JP2004309130A - Showcase cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To integrally and rationally control a showcase and a refrigerator to attain high freshness management of merchandise, energy saving, facilitation of maintenance and optimization of refrigerator capacity. <P>SOLUTION: This showcase cooling device is composed of one or more showcases wherein the flow of a refrigerant to an evaporator is controlled on/off through solenoid valves based on deviation between the temperature of blowoff air and the set value, and the common refrigerator constituting a refrigerating cycle with the showcases. The showcase cooling device is provided with a temperature sensor for measuring the temperature of a merchandise housing part of each showcase, and a temperature set value correcting part for correcting the set value of the blowoff air temperature based on the measured temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a showcase cooling device that comprehensively and rationally controls a showcase and a refrigerator that constitute a refrigeration cycle to realize high freshness management and energy saving of products.

  A conventional example will be described with reference to FIGS. FIG. 15 is a block diagram showing a configuration of a conventional example. The conventional example is roughly divided into a showcase group 1 and a refrigerator 6. One showcase group 1 is a group in which all showcases 1A, 1B, 1C,... (Hereinafter referred to as 1A...) Are arranged side by side in a store to form one group. Each of the evaporators 2A, a showcase controller 34A for controlling on / off of the flow of the refrigerant to the evaporators 2A, a solenoid valve (not shown) as an operation end for turning on / off the flow of the refrigerant, and , Which measure the temperature of the air blown out of the showcase. Here, the reason why the location where air is blown was selected as the temperature measurement location in the showcase is that one is a location that is not affected by the quantity of stored products, and another is a temperature based on control. This is because control is convenient because the change is the place where the change appears first. The other refrigerator 6 includes a compressor 9, a condenser 31, a low-pressure pressure sensor 7 for measuring a suction refrigerant pressure of the compressor 9, and a compressor 9 based on a deviation between the measured pressure value and a set value thereof. A refrigerator controller 12 for ON / OFF control is provided.

  The evaporators 2A are connected in parallel with each other, and the compressor 9 and the condenser 31 are connected in series to the parallel-connected ones, thereby forming a refrigeration cycle. Each controller 34A... Controls the flow of the refrigerant to the corresponding evaporator 2A... Based on the difference between the temperature signal from the corresponding temperature sensor 14A and the set value. The refrigerant is split from the compressor 9 after passing through the condenser 31 and flows to each of the evaporators 2A, or circulates back to the compressor 9 after being prevented from flowing. Here, the control signals of the controllers 34A are simply shown to be input to the preceding stage of the corresponding evaporators 2A, and the on / off control of the flow of the refrigerant is shown (see FIG. 16 for details). reference).

  FIG. 16 is a block diagram showing the configuration of a conventional refrigeration cycle in detail. This refrigeration cycle is composed of a compressor 9 and a condenser 31 built in the refrigerator 6, an evaporator 2A built in each showcase 1A, a corresponding solenoid valve 33A and a temperature expansion valve 32A. Is done.

  In the showcase 1A, the control operation of the refrigeration cycle is based on the deviation between the set value of the blown air temperature and the value measured by the temperature sensor 14A (see FIG. 15). .. On / off control of the flow of the refrigerant to. That is, when the deviation is plus (measured value ≧ set value), the solenoid valves 33A are opened (on), and when the deviation is minus (measured value <set value), the solenoid valves 33A are closed (off). Turn on / off the flow of the refrigerant to the evaporators 2A. In the refrigerator 6, on / off control of the operation of the compressor 9 is performed via the controller 12 based on the difference between the set value of the suction refrigerant pressure of the compressor 9 in FIG. That is, the compressor 9 is turned on or off when the measured pressure value is equal to or more than the set value. Since the on / off control is performed, the set value here actually consists of the upper limit and the lower limit.

  The operation of the conventional showcase refrigeration cycle will be described with reference to the time chart of FIG. In this figure, (1) At time 1, all the measured values of the blown air temperature of the showcase 1A by the temperature sensor 14A (not shown) are equal to or lower than the set value (lower limit). Then, the solenoid valve 33A is closed (off). At this time, since the measured value of the pressure of the suction refrigerant by the pressure sensor (not shown) is equal to or lower than the set value (lower limit), the compressor is stopped, and the temperature of the blown air tends to increase. (2) At time point 2, the blow-out air temperature of the showcase 1A rises and exceeds the set value (upper limit set value), so the solenoid valve 33A opens (ON). At the same time, since the measured value of the pressure of the suction refrigerant becomes equal to or higher than the set value (upper limit), the compressor is operated. Thereafter, the blow-out air temperature of the showcases 1B and 1C sequentially increases and exceeds the set value (upper limit), so that the solenoid valves 33B and 33C are opened. Are cooled by the refrigerator, and the temperature of each blown air drops. (3) At time 3, first, the temperature of the blown air from the showcase 1A becomes lower than the set value, the solenoid valve 33A is closed, and subsequently, the solenoid valves 33B and 33C are sequentially closed. (4) At time point 4, all solenoid valves are closed, and a so-called pump-down operation is performed in which the refrigerant between the evaporators 2A ... and the refrigerator is recovered by the refrigerator. As a result, (5) At time point 5, the measured value of the pressure of the suction refrigerant becomes equal to or less than the set value (lower limit), and the compressor is stopped.

  FIGS. 18 (a) and 18 (b) show the operation and stop of the compressor and the temporal change of the air temperature blown out of the showcase, respectively. In FIG. 3A, the compressor is continuously operated and stopped (on / off), and in FIG. 3B, the blown air temperature fluctuates up and down around the set value. In addition, the display of each set value of an upper limit and a lower limit was omitted.

  The conventional refrigeration cycle has the following problems. (1) The refrigerator is independently controlled based on the measured value of the pressure sensor, and the showcase 1A is independently controlled based on the measured value of the temperature sensor 14A, and exchanges the measured values of the pressure sensor and the temperature sensor with each other. It does not mean that it is controlled. Therefore, there are some problems in controlling the showcase refrigeration cycle including the showcase and the refrigerator comprehensively and rationally to perform a sufficiently efficient operation. (2) In general, the capacity of a refrigerator is selected based on the required load in summer, so the refrigeration function capacity is excessive compared to the showcase load except in summer, and one of the reasons is wasteful power consumption and low power consumption. Efficient operation is attained, and secondly, the frequency of operation and stoppage of the compressor is increased, which causes a problem that the variation in the temperature of the blown air from the showcase, that is, the fluctuation range becomes large. (3) After the showcase has been installed and the initial adjustments have been made, if the cooling condition deteriorates due to load fluctuations or environmental changes, it is necessary to manually adjust the set value of the blow-out air temperature for that showcase. Maintenance was troublesome. (4) Since it takes time for return cooling after defrosting, that is, pull-down, the freshness of the product may be reduced during that time. (5) Since the corresponding showcase is operated according to the blown air temperature, all the showcases may be operated simultaneously, that is, the showcase group may be operated collectively. Therefore, the capacity of the refrigerator is selected on the assumption that the showcase group is operated collectively at the peak load in summer. As a result, the selected chiller actually tends to have excessive capacity and therefore excessive cost.

  The problem to be solved by the present invention is to solve the problems more than the conventional technology has, and to comprehensively and rationally control a showcase and a refrigerator that constitute a refrigeration cycle, thereby managing a high freshness of a product. Another object of the present invention is to provide a showcase cooling device that realizes energy saving, easy maintenance, optimizing the capacity of a refrigerator, and the like.

  The present invention comprises one or more showcases for controlling the flow of refrigerant to an evaporator on / off via an electromagnetic valve based on a deviation between the temperature of blown air and a set value thereof, and a refrigeration cycle with the showcase. Temperature sensor for measuring the temperature of the product storage location of each showcase in a showcase cooling device comprising a common refrigerator; and a temperature set value correction unit for correcting the set value of the blow-out air temperature based on the measured temperature. And ;.

  Still further, the present invention provides that when a predetermined number or more of the solenoid valves are to be turned on at the same time, 1) turn on the solenoid valves that should reach the predetermined number until one of the solenoid valves already on is turned off. Do not leave it in the off state without leaving it, 2) in which the solenoid valve of the showcase is turned off in the order that the temperature of the product storage location is closer to its set value, 3) in which the show based on the predetermined priority The number of operating units that keeps the solenoid valve in the case off, or 4) stops the solenoid valve in the off state in ascending order of operation rate, and keeps the number of solenoid valves in the on state at the same time less than a predetermined number. It is preferable to provide a configuration in which a restriction unit is provided.

  Further, in the present invention, the set value of the blow-out air temperature can be corrected by the temperature set value correction unit based on the measured temperature of the product storage location of each showcase, that is, the actual degree of cooling of the product.

Further, in the present invention, when a predetermined number or more of the solenoid valves are to be simultaneously turned on by the operating number limiting unit, the number of the solenoid valves that are simultaneously turned on by any one of the following methods (1) to (4) is reduced to less than the predetermined number. Can be suppressed.
(1) The solenoid valves that should reach the predetermined number are kept off without being turned on until one of the solenoid valves already on is turned off.
(2) Among the solenoid valves to be turned on at the same time, the showcase solenoid valves are turned off in the order in which the temperature of the product storage location is closer to the set value.
(3) Among the solenoid valves to be turned on at the same time, the solenoid valves in the showcase are kept off based on a predetermined priority.
(4) Among the solenoid valves to be turned on at the same time, the solenoid valves are kept in the off state in order of the lowest operation rate.

According to the present invention, the following excellent effects can be expected.
(1) Since the set value of the blow-out air temperature can be automatically corrected based on the measured temperature of the product storage location of each showcase, that is, the actual degree of cooling of the product, freshness management of the product is well performed. At the same time, compared to the manual correction of the conventional example, the trouble of the correction can be saved and the maintenance can be facilitated.
(2) It is possible to reduce the number of solenoid valves that are on at the same time to less than a predetermined number, that is, to limit the maximum power consumption of the showcase group at the peak load in the summer season. As a result, the cost of the apparatus can be reduced, and the space and energy of the apparatus can be saved.

  First Embodiment As an embodiment of the present invention, a first embodiment will be described with reference to a block diagram showing the configuration of FIG. In FIG. 1, an integrated controller 34 for newly and comprehensively and rationally controlling both the showcase group 1 and the refrigerator 6 is provided in a manner interposed between the refrigerator 1 and the showcase group 1. The general controller 34 includes an operation rate calculation unit 3, a pressure set value calculation unit 4, and a rotation speed command calculation unit 5.

  (See FIG. 16) The operating rate calculation unit 3 obtains an electromagnetic valve operating rate, which is the ratio of the ON time of each of the solenoid valves 33A... The pressure set value calculation unit 4 calculates a set value relating to the next predetermined time with respect to the suction refrigerant pressure of the compressor 9 operated via the inverter 8 on the side of the refrigerator 6 based on the determined solenoid valve operation rate. (Update). The rotational speed command calculation unit 5 obtains a rotational speed command (update) for the next fixed time for the compressor 9 based on the deviation between the determined set value of the suction refrigerant pressure and the actual pressure.

  The technical meaning of the pressure set value calculation unit 4 will be described below with reference to FIGS. FIG. 2 is a relationship diagram between the refrigeration function capacity, the showcase load, the power consumption, and the pressure set value (of the refrigerant sucked into the compressor). The horizontal axis represents the pressure set value, and the vertical axis represents the refrigerating function, the showcase load, and the power consumption. Both the refrigerating function and the power consumption decrease as the pressure set value increases. Here, the refrigerating function shifts in the arrow direction, that is, in each of the upper right and lower left directions according to the level of the ambient temperature (that is, using the ambient temperature as a parameter). The showcase load shifts in the direction of the arrow, that is, in the upward and downward directions according to the level of the ambient temperature and humidity, but is constant regardless of the pressure set value. From the above, it can be said that the pressure set value that effectively and completely minimizes the power consumption for cooling the showcase, that is, the pressure setting value when the relationship of refrigeration function power = showcase load holds, is established. This is the limit.

  The pressure setting limit value fluctuates according to changes in the ambient temperature of the refrigerator or the ambient temperature and humidity of the showcase. Fig. 3 is a diagram showing changes in ambient temperature and humidity, (b) is a diagram showing changes in set pressure, and (c) is a diagram showing changes in refrigeration capacity and showcase load. . As shown in Fig. 3 (a), the temperature of the refrigerator fluctuates sinusoidally according to the four seasons, but the showcase is originally installed in an air-conditioned room. Temperature and humidity are almost constant throughout the four seasons. When the pressure set value is updated (changed) so as to become the above-mentioned limit value according to the four seasons as indicated by the solid line in FIG. It is almost constant throughout the year, and also takes a slightly higher value than the showcase load that is almost constant throughout the four seasons. Note that the showcase load changes according to the ambient temperature and humidity (and therefore according to the four seasons) as described above, but since the degree is small, it is shown as constant in the figure. On the other hand, if the pressure set value is constant throughout the four seasons, as indicated by the dotted line in Fig. (B) for reference, the refrigerating function will change according to the four seasons, as indicated by the dotted line in Fig. (C). Will do.

  Therefore, as shown in FIG. 3 (c), the optimal pressure setting value for minimizing the power consumption, that is, the pressure setting limit value is conclusively small in summer, large in winter, and large in spring. It is set in the middle in autumn. That is, in FIG. 2, the refrigeration function / pressure setting value line shifts to the lower left when the refrigerator ambient temperature increases in summer, and one showcase load / pressure setting value line shows the showcase ambient temperature / pressure setting value line. Since the humidity is almost constant throughout the four seasons, the intersection shifts to the left (the direction in which the pressure set value decreases). Conversely, in winter, the intersection moves in the right direction (the direction in which the pressure set value increases) for the same reason. ).

  As described above, in order to optimally update the pressure set value so that the power consumption becomes a necessary minimum, the refrigeration function power and the showcase load in each environmental condition may be known. Difficult to measure. Therefore, actually, while checking the balance between the refrigeration function capacity and the showcase load, it is determined whether the refrigeration function capacity is insufficient, appropriate, or excessive, and the pressure set value is optimally updated based on this. In addition, the balance between the refrigeration function and the showcase load is determined based on the operating rate of the solenoid valve of the showcase. That is, when the operation rate of the solenoid valve is low, the refrigeration function is excessive with respect to the showcase load, and when the operation rate of the solenoid valve is high, the refrigeration function is insufficient with respect to the showcase load, and the operation rate of the solenoid valve is low. When appropriate, it is determined that the refrigeration function is appropriate for the showcase load. The determination as to whether the operation rate of the solenoid valve is high, low, or appropriate is based on experience. This will be described below.

FIG. 5 is a diagram showing the relationship between the pressure setting value and the showcase operation rate in relation to the updating of the pressure setting value. This is an empirical rule for updating the pressure set value, and this content is implemented by the pressure set value calculation unit 4 in FIG. In other words, (1) If the operating rate of at least one showcase (solenoid valve) is 90% or more, it is determined that the refrigeration function is insufficient, and the pressure set value is reduced (updated) by 0.01 MPa (0.1 kg / cm ² ). And increase the refrigeration function. (2) If the operating rates of all showcases (solenoid valves) are 40 to 90%, it is determined that the refrigeration function is appropriate, and the pressure set value is maintained as it is. (3) If the showcase (solenoid valve) operation rate is 90% or less for all the units and at least one unit is 40% or less, it is determined that the refrigeration function is excessive, and the pressure set value is increased by 0.01 MPa (updated). To reduce the refrigeration function.

  By the way, instead of judging the balance between the refrigeration function and the showcase load based on the operation rate of the solenoid valve of the showcase as described above, it corresponds to the case where the solenoid valve is repeatedly turned on to turn on the flow of the refrigerant. The determination can be made based on the average rate of decrease of the air temperature at a predetermined location in the main body of the showcase, or based on the average ON / OFF cycle when the solenoid valve is repeatedly turned ON / OFF. These different determination methods will be described below.

  In a method of determining the balance between the refrigerating function and the showcase load based on the average descent rate of the air temperature at a predetermined location in the main body of the showcase, the general controller 34X in FIG. 6 is used. This general controller 34X is a first modification example of the general controller 34 in FIG. 1, and a temperature lowering speed calculator 3X is used instead of the solenoid valve operation rate calculator 3 in the general controller 34. Based on the operating signal of the solenoid valve of each showcase and the temperature signal of the blown air, the temperature drop speed calculating unit 3X repeatedly turns on the solenoid valve at a certain time before the certain time, and turns on the flow of the refrigerant. The average falling speed of the temperature of the blown air of the corresponding showcase when turned on is determined. In addition, instead of the temperature signal of the blown air, an average descent speed may be calculated for the air temperature signal of the product storage location.

  Now, whether the refrigeration function is excessive or insufficient with respect to the showcase load can be determined based on whether the average descending speed of the temperature of the blown air is high or low. The determination is based on the rule of thumb shown in FIG. It is done based on. FIG. 9 is a diagram showing the relationship between the pressure setting value and the descending speed of the blown air temperature in relation to the updating of the pressure setting value, and this content is executed by the pressure setting value calculation unit 4 in FIG. That is, (1) If at least one of the units has a descent speed below the lower limit value, it is determined that the refrigeration function is insufficient, and the refrigeration function is increased by lowering the pressure set value. (2) If the descent speed is within the set range for all showcases, it is determined that the refrigeration function is appropriate, and the set pressure value is maintained as it is. (3) If at least one of the units has a descent speed equal to or higher than the upper limit value, it is determined that the refrigerating function is excessive, and the pressure setting value is increased to decrease the refrigerating function.

  In a method of determining the balance between the refrigeration function power and the showcase load based on the average ON / OFF cycle when the solenoid valve of the showcase is repeatedly turned ON / OFF, the general controller 34Y shown in FIG. 7 is used. This is a second modification of the general controller 34 in FIG. 1, in which an on / off cycle calculating unit 3Y is used instead of the solenoid valve operation rate calculating unit 3 in the general controller 34. The on / off cycle calculating unit 3Y calculates an average on / off cycle when each solenoid valve is repeatedly turned on / off at a certain time before the certain time, based on the solenoid valve operation signal of each showcase. You can ask.

  Now, it can be determined whether the refrigeration function is excessive or insufficient for the showcase load depending on whether the average ON / OFF cycle is small or large, and the determination is made based on the empirical rule shown in FIG. It is. FIG. 10 is a diagram showing the relationship between the pressure setting value and the ON / OFF cycle of the solenoid valve in relation to the updating of the pressure setting value, and the contents will be implemented by the pressure setting value calculation unit 4 in FIG. In other words, (1) If at least one of the ON / OFF cycles exceeds the upper limit, it took more time for cooling, so it was judged that the refrigeration function was insufficient, and the pressure setting value was lowered to reduce the refrigeration function. Increase power. (2) For all showcases, if the ON / OFF cycle is within the set range, it is determined that the refrigeration function is appropriate, and the pressure set value is maintained as it is. (3) If at least one unit has an ON / OFF cycle that is less than the lower limit, cooling has been performed in a shorter period of time, so it is determined that the refrigeration function is excessive. Decrease.

  By the way, in order to determine whether the refrigeration function is excessive or inadequate with respect to the showcase load, it is essentially the same as looking at the air temperature drop rate and looking at the on / off cycle of the solenoid valve. That is. In practice, the easiness of detection and calculation is a problem, and in that regard, it is better to look at the ON / OFF cycle of the solenoid valve.

  As described above, the pressure set value is calculated by the pressure set value calculation unit 4. However, in order to further enhance the freshness management of the stored product, the initial value of the stored product must be iced. It is desirable to use a combination of frozen foods such as cream, meat, and fresh fish, daily items such as dairy products, and fruits and vegetables such as vegetables and fruits. With this initial value setting, it is possible to quickly cool to the respective optimum temperatures. A method for determining the initial value of the pressure setting will be described below.

For this purpose, the general controller 34Z shown in FIG. 6 is used. This general controller 34Z is a third modified example of the general controller 34 in FIG. 1, and is provided with an initial value setting section 40 at a stage preceding the pressure set value calculation section 4 in the general controller 34. The initial value setting unit 40 operates the sign key corresponding to the type of the stored product or the application based on the type of the stored product common to all the showcases, that is, the application, and in advance, An initial value for the pressure setting can be determined. The empirical rule relating to the initial value setting is shown in the correspondence diagram of the initial value of pressure setting / type of stored product in FIG. In the figure, the types (uses) of stored products are divided into six stages: frozen, chilled (refrigerated), ice temperature, meat, fresh fish, daily items, and fruits and vegetables. Value, for example, from 1.0 Kg / cm ² (corresponding to an operating temperature of -18 ° C) to the highest value of the rightmost “vegetables”, for example, 2.5 Kg / cm ² (corresponding to an operating temperature of 5 to 10 ° C). Determine. A sign key is provided corresponding to the above six steps.

  The configuration of the compressor rotation speed command calculation unit 5 will be described with reference to a block diagram showing the configuration of the rotation speed command calculation unit 5 and the refrigerator 6 in FIG. In the figure, a rotational speed command calculation unit 5 is provided with a circle-shaped deviation means for obtaining a deviation between a pressure set value input from a preceding stage and a pressure measurement value from a pressure sensor 7 of the refrigerator 6, and a PID calculator 10. Consists of The pressure deviation is converted into a rotational speed command for the compressor via the PID calculator 10 and transmitted to the compressor 9 via the inverter 8 on the side of the refrigerator 6 to change the rotational speed. The suction refrigerant pressure of the compressor 9 is fed back to the deviation means of the rotational speed command calculation unit 5 via the pressure sensor 7, where a negative feedback control circuit for setting the input pressure target value is formed. The compressor rotation speed is controlled such that the average value decreases as the pressure set value increases, and the average value increases as the pressure set value decreases.

  As a result, the compressor suction refrigerant pressure, the compressor rotation speed, and the blowout air temperature (in the showcase) are as shown in the time charts of FIGS. 4A, 4B, and 4C, respectively. As shown in FIG. 4A, the compressor suction refrigerant pressure fluctuates according to the pressure set value. Accordingly, as shown in FIG. 4 (b), the average value of the compressor speed which fluctuates finely decreases as the pressure set value increases, and increases as the pressure set value decreases. As a result of operating so that the showcase load and the refrigeration function power become approximately equal, power consumption can be minimized. In addition, a compressor rotation speed command is issued according to the pressure set value, and the frequency of operation and stoppage of the compressor becomes lower than in the conventional example. As a result, the blow-out air temperature of the showcase becomes smaller than the conventional example because the overshoot amount of the control becomes smaller (see FIGS. 4C and 12B). ). In the first embodiment, a solution to "problems to be solved by the invention" (1) and (2) is incorporated.

  A second embodiment will be described with reference to FIG. 13 which is a block diagram showing the configuration. In the second embodiment, in addition to the first embodiment, solutions to the "problems to be solved by the invention" (3), (4), and (5) are incorporated. That is, with respect to the problem (3), it is easy to adjust the set value of the blow-out air temperature when a showcase with a poor cooling state occurs due to a load change or an environmental change. In order to solve the problem (4), the recovery cooling after defrosting, that is, the time for pull-down is shortened, and the freshness of the product during that period is prevented. In order to solve the problem (5), the number of simultaneously operated showcases is limited to rationalize the refrigerator capacity so that the selected capacity does not become excessively large.

  In the second embodiment of FIG. 13, a part added to the first embodiment of FIG. 1 is a temperature sensor 15A for measuring the temperature of the product storage location of each showcase as a solution to the problem (3). And a temperature set value correction unit 21, a mode switch 22 and a high rotation speed command unit 23 as a solution to the problem (4), and a simultaneous operation restriction unit 24 as a solution to the problem (5). These will be described below in order.

  The temperature set value correction unit 21 measures the temperature of the product storage location of each showcase 1A via the respective temperature sensors 15A, and grasps the actual degree of cooling of the product based on the measured values. Next, the set value of the blown air temperature for the controllers 34A is automatically corrected in accordance with this. FIG. 14 shows rules (empirical rules) for this correction.

  In FIG. 14, the product storage location temperature is divided into three cases: (1) when the blow-out air temperature is equal to or more than the set value + 5 ° C .; (2) when the product is equal to or less than the set value + 2 ° C .; The blow-out air temperature set value is corrected as follows in each case. In the case of (1), the initial set value is -1 ° C, in the case of (2), the initial set value is + 1 ° C, and in the case of (3), the initial set value is kept. By using the temperature set value correction unit 21, the trouble of the conventional manual correction is remarkably improved.

  In contrast to the normal operation, after the so-called defrosting operation for removing frost adhering to each showcase, it is necessary to take an operation of rapidly performing return cooling, that is, pull-down, in order to control the high freshness of the product. Returning to FIG. 13, a mode switch 22 for switching between the “normal operation mode” and the “operation mode after defrosting” is provided at the subsequent stage of the showcase group 1. Therefore, the operation rate signal of each solenoid valve is transmitted via the mode switch 22 to the integrated controller 34 in the “normal operation mode” and the high rotation speed command unit 23 in the “operation mode after defrosting”. Is switched and sent. In the high rotation speed command unit 23, immediately after the defrosting operation, until the blowout air temperatures of all the showcases become equal to or less than the respective set values, or until the temperatures of the product storage locations become equal to or less than the respective set values. It is possible to command a predetermined high rotation speed to the inverter compressor to perform quick refrigeration. By this rapid freezing, each showcase realizes the return cooling after defrosting, that is, the pull-down time is shortened, and the freshness of the product during that time can be prevented.

  The simultaneous operation number limiting unit 24 is provided between the mode switch 22 and the general controller 34, and limits that all of the solenoid valves 33A... (That is, the showcase 1A. As described above, the purpose is to select the refrigerator capacity assuming that the showcase group will be operated collectively during peak load in summer, and as a result, the selected refrigerator will have excessive capacity and excessive cost. Because it becomes. Here, it is described that all the solenoid valves are simultaneously turned on. However, generally, it is a wide measure to limit that a predetermined number or more of the solenoid valves are simultaneously turned on. The simultaneous operation number limiting unit 24 is configured to perform any one of the following operations 1) to 4). That is, when all of the solenoid valves are to be turned on at the same time, 1) the previous solenoid valve to reach the total number is turned off without turning on until one of the solenoid valves that are already on is turned off. Or 2) the temperature of the product storage location is close to its set value, that is, the solenoid valve of the showcase that is relatively cool is turned off, or 3) based on a predetermined priority, that is, The showcase solenoid valve was turned off in consideration of the importance of the stored products, or 4) The operating rate was low, that is, the cooling condition of the products was relatively good and the cooling operation time of the showcase was short in the past For example, the solenoid valve is turned off. Thus, it is possible to prevent all the solenoid valves (showcases) from being turned on at the same time. Here, the simultaneous operating number limiting unit 24 corresponds to the operating number limiting unit in the present invention.

1 is a block diagram showing a configuration of a first embodiment according to the present invention. Diagram of relationship between refrigeration function capacity, showcase load, power consumption, and pressure set value Regarding changes in each value according to the four seasons, (a) is a diagram of changes in ambient temperature and humidity, (b) is a diagram of changes in set pressure, (c) is a diagram of changes in refrigeration capacity and showcase load (A) is a time chart of compressor suction refrigerant pressure, (b) is a time chart of compressor speed, and (c) is a time chart of blow-out air temperature. Correspondence diagram of pressure set value / showcase operation rate related to update of pressure set value Block diagram showing a first modification of the integrated controller. Block diagram showing a second modification of the integrated controller. Block diagram showing a third modification of the integrated controller. Correspondence diagram of pressure set value / blow-off air temperature drop speed related to pressure set value update Correspondence diagram of pressure set value / ON / OFF cycle of solenoid valve related to update of pressure set value Diagram of initial pressure setting / type of stored product Block diagram showing the configuration of the compressor rotation speed command calculation unit and the refrigerator FIG. 4 is a block diagram showing the configuration of the second embodiment. Correspondence diagram of blow-off air temperature set value / product storage location temperature for correction of blow-out air temperature set value Block diagram showing the configuration of a conventional example Block diagram showing the configuration of a conventional refrigeration cycle in detail Time chart showing the operation of a conventional refrigeration cycle (A) Time chart of compressor start / stop, (b) Time chart of blown air temperature

Explanation of reference numerals

Reference Signs List 1 showcase group 1A, 1B, 1C showcase 2A, 2B, 2C evaporator 3 operation rate calculator 3X temperature drop speed calculator 3Y on / off cycle calculator 4 pressure set value calculator 5 rotation speed command calculator 6 refrigeration Machine 7 Pressure sensor 8 Inverter 9 Compressor 10 PID calculator 14A, 14B, 14C Temperature sensor (blowing air)
15A, 15B, 15C Temperature sensor (product storage location)
Reference Signs List 21 Temperature set value correction unit 22 Mode switch 23 High rotation speed command unit 24 Simultaneous operation number limit unit 31 Condenser 32A, 32B, 32C Temperature expansion valve 33A, 33B, 33C Solenoid valve 34, 34X, 34Y, 34Z General controller 34A , 34B, 34C Controller (individual showcase)
40 Initial value setting section

Claims (5)

One or more showcases that control the flow of refrigerant to the evaporator on / off via an electromagnetic valve based on the difference between the temperature of the blown air and its set value, and a common refrigeration that forms a refrigeration cycle with this. A temperature sensor for measuring the temperature of the product storage location of each showcase; and a temperature set value correction unit for correcting the set value of the blow-out air temperature based on the measured temperature. A showcase cooling device, comprising: 2. The apparatus according to claim 1, wherein when a predetermined number or more of the solenoid valves are to be turned on at the same time, the solenoid valves to be reached the predetermined number are turned on until one of the solenoid valves already on is turned off. A showcase cooling device comprising: an operating number limiting unit that keeps the number of solenoid valves in the on state at the same time, while keeping the solenoid valve in the on state, less than a predetermined number. 2. The apparatus according to claim 1, wherein when more than a predetermined number of solenoid valves are to be turned on at the same time, the solenoid valves of the showcase are turned off in the order in which the temperature of the product storage location is closer to the set value. A showcase cooling device comprising an operating number limiter for suppressing the number of solenoid valves that are simultaneously turned on to less than a predetermined number. 2. The apparatus according to claim 1, wherein when a predetermined number or more of the solenoid valves are to be turned on at the same time, the solenoid valves of the showcase based on a predetermined priority are stopped in the off state, and simultaneously turned on. A showcase cooling device, comprising: an operating number limiter that suppresses a certain solenoid valve to less than a predetermined number. 2. The apparatus according to claim 1, wherein when at least a predetermined number of the solenoid valves are to be turned on at the same time, the solenoid valves are kept in the off state in ascending order of the operation rate, and the solenoid valves are simultaneously turned on. A showcase cooling device, comprising: a number-of-operated-units limiting unit that keeps the number to be less than a predetermined number.

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