JP2009103379A - Cooling storage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the unnecessary operation of a compressor when supplementing the shortage of a refrigerating capacity by the auxiliary drive of the compressor. <P>SOLUTION: This storage has a function capable of operating a constant-velocity compressor 32B of the second refrigerating circuit 31B provided independently together, when the refrigerating capacity is insufficient only by the operation of an inverter compressor 32A of the first refrigerating circuit 31A. In this case, the constant-velocity compressor 32B is started, only when an acceleration command is issued continuously four times to the inverter compressor 32A after the inverter compressor 32A reaches the highest rotational frequency. The unnecessary drive of the constant-velocity compressor 32B can be avoided when an instantaneous temperature change in the storage or the like occurs. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cooling storage, and more particularly to a cooling storage that has been improved in operation control of a compressor constituting a refrigeration apparatus.

Conventionally, what was described in patent document 1 is known as an example which cools the inside of a store | warehouse | chamber to the preset preset temperature vicinity. This system has a structure in which the refrigeration system has two independent refrigeration circuits, one refrigeration circuit is equipped with an inverter compressor, and the other refrigeration circuit is equipped with a constant speed compressor. During the cooling operation, the detected internal temperature is compared with the set temperature, and the inverter compressor is controlled to increase / decrease in accordance with the temperature difference, thereby maintaining the internal temperature near the set temperature. In addition, if the internal temperature rises greatly due to the opening and closing of the door, the inverter compressor reaches the maximum number of revolutions, and there is a temperature difference between the internal temperature and the set temperature, the other By driving together the constant speed compressor of the refrigeration circuit, the inside of the warehouse can be cooled early, and the constant speed compressor is stopped when the inside temperature decreases.
JP 2005-16874 A

By the way, when opening and closing the door as described above, if it is a short time, when the door is opened, the temperature in the vicinity of the internal temperature sensor rises rapidly and when the door is closed, The temperature drops rapidly to a slightly higher temperature.
Therefore, in the conventional control method described above, the constant-speed compressor is started by detecting the internal temperature that has risen momentarily. However, since the internal temperature decreases quickly, the constant-speed compressor Will stop. That is, since the constant-speed compressor, which can be said to be unnecessary, is repeatedly driven and stopped, power consumption is unnecessarily increased, and the constant-speed compressor can be operated for a short time. However, there is a risk that reliability may be deteriorated, for example, due to insufficient lubrication and poor lubrication.
The present invention has been completed based on the above-described circumstances, and its purpose is to suppress unnecessary operation of the compressor when the lack of refrigeration capacity is compensated by driving the auxiliary compressor. It is in.

  The cooling storage of the present invention has a plurality of independent refrigeration circuits, one of which is a refrigeration apparatus provided with a variable capacity compressor, and a cooling target based on a predetermined physical quantity related to internal cooling On the basis of the output from the storage means storing the physical quantity and the physical quantity sensor for detecting the physical quantity, the capacity of the compressor is changed so that the physical quantity approaches the cooling target read from the storage means, and And an operation control means for driving the compressor of another refrigeration circuit together when the capacity of the compressor is still requested to be increased even when the compressor is in a state of maximum capacity. In addition, the operation control means includes drive restriction means that allows the compressor of the other refrigeration circuit to be driven only after the request for the increase in capacity to the compressor of the main refrigeration circuit continues for a predetermined time. Has features in That.

According to this configuration, when the refrigeration capacity of the main refrigeration circuit having the variable capacity compressor alone is insufficient, and the refrigeration capacity of other refrigeration circuits is used together, the main refrigeration circuit is compressed. The compressor of another refrigeration circuit is driven only when a request for an increase in capacity is continuously made to the compressor for a predetermined time in a state where the machine is maximizing its capacity.
In this control method, it is not necessary to unnecessarily drive the compressors of other refrigeration circuits in response to an instantaneous change in the internal temperature that occurs when the door is opened and closed for a short time. Therefore, an increase in power consumption is suppressed, and it is avoided that a situation where the lubricating oil does not spread sufficiently due to the operation of the compressors of other refrigeration circuits only for a short time, and therefore Driving reliability is ensured.

The following configuration may also be used.
(1) A refrigeration apparatus having a plurality of independent refrigeration circuits, one main refrigeration circuit having a variable capacity compressor, and a cooling characteristic indicating a temporal change mode of a target temperature drop. Based on the output from the storage means and the temperature sensor for detecting the internal temperature of the main refrigeration circuit so that the internal temperature drops in accordance with the cooling characteristics read from the storage means. When the capacity of the compressor is changed, and when the capacity of the compressor is still requested to be increased even when the compressor is in the state of maximum capacity, the compressors of other refrigeration circuits are driven together. The operation control means is provided, and the operation control means includes a compressor of the other refrigeration circuit only after the request for the increase in capacity to the compressor of the main refrigeration circuit continues for a predetermined time. Drive restriction means that allows the drive of It has been.

(2) The compressor of the main refrigeration circuit is an inverter compressor capable of speed control, and the operation control means calculates the degree of decrease in the internal temperature based on the signal of the temperature sensor at every predetermined sampling time. A temperature change calculation unit; a target temperature drop degree output unit that outputs a target temperature drop degree at the internal temperature of the sampling time based on the cooling characteristics stored in the storage unit for each sampling time; and the temperature change A comparison unit that compares the actual temperature drop calculated by the calculation unit with the target temperature drop output from the target temperature drop output unit, and the actual temperature based on the comparison result of the comparison unit When the degree of decrease is smaller than the target temperature drop, a speed increase command is issued to the inverter compressor, and the actual temperature drop is larger than the target temperature drop. Includes an acceleration / deceleration command unit that issues a deceleration command to the inverter compressor, and the drive restricting means is configured to output the acceleration command a predetermined number of times in a state where the inverter compressor of the main refrigeration circuit is at the maximum rotation speed. When it comes out continuously, the drive of the compressor of the other refrigeration circuit is permitted.
Here, the degree of temperature drop is defined as the amount of temperature drop per unit time.

In this configuration, only the inverter compressor of the main refrigeration circuit is initially operated, and the actual temperature drop degree is calculated based on the detected internal temperature at every predetermined sampling time, while the cooling characteristic data is used. The target temperature drop degree at the internal temperature is output, and if the actual temperature drop degree is smaller than the target temperature drop degree, the inverter compressor is controlled to increase speed, and in the opposite case, the inverter compressor is controlled to decelerate. Cooled according to the cooling characteristics. Here, when only the refrigeration capacity of the main refrigeration circuit provided with the inverter compressor is insufficient, and the refrigeration capacity of other refrigeration circuits is used together, the inverter compressor of the main refrigeration circuit is at the maximum rotation speed. In this state, the compressors of the other refrigeration circuits are driven only after a speed increase command to the inverter compressor is continuously issued a predetermined number of times.
In this control method, it is not necessary to unnecessarily drive the compressors of other refrigeration circuits in response to an instantaneous change in the internal temperature that occurs when the door is opened and closed for a short time. Therefore, an increase in power consumption is suppressed, and it is avoided that a situation where the lubricating oil does not spread sufficiently due to the operation of the compressors of other refrigeration circuits only for a short time, and therefore Driving reliability is ensured.

(3) The drive restricting means includes a counter for accumulating the number of times the speed increasing command is issued when the inverter compressor of the main refrigeration circuit is at the maximum rotation speed, and an integrated value by the counter reaches a predetermined value. In this case, the drive control unit outputs a drive signal to the compressor of the other refrigeration circuit.
In this configuration, when the speed increase command is issued when the inverter compressor of the main refrigeration circuit is at the maximum number of revolutions, the number of times is integrated by the counter, and when the integrated value reaches a predetermined value, the compression of the other refrigeration circuits is performed. The machine is driven.

(4) After the compressors of the other refrigeration circuits are driven together, the operation control means is configured to increase / decrease commands to the inverter compressor of the main refrigeration circuit based on the comparison result of the comparison unit. It has a function to issue.
In this configuration, after the compressor of the other refrigeration circuit is driven, the inverter compressor of the main refrigeration circuit continues to operate, and the inverter compressor is controlled to increase / decrease based on the comparison result of the comparison unit. .

  According to the present invention, it is possible to suppress unnecessary operation of the compressor of another refrigeration circuit when performing the internal temperature control, thereby suppressing an increase in power consumption, and driving reliability of the compressor. Can be secured.

<Embodiment>
An embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a commercial vertical freezer is illustrated.
1 and 2, reference numeral 10 denotes a freezer main body formed of a heat insulating box having an opening on the front surface. The inside is a freezer compartment 11. A double-spread type heat insulating door 12 is mounted. The freezer body 10 is supported by legs 13 disposed at the four corners of the bottom surface, and a machine room 14 is configured on the top surface by a panel standing around.

  A rectangular opening 15 is formed at substantially the center of the ceiling wall 10A of the freezer main body 10 which is the bottom surface of the machine room 14, and a unit which will be described in detail later is formed so as to close the upper surface of the opening 15. A unit table 20 on which the refrigeration apparatus 30 is mounted is placed. A cooling duct 22 that doubles as a drain pan extends from the position of the edge of the lower surface on the front side (right side in FIG. 2) of the opening 15 toward the back wall, and evaporates between the unit base 20 and the unit base 20. A chamber 23 is formed. A suction port 25 is formed on the front end side of the cooling duct 22, and an internal fan 26 is provided on the back surface thereof, and an air outlet 27 is formed on the rear end side of the cooling duct 22.

The refrigeration apparatus 30 includes two independent refrigeration circuits, that is, a first refrigeration circuit 31A (corresponding to the main refrigeration circuit of the present invention) and a second refrigeration circuit 31B (corresponding to other refrigeration circuits of the present invention). ing. The refrigeration circuits 31A and 31B are roughly different from each other in the compressor, while the evaporator and the condenser are shared.
As schematically shown in FIG. 3, the first refrigeration circuit 31A includes an inverter compressor 32A having a variable rotation speed, a common condenser 33, a dryer 35A, and a capillary tube 36A that is a decompression unit. The evaporator 37 is circulated and connected by a refrigerant pipe. In the first refrigeration circuit 31 </ b> A, an accumulator 38 is interposed in the refrigerant pipe on the outlet side of the evaporator 37.
The second refrigeration circuit 31B includes a constant speed compressor 32B having a constant rotation speed, a common condenser 33, a dryer 35B, a capillary tube 36B as decompression means, and a common evaporator 37, which are connected by refrigerant piping. It is formed by circulation connection.

Among the components of both the refrigeration circuits 31A and 31B, the inverter compressor 32A, constant speed compressor 32B, common condenser 33, both dryers 35A and 35B, and both capillary tubes 36A and 36B are provided on the upper surface of the unit base 20. On the other hand, a common evaporator 37 is suspended and attached to the lower surface side of the unit table 20 to form a unit. A common condenser fan 34 is installed on the back surface of the common condenser 33. When the unit table 20 is placed by closing the opening 15 of the ceiling wall 10A of the freezer body 10, the evaporator 37 is accommodated in the evaporator chamber 23 at a position behind the internal fan 26. It has become.
Basically, when the refrigeration apparatus 30 and the internal fan 26 are driven, the air in the freezer compartment 11 is sucked into the evaporator compartment 23 from the suction port 25 as shown by the arrow in FIG. The inside of the freezer compartment 11 is cooled by circulating the cold air generated by heat exchange while passing through the evaporator 37 such that it is blown out from the outlet 27 to the freezer compartment 11. Yes.

In the present embodiment, means for controlling the temperature in the freezer compartment 11 (internal temperature) along a predetermined temperature curve is provided, which will be described below.
The cooling mode inside the cabinet is controlled cooling that keeps the inside of the cabinet close to the set temperature, and when the cabinet temperature rises due to an increase in the cabinet load or an increase in ambient temperature, the interior is set rapidly. There is pull-down cooling that lowers the temperature to near the temperature.
As shown in FIG. 4, the control device includes a control unit 40 that includes a microcomputer or the like and executes a predetermined program, and is housed in an electrical box 28 provided on the upper surface of the unit base 20. An internal temperature sensor 39 for detecting the internal temperature is connected to the input side of the control unit 40. The internal temperature sensor 39 is connected to the internal fan 26 in the evaporator chamber 23 as shown in FIG. It is arranged downstream.

The control unit 40 is provided with a data storage unit 42 together with the clock signal generation unit 41. The data storage unit 42 includes target temperature curves Xc and Xp during control cooling and pull-down cooling as shown in FIG. Is stored as data.
The control region is a temperature region between an upper limit temperature TH that is higher than a predetermined set temperature To by a predetermined value (eg, 1K) and a lower limit temperature TL that is lower than the set temperature To by a predetermined value (eg, 2K). The region is a region that exceeds the upper limit temperature TH.

The target temperature curve Xp in the pull-down region is shown as a straight line having a relatively steep linear function, and the target temperature drop degree (temperature drop amount per unit time: ΔT / Δt) related to the temperature curve Xp. Is a constant value Ap (K / min) regardless of the internal temperature. The target internal temperature drop Ap may be simply referred to as a target value Ap.
The target temperature curve Xc in the control region is shown as a straight line of a linear function with a gentler slope than the target temperature curve Xp during pull-down cooling. Even in the same temperature curve Xc, the target temperature drop degree Ac (K / min) (sometimes simply referred to as target value Ac) is constant, but the target temperature drop degree (target value) Ap during pull-down cooling is constant. Compared to a smaller value.
In the flowchart of FIG. 6, the target temperature drop degree (target value) Ap at the time of pull-down cooling and the target temperature drop degree (target value) Ac at the time of control cooling are collectively expressed as a target temperature drop degree A. However, “Ap” is output as the target temperature drop degree A in the pull-down area, and “Ac” is output as the target temperature drop degree A in the control area.

The target temperature curves Xp and Xc in both regions are stored in the data storage unit 42 of the control unit 40 and are used when executing the program related to the cooling operation.
The inverter compressor 32 </ b> A described above is connected to the output side of the control unit 40 through an inverter circuit 44. In the inverter compressor 32A of the present embodiment, the rotational speed is switched to, for example, five stages.
In order to perform basic cooling control, the control unit 40 includes a temperature change calculation unit 45 that calculates the degree of decrease in the internal temperature based on the signal of the internal temperature sensor 39 at every predetermined sampling time, and the same sampling time. A target temperature drop degree output unit 46 for outputting the target temperature drop degree A at the internal temperature of this sampling time based on the data of the target temperature curves Xp and Xc stored in the data storage part 42 for each time, and temperature change calculation A comparison unit 47 that compares the actual temperature drop S calculated by the unit 45 with the target temperature drop A output from the target temperature drop output unit 46, and an inverter circuit based on the comparison result of the comparison unit 47 An acceleration / deceleration command unit 48 that issues an acceleration / deceleration command to 44 is provided.
In this embodiment, the sampling time is set to 0.5 minutes, for example.

The control unit 40 has the following characteristic functions. That is, in the state where the inverter compressor 32A is operating at the maximum rotation speed, if a speed increase command is issued from the speed increase / decrease command unit 48, the constant speed compressor 32B of the second refrigeration circuit 31B is started. However, the same constant speed compressor 32B is driven only after a speed increase command is issued continuously a predetermined number of times (four times in the present embodiment).
For this reason, a constant speed compressor 32B is connected to the output side of the control unit 40, and a speed increase command is issued to the control unit 40, and a rotation speed detection unit 49 that detects the rotation speed of the inverter compressor 32A. A counter 50 that counts the number is provided.

Further, the control unit 40 has the following functions.
After the constant speed compressor 32 </ b> B is driven by the above control, the inverter compressor 32 </ b> A continues to operate, and the inverter compressor 32 </ b> A is subjected to acceleration / deceleration control based on the comparison result of the comparison unit 47.
When the inverter compressor 32A and the constant speed compressor 32B are both operated, if a deceleration command is issued to the inverter compressor 32A while the inverter compressor 32A is at the minimum rotation speed, the constant speed compression is performed. The machine 32B is stopped.
When it is detected that the internal temperature TR has reached a predetermined cooling lower limit temperature (the lower limit temperature TL of the set temperature To in the present embodiment), the inverter compressor 32A is stopped.

Next, the operation of this embodiment will be described with reference to the flowcharts of FIGS.
First, basic cooling control from the pull-down area to the control area will be described. In the flowchart of FIG. 6, the internal temperature TR is detected at every predetermined sampling time (step S1), the internal temperature TR is determined in step S2, and the pull-down area exceeds the upper limit temperature TH of the set temperature To. Therefore, in step S3, the inverter compressor 32A is activated (operation is maintained during operation). At the same time, in step S4, the actual internal temperature drop degree S is calculated based on the detected internal temperature TR, and in the subsequent step S5, the calculated value S of the internal temperature drop is stored in the data storage unit 42. Is compared with the target value Ap of the temperature drop degree inside the chamber relating to the temperature curve Xp for pull-down cooling read out from.

If the calculated value S is smaller than the target value Ap, in step S6, a speed increase command is issued to the inverter compressor 32A, and the current rotational speed is not the maximum rotational speed (step S7 is "No"). The rotation speed is increased by one step (step S8), and if the rotation speed is the maximum rotation speed (step S7 is “Yes”), the rotation speed is maintained. When the calculated value S is equal to the target value Ap, the inverter compressor 32A maintains the current rotational speed (step S9). When the calculated value S is larger than the target value Ap, a deceleration command is issued to the inverter compressor 32A in step S10, and the inverter compressor 32A does not have the current rotation speed as the minimum rotation speed (step S11). Is “No”), the rotational speed is decreased by one step (step S12), and if the rotational speed is the minimum rotational speed (step S11 is “Yes”), the rotational speed is maintained.
The above control is repeatedly executed every predetermined sampling time, and the pull-down cooling is performed along the target temperature curve Xp in the pull-down region shown in FIG.

When pull-down cooling proceeds and the internal temperature TR falls below the upper limit temperature TH, that is, enters the control region, in step S2, a determination of “TL ≦ TR ≦ TH” is made, and the operation of the inverter compressor 32A is continued. In the state (step S13), the internal temperature drop degree S is similarly calculated in step S4. In the subsequent step S5, the calculated value S of the internal temperature drop is obtained from the data storage unit 42 this time. The read value is compared with the target value Ac of the temperature drop degree in the chamber related to the temperature curve Xc for control cooling.
Similarly, when the calculated value S is smaller than the target value Ac, a speed increase command is issued to the inverter compressor 32A (step S6), and the current rotational speed is not the maximum rotational speed (step S7). Is “No”), the rotational speed is increased by one step (step S8), and if it is the maximum rotational speed (step S7 is “Yes”), the rotational speed is maintained. If the calculated value S is equal to the target value Ac, the inverter compressor 32A maintains the current rotational speed (step S9). If the calculated value S is larger than the target value Ac, a deceleration command is issued to the inverter compressor 32A (step S10), and the inverter compressor 32A does not have the current rotational speed as the minimum rotational speed (step S11). Is “No”), the rotational speed is decreased by one step (step S12), and if the rotational speed is the minimum rotational speed (step S11 is “Yes”), the rotational speed is maintained.
The above control is repeatedly executed every predetermined sampling time, and control cooling is performed along the target temperature curve Xc in the control region shown in FIG.

When the control cooling proceeds and the internal temperature TR falls to a temperature lower than the lower limit temperature TL of the set temperature To, a determination of “TL> TR” is made in step S2, and based on the same determination, in step S14, the inverter The compressor 32A is stopped.
After that, as shown in FIG. 5, after waiting for the natural rise of the internal temperature, when the internal temperature TR returns to the upper limit temperature TH of the set temperature To, the cooling control according to the target temperature curve Xc in the control region. Is resumed.

Now, during the above control cooling, when the ambient temperature rises or the internal load increases, the inverter compressor 32A reaches the maximum rotational speed to cool along the temperature curve Xc. In the state (“Yes” in step S7), a speed increase command may be issued to the inverter compressor 32A (step S6). At that time, since the constant speed compressor 32B is stopped (“No” in step S15), as long as the count value N of the counter 50 is less than “3” (“No” in step S16), in step S17. “1” is added to the counter 50. In the subsequent two sampling times, when a speed increase command is issued, the count value N of the counter 50 becomes “3” (“Yes” in step S16), so that the speed increasing signal is further increased in the next sampling time. When it is discharged, the constant speed compressor 32B is started in step S18, the counter 50 is reset in step S19, and then the process returns to step S1.
Thereafter, in the state where both the inverter compressor 32A and the constant speed compressor 32B are operated, the calculated value S of the internal temperature drop and the internal temperature drop for control cooling are the same as described above. Is compared with the target value Ac, and the rotational speed of the inverter compressor 32A is controlled to be increased or decreased according to the comparison result.

Here, the reason why the constant speed compressor 32B is started only after the speed increase command is issued four times in succession from the state in which the inverter compressor 32A is at the maximum rotational speed is as follows. In short, the constant speed compressor 32B is not activated for every momentary increase in the internal load.
For example, when the heat insulation door 12 is opened, the temperature in the vicinity of the position where the internal temperature sensor 39 is disposed increases greatly instantaneously. Therefore, in the next sample time, “TH <TR” is determined in step S2, and the step In S5, the calculated value S of the degree of temperature drop in the cabinet is compared with the target value Ap of the degree of temperature drop in the compartment for pull-down cooling. Naturally, since the calculated value S is smaller than the target value Ap (S <Ap), a speed increase command is issued to the inverter compressor 32A (step S6), and the inverter compressor 32A is at the maximum rotational speed. (Step S7 is “Yes”), if there is no restriction by the numerical value of the counter 50 (step S16), which is a feature of the present embodiment, the constant speed compressor 32B is started in step S18.

After that, when the heat insulating door 12 is closed after a short time, the air in the freezer compartment 11 is circulated and introduced in the vicinity of the internal temperature sensor 39, but the temperature inside the freezer compartment 11 has not increased so much. The internal temperature TR detected by the temperature sensor 39 rapidly decreases to a temperature slightly higher than the temperature before the heat insulating door 12 is opened. At this time, if the operation of the constant speed compressor 32B is continued, the refrigeration capacity becomes excessive and a so-called overcooling state occurs, so the constant speed compressor 32B needs to be stopped. In other words, when there is an instantaneous increase in the internal load, such as when the heat insulating door 12 is opened and closed for a short time, there is no need to start the constant speed compressor 32B, and the constant speed as described above. When the compressor 32B is stopped for a short time, there is a concern that the lubricating oil may not be sufficiently distributed to the mechanism portion, resulting in poor lubrication.
Therefore, in the present embodiment, as described above, the constant speed compressor 32B is started only after the speed increase command is issued four times continuously from the state where the inverter compressor 32A is at the maximum rotation speed. When the load in the warehouse increases instantaneously, it is refrained from starting up the constant speed compressor 32B itself.

In addition, when the opening time of the heat insulation door 12 becomes long, after the heat insulation door 12 is closed, the inside temperature may rise to the pull-down region and remain there. At this time, pull-down cooling control is performed, a speed increasing command is issued to the inverter compressor 32A, the speed of the inverter compressor 32A is increased, and after reaching the maximum number of revolutions ("Yes" in step S7), the speed increases. After waiting for the speed command to be issued four times in succession (“Yes” in step S16), the constant speed compressor 32B is started in step S18.
Thereafter, in a state where the inverter compressor 32A and the constant speed compressor 32B are both operated, the calculated value S of the internal temperature drop is compared with the target value Ap of the internal temperature drop for pull-down cooling. Then, pull-down cooling is performed along the target temperature curve Xp in the pull-down region while the rotation speed of the inverter compressor 32A is controlled to increase or decrease according to the comparison result.
As a result, when the internal temperature TR falls to the control region, the calculated value S of the internal temperature drop is compared with the target value Ac of the internal temperature decrease for control cooling, and an inverter is selected according to the comparison result. Control cooling is performed along the target temperature curve Xc in the control region while the rotational speed of the compressor 32A is increased or decreased.

When the inverter compressor 32A and the constant speed compressor 32B are both operated (step S20 is “Yes”) and the pull-down cooling control or the control cooling control is performed, in step S5, the temperature drop degree in the refrigerator When the calculated value S is determined to be larger than the target values Ap and Ac of the temperature drop degree for the pull-down cooling or control cooling (S> A), the inverter compressor 32A is decelerated in step S10. A command is issued, but when the inverter compressor 32A is in the minimum rotational speed state ("Yes" in step S11) and a deceleration command is issued to the inverter compressor 32A, a constant speed is obtained in step S21. The compressor 32B is stopped.
Thereafter, the operation of the inverter compressor 32A is continued, and the calculated value S of the internal temperature drop is compared with the target values Ap and Ac of the internal temperature drop for pull-down cooling or control cooling, and the comparison Pull-down cooling or control cooling is performed along the target temperature curves Xp and Xc in the pull-down region or the control region while the rotation speed of the inverter compressor 32A is controlled to increase or decrease according to the result.
When the control cooling proceeds and the internal temperature TR falls to a temperature lower than the lower limit temperature TL of the set temperature To, a determination of “TL> TR” is made in step S2, and the inverter compressor 32A is stopped based on the determination. (Step S14) is as described above.

As described above, according to the present embodiment, the constant speed compressor 32B of the second refrigeration circuit 31B provided independently when the refrigeration capacity is insufficient only by the operation of the inverter compressor 32A of the first refrigeration circuit 31A. When the inverter compressor 32A reaches the maximum number of revolutions, a speed increase command is issued four times in succession to the inverter compressor 32A. Only then is the constant speed compressor 32B activated.
When such a control method is adopted, the constant-speed compressor 32B is not unnecessarily driven with respect to an instantaneous change in the internal temperature caused by a short time opening and closing of the heat insulating door 12 or the like. Therefore, an increase in power consumption can be suppressed. Further, it is possible to avoid a situation in which the lubricating oil does not spread sufficiently due to the constant speed compressor 32B being operated only for a short time, thereby ensuring the reliability of driving of the same constant speed compressor 32B.

<Related technologies>
7 and 8 show related technologies. In this related technology, when the refrigeration capacity is insufficient only by the operation of the inverter compressor 32A of the first refrigeration circuit 31A due to a change in the internal load or the like, the constant speed compressor of the second refrigeration circuit 31B provided independently is provided. The specific control for supplementing the refrigerating capacity by operating the 32B together is different from the above embodiment.
Below, the part which is mainly different from the said embodiment is demonstrated. In the flowchart of FIG. 7 according to the related technology, steps having the same functions as those in the flowchart of FIG. 6 of the above-described embodiment are denoted by the same step numbers, and description thereof is simplified or omitted.

In this related technique, when the interior of the refrigerator is cooled along the temperature curve Xc in the control cooling, the constant speed compressor 32B is stopped in the flowchart of FIG. 7 (step S15 is “No”), and the inverter compressor When the refrigerating capacity is insufficient only by the first refrigeration circuit 31A provided with 32A, specifically, the inverter compressor 32A is in a state where the inverter compressor 32A has reached the maximum rotational speed (step S7 is “Yes”). When the speed increasing command is issued (step S6), the constant speed compression is performed in step S18 on condition that the stop time of the constant speed compressor 32B is 5 minutes or longer (step S30 is “Yes”). The machine 32B is started, and at the same time, in step S31, the rotational speed of the inverter compressor 32A is changed to the minimum rotational speed.
The reason for waiting for a stop time of at least 5 minutes before starting the constant speed compressor 32B is to wait for equalization between the high pressure side and the low pressure side, and to ensure good startability.
Thereafter, in the state where both the inverter compressor 32A and the constant speed compressor 32B are operated, the calculated value S of the internal temperature drop and the internal temperature drop for control cooling are the same as in the above embodiment. Is compared with the target value Ac, and the rotational speed of the inverter compressor 32A is controlled to be increased or decreased according to the comparison result.

Further, when the inverter compressor 32A and the constant speed compressor 32B are both operated as described above (step S20 is “Yes”) and controlled cooling is performed, the inverter compressor 32A reaches the minimum number of rotations. In this state (step S11 is “Yes”), when a deceleration command is issued to the inverter compressor 32A (step S10), the constant speed compressor 32B is stopped in step S21, and at the same time, in step S32, the inverter compressor The rotational speed of 32A is changed to the maximum rotational speed.
Thereafter, control cooling is performed while the speed of the inverter compressor 32A is controlled to increase and decrease.

In this related technology, when the constant speed compressor 32B is started while the inverter compressor 32A is operating at the maximum rotation speed, the inverter compressor 32A is changed to the minimum rotation speed simultaneously with the start of the constant speed compressor 32B. When the constant speed compressor 32B is stopped while the inverter compressor 32A is operating at the minimum speed, the inverter compressor 32A is changed to the maximum speed simultaneously with the stop of the constant speed compressor 32B. As shown in Fig. 5, there is an advantage that the change in the refrigerating capacity can be made almost continuous, and the refrigerating capacity corresponding to the load in the warehouse is easily obtained.
In this related technique, the condenser 33 is shared by the first and second refrigeration circuits 31A and 31B as in the above-described embodiment, and there is a temporary condensation load when the constant speed compressor 32B is started. In contrast to the increase, the inverter compressor 32A is set to the minimum rotational speed to reduce the condensation load, thereby suppressing the increase in the high pressure of the second refrigeration circuit 31B on the constant speed compressor 32B side, Reliability can be ensured and energy can be saved.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above embodiment, the case where the compressor of the second refrigeration circuit to be used supplementarily is a constant speed compressor, but an inverter compressor may be used as the compressor of the auxiliary refrigeration circuit.
(2) Three or more independent refrigeration circuits may be provided, one of which may be used as a main refrigeration circuit and the other as an auxiliary refrigeration circuit.
(3) In the above embodiment, when the constant speed compressor is started to supplement the refrigerating capacity, the speed is increased four times in succession with respect to the inverter compressor from the state where the inverter compressor has reached the maximum rotational speed. By starting the constant speed compressor for the first time after the command is issued, unnecessary start of the constant speed compressor is avoided, but the number of speed increase commands is not limited to four, Other times may be used depending on conditions such as the interval.

(4) In the above embodiment, a straight line of a linear function is exemplified as the target control cooling characteristic data. However, a linear function of temperature-time, or an internal temperature and a target temperature drop degree It is also possible to use a look-up table that contrasts the two.
(5) In the above-described embodiment, the cooling characteristics to be copied are exemplified by the manner in which the internal temperature changes with time. However, other measures such as the low pressure of the refrigerant and the evaporating temperature over time are also provided. A change mode may be shown.
(6) Further, as a method for controlling the cooling of the interior to the vicinity of a predetermined set temperature, the inverter compressor is controlled to increase / decrease based on the deviation between the set temperature of the interior temperature and the actual detected temperature. Also good. Further, based on the deviation between the set pressure of the refrigerant low pressure and the detected pressure detected by the pressure sensor, or the difference between the set temperature of the refrigerant evaporation temperature and the detected temperature detected by the temperature sensor. The inverter compressor may be controlled to increase / decrease.

(7) In the above embodiment, the case where an inverter compressor is used as a compressor is exemplified as means for adjusting the refrigeration capacity of the cooling device. However, the present invention is not limited to this, and the number of cylinders driven according to the load is not limited to this. Other variable capacity compressors such as a compressor with an unload function for adjusting the pressure may be used.
(8) The present invention is not limited to the freezer exemplified in the above embodiment, and can be widely applied to other cooling storages such as a refrigerator, a refrigerator, and a constant temperature and high humidity storage.

The external appearance perspective view of the freezer which concerns on one Embodiment of this invention. Sectional view of the vicinity of the refrigeration unit installation position Circuit diagram of refrigeration equipment Block diagram of compressor control mechanism Graph showing cooling characteristics Compressor operation control flowchart Flow chart of compressor operation control according to related technology Graph showing its refrigeration capacity

Explanation of symbols

  30 ... Cooling device 31A ... First refrigeration circuit (main refrigeration circuit) 31B ... Second refrigeration circuit (other refrigeration circuits) 32A ... Inverter compressor (variable capacity compressor) 32B ... Constant speed compressor 39 ... Inside Temperature sensor 40 ... Control unit (operation control means) 42 ... Data storage unit (storage means) 44 ... Inverter circuit 45 ... Temperature change calculation unit 46 ... Target temperature drop degree output unit 47 ... Comparison unit 48 ... Acceleration / deceleration command unit 50 ... Counter TR ... Inside temperature TL ... Lower limit temperature (cooling lower limit temperature) (to set temperature To) Xp, Xc ... Target temperature curve (cooling characteristics) A, Ap, Ac ... Target temperature drop degree S ... Actual temperature Degree of descent

Claims (5)

A refrigeration apparatus having a plurality of independent refrigeration circuits, one of which has a variable capacity compressor in the main refrigeration circuit,
Storage means for storing a cooling target based on a predetermined physical quantity related to internal cooling;
Based on the output from the physical quantity sensor for detecting the physical quantity, the capacity of the compressor is changed so that the physical quantity approaches the cooling target read from the storage means, and the compressor is in a state where the maximum capacity is exhibited. However, when an increase in the capacity of the compressor is still required, an operation control means for driving the compressor of the other refrigeration circuit is provided,
In addition, the operation control means is provided with a drive restricting means that allows the compressor of the other refrigeration circuit to be driven only after the request for the increase in capacity to the compressor of the main refrigeration circuit continues for a predetermined time. Cooling storage characterized by being. A refrigeration apparatus having a plurality of independent refrigeration circuits, one of which has a variable capacity compressor in the main refrigeration circuit,
Storage means in which cooling characteristics indicating a temporal change mode of a target temperature drop are stored as data;
Based on the output from the temperature sensor for detecting the internal temperature, the capacity of the compressor of the main refrigeration circuit is changed so that the internal temperature drops following the cooling characteristics read from the storage means. And, even when the compressor is in a state of maximum capacity, when it is requested to increase the capacity of the compressor, operation control means for driving the compressor of the other refrigeration circuit together, Is provided,
In addition, the operation control means is provided with a drive restricting means that allows the compressor of the other refrigeration circuit to be driven only after the request for the increase in capacity to the compressor of the main refrigeration circuit continues for a predetermined time. Cooling storage characterized by being. The compressor of the main refrigeration circuit is an inverter compressor capable of speed control,
The operation control means includes a temperature change calculation unit that calculates a degree of decrease in the internal temperature based on a signal of the temperature sensor at predetermined sampling times;
A target temperature drop output unit that outputs a target temperature drop at the internal temperature of the sampling time based on the cooling characteristics stored in the storage means for each sampling time;
A comparison unit that compares the actual temperature drop calculated by the temperature change calculator with the target temperature drop output from the target temperature drop output unit;
Based on the comparison result of the comparison unit, when the actual temperature drop degree is smaller than the target temperature drop degree, a speed increase command is issued to the inverter compressor, and the actual temperature drop degree is determined based on the target temperature drop. When the degree of descent is greater than, it is composed of an acceleration / deceleration command unit that issues a deceleration command to the inverter compressor,
The drive restricting means drives the compressor of the other refrigeration circuit when the speed increase command is continuously issued a predetermined number of times in a state where the inverter compressor of the main refrigeration circuit is at the maximum rotation speed. The cooling storage according to claim 2, wherein the cooling storage is allowed. The drive restricting means includes a counter that accumulates the number of times that the speed increase command has been issued when the inverter compressor of the main refrigeration circuit is at the maximum number of revolutions, and when the accumulated value by the counter reaches a predetermined value. The cooling storage according to claim 3, comprising a drive control unit that outputs a drive signal to the compressor of the other refrigeration circuit. The operation control means is a function of issuing an acceleration / deceleration command to the inverter compressor of the main refrigeration circuit based on the comparison result of the comparison unit after the compressor of the other refrigeration circuit is driven together. The cooling storage according to claim 3 or 4, characterized by comprising:

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