JP6040041B2 - Showcase cooling system - Google Patents

Description

  The present invention relates to a showcase cooling apparatus that distributes and supplies refrigerant discharged from a compressor to a plurality of showcase evaporators and cools each showcase.

  Conventionally, multiple showcases have been installed in stores such as convenience stores, and refrigerant is distributed and supplied to the evaporators of each showcase from the compressors of refrigerators installed outside the store. Yes. In this case, the refrigerant compressed by the compressor radiates heat in the condenser similarly installed in the refrigerator, condenses, and then is supplied to each showcase via the refrigerant pipe constituting the refrigerant circuit. An expansion valve and an evaporator are installed in the showcase, and after the refrigerant is throttled by the expansion valve, it flows into the evaporator and evaporates there to cool the cold air circulated in the showcase cabinet (For example, refer to Patent Document 1).

  The expansion valve adjusts the degree of throttling so that the degree of superheat of the refrigerant exiting the evaporator becomes the optimum specified value, thereby realizing efficient cooling of the showcase and prevention of liquid back to the compressor. The expansion valve includes a mechanical type and an electronic type (electric expansion valve). In the case of a mechanical expansion valve, it operates independently so as to have a specified superheat degree (specified value) set by itself, and in the case of an electronic expansion valve, the control device sets a target superheat degree. The valve opening was controlled. In addition, a liquid electromagnetic valve is provided in front of each expansion valve, and the liquid electromagnetic valve is closed when the interior of the showcase is sufficiently cooled (in the case of an electronic expansion valve, Can be fully closed, so the liquid solenoid valve may not be provided).

  Further, the compressor is generally controlled based on the low pressure of the refrigerant circuit, for example, the operation frequency. In this case, the target low pressure is set by the control device to a value that can sufficiently cool each showcase based on the enthalpy in the store, for example, and the operating frequency of the compressor is set so that the low pressure becomes the target low pressure. It was controlled. The compressor capacity control is not limited to the operating frequency, and there may be a case where a plurality of compressors are provided and the number of operating units is switched.

Japanese Patent No. 5053527

  Here, because the load on multiple showcases (ambient temperature, humidity, wind effects, internal temperature control and defrost control for cooling display products, etc.) are different, the liquid solenoid valve is opened and closed (electronic expansion In the case of a valve, the valve opening) depends on them. On the other hand, since the operation frequency of the compressor is conventionally controlled based on the low pressure of the refrigerant circuit, a situation in which the liquid electromagnetic valves of a plurality of showcases are opened or closed simultaneously (that is, performed synchronously). In the case of an electronic expansion valve, the adjustment direction of the valve opening degree tends to be the same in a plurality of electronic expansion valves (the same tendency is a tendency for closing to overlap, and in the most prominent case, it is fully closed, or When the adjustment is performed simultaneously or substantially simultaneously, the low-pressure pressure fluctuates greatly, and the operating frequency of the compressor fluctuates as a result. That is, when the cooling load varies due to the opening and closing of the liquid solenoid valve of the showcase, the low-pressure pressure varies, so the ease of cooling of other showcases changes, and the operation is chained. Then, the operating frequency of the compressor greatly fluctuates so as to suppress this low pressure fluctuation.

  Thus, conventionally, the operating frequency of the compressor greatly fluctuates due to the low pressure, resulting in an increase in power consumption. In addition, as described above, the load is different in each showcase, while the target low pressure is set to a value that can sufficiently cool all the showcases. ) Had excessive compressor capacity, which also led to energy loss.

  The present invention has been made to solve the conventional technical problems, and is capable of cooling all of the plurality of showcases without hindrance while suppressing the power consumption of the compressor. An object is to provide an apparatus.

  In order to solve the above problems, the showcase cooling device of the present invention distributes and supplies the refrigerant discharged from the compressor to the evaporators provided in a plurality of showcases, It is equipped with an internal temperature sensor for detecting the temperature and a control means for controlling the operation of the compressor, and this control means compresses based on the internal temperature of the showcase that is the most difficult to cool out of each showcase. It is characterized by controlling the operation of the machine.

  The showcase cooling device of the invention of claim 2 is the superheat degree adjusting means according to the invention, wherein each showcase squeezes the refrigerant flowing into the evaporator and adjusts the superheat degree of the refrigerant coming out of the evaporator to a specified value. And an on-off valve that controls the inflow of the refrigerant to the evaporator, and the control means controls the operation of the compressor based on the inside temperature of the showcase that is most difficult to cool and adjusts the inside temperature of the other showcase. On the basis of this, the target superheat degree of the showcase is set, and the on-off valve is opened and closed based on the target superheat degree and a predetermined value of the superheat degree.

  According to a third aspect of the present invention, there is provided a showcase cooling apparatus according to the first aspect, wherein each showcase throttles the refrigerant flowing into the evaporator and adjusts the superheat degree of the refrigerant coming out of the evaporator to a specified value. Means and an on-off valve for controlling the inflow of refrigerant to the evaporator, and the control means controls the operation of the compressor based on the inside temperature of the showcase that is most difficult to cool, and stores other showcases. When opening and closing the opening / closing valve based on the internal temperature and opening / closing the opening / closing valve of the other showcase, the opening / closing of each opening / closing valve is executed at different timings.

  The showcase cooling device according to a fourth aspect of the present invention is the expansion valve according to the first aspect, wherein each showcase throttles the refrigerant flowing into the evaporator and controls the superheat degree of the refrigerant coming out of the evaporator to the target superheat degree. The control means controls the opening degree of the expansion valve of the showcase with the target superheat degree of the showcase that is hard to cool as a specified value, and operates the compressor based on the internal temperature of the showcase And a target superheat degree of the showcase is set based on the inside temperature of the other showcase, and the valve opening degree of the expansion valve of the showcase is controlled.

  In the showcase cooling apparatus of the invention of claim 5, in each of the above inventions, the control means determines the showcase that is most difficult to cool among each showcase, and controls the operation of the compressor based on the internal temperature. When there is another showcase that is harder to cool than the existing showcase, the operation is switched to a state in which the operation of the compressor is controlled based on the inside temperature of the showcase.

  The showcase cooling device of the invention of claim 6 is characterized in that, in the above invention, the control means discriminates the showcase that is most difficult to cool among the showcases in a state in which the internal temperature is stable. .

  According to a seventh aspect of the present invention, there is provided a showcase cooling apparatus according to the above invention, wherein the control means controls the operating frequency of the compressor based on the inside temperature of the showcase that is most difficult to cool.

  A showcase cooling device according to an eighth aspect of the present invention includes a blowout temperature sensor that is provided in a cold air blowout portion of each showcase in the above invention and detects a blowout temperature of the cold air to each showcase, and the control means includes: The target blow temperature of the cool air to the showcase is determined by PID calculation based on the deviation between the case internal temperature and the set value of the internal temperature, and the blow temperature and target blow temperature detected by the blow temperature sensor are determined. The target operating frequency and / or the target superheat degree of the compressor is determined by PID calculation based on the deviation.

  A showcase cooling device according to a ninth aspect of the present invention comprises the evaporator temperature sensor for detecting the temperature of the evaporator of each showcase according to the seventh aspect of the invention, and the control means includes the temperature inside the showcase and the temperature of the store. By the PID calculation based on the deviation from the set value of the internal temperature, the target evaporator temperature of the showcase is determined, and by the PID calculation based on the deviation between the evaporator temperature detected by the evaporator sensor and the target evaporator temperature Determining a target operating frequency of the compressor and / or a target superheat degree.

  According to the present invention, in a showcase cooling apparatus that supplies and distributes refrigerant discharged from a compressor to evaporators provided in a plurality of showcases, an internal temperature sensor that detects the internal temperature of each showcase. And a control means for controlling the operation of the compressor. The control means controls the operation of the compressor based on the inside temperature of the showcase that is hard to cool among the showcases. Therefore, it is less affected by the operation of the open / close valve and the expansion valve of each showcase as compared with the case where the control is performed with the low pressure.

  Thereby, the fluctuation | variation of the driving | running state of a compressor is suppressed and power consumption is reduced. On the other hand, the cooling of the showcase that is the hardest to cool among the showcases is surely performed, so that the energy loss due to the excessive compressor capacity with respect to the other showcases is also eliminated. Thus, according to the present invention, it is possible to cool all of the plurality of showcases without hindrance while suppressing power consumption in the compressor.

  In this case, as in the invention of claim 2, each showcase restricts the refrigerant flowing into the evaporator and adjusts the superheat degree of the refrigerant coming out of the evaporator to a specified value, and the refrigerant to the evaporator When a so-called mechanical expansion valve is used as the superheat degree adjusting means, the control means is based on the inside temperature of the showcase that is most difficult to cool. To control the operation of the compressor, set the target superheat degree of the showcase based on the inside temperature of the other showcase, and open and close the open / close valve based on the target superheat degree and the predetermined value of the superheat degree By doing so, it becomes possible to smoothly control the internal temperature of all the showcases by controlling the compressor by the showcase that is hard to cool and the on / off valves of other showcases.

  Further, as in the invention of claim 3, each showcase squeezes the refrigerant flowing into the evaporator, superheat degree adjusting means for adjusting the superheat degree of the refrigerant coming out of the evaporator to a specified value, and the refrigerant to the evaporator In the case where a so-called mechanical expansion valve is used as the superheat degree adjusting means, the control means is based on the inside temperature of the showcase that is hard to cool down. Controls the operation of the compressor, opens and closes the open / close valve based on the internal temperature of the other showcase, and opens and closes the open / close valve of the other showcase at different timings. By executing this function, the control of the compressor with the coolest showcase and the control of the temperature inside all the showcases by the control of the other showcase on / off valves can be performed smoothly, and the on / off valves on multiple showcases can be synchronized. Shi Inconvenience of opening and closing is eliminated, variations in the operating condition of the compressor by which is also suppressed.

  Further, as in the invention of claim 4, each showcase is provided with an expansion valve for restricting the refrigerant flowing into the evaporator and controlling the superheat degree of the refrigerant coming out of the evaporator to the target superheat degree. When a so-called electronic expansion valve is used as the valve, the control means controls the opening degree of the expansion valve of the showcase with the target superheat degree of the showcase that is hard to cool as a specified value, and Control the operation of the compressor based on the interior temperature of the case, set the target superheat degree of the showcase based on the interior temperature of the other showcase, and set the opening degree of the expansion valve of the showcase By controlling, it becomes possible to smoothly control the internal temperature of all the showcases by controlling the compressor by the showcase that is hard to cool and the opening / closing valves of other showcases.

  Further, as in the invention of claim 5, the control means discriminates the showcase that is most difficult to cool out of each showcase, and it is harder to cool than the showcase that controls the operation of the compressor based on the internal temperature. If there is a showcase, the switch to a state where the compressor operation is controlled based on the inside temperature of the showcase will change to the showcase that is most difficult to cool due to changes in the load of each showcase. Even in the case of occurrence of a failure, it is possible to switch the operation state without any trouble.

  In this case, if the control means discriminates the showcase that is most difficult to cool among the showcases in a state in which the inside temperature is stable as in the invention of claim 6, during the defrosting or pull-down It is possible to effectively prevent the occurrence of erroneous determination due to determination inside.

  The above is particularly effective when the control means controls the operation frequency of the compressor on the basis of the temperature inside the showcase which is hard to cool down as in the invention of claim 7.

  Furthermore, as in the invention of claim 8, in the case where the control means is provided with a blowout temperature sensor that is provided at the cold blowout portion of each showcase and detects the blowout temperature of the cold to each showcase, The PID calculation based on the deviation between the internal temperature and the set value of the internal temperature determines the target blowing temperature of the cool air to the showcase, and the deviation between the blowing temperature detected by the blowing temperature sensor and the target blowing temperature If the target operating frequency of the compressor and / or the target superheat degree is determined by the PID calculation based on the above, the PID calculation is performed by stratifying the slowly changing internal temperature and the suddenly changing outlet temperature. The compressor, the on-off valve and the expansion valve can be controlled, and the cooling lag in the refrigerant supply to each showcase evaporator is eliminated as much as possible to ensure accurate cooling control. In which it becomes possible to realize.

  Further, when an evaporator temperature sensor for detecting the temperature of the evaporator of each showcase is provided as in the invention of claim 9, the control means sets the showcase internal temperature and the internal temperature. The target evaporator temperature of the showcase is determined by the PID calculation based on the deviation from the value, and the compressor of the compressor is determined by the PID calculation based on the deviation between the evaporator temperature detected by the evaporator sensor and the target evaporator temperature. By determining the target operating frequency and / or the target superheat degree, the PID calculation is performed by stratifying the internal temperature where the change is gentle and the temperature of the evaporator where the change is steep, and the compressor and the on-off valve And the expansion valve can be controlled, and it is possible to eliminate the time lag of the refrigerant supply to the evaporator of each showcase as much as possible and to realize accurate cooling control. .

It is a piping lineblock diagram of a showcase cooling device of an example to which the present invention is applied. It is a piping block diagram in the refrigerator of the showcase cooling device of FIG. (Example 1) which is the piping block diagram in the showcase of the showcase cooling device of FIG. It is a control block diagram of the showcase cooling device of FIG. It is a figure which shows the data communication of the showcase cooling device of FIG. FIG. 10 is a timing chart for explaining another liquid electromagnetic valve control by the main controller of FIG. 4 in the case of the showcase of FIG. 3 (Example 2). (Example 3) which is another piping block diagram in the showcase of the showcase cooling device of FIG. It is a control block diagram of the showcase cooling device in the case of FIG. FIG. 9 is a control block diagram of a compressor operating frequency, a liquid electromagnetic valve, and an electronic expansion valve by the main controller of FIGS. 4 and 8.

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

  In the piping configuration diagram of FIG. 1, a showcase cooling apparatus 1 according to the embodiment cools a plurality of showcases 3 </ b> A to 3 </ b> H installed in a store 2 of a convenience store (store). A refrigerator 6 connected to each showcase 3A to 3H and refrigerant pipes 4 and 5 is installed outside the store, and the showcase cooling apparatus 1 of the embodiment is configured by these showcases 3A to 3H and the refrigerator 6. Has been.

  Showcases 3A to 3F are open showcases. Of these, showcases 3A and 3C to 3F display and sell chilled foods (products) in the cabinet (display room). It is cooled to a relatively low refrigeration temperature range (0 ° C. to + 5 ° C.) suitable for cooling food. Showcase 3B sells lunch boxes (products) in the cabinet (display room) and cools the cabinet to a relatively high refrigeration temperature range (+ 15 ° C to + 20 ° C) suitable for cooling the lunchbox. Is done. Moreover, although not shown in drawing, the frozen showcase which displays frozen food and ice cream in a frozen state (-20 degreeC--25 degreeC) shall also be installed.

  On the other hand, showcases 3G and 3H are closed-type showcases called walk-ins that have transparent glass doors and are installed on the wall of the store, and display beverages (products) in the store (display room). The interior is cooled to a refrigeration temperature zone (0 ° C. to + 5 ° C.) suitable for cooling beverages. Each showcase 3 </ b> A to 3 </ b> H is connected in parallel to the refrigerator 6 by the refrigerant pipes 4 and 5.

  FIG. 2 shows a piping configuration in the refrigerator 6 in FIG. The refrigerator 6 is provided with a compressor 7 driven by a motor 7M, a condenser 8, a condenser blower 9, and various sensors including a low-pressure sensor 11. The inlet pipe 8A of the condenser 8 is connected to the discharge pipe 7D (high-pressure side) of the compressor 7, and the outlet pipe 8B of the condenser 8 is connected to the refrigerant pipe 4 that goes to the store 2. Further, the refrigerant pipe 5 from the store 2 is connected to the suction pipe 7S (low pressure side) of the compressor 7. The condenser blower 9 is operated to air-cool the condenser 8. The low pressure sensor 11 is provided so as to detect the refrigerant pressure in the suction pipe 7S of the compressor 7.

  On the other hand, FIG. 3 has shown the piping structure in each showcase 3A-3H of FIG. The showcases 3A to 3H of this embodiment include a liquid electromagnetic valve 12 as an on-off valve, a mechanical expansion valve 13 as a superheat degree adjusting means, an evaporator 14, a cooler circulation blower 16, and an internal temperature sensor. 17, main sensors including an outlet temperature sensor 18 and a suction temperature sensor 19 are provided. The expansion valve 13 is connected to the outlet of the liquid electromagnetic valve 12, the evaporator 14 is connected to the outlet of the expansion valve 13, the inlet pipe 12 </ b> A of the liquid electromagnetic valve 12 is connected to the refrigerant pipe 4, and the outlet of the evaporator 14 is connected. The pipe 14 </ b> A is connected to the refrigerant pipe 5. As described above, the series circuit of the liquid electromagnetic valve 12, the expansion valve 13, and the evaporator 14 in each showcase 3 </ b> A to 3 </ b> H is connected in parallel between the refrigerant pipes 4 and 5.

  The cool air circulation blower 16 sucks cool air in the interior 21 to exchange heat with the evaporator 14 and blows it out to the interior 21 to cool the interior 21 to the above-described refrigeration temperature zone. Further, the internal temperature sensor 17 detects the temperature (internal temperature) of the internal chamber 21, the blowout temperature sensor 18 detects the temperature of the cold air blown out into the internal chamber 21 (outlet temperature), and the suction temperature sensor 19 It is provided so as to detect the temperature (suction temperature) of the cool air sucked into the cool air circulation blower 16 from the interior 21.

  With such a piping configuration, the compressor 7 and the condenser 8 of the refrigerator 6, the expansion valve 13 and the evaporator 14 of the showcases 3 </ b> A to 3 </ b> H constitute a known refrigerant circuit 22. The operating frequency of the motor 7M of the compressor 7 of the refrigerator 6 of the embodiment is controlled. When the compressor 7 is operated, the gas refrigerant that has been compressed to a high temperature and high pressure flows into the condenser 8, where it is cooled by the condenser blower 9 and condensed. The refrigerant (liquid refrigerant) condensed in the condenser 8 reaches the store 2 through the refrigerant pipe 4, and is distributed and supplied from there to the showcases 3A to 3H.

  The liquid refrigerant that has flowed into each showcase 3A to 3H reaches the expansion valve 13 via the liquid electromagnetic valve 12, is throttled and depressurized there, and flows into the evaporator 14. The refrigerant flowing into the evaporator 14 evaporates there, and exhibits a cooling effect due to the endothermic action generated at that time. Then, the refrigerant exiting the evaporator 14 returns to the refrigerator 6 through the refrigerant pipe 5 and repeats circulation that is sucked into the compressor 7.

  The mechanical expansion valve 13 of this embodiment controls the degree of throttling independently by the action of a bellows (not shown) that expands and contracts in accordance with the temperature of the outlet pipe 14A of the evaporator 14, and the refrigerant that exits the evaporator 14 Is adjusted to a preset specified value (for example, a fixed superheat degree of 3K). Thereby, the refrigerant supply to the evaporator 14 is adjusted, and the liquid back to the compressor 7 is prevented.

  Next, FIG. 4 and FIG. 5 show the control configuration of the showcase cooling apparatus 1. In each figure, reference numeral 23 denotes a main control device called a store master. The main controller 23 is installed in a store management room or the like to centrally control the operation of the refrigerator 6 and the showcases 3A to 3H. The refrigerator 6 and the showcases 3 </ b> A to 3 </ b> H are also provided with a refrigerator control device 24 and a showcase control device 26, respectively, which are connected to the main control device 23 by a communication line 27. The main control device 23, the refrigerator control device 24, and the showcase control device 26 are all composed of a microcomputer, and these constitute the control means of the showcase cooling device 1.

  Each showcase control device 26 is assigned an individual ID of 101 to 108, for example, and the refrigerator control device 24 is assigned an ID of 301. The main control device 23 identifies each showcase control device 26 and the refrigerator control device 24 with these IDs. As shown in FIG. 5, each showcase control device 26 determines the inside temperature of the showcases 3 </ b> A to 3 </ b> H. Receives data related to blowing temperature and suction temperature. The main controller 23 transmits data related to the opening / closing instruction of the liquid electromagnetic valve 12 to the showcase controllers 26 of the showcases 3A to 3H, and the target low pressure is supplied to the refrigerator controller 24 of the refrigerator 6. Data relating to a target value instruction such as pressure and a target operating frequency of the compressor 7 is transmitted.

  A temperature / humidity sensor 28 is connected to the main controller 23. The temperature / humidity sensor 28 detects the temperature / humidity in the store 2. The main controller 23 calculates the enthalpy of the store 2 based on the temperature / humidity data of the store 2 detected by the temperature / humidity sensor 28 and sets the target low pressure of the refrigerant circuit 22. The target low pressure is set to a value that can sufficiently cool all the showcases 3A to 3H. In addition, the main controller 23 can input the set values of the internal temperatures of the showcases 3A to 3H, and the data such as the internal temperatures of the showcases 3A to 3H can be confirmed. Centralized management of the showcases 3A to 3H in the store using the main control device 23 is realized.

  Next, the operation of the showcase cooling apparatus 1 according to this embodiment will be described. First, the main control device 23 constantly monitors the internal temperature (detected by the internal temperature sensor 17) received from each showcase control device 26, and compares it with the set value of the internal temperature of each showcase 3A to 3H. And they are monitoring their coldness. And the showcase which is hard to cool out of each showcase 3A-3H is discriminate | determined. For example, although the liquid solenoid valve 12 of the showcases 3G and 3H is continuously opened compared to other showcases, it takes a long time until the inside temperature reaches a set value, Alternatively, when the state in which the internal temperature is equal to or higher than the set value has continued for a long time, the main control device 23 determines the showcases 3G and 3H as the showcase that is most difficult to cool. It should be noted that the present invention is not limited to two showcases, and may be a single showcase.

  When the showcases 3G and 3H are thus determined as the most difficult to cool down, the main controller 23 sends an instruction to the showcase controller 26 of the showcases 3G and 3H to open the liquid electromagnetic valve 12 100%. State. As a result, the liquid refrigerant throttled by the expansion valve 13 is constantly supplied to the evaporators 14 of the showcases 3G and 3H (operation rate 100%). The main controller 23 controls the operating frequency of the compressor 7 (motor 7M) of the refrigerator 6 based on the inside temperature of the showcases 3G and 3H, and sets the inside temperature of the showcases 3G and 3H to a set value. Control.

  A specific control method in that case will be described with reference to FIG. First, the main control device 23 compares the internal temperature detected by the internal temperature sensor 17 of the showcases 3G and 3H with a set value (target value), and performs PID calculation of the deviation e1 by the PID calculation unit 31. To determine the target blowout temperature (control amount). Next, the blowout temperature detected by the blowout temperature sensor 18 of the showcases 3G and 3H is compared with the target blowout temperature, and the deviation e2 is subjected to PID calculation by the PID calculation unit 32, whereby the target operating frequency of the compressor 7 is obtained. (Control amount) is determined.

  The determined target operating frequency is instructed from the main controller 23 to the refrigerator control device 24 of the refrigerator 6. The refrigerator control device 24 controls the operation frequency of the compressor 7 (motor 7M) so that the received target operation frequency is obtained. Here, when the cooling effect in the evaporator 14 is changed by changing the operating frequency of the compressor 7, the change in the internal temperature of the showcases 3G and 3H is gradual, but the change in the blowing temperature is steep. For this reason, if the PID calculation units 31 and 32 perform the PID calculation by stratifying the internal temperature where the change is gentle and the blowing temperature where the change is steep as in the embodiment, the compressor 7 shows the showcases 3G and 3H. The time lag of the refrigerant supply to the evaporator is reduced.

  On the other hand, for the other showcases 3A to 3F that are more easily cooled than the showcases 3G and 3H, the main controller 23 sets the target based on the internal temperature and the set value detected by the internal temperature sensor 17 of each of the showcases 3A to 3F. Determine the degree of superheat. In determining the target superheat degree, the main controller 23 similarly performs the PID calculation of FIG. However, in this case, the operation amount of the PID calculation unit 32 is the target superheat degree of the showcases 3A to 3F. That is, when the internal temperature is higher than the set value, the target superheat degree is small, and when it is low, it is large.

  Based on the determined target superheat degree and a predetermined value of the superheat degree of the expansion valve 13 (fixed superheat degree 3K), the main controller 23 calculates and calculates the open / close rate of the liquid electromagnetic valve 12 of each showcase 3A to 3F. To do. For example, when the target superheat degree of the showcase 3D is 5K, the open / close rate (that is, the operation rate) of the liquid electromagnetic valve 12 is 60%. The main control device 23 transmits an instruction for opening / closing the liquid electromagnetic valve 12 to each showcase control device 26 based on the determined open / close rates for the showcases 3A to 3F. The showcase control device 26 controls the internal temperature of the showcases 3A to 3F to a set value by opening and closing (on / off) the liquid electromagnetic valve 12 based on the received opening / closing instruction.

  As described above, the main controller 23 controls the operation of the compressor 7 based on the inside temperature of the showcase that is hard to cool among the showcases 3A to 3H. In comparison, the operation of the liquid solenoid valves 12 of the showcases 3A to 3H is less likely to be affected. Thereby, the fluctuation | variation of the driving | running state of the compressor 7 is suppressed and power consumption is reduced. On the other hand, among the showcases 3A to 3H, the coolest showcase (3G, 3H in the embodiment) is surely cooled, so it is excessive with respect to other showcases (3A to 3F in the embodiment). The energy loss due to the ability of the compressor 7 is also eliminated. Accordingly, it is possible to cool all of the plurality of showcases 3A to 3H without hindrance while suppressing power consumption in the compressor 7.

  In particular, when a mechanical expansion valve is employed as the expansion valve 13 as in this embodiment, the main controller 23 is based on the internal temperature of the showcase (3G, 3H in the embodiment) that is most difficult to cool. In addition to controlling the operation of the compressor 7, the target superheat degree of the showcase is set based on the inside temperature of the other showcase (3A to 3F in the embodiment), and the target superheat degree and a specified value (fixed) By calculating the opening / closing rate of the liquid solenoid valve 12 based on the degree of superheat), all the showcases by the control of the compressor 7 by the showcase that is hard to cool and the control of the liquid solenoid valve 12 of other showcases It is possible to smoothly control the internal temperature of 3A to 3H. As a result, there is an effect that the setting control of the target low pressure based on the in-store enthalpy by the temperature / humidity sensor 28 described above becomes unnecessary.

  As described above, the main controller 23 constantly monitors the cooling state of each of the showcases 3A to 3H, and determines the showcase that is most difficult to cool. And if there is another showcase that is harder to cool than the showcases 3G and 3H that are currently controlling the operating frequency of the compressor 7 based on the internal temperature, the showcase that is the hardest to cool the other showcase And switch to a state in which the operation of the compressor 7 is controlled based on the internal temperature. As a result, even when the showcases 3A to 3H are replaced with the most difficult-to-cool showcases due to the amount of displayed products (loads) or changes in the environment, it is possible to switch the operating state without any trouble.

  However, the main control device 23 executes the determination of the showcase that is hard to cool as described above only when the internal temperature of each of the showcases 3A to 3H is stable. That is, during the defrosting of each showcase 3A to 3H (executed four times a day) or during pull-down, the most difficult showcase is not determined, and the control state before the defrosting is maintained. This avoids the occurrence of erroneous determination.

  Here, in the above embodiment, for the other showcases 3A to 3F, the target superheat degree is determined and the open / close rate of the liquid electromagnetic valve 12 is calculated to control the inside cooling of the showcase. However, the liquid electromagnetic valves 12 may be controlled to open and close based on the internal temperature of each showcase 3A to 3F and the set value. In this case, the liquid electromagnetic valve 12 is opened / closed based on the ON temperature (upper limit value) and OFF temperature (lower limit value) set with a predetermined differential above and below the set value of the internal temperature. (The set value is the average temperature.) If the load of each showcase 3A to 3F is approximated as it is, the liquid electromagnetic valve 12 opens and closes synchronously, and the operating frequency of the compressor 7 is affected by that. There is a risk that will vary greatly.

  FIG. 6 shows an example of control by the main controller 23 that eliminates such inconvenience. 6 shows the case where the liquid electromagnetic valve 12 is opened at the ON temperature and closed at the OFF temperature as described above. When each showcase 3A to 3F has the same ease of cooling, the risk that the liquid electromagnetic valves 12 of all the showcases 3A to 3F are opened and closed synchronously increases. Therefore, the control of the second, third, and lowermost stages from the top including the uppermost stage in FIG. 6 is executed in each of the showcases 3A to 3F. That is, the showcase 3A is the top level, the showcases 3C and 3D are the second level from the top, the showcase 3F is the third level from the top, the showcase 3B is the bottom level, and so on.

  The control in the second stage from the top in FIG. 6 is a control in which the liquid electromagnetic valve 12 is opened when the internal temperature becomes equal to or higher than the ON temperature, and is closed when the internal temperature becomes less than the set value. In this case, the liquid electromagnetic valve 12 is opened and closed more frequently than in the uppermost stage, and the average temperature (thick broken line) is slightly higher than the set value. Further, the control in the third step from the top in FIG. 6 is a control in which the liquid electromagnetic valve 12 is opened when the internal temperature becomes equal to or higher than the ON temperature, and is closed when the internal temperature becomes lower than the ON temperature. In this case, the liquid electromagnetic valve 12 is opened and closed more frequently, and the average temperature (thick broken line) becomes higher than the set value. Further, the lowermost control in FIG. 6 is a control in which the liquid electromagnetic valve 12 is opened when the internal temperature becomes equal to or higher than the ON temperature, and is closed when the temperature starts to drop. In this case, the liquid electromagnetic valve 12 is opened and closed more frequently, and the average temperature (thick broken line) becomes higher than the set value. Therefore, the set value is shifted to a lower value in advance as the average temperature increases.

  In this case, the upper control in FIG. 6 may be assigned to a showcase that is difficult to cool and hard to warm (the temperature change is large), and the lower control in FIG. 6 is assigned to a showcase that is easy to cool and warm (the temperature change is small). Whether it is difficult to cool (hard to warm) or easy to cool (easy to warm) is ranked according to the temperature change in the chamber after the opening / closing of the liquid electromagnetic valve 12 and its fluctuation range when the chamber temperature is stable.

  By performing the opening / closing control of the liquid electromagnetic valve 12 in combination with each of the showcases 3A to 3F, the operation timings of the liquid electromagnetic valves 12 are shifted from each other, and the opening / closing thereof is performed at different timings. . Thereby, the operation control of the compressor 7 by the showcases 3G and 3H which are hard to cool down and the inside temperature control of all the showcases 3A to 3H by the control of the liquid solenoid valves 12 of the other showcases 3A to 3F are smoothly performed. While performing, the inconvenience that the opening / closing valves of the plurality of showcases 3A to 3F are opened / closed in synchronization is solved, and the fluctuation of the operating state of the compressor 7 due to this is also suppressed.

  In the above-described embodiment, the opening / closing timing is shifted by switching the temperature at which the liquid electromagnetic valve 12 is opened / closed. However, the present invention is not limited to this, and the set value is set for each showcase 3A to 3F without changing the differential between the ON temperature and the OFF temperature. May be shifted to different values.

  Next, control when an electronic expansion valve (electric expansion valve) that operates with, for example, a stepping motor is used as the expansion valve of the showcases 3A to 3H will be described. FIG. 7 is a piping configuration diagram in the showcases 3A to 3H in that case, and FIG. 8 is a control configuration diagram. In addition, what is shown with the same code | symbol as FIG. 3 thru | or FIG. 5 in each figure shall show | play the same or the same function.

  In this case, an electronic expansion valve (electric expansion valve) 33 is employed in each of the showcases 3A to 3H instead of the mechanical expansion valve. Further, an evaporator inlet temperature sensor 36 and an evaporator outlet temperature sensor 37 are provided in the evaporator inlet pipe 14B and the outlet pipe 14A, respectively, so that the temperature of the refrigerant entering the evaporator 14 and the temperature of the refrigerant exiting the evaporator 14 can be determined. To detect. These outputs are transmitted to the main control device 23 via the showcase control device 26, and the main control device 23 calculates the degree of superheat of the evaporator 14 from the temperature difference therebetween. Further, the opening degree of the expansion valve 33 is controlled by the main control device 23 via the showcase control device 26.

  Next, the operation in this case will be described. Also in this case, the main control device 23 constantly monitors the internal temperature (detected by the internal temperature sensor 17) received from each showcase control device 26, and the set value of the internal temperature of each showcase 3A to 3H. In comparison, they are monitoring their coldness. And the showcase which is hard to cool out of each showcase 3A-3H is discriminate | determined. For example, although the opening degree of the expansion valve 33 of the showcases 3G and 3H is continuously large as compared with other showcases, it takes a long time until the inside temperature reaches the set value. In other words, or when the state in which the internal temperature is equal to or higher than the set value continues for a long time, the main control device 23 determines the showcases 3G and 3H as the showcase that is most difficult to cool. It should be noted that the present invention is not limited to two showcases, and may be a single showcase.

  When the showcases 3G and 3H are thus determined as the most difficult to cool down, the main controller 23 sends an instruction to the showcase controller 26 of the showcases 3G and 3H to increase the valve opening of the expansion valve 33. The superheat degree of the evaporator 14 is controlled to a specified value (for example, 5K). Moreover, the main control apparatus 23 controls the operating frequency of the compressor 7 (motor 7M) of the refrigerator 6 based on the inside temperature of the showcases 3G and 3H. The specific control method in that case is the same as that in FIG. Thereby, the internal temperature of the showcases 3G and 3H is controlled to a set value.

  On the other hand, for the other showcases 3A to 3F that are more easily cooled than the showcases 3G and 3H, the main controller 23 sets the target based on the internal temperature and the set value detected by the internal temperature sensor 17 of each of the showcases 3A to 3F. Determine the degree of superheat. In determining the target superheat degree, the main controller 23 similarly performs the PID calculation of FIG. However, in this case, the operation amount of the PID calculation unit 32 is the target superheat degree of the showcases 3A to 3F. That is, when the internal temperature is higher than the set value, the target superheat degree is small, and when it is low, it is large.

  The main controller 23 determines the target valve opening degree of the expansion valve 33 so that the superheat degree of the evaporator 14 of each showcase 13A to 13F becomes the determined target superheat degree. The main controller 23 transmits an instruction regarding the valve opening of the expansion valve 33 to each showcase controller 26 based on the determined target valve openings regarding the showcases 3A to 3F. The showcase control device 26 controls the valve opening of the expansion valve 33 based on the received target valve opening. The liquid solenoid valve 12 is opened. Thereby, the internal temperature of showcase 3A-3F is controlled to a setting value. In the embodiment, the liquid electromagnetic valve 12 is provided in front of the expansion valve 33. However, since the expansion valve 33, which is an electronic expansion valve, can be fully closed, the liquid electromagnetic valve 12 may be deleted depending on control followability. May be. Further, when the plurality of expansion valves 33 are opened from the fully closed state, by controlling so that the timing is different, fluctuations in the operating state of the compressor 7 can be suppressed as described above. .

  As described above, when the showcases 3A to 3H employ the electronic expansion valve 33 as the expansion valve as in this embodiment, the main controller 23 sets the target superheat degree of the showcases 3G and 3H that are most difficult to cool. The opening degree of the expansion valve 33 of the showcases 3G and 3H is controlled as a specified value, and the operation of the compressor 7 is controlled based on the internal temperature of the showcases 3G and 3H. By setting the target superheat degree of the showcases 3A to 3F based on the internal temperature of 3A to 3F and controlling the valve opening degree of the expansion valve 33 of the showcases 3A to 3F, the showcase 3G that is hard to cool down It is possible to smoothly control the internal temperature of all the showcases 3A to 3H by the control of the compressor 7 by 3H and the control of the expansion valve 33 of the other showcases 3A to 3F. .

  In each of the above embodiments, the main control device 23 has been described with a method of controlling the liquid electromagnetic valves 12 and the expansion valves 33 by transmitting control instructions to the showcases 3A to 3H, but the main control device is not limited thereto. 23 determines the showcase that is most difficult to cool, instructs the determined showcase that the showcase is the most difficult to cool, and operates the compressor 7 based on the internal temperature of the showcase. In addition to controlling the frequency, the target superheat degree is transmitted to each showcase, and the actual control of the liquid electromagnetic valve 12 and the expansion valve 33 in each showcase is executed by the showcase control device 26 of each showcase. May be.

  Further, in the embodiment, the case where the mechanical expansion valve 13 is used in all the showcases 3A to 3H and the case where the electronic expansion valve 33 is used have been described, but the present invention is also effective when they are mixed. It is. In that case, the liquid solenoid valve 12 is opened for the most difficult-to-cool showcase using the mechanical expansion valve 13, and the target superheat degree is set as the specified value for the most difficult-to-cool showcase using the electronic expansion valve 33. An instruction to control the valve opening degree of the expansion valve 33 is transmitted to the showcase control device 26 of the showcase. In addition, the compressor 7 of the refrigerator 6 is controlled by the temperature inside the refrigerator, and the open / close rate of the liquid electromagnetic valve 12 is changed to an electronic expansion valve for other easy-to-cool showcases using the mechanical expansion valve 13. For other easily cool showcases using 33, the main controller 23 may calculate the target superheat degree and instruct each showcase controller 26.

  Furthermore, in the said Example, a target blowing temperature is determined by PID calculation based on the deviation of the chamber internal temperature and the setting value of the said chamber internal temperature, and based on the deviation of the blowing temperature detected by the blowing temperature sensor 18 and a target blowing temperature. Although the target operating frequency of the compressor 7 and the target superheat degree of the refrigerant coming out of the evaporator 14 are determined by PID calculation, the temperature of the evaporator 14 can also be adopted in the sense that the change is steep. Regardless, a temperature sensor for detecting the temperature of the evaporator 14 is provided, the target evaporator temperature is determined by the internal temperature and the set value, and the temperature of the evaporator 14 detected by the temperature sensor of the evaporator 14 and the target evaporator PID calculation may be performed based on the temperature to determine the target operating frequency and the target superheat degree.

  Furthermore, in the embodiment, both the target operating frequency of the compressor 7 and the target superheat degree of the refrigerant coming out of the evaporator 14 are determined by the control of FIG. 9, but not limited thereto, the target superheat degree or the target operating frequency is determined. Any one of these may be determined by the control of FIG. 9, and the other may be determined by a normal PID calculation based on the internal temperature and the set value.

  In the embodiment, the present invention is applied to a refrigerant circuit using a mechanical expansion valve or an electronic expansion valve. However, the invention of claim 1 is not limited thereto, and the capillary tube is used to throttle the refrigerant flowing into the evaporator. Is also effective.

DESCRIPTION OF SYMBOLS 1 Showcase cooling device 3A-3H Showcase 4, 5 Refrigerant piping 6 Refrigerator 7 Compressor 8 Condenser 12 Liquid solenoid valve (open / close valve)
13, 33 Expansion valve 14 Evaporator 17 Internal temperature sensor 17 Blowout temperature sensor 23 Main controller (control means)
24 Refrigerator control device (control means)
26 Showcase control device (control means)
31, 32 PID calculation unit

Claims (9)

In a showcase cooling device that distributes and supplies refrigerant discharged from a compressor to evaporators provided in a plurality of showcases,
An internal temperature sensor for detecting the internal temperature of each showcase,
Control means for controlling the operation of the compressor,
The control means controls the operation of the compressor based on the inside temperature of the showcase that is hard to cool among the showcases. Each showcase includes a superheat degree adjusting means for restricting a refrigerant flowing into the evaporator and adjusting a superheat degree of the refrigerant coming out of the evaporator to a specified value, and an on-off valve for controlling the refrigerant flow into the evaporator And
The control means controls the operation of the compressor based on the inside temperature of the showcase that is hard to cool, and sets the target superheat degree of the showcase based on the inside temperature of the other showcase. The showcase cooling apparatus according to claim 1, wherein the on-off valve is opened and closed based on the target superheat degree and a predetermined value of the superheat degree. Each showcase includes a superheat degree adjusting means for restricting a refrigerant flowing into the evaporator and adjusting a superheat degree of the refrigerant coming out of the evaporator to a specified value, and an on-off valve for controlling the inflow of the refrigerant to the evaporator And
The control means controls the operation of the compressor based on the inside temperature of the showcase that is hard to cool, opens and closes the on-off valve based on the inside temperature of the other showcase, and 2. The showcase cooling apparatus according to claim 1, wherein when opening / closing the opening / closing valve of another showcase, the opening / closing of each opening / closing valve is executed at different timings. Each showcase includes an expansion valve that restricts the refrigerant flowing into the evaporator and controls the degree of superheat of the refrigerant that exits the evaporator to a target superheat degree.
The control means controls the opening degree of the expansion valve of the showcase with the target superheat degree of the showcase that is hard to cool as a specified value, and operates the compressor based on the internal temperature of the showcase And controlling the valve opening degree of the expansion valve of the showcase by setting a target superheat degree of the showcase based on the inside temperature of the other showcase. The showcase cooling device described. The control means discriminates the showcase that is most difficult to cool among the showcases,
When there is another showcase that is harder to cool than the showcase that controls the operation of the compressor based on the internal temperature, the operation of the compressor is controlled based on the internal temperature of the showcase. The showcase cooling apparatus according to claim 1, wherein the showcase cooling apparatus is switched to a state.   6. The showcase cooling apparatus according to claim 5, wherein the control means determines the showcase that is most difficult to cool among the showcases in a state where the inside temperature is stable.   The showcase cooling according to any one of claims 1 to 6, wherein the control means controls an operating frequency of the compressor based on an inside temperature of the showcase that is hard to cool. apparatus. Provided in the cold air blowing part of each showcase, provided with a blowing temperature sensor for detecting the cold air blowing temperature to each showcase,
The control means determines a target blowing temperature of cool air to the showcase by PID calculation based on a deviation between the inside temperature of the showcase and a set value of the inside temperature,
The target operating frequency and / or the target superheat degree of the compressor is determined by PID calculation based on a deviation between the outlet temperature detected by the outlet temperature sensor and the target outlet temperature. 8. The showcase cooling device according to 7. An evaporator temperature sensor for detecting the temperature of each showcase evaporator;
The control means determines a target evaporator temperature of the showcase by a PID calculation based on a deviation between the inside temperature of the showcase and a set value of the inside temperature,
The target operating frequency of the compressor and / or the target superheat degree is determined by PID calculation based on a deviation between the temperature of the evaporator and the target evaporator temperature detected by the evaporator sensor. The showcase cooling apparatus according to claim 7.

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