooling circuit 40-1 with a system configured with the meat case 12A as a center. Cooling circuits configured around the case are set as sub-cooling circuits 40-2 to 40-5.

  The temperature measured by the thermometer 32 of the meat case 12 </ b> A is input as an electrical signal to the computer 22 via the router 50. Based on this electrical signal, the computer 22 generates an expansion valve opening signal or an expansion valve closing signal, and this signal is input to the expansion valve control switch 26.

  The expansion valve control switch 26 opens or expands the expansion valve 18 that is electromagnetically opened and closed via the router 50 based on the expansion valve opening signal or the expansion valve closing signal input from the computer 22. Send closure instructions.

  At this time, each of the sub-cooling circuits 40-2 to 40-5, that is, the fresh fish case 12B, the vegetable case 12C, the frozen dessert case 12D, and the frozen food case 12E, each expansion valve 18 of each sub-cooling circuit. Is controlled so as to synchronize with the opening / closing timing of the expansion valve 18 of the main cooling circuit configured around the meat case 12A.

  In this way, by controlling the opening and closing of each expansion valve 18, the refrigerated freezer showcase 12 (42-) constituted by the meat case 12A, the fresh fish case 12B, the vegetable case 12C, the frozen dessert case 12D, and the frozen food case 12E. 1-42-n) and the refrigerant pressure are adjusted between the compressor 14 and cooling and defrosting are repeated alternately until the set lower limit temperature is reached.

  The present invention is not limited to the above-described embodiments and application examples, and various modifications can be made without departing from the spirit of the invention. In the second embodiment, the case where the thermometer 32 is provided in each of the plurality of refrigerated showcases 42-1 to 42-n has been described. For example, the refrigerated refrigeration constituting the main cooling circuit 40-1. You may provide only in the main showcase 42-1.

  In the above application example, the case where the cooling system 10 (40) is applied to the refrigerated freezer showcase 12 (42-1 to 42-n) of the large-scale retail store 100 has been described. For example, a refrigerated freezer of a commercial warehouse It can also be applied to.

DESCRIPTION OF SYMBOLS 10 Cooling system 12 Refrigerated freezer showcase 12a Evaporator 14 Compressor 16 Condenser 18 Expansion valve (valve)
20 Control mechanism 22 Computer (control unit)
40 Cooling System 40-1 Main Cooling Circuit 40-2 to 40-n Subcooling Circuit 42-1 Refrigerated Refrigeration Main Showcase 42-2 to 42-n Refrigerated Refrigeration Subshowcase DT1 Differential Time (Previous Defrost Time)
DT2 differential time (later defrost time)

Claims (6)

A refrigerated showcase supplied with the refrigerant on the low pressure side of the refrigerant, a compressor compressing the refrigerant supplied to the refrigerated showcase downstream of the refrigerated showcase, the compressor and the refrigerated A valve for adjusting the refrigerant pressure between the refrigeration showcase and a defrosting time prior to defrosting the frost in the refrigerated freezing showcase cooled by the refrigerant, and the previous defrosting time In a control method of a cooling system for controlling a temperature in the refrigerated freezer showcase by executing a cooling cycle that repeats a defrosting time after defrosting in the refrigerated freezer showcase caused by subsequent cooling ,
The valve is controlled to open and close between the previous defrosting time and the subsequent defrosting time, and the temperature in the refrigerated showcase is reached when the subsequent defrosting time is reached. Cooling and defrosting are alternately repeated to reach a preset lower limit temperature based on the rated capacity of the showcase,
By closing the valve, the temperature in the refrigerated freezer showcase rises and the compression rate of the refrigerant by the compressor increases, so that the refrigerant pressure on the low pressure side is preliminarily based on the rated capacity of the refrigerated freezer showcase. Stop operation of the compressor when the set refrigerant pressure lower limit is reached,
A control method for a cooling system.   The method of controlling a cooling system according to claim 1, wherein the operation of the compressor is stopped when the refrigerant pressure reaches a value immediately before reaching the refrigerant pressure lower limit value.   The cooling according to claim 2, wherein the operation of the compressor is stopped based on a control signal generated by a controller in which a value immediately before the refrigerant pressure reaches the refrigerant pressure lower limit value is set in advance. How to control the system. After defrosting the frost in the refrigerated freezer showcase generated by the defrosting time before the defrosting in the refrigerated freezer showcase cooled with the refrigerant and the cooling after the previous defrosting time In the cooling system for controlling the temperature in the refrigerated freezer showcase by executing a cooling cycle that repeats the defrosting time of
A refrigerated main showcase to which the refrigerant is supplied on the low pressure side of the refrigerant pressure, a compressor for compressing the refrigerant supplied to the refrigerated main showcase downstream of the refrigerated main showcase, and the compressor A main cooling circuit having a valve for adjusting the refrigerant pressure between the refrigerated freezer main showcase;
A refrigeration sub-showcase supplied with the refrigerant from the main cooling circuit, a sub-cooling circuit having a valve for adjusting the refrigerant pressure between the refrigeration sub-showcase and the compressor of the main cooling circuit;
Controlling the opening / closing timing of the valve of the sub-cooling circuit in synchronization with the opening / closing timing of the valve of the main cooling circuit between the previous defrosting time and the subsequent defrosting time, Cooling and defrosting are alternately performed so that the temperature in the refrigerated freezer showcase reaches a preset lower limit temperature based on the rated capacity of the refrigerated freezer showcase when the subsequent defrosting time is reached A controller that repeats,
By closing the valve of the main cooling circuit and the valve of the sub cooling circuit, the temperature inside the refrigerated refrigeration showcase rises and the compression rate of the refrigerant by the compressor increases, so that the refrigerant pressure on the low pressure side. Stops the operation of the compressor when the refrigerant pressure lower limit value set in advance based on the rated capacity of the refrigerated main showcase and the refrigerated freezer sub-showcase is reached.
A cooling system characterized by that. The controller is
5. The cooling system according to claim 4, wherein when the refrigerant pressure reaches a value immediately before reaching the refrigerant pressure lower limit value, control is performed to stop the operation of the compressor.   The cooling system according to claim 4 or 5, wherein a plurality of the sub cooling circuits are provided.

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