JP2012242049A - Refrigerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating apparatus that has improved stability of temperature inside a storage, and to provide a refrigerating apparatus which has reduced power consumption.SOLUTION: A control means 50 obtains a first vaporization temperature deviation (ΔTe) in a first period based upon a target temperature (Tam) in a space to be cooled and a detection result (Ta) of temperature detection means 13, updates capacity (F') of a compressor 1 based upon the first vaporization temperature deviation (ΔTe), calculates a vaporization temperature (Te) corresponding to a detection result of suction pressure detection means 12, calculates a target vaporization temperature (Tem) based upon the vaporization temperature (Te) and first vaporization temperature deviation (ΔTe), and also calculates a vaporization temperature (Te) corresponding to the detection result of the suction pressure detection means 12 in a second period and updates capacity (F') of the compressor 1 based upon the vaporization temperature (Te) and the target vaporization temperature (Tem) calculated in the first period.

Description

  The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus that has been improved in temperature control of a space to be cooled.

As a capacity control method of the compressor, a method of controlling based on the temperature of the space to be cooled (indoor, warehouse, refrigerator, etc.) (for example, see Patent Document 1) or a method of controlling based on the pressure of the refrigerant (for example, And Patent Document 2) have been proposed.
The technique described in Patent Literature 1 is based on the difference between the detection result of a sensor that detects the room temperature and a preset temperature, and the current value (primary current) that flows in the primary winding of the motor. The number of rotations is controlled.
The technique described in Patent Document 2 controls the rotation speed of the compressor by comparing the refrigerant pressure difference between the suction side and the discharge side of the compressor with a preset set pressure.

Japanese Patent Laid-Open No. 63-263346 (see, for example, the lower right part of page 2 to the upper part of page 3) Japanese Patent Laid-Open No. 60-14032 (for example, see the upper left of page 3 and the upper page of page 4, and FIG. 6)

  When the technique described in Patent Document 1 is employed in, for example, a warehouse, there is a possibility that the rotational speed of the compressor is not a rotational speed that reflects the current temperature in the warehouse. This is because the heat capacity is large due to the wide space that the warehouse cools, so that it takes time for the change in the internal temperature to appear after the compressor speed changes. Therefore, there is a possibility that the temperature in the warehouse that is sequentially detected deviates greatly from the target temperature in the warehouse.

  Further, in the technique described in Patent Literature 1, when the temperature of the cooling target space deviates from the target internal temperature, feedback is applied to bring the cooling target space temperature into the target internal temperature range, and the rotation speed of the compressor Cause sudden changes and frequent stops. Accordingly, there is a possibility that the cooling target space temperature may cause hunting, overshoot, or the like, or the cooling target space temperature may be excessively lowered and the refrigeration apparatus may cause the thermo OFF or the like.

  Furthermore, in the technique described in Patent Document 1, in addition to the large heat capacity as in a warehouse, when the frequency of the cooling target space temperature deviating from the target internal temperature increases, the compressor is set at the maximum capacity or the minimum capacity. Driving time will be longer. As a result, there is a possibility that the amount of power consumption increases. This is because the inverter-driven refrigeration apparatus has a maximum coefficient of performance (COP) indicating the efficiency of the apparatus at an intermediate capacity (partial load) between the maximum capacity and the minimum capacity.

  The technology described in Patent Document 2 performs compressor capacity control by controlling the evaporation temperature to be constant, but since it is not based on the detection result of the room temperature in the first place, controlling the room temperature to the target temperature is not possible. There was a problem that it was difficult.

  The present invention has been made to solve the above-described problems, and a first object thereof is to provide a refrigeration apparatus that can improve the temperature stability of the space to be cooled. It is a second object to provide a refrigeration apparatus that can reduce power consumption.

A refrigerating apparatus according to the present invention has a variable capacity compressor, a condenser, an expansion valve, and an evaporator, and these are connected by a refrigerant pipe to constitute a refrigerating cycle. Repetitive suction pressure detection means, temperature detection means for detecting the temperature of the space to be cooled, the first period, and one or more second periods following the first period as a set, each period And a control means for controlling the compressor based on the updated capacity of the compressor in the first cycle, and the control means has a target temperature (Tam) of the space to be cooled in the first period. And a detection result (Ta) of the temperature detection means to obtain a first evaporation temperature deviation (ΔTe), update the compressor capacity (F ′) based on the first evaporation temperature deviation (ΔTe), Evaporation temperature corresponding to the detection result of the suction pressure detection means (Te) is calculated, the target evaporation temperature (Tem) is calculated based on the evaporation temperature (Te) and the first evaporation temperature deviation (ΔTe), and the detection result of the suction pressure detection means in the second period The evaporation temperature (Te ^* ) corresponding to is calculated, and the compressor capacity (F ′ ^* ) is updated based on the evaporation temperature (Te ^* ) and the target evaporation temperature (Tem) calculated in the first cycle. To do.

In the refrigeration apparatus according to the present invention, in the first period, the control means has a first evaporation temperature deviation (ΔTe) based on the target temperature (Tam) of the space to be cooled and the detection result (Ta) of the temperature detection means. And the compressor capacity (F ′) is updated based on the first evaporation temperature deviation (ΔTe), the evaporation temperature (Te) corresponding to the detection result of the suction pressure detecting means is calculated, and this evaporation temperature ( The target evaporation temperature (Tem) is calculated based on Te) and the first evaporation temperature deviation (ΔTe), and the evaporation temperature (Te ^* ) corresponding to the detection result of the suction pressure detecting means is calculated in the second period. The compressor capacity (F ′ ^* ) is updated based on the evaporation temperature (Te ^* ) and the target evaporation temperature (Tem) calculated in the first period. Thereby, the stability of the space temperature to be cooled of the refrigeration apparatus can be improved. Moreover, the power consumption of the refrigeration apparatus can be reduced.

It is a figure explaining an example of the refrigerant circuit structure of the freezing apparatus which concerns on embodiment of this invention. It is a flowchart explaining the example of control of the internal temperature of the freezing apparatus shown in FIG. It is a figure explaining the temperature range of a dead zone in the set target internal temperature, and the temperature range of a desired temperature zone. In the control shown in FIG. 2, it is a flowchart explaining the control when a restriction | limiting upper limit and a restriction | limiting lower limit are provided in target evaporation temperature. In the control shown in FIG. 2, it is a flowchart explaining the control when an allowable evaporation temperature width is set for the rated evaporation temperature Tec. It is a figure explaining the relationship between the refrigerant | coolant suction pressure and the chamber internal temperature in the evaporator shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment.
FIG. 1 is a diagram illustrating an example of a refrigerant circuit configuration of a refrigeration apparatus 100 according to an embodiment of the present invention.
The refrigeration apparatus 100 according to the present embodiment is an improvement in the control of the capacity of the compressor 1, and the temperature of the space to be cooled (room, warehouse, refrigerator, etc.) corresponds to the suction pressure of the compressor 1. The rotation temperature of the compressor 1 is controlled based on the increase or decrease of the evaporation temperature.

Refrigeration apparatus 100 according to the present embodiment flows out of compressor 1 that compresses and conveys refrigerant, oil separator 2 that separates refrigeration oil contained in the refrigerant, condenser 3 that condenses the refrigerant, and condenser 3. An intermediate cooler 4 that cools the refrigerant, an evaporator 6 that evaporates the refrigerant, an oil cooler 7 that cools refrigeration oil flowing out from the oil separator 2, and a suction pressure detection that detects the pressure of the refrigerant sucked into the compressor 1 Means 12, internal temperature detection means 13 for detecting the temperature of the space to be cooled, and control device 50 for controlling various devices.
A main expansion valve 5, an evaporator 6, an in-chamber temperature detection means 13, and the like are mounted on a casing 11 on which an object to be cooled (load, food, etc.) is placed. The casing 11 here corresponds to a heat insulating casing of the refrigerator when the refrigeration apparatus 100 is used in a refrigerator or the like, and in a room or a warehouse when the refrigeration apparatus 100 is used in a building or the like. Correspond. And the inside of the housing | casing 11 respond | corresponds to cooling object space. In the following description, the temperature of the space to be cooled may be referred to as the internal temperature.

[Refrigerant circuit configuration]
The refrigerant circuit configuration of the refrigeration apparatus 100 will be described with reference to FIG. As shown in FIG. 1, the refrigerant circuit of the refrigeration apparatus 100 includes a compressor 1, an oil separator 2, a condenser 3, an intercooler 4, four expansion valves 5, 8 to 10, an evaporator 6, and an oil cooler. 7 are connected by refrigerant piping.

The compressor 1 sucks a refrigerant, compresses the refrigerant, puts the refrigerant in a high temperature / high pressure state, and conveys the refrigerant to a refrigerant circuit. In FIG. 1, the compressor 1 is described as a two-stage compressor, but is not limited thereto. Further, the compressor 1 will be described as a compressor whose rotational speed is controlled by an inverter. However, the compressor 1 only needs to be capable of capacity control, and may be, for example, a compressor provided with a slide valve that is a capacity adjustment valve. .
The compressor 1, which is a two-stage compressor, is a first-stage compression mechanism in which a refrigerant to be compressed in the first stage is enclosed, and an intermediate in which a refrigerant that has been compressed in the first stage and has become an intermediate pressure is enclosed. The second stage compression mechanism includes a second stage compression refrigerant. The compressor 1 is formed with four suction ports A to D for sucking refrigerant and a discharge port G for discharging refrigerant. The compressor 1 is formed with two suction ports E and F for sucking the refrigerating machine oil separated by the oil separator 2.
However, the pipes connected to the suction ports B, C, and D may be joined before being connected to the compressor 1 and connected to the compressor 1 as one or two pipes. In addition, when it is set as the structure connected to the compressor 1 as one piping, it connects to the suction port corresponding to any one of the suction ports B, C, and D, and connects to the compressor 1 as two piping. In the case of the configuration to be configured, it is only necessary to connect to suction ports corresponding to any two of the suction ports B, C, and D.
The pipes connected to the suction ports E and F may be joined before being connected to the compressor 1 and connected to the compressor 1 as one pipe. In this case, it is preferable that the compressor internal flow path for supplying the refrigeration oil to the first stage and the second stage is formed in the compressor 1.

The suction port A is connected to the evaporator 6, and the refrigerant gasified by the evaporator 6 flows in. The refrigerant flowing in from the suction port A is compressed by the compressor 1, compressed again, and discharged from the discharge port G. The suction port A is formed in the first-stage compression mechanism.
In addition, the suction port B is connected to the motor cooling expansion valve 10, and refrigerant that has been expanded and cooled by the action of the motor cooling expansion valve 10 flows into the suction port B. The refrigerant flowing in from the suction port B cools the motor (not shown) of the compressor 1 and is then compressed again and discharged from the discharge port G. Note that the refrigerant flowing from the suction port B is reduced to a pressure of about the intermediate pressure. Therefore, the suction port B is formed in a motor casing part (not shown) having a pressure of about the intermediate pressure.

The suction port C is connected to the intermediate cooler 4, and the refrigerant that exchanges heat with the refrigerant flowing in from the condenser 3 flows in.
Further, the suction port D is connected to the oil cooler 7, and the refrigerant that exchanges heat with the refrigerating machine oil flowing in from the oil separator 2 flows in.
Note that the refrigerant flowing from the suction ports C and D has a higher pressure than the low-pressure refrigerant flowing from the suction port A, and has a lower pressure than the high-pressure refrigerant discharged from the discharge port G. Therefore, the suction ports C and D are formed in an intermediate stage in which the low-pressure refrigerant and a medium-level refrigerant between the high-pressure refrigerant are sealed.

The suction ports E and F are connected to the oil separator 2 via the oil cooler 7, and the refrigeration oil cooled by the oil cooler 7 flows in. Here, the suction port E is formed in a first-stage compression mechanism in which a refrigerant having the same pressure as the low-pressure refrigerant flowing from the suction port A is enclosed. Further, the suction port F is formed in a second-stage compression mechanism in which a refrigerant having a pressure similar to that of the high-pressure refrigerant flowing out from the discharge port G is enclosed.
The discharge port G is connected to the oil separator 2, and the refrigerant that has become high temperature and high pressure by the action of the compressor 1 flows out. That is, the refrigerant containing the refrigerating machine oil flowing in from the suction ports A to F is compressed and then flows out from the discharge port G. The discharge port G is formed in the second-stage compression mechanism.

  The oil separator 2 separates refrigeration oil from the refrigerant. The fluid inflow side of the oil separator 2 is connected to the compressor 1. In addition, one of the fluid outflow sides of the oil separator 2 is connected to the condenser 3 and the other is connected to the oil cooler 7.

The condenser 3 performs heat exchange between the air supplied by the action of the attached blower fan 3A and the refrigerant, and condenses and liquefies the refrigerant. One of the condensers 3 is connected to the oil separator 2 and the other is connected to the intercooler 4.
The evaporator 6 exchanges heat between the air supplied by the action of the attached fan 6A and the refrigerant and evaporates the refrigerant. One of the evaporators 6 is connected to the main expansion valve 5, and the other is connected to the compressor 1 through the suction port A.
The condenser 3 and the evaporator 6 may be configured by a plate fin and tube heat exchanger that can exchange heat between the refrigerant flowing through the refrigerant pipe and the air passing through the fins, for example.

The intermediate cooler 4 exchanges heat between the refrigerant flowing in from the condenser 3 and the refrigerant flowing in from the intermediate cooling expansion valve 8. That is, the refrigerant cooled by the action of the intermediate cooling expansion valve 8 cools the refrigerant flowing in from the condenser 3. The intermediate cooler 4 is connected to the compressor 1 via the condenser 3, the four expansion valves 5, 8 to 10, and the suction port C.
The oil cooler 7 exchanges heat between the refrigerating machine oil flowing in from the oil separator 2 and the refrigerant flowing in from the oil cooling expansion valve 9. That is, the refrigerant cooled by the action of the oil cooling expansion valve 9 cools the refrigeration oil flowing from the oil separator 2. The oil cooler 7 is connected to the compressor 1 via an oil separator 2, an oil cooling expansion valve 9, and suction ports D to F.

The four expansion valves 5 and 8 to 10 expand the refrigerant by depressurizing it.
One of the main expansion valves 5 is connected to the evaporator 6, and the other is connected to the intermediate cooler 4, the intermediate cooling expansion valve 8, the oil cooling expansion valve 9, and the motor cooling expansion valve 10.
One of the intermediate cooling expansion valves 8 is connected to the compressor 1 via the intermediate cooler 4 and the suction port C, and the other is connected to the intermediate cooler 4, the main expansion valve 5, the oil cooling expansion valve 9, and The motor cooling expansion valve 10 is connected.
One of the oil cooling expansion valves 9 is connected to the suction port D via the oil cooler 7, and the other is connected to the intermediate cooler 4, the main expansion valve 5, the intermediate cooling expansion valve 8, and the motor cooling expansion. Connected to the valve 10.
Further, one of the motor cooling expansion valves 10 is connected to the suction port B, and the other is connected to the intermediate cooler 4, the main expansion valve 5, the intermediate cooling expansion valve 8, and the oil cooling expansion valve 9. .
These four expansion valves 5 and 8 to 10 may be constituted by, for example, a capillary tube, an electronic expansion valve, or the like.

The suction pressure detection means 12 detects the pressure of the refrigerant that flows out of the evaporator 6 and flows into the compressor 1 through the suction port A. The suction pressure detection means 12 is installed in the vicinity of the suction port A in the refrigerant pipe connecting the evaporator 6 and the suction port A, as shown in FIG. However, the installation position of the suction pressure detection means 12 is not limited to the vicinity of the suction port A, and may be set to any position in the evaporator 6 or in the suction pipe portion from the evaporator 6 to the compressor 1. Good.
The internal temperature detection means 13 detects the temperature in the housing 11. The position where this internal temperature detection means 13 is installed is not particularly limited.

The control device 50 calculates the evaporation temperature corresponding to the pressure from the refrigerant pressure on the suction side of the compressor 1 which is the detection result of the suction pressure detection means 12. And the control apparatus 50 is based on the evaporation temperature and the detection result of the internal temperature detection means 13, and the rotation speed of the compressor 1, the fan rotation speed of the ventilation fans 3A and 6A, and the four throttle devices 5, The opening degree of 8-10 is controlled.
The control device 50 stores conversion formulas shown in the following formulas 1 to 7, and calculates the rotation speed of the compressor 1 based on the detection results of the suction pressure detection means 12 and the internal temperature detection means 13. be able to. Further, the control device 50 stores, for example, a table in which the saturation pressure and the saturation temperature (evaporation temperature) are associated one-on-one, and the saturation temperature corresponding to the detection result of the suction pressure detection means 12 can be obtained. . However, the saturation pressure conversion of the detected pressure is not limited to the above table, and the conversion formula between the saturation pressure and the saturation temperature is stored in the control device 50, and the detected value of the suction pressure detecting means 12 detected sequentially. A saturation temperature (evaporation temperature) may be calculated by substituting a certain suction pressure into this conversion formula.
It should be noted that these stored conversion formulas and table setting values may be settable. Thereby, setting adjustment becomes easy according to the local system in which refrigeration equipment 100 is installed.
In addition, as illustrated in FIG. 1, the control device 50 is illustrated as being installed outside the housing 11, but is not limited thereto.

[Description of operation (flow of refrigerant)]
High-temperature and high-pressure gas refrigerant is discharged from the compressor 1, the refrigerant separated from the oil through the oil separator 2 flows into the condenser 3, and the refrigerating machine oil separated from the refrigerant flows into the oil cooler 7. .
The refrigerant flowing into the condenser 3 is condensed by exchanging heat with air and becomes a high-pressure and high-temperature liquid refrigerant. On the other hand, the refrigerating machine oil flowing into the oil cooler 7 is cooled by the refrigerant cooled by the action of the oil cooling expansion valve 9 and then sucked into the compressor 1 through the suction ports E and F.
The refrigerant flowing out of the condenser 3 is cooled to the refrigerant cooled by the action of the intermediate cooling expansion valve 8, and then the main expansion valve 5, the intermediate cooling expansion valve 8, the oil cooling expansion valve 9, and the motor cooling. Flows into the expansion valve 10.

The refrigerant flowing into the main expansion valve 5 is expanded by the action of the main expansion valve 5 and becomes a low-pressure / low-temperature two-phase refrigerant. The two-phase refrigerant flows into the evaporator 6 and evaporates by cooling the air in the housing 11, and is then sucked into the compressor 1 through the suction port A.
The refrigerant that has flowed into the intermediate cooling expansion valve 8 is expanded by the action of the intermediate cooling expansion valve 8 and becomes a low-pressure, low-temperature two-phase refrigerant. The two-phase refrigerant flows into the intercooler 4 and cools the refrigerant flowing out of the condenser 3, and is then sucked into the compressor 1 through the suction port C.
The refrigerant flowing into the oil cooling expansion valve 9 is expanded by the action of the oil cooling expansion valve 9 to become a low-pressure, low-temperature two-phase refrigerant. The two-phase refrigerant cools the refrigeration oil flowing into the oil cooler 7 and flowing out from the oil separator 2, and is then sucked into the compressor 1 through the suction port D.
The refrigerant flowing into the motor cooling expansion valve 10 is expanded by the action of the motor cooling expansion valve 10 to become a low-pressure, low-temperature two-phase refrigerant. The two-phase refrigerant is sucked into the intermediate stage of the compressor 1 through the suction port B, and then cools the motor of the compressor 1.

[Description of operation (control of compressor 1)]
In the refrigeration apparatus 100 according to the present embodiment, an example will be described in which the control apparatus 50 performs the internal temperature control by proportional control (hereinafter also referred to as P control).
Here, when this P control is executed based on the internal temperature, the rotational speed of the compressor 1 is calculated as described below. That is, a deviation is calculated from the preset target value of the internal temperature and the detection result of the internal temperature detection means 13 by the following formulas 1 to 3, and the rotational speed of the compressor 1 is determined.
(1) In Equation 3, the internal temperature deviation is determined based on the detection result of the internal temperature detection means 13 and a preset target value of the internal temperature.
(2) In Formula 2, if the internal temperature deviation of Formula 3 is substituted, the amount of change in the rotational speed of the compressor 1 is calculated.
(3) In Equation 1, the rotation number obtained by adding the change calculated in Equation 2 and the current rotation number is the rotation number of the compressor 1 after the update.
The internal temperature is controlled by sequentially executing steps (1) to (3) while the refrigeration apparatus 100 is in operation.

On the other hand, when this P control is executed based on the suction pressure, the suction pressure is converted into an evaporation temperature. Then, from the following equations 4 to 6, a deviation is calculated from the target value of the evaporation temperature and the detection result of the suction pressure detecting means 12, and the rotational speed of the compressor 1 is determined. In the refrigerating apparatus 100 according to the present embodiment, the suction pressure is made to correspond to the evaporation temperature. Therefore, in the following description, the suction pressure may be expressed as the suction pressure (evaporation temperature).
(4) In Equation 6, the evaporation temperature deviation is determined by the detection result of the suction pressure detection means 12 and the target value of the evaporation temperature.
(5) In Expression 5, when the evaporation temperature deviation of Expression 4 is substituted, the change in the rotational speed of the compressor 1 is calculated.
(6) In Expression 4, the rotation speed obtained by adding the change calculated in Expression 5 and the current rotation speed is the rotation speed of the updated compressor 1.
The internal temperature is controlled by sequentially executing steps (4) to (6) while the refrigeration apparatus 100 is in operation.

  Here, when the suction pressure (evaporation temperature) is compared with the internal temperature, the suction pressure has better temporal response to a change in the rotational speed of the compressor 1. In other words, when the rotation speed of the compressor 1 is increased, the suction pressure decreases (changes) relatively quickly, but the internal temperature decreases with a heat load (heat capacity) such as an object to be cooled. It will take. Therefore, the refrigeration apparatus 100 according to the present embodiment replaces the internal temperature with the suction pressure, and controls the rotation speed of the compressor 1 based on the increase or decrease of the suction pressure.

Specifically, the internal temperature deviation is calculated based on the target value of the internal temperature and the detection result of the internal temperature detection means 13 (see Formula 3). The number of rotations of the compressor 1 is changed by an amount corresponding to this internal temperature deviation. Here, for example, the internal temperature deviation is replaced with the suction pressure deviation (evaporation temperature deviation) by the substitution formula shown in the following formula 7. Then, the amount of change is calculated by substituting the value of the suction pressure deviation obtained in Equation 7 into Equation 5. Further, the updated number of revolutions of the compressor 1 is obtained by substituting the change of Expression 5 into Expression 4. Thus, since the rotation speed control of the compressor 1 can be executed based on the suction pressure, the refrigeration apparatus 100 can finely (precisely) control the internal temperature.

[Method 1 for controlling internal temperature of refrigeration apparatus 100]
FIG. 2 is a flowchart for explaining a control example of the internal temperature of the refrigeration apparatus 100 shown in FIG. With reference to FIG. 2, a method for controlling the internal temperature of the refrigeration apparatus 100 will be described.
The control of the internal temperature is composed of steps 1 to 12 as shown in FIG. In Steps 1 to 12, there are roughly two loops. One is a loop of step S1 → step S11 → step S1, and is a loop called internal temperature control.
The other is a loop of step S8 → step S12 → step S8, which is called a suction pressure control.
The internal temperature control cycle (first cycle) is longer than the suction pressure control cycle (second cycle). Therefore, in the following description, the internal temperature control cycle may be referred to as a long cycle, and the suction pressure control cycle may be referred to as a short cycle. The internal temperature control cycle may be set to 2 to 3 minutes, for example, and the suction pressure control cycle may be set to 20 to 30 seconds, for example.

(Step 1)
The control device 50 calculates the internal temperature deviation based on Expression 3, the detection result of the internal temperature detection means 13, and the target temperature set in advance. Thereafter, the process proceeds to step 2.

(Step 2)
The control device 50 calculates the evaporation temperature deviation (first evaporation temperature deviation) based on Equation 7 and the internal temperature deviation calculated in Step 1. Thereafter, the process proceeds to step 3.

(Step 3)
The control device 50 calculates the evaporation temperature (saturation temperature) corresponding to the detection result based on the detection result of the suction pressure detection means 12. Then, it progresses to step 4.

(Step 4)
The control device 50 calculates the target evaporation temperature based on Equation 6, the evaporation temperature deviation calculated in Step 2, and the evaporation temperature calculated in Step 3. Thereafter, the process proceeds to step 5.

(Step 5)
The control device 50 calculates the rotation speed of the compressor 1 based on the evaporation temperature deviation calculated in Expression 4, Expression 5, and Step 2. And the control apparatus 50 updates the rotation speed of the compressor 1 to the calculation result. Then, it progresses to step 6.

(Step 6)
The control device 50 drives the compressor 1 at the rotation speed updated in step 5. Thereafter, the process proceeds to step 7.

(Step 7)
The controller 50 determines whether or not a time longer than the suction pressure control period (second period) has elapsed since the compressor 1 was operated at the updated number of revolutions.
If the suction pressure control period or more has elapsed, the process proceeds to step 8.
If the suction pressure control period has not elapsed, the process proceeds to step 6.

(Step 8)
The control device 50 calculates the evaporation temperature (saturation temperature) corresponding to the detection result based on the detection result of the suction pressure detection means 12. Thereafter, the process proceeds to step 9.

(Step 9)
The control device 50 calculates an evaporation temperature deviation (second evaporation temperature deviation) based on the target evaporation temperature calculated in equations 4 and 5 and step 4 and the evaporation temperature calculated in step 8. Based on the calculated evaporation temperature deviation, the rotational speed of the compressor 1 is calculated. Then, the control device 50 updates the calculation result as the rotation speed of the compressor 1. Thereafter, the process proceeds to step 10.

(Step 10)
The control device 50 drives the compressor 1 at the rotation speed updated in step 9. Thereafter, the process proceeds to step 11.

(Step 11)
The controller 50 determines whether or not a time equal to or greater than the internal temperature control period (first period) has elapsed since the compressor 1 was operated at the updated number of revolutions in Step 6.
When the internal temperature control period or more has elapsed, the process proceeds to step 1.
If the internal temperature control period has not elapsed, the process proceeds to step 12.

(Step 12)
The controller 50 determines whether or not the suction pressure control period (second period) has elapsed since the compressor 1 was driven at the updated number of revolutions in Step 10.
If the suction pressure control period or more has elapsed, the process proceeds to step 8.
If the suction pressure control period has not elapsed, the process proceeds to step 10.

  From the loop of step S8 → step S12 → step S8, the process exits to step 1 when the internal temperature control period or more has elapsed in step 11. Then, after the sequential transition from Step 1 to Step 2 and Step 3, the routine proceeds to Step 4 where the target evaporation temperature is calculated, and the calculated target evaporation temperature is updated. Therefore, it should be noted that the target evaporation temperature in step 9 is the same value while step S8 → step S12 → step S8 is looped.

[Setting of control cycle, proportional constant and correction coefficient]
The control period, the proportionality constant K ′, and the correction coefficient α may be set according to a time constant determined from the scale of the casing 11 of the refrigeration apparatus 100, the capacity of the evaporator 6, and the like. Hereinafter, setting of the control cycle, the proportionality constant, and the correction coefficient will be described.
(1) Setting of control cycle The internal temperature control cycle may be set in consideration of a time constant determined from the scale of the housing 11 and the like. That is, the internal temperature control cycle is set so that the blown air temperature Tao of the evaporator 6 is mixed with the air in the housing 11 and changes in the internal temperature appear (for example, 3 to 5 minutes). ).
The suction pressure control cycle may be set in consideration of a time constant determined from the capacity of the evaporator 6 and the length of the refrigerant pipe connecting the compressor 1 and the evaporator 6. That is, the suction pressure control cycle is set to a time until the change in the suction pressure becomes dull (saturates) after the change in the rotation speed of the compressor 1 (for example, 20 seconds to 30 seconds).
Thus, since the suction pressure control cycle of the control device 50 of the refrigeration apparatus 100 is shorter than the internal temperature control cycle (first cycle), the suction pressure control cycle (second cycle) in steps 6 and 7. After that, the suction pressure control cycle (second cycle) in steps 10 to 12 is repeated a plurality of times.
Here, the value of the suction pressure control period in steps 6 and 7 and the value of the suction pressure control period in steps 10 to 12 may be the same period, or may be set to different periods. Further, it is desirable that the internal temperature control cycle and the suction pressure control cycle be set and adjusted so as to be optimized according to the local system.

(2) Setting of proportionality constant K ′ The proportionality constant K ′ is set to a different value depending on the scale of the housing 11 and the like. The proportionality constant K ′ may be set to about 0.01 to 1.00, for example.

(3) Setting of correction coefficient α (3-1) Setting example 1 of correction coefficient α
A constant value may be adopted as the correction coefficient α regardless of the internal temperature. When a constant value is adopted, α <1 may be set in order to finely control the internal temperature. If α> 1 is set, the evaporation temperature deviation is further increased when the internal temperature deviation is large, which may cause a rapid change in the rotational speed of the compressor 1. However, by setting α <1, it is possible to suppress a rapid change in the rotational speed of the compressor 1.
Also, by setting α <1, the difference between the blown air temperature Tao of the evaporator 6 and the evaporation temperature Te can be kept small, so that frost formation on the evaporator 6 can be prevented.
(3-2) Setting example 2 of the correction coefficient α
FIG. 3 is a diagram for explaining the temperature range of the dead zone and the temperature range of the desired temperature zone at the set target internal temperature. The correction coefficient α may be changed according to the internal temperature. That is, it changes according to the area | region (A)-(C) shown in FIG. Hereinafter, the set value of α in each of the regions (A) to (C) will be described.
(A) Area As shown in FIG. 3, a range that is allowed as a difference between the internal temperature and the target internal temperature is defined as a desired temperature width. As shown in FIG. 3A, when the internal temperature is far from the desired temperature range, it is desirable to change the internal temperature relatively rapidly. That is, when the detection result of the internal temperature detection means 13 is the temperature range of the region (A), α = 1 may be set.
(B) Region As shown in FIG. 3B, when the internal temperature is slightly deviated from the desired temperature range, the amount of change in the internal temperature is set smaller than that in the region (A). Therefore, if the detection result of the internal temperature detection means 13 is the temperature range of the region (B), α = 0.7 may be set.
(C) Region As shown in FIG. 3C, when the internal temperature does not deviate from the desired temperature range, the amount of change in the internal temperature is set smaller than the region (B). Therefore, if the detection result of the internal temperature detection means 13 is the temperature range of the region (C), α = 0.5 may be set.
In addition, it is set as the structure which can set-adjust according to a local system also about the setting of these (alpha), and the structure which the update of (alpha) corresponding to each area | region of (A)-(C) is made automatically by the control apparatus 50. Is desirable.

[Method 2 for controlling internal temperature of refrigeration apparatus 100]
The refrigeration apparatus 100 has a predetermined cooling temperature range (apparatus usage range) depending on the application. Therefore, it is usual to provide a limit upper limit value and a limit lower limit value for the target evaporation temperature so that the refrigeration apparatus 100 does not deviate from the cooling temperature range.
That is, when the target evaporation temperature Tem> the upper limit limit of the target evaporation temperature, the target evaporation temperature Tem is set as the upper limit limit, and when the target evaporation temperature Tem <the lower limit limit of the target evaporation temperature. The target evaporation temperature Tem is set as the lower limit limit.

FIG. 4 is a flowchart for explaining the control when a limit upper limit value and a limit lower limit value are provided for the target evaporation temperature in the control shown in FIG. With reference to FIG. 4, the control when the upper limit limit and the lower limit limit are provided for the target evaporation temperature will be described.
FIG. 4 is obtained by adding Steps 13 to 15 between Step 4 and Step 5 in the flowchart shown in FIG. Steps 1 to 12 in FIG. 4 are the same as those in FIG. Therefore, the description of the steps for performing the same processing as in FIG. 2 is omitted.
(Step 13)
The control device 50 determines whether or not the target evaporation temperature calculated in step 4 is larger than a preset upper limit value of the target evaporation temperature.
Further, the control device 50 determines whether or not the target evaporation temperature calculated in step 4 is smaller than a preset lower limit value of the evaporation temperature.
If the target evaporation temperature is not less than the limit lower limit and not more than the limit upper limit, the process proceeds to step 5.
If the target evaporation temperature is lower than the lower limit limit or higher than the upper limit limit, the process proceeds to step 14.
(Step 14)
When the target evaporation temperature is higher than the limit upper limit value, the control device 50 sets the target evaporation temperature to the limit upper limit value. Thereafter, the process proceeds to step 15.
When the target evaporation temperature is smaller than the limit lower limit value, the control device 50 sets the target evaporation temperature to the limit lower limit value. Thereafter, the process proceeds to step 15.
(Step 15)
The control device 50 calculates an evaporation temperature deviation based on the evaporation temperature calculated in step 3 and the target evaporation temperature obtained in step 14. Thereafter, the process proceeds to step 5.

[Control Method 3 for Internal Temperature of Refrigeration Apparatus 100]
The rated evaporation temperature Tec is given by the difference between the blown air temperature Ta of the evaporator 6 and the TD condition in the evaporator design (selection). That is, Tec = Ta−TD. Here, TD is the difference between the blown air temperature and the evaporator evaporation temperature, and is generally selected to be about 10K and used for the design (selection) of the evaporator. When TD is large, the frosting of the evaporator 6 becomes remarkable, and the performance of the evaporator 6 is reduced.
At this time, an allowable evaporation temperature width may be set with respect to the rated evaporation temperature Tec. That is, when the target evaporation temperature Tem <Tec−δc, Tem = Tec−δc, and when the target evaporation temperature Tem> Tec + δc, Tem = Tec + δc. Here, when Tem> Tec, the TD can be reduced and effective in preventing frost formation. However, in order to avoid the possibility of cooling due to Tem≈Ta, a process for Tem> Tec + δc is added. Yes. Thereby, since TD can be suppressed within the range of Ta−Tem−δc ≦ TD ≦ Ta−Tem + δc, frost formation is suppressed while avoiding the inability to cool, and the heat exchange capability of the evaporator 6 Can be reduced. Specifically, FIG. 5 shows a control flowchart.

FIG. 5 is a flowchart for explaining the control when the allowable evaporation temperature width is set for the rated evaporation temperature Tec in the control shown in FIG.
FIG. 5 is obtained by adding Step 16 and Step 17 between Step 4 and Step 5 in the flowchart shown in FIG. Steps 1 to 12 in FIG. 4 are the same as those in FIG. Therefore, the description of the steps for performing the same processing as in FIG. 2 is omitted.

(Step 16)
The control device 50 determines whether or not the target evaporation temperature calculated in step 4 is greater than a preset upper limit value (Tec + δc) of the target evaporation temperature.
Further, the control device 50 determines whether or not the target evaporation temperature calculated in step 4 is smaller than a preset lower limit value (Tec−δc) of the evaporation temperature.
If the target evaporation temperature is not less than the limit lower limit and not more than the limit upper limit, the process proceeds to step 5.
If the target evaporation temperature is lower than the lower limit limit or higher than the upper limit limit, the process proceeds to step 17.

(Step 17)
When the target evaporation temperature is higher than the limit upper limit value (Tec + δc), the control device 50 sets the target evaporation temperature to the limit upper limit value. Thereafter, the process proceeds to step 15.
When the target evaporation temperature is smaller than the lower limit limit (Tec−δc), the control device 50 sets the target evaporation temperature to the lower limit limit. Thereafter, the process proceeds to step 15.

[Effects of the refrigeration apparatus 100]
FIG. 6 is a view for explaining the relationship between the refrigerant suction pressure and the internal temperature in the evaporator 6 shown in FIG. The vertical axis in FIG. 6 indicates the temperature of the air blown from the evaporator 6 and the evaporation temperature corresponding to the suction pressure that is the detection result of the suction pressure detection means 12. In addition, the horizontal axis in FIG. 6 indicates the passage of time.
6 represents the temperature of the air before being supplied to the evaporator 6, and the solid line Tao and the broken line Tao * are cooled by the action of the evaporator 6 and then the evaporator 6 It represents the temperature of the air blown out from. The solid line Te and the broken line Te * are obtained by converting the suction pressure, which is the detection result of the suction pressure detection means 12, into the evaporation temperature.

The refrigeration apparatus 100 according to the present embodiment performs suction pressure control in a short cycle. When the short cycle elapses, the evaporation temperature deviation is updated, and the solid line Te in FIG. 6 falls as shown by the broken line Te *. Here, as shown in the solid line Te and the broken line Te * in FIG. 6, the rapid change in the suction pressure (evaporation temperature) can be suppressed and the pressure can be kept almost constant as the suction pressure is controlled in a short cycle. I understand what I can do.
Moreover, the refrigeration apparatus 100 according to the present embodiment executes the internal temperature control in a long cycle. That is, when the long cycle elapses, the internal temperature deviation is updated, and the solid line Tao in FIG. 6 falls as indicated by the broken line Tao *. It can be understood that the solid line Tao in FIG. 6 gradually approaches the target internal temperature as shown by the broken line Tao * as much as the internal temperature is controlled in a long cycle.

The refrigeration apparatus 100 has a high response to the rotation speed of the compressor 1 with a long cycle (internal temperature control cycle) of about 3 to 5 minutes, as shown in Step 2 of FIGS. 2, 4, and 5. The evaporation temperature and the internal temperature are made to correspond (internal temperature control). In addition, the refrigeration apparatus 100 updates the target evaporation temperature for suction pressure control in this internal temperature control cycle.
Specifically, during the internal temperature control shown in steps 1-11 of FIG. 2, steps 1-11, 13-15 of FIG. 4, and steps 1-11, 16, 17 of FIG. The target evaporation temperature is updated with a long period of about 3 to 5 minutes. Thereby, since the refrigerating apparatus 100 does not frequently update the target evaporation temperature, the suction pressure control is stabilized, and rapid changes in the rotation speed of the compressor 1 and frequent start / stop can be suppressed.
In other words, the refrigeration apparatus 100 can suppress the occurrence of hunting, overshoot, thermo-off, etc. because the suction pressure control is stable and rapid changes in the rotation speed of the compressor 1 and frequent start / stop can be suppressed. can do.

The refrigeration apparatus 100 updates the suction pressure (evaporation temperature) at a short cycle (suction pressure control cycle) of, for example, about 20 seconds to 30 seconds, and the updated suction pressure (evaporation temperature) and internal temperature control cycle. The control (suction pressure control) for setting the rotational speed of the compressor 1 is executed based on the target evaporation temperature updated in step S2.
Specifically, during the suction pressure control shown in steps 8 to 12 in FIG. 2, steps 8 to 12 in FIG. 4 and steps 8 to 12 in FIG. 5, the refrigeration apparatus 100 has a time constant in step 4. The number of revolutions of the compressor 1 is controlled by the target evaporation temperature obtained by replacing the internal temperature, which is largely inferior in temperature controllability, with the suction pressure (evaporation temperature) having a short time constant. Then, it is possible to update the evaporation temperature in a short cycle and precisely control it near the target evaporation temperature, and to reliably adjust the chamber temperature to the target chamber temperature (because the control cycle can be shortened, the temperature of the controlled variable The fluctuation range is small). As a result, the refrigeration apparatus 100 is largely prevented from deviating from the target internal temperature.

  In addition, since the refrigeration apparatus 100 according to the present embodiment is prevented from deviating from the target internal temperature, it is possible to reduce the maximum capacity operation time for setting the internal temperature to the target internal temperature. it can. That is, since the refrigeration apparatus 100 has a short time for maximum capacity operation and can fully utilize the high partial load characteristics of the compressor 1 that is inverter controlled, power consumption during operation can be suppressed. Moreover, since the frequency | count of the frequent start / stop caused by performing a maximum capacity | capacitance driving | operation can be reduced, the hunting of the internal temperature accompanying the start / stop can be suppressed.

  Furthermore, since the refrigeration apparatus 100 according to the present embodiment is prevented from deviating from the target internal temperature, it is possible to reduce the minimum capacity operation time for setting the internal temperature to the target internal temperature. it can. In other words, unlike the conventional internal temperature control, the refrigeration apparatus 100 calculates the internal temperature deviation in a long cycle and thereby obtains the target evaporation temperature, so that it is difficult to cause a rapid decrease in the compressor rotational speed. Therefore, since the minimum capacity operation time at which the efficiency of the refrigeration system is significantly reduced can be shortened, the high partial load characteristics of the compressor 1 that is inverter control can be fully utilized, and the power consumption during operation can be suppressed. it can.

The refrigeration apparatus 100 according to the present embodiment has been described by taking the example of executing the P control, but is not limited thereto. In other words, PI control or PID control may be employed as long as the internal temperature deviation and the evaporation temperature deviation are used.
Needless to say, the control of the present embodiment can be applied to heating operation and the like. In the case of adopting the heating operation, the capacity of the compressor 1 may be controlled by using the target condensation temperature as the discharge pressure equivalent saturation temperature, that is, the condensation temperature, instead of the target evaporation temperature.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Oil separator, 3 Condenser, 3A Blower fan, 4 Intermediate cooler, 5 Main expansion valve, 6 Evaporator, 6A Blower fan, 7 Oil cooler, 8 Intermediate cooling expansion valve, 9 Oil cooling Expansion valve, 10 motor cooling expansion valve, 11 housing, 12 suction pressure detection means, 13 internal temperature detection means, 50 control device, 100 freezing device, A to F suction port, G discharge port.

Claims (7)

In a refrigeration apparatus having a variable capacity compressor, a condenser, an expansion valve, and an evaporator, which are connected by refrigerant piping to constitute a refrigeration cycle,
A suction pressure detecting means for detecting a suction pressure of the compressor;
Temperature detection means for detecting the temperature of the space to be cooled;
The first cycle and one or more second cycles following the first cycle are repeated as a set, the capacity of the compressor is updated in each cycle, and based on the updated capacity of the compressor Control means for controlling the compressor;
With
The control means includes
In the first period,
A first evaporation temperature deviation (ΔTe) is obtained based on the target temperature (Tam) of the space to be cooled and the detection result (Ta) of the temperature detection means, and based on the first evaporation temperature deviation (ΔTe) Update the compressor capacity (F ')
An evaporation temperature (Te) corresponding to the detection result of the suction pressure detecting means is calculated, and a target evaporation temperature (Tem) is calculated based on the evaporation temperature (Te) and the first evaporation temperature deviation (ΔTe). ,
In the second period,
The evaporation temperature (Te ^* ) corresponding to the detection result of the suction pressure detecting means is calculated, and the compression is performed based on the evaporation temperature (Te ^* ) and the target evaporation temperature (Tem) calculated in the first period. A refrigerating machine characterized by renewing the capacity (F ' ^* ) of the machine. The control means includes
In the second period,
A second evaporation temperature deviation (ΔTe ^* ) is calculated based on the target evaporation temperature (Tem) and the evaporation temperature (Te) calculated in the first period, and the second evaporation temperature deviation (ΔTe). The refrigeration apparatus according to claim 1, wherein the capacity of the compressor is updated based on ^* ). The control means includes
In the first period,
When the target evaporation temperature (Tem) is larger than the upper limit limit,
The second evaporation temperature deviation (ΔTe ^* ) is calculated based on the limit upper limit value and the first evaporation temperature deviation (ΔTe), and the compression is performed based on the second evaporation temperature deviation (ΔTe ^* ). Update the capacity of the machine,
When the target evaporation temperature (Tem) is smaller than the lower limit limit,
The second evaporation temperature deviation (ΔTe ^* ) is calculated based on the lower limit limit and the first evaporation temperature deviation (ΔTe), and the compression is performed based on the second evaporation temperature deviation (ΔTe ^* ). The refrigerating apparatus according to claim 2, wherein the capacity of the machine is updated. The refrigeration apparatus according to any one of claims 1 to 3, wherein a period in which the first period and the second period are set is set to 3 minutes or more. The refrigeration apparatus according to any one of claims 1 to 4, wherein the second period is set to 30 seconds or less. The control means includes
The refrigeration apparatus according to claim 1, wherein the first evaporation temperature deviation (ΔTe) is obtained by the following equation.
ΔTe = (Ta−Tam) × α
Where α is a constant. The control means includes
The capacity (F ′ ^* ) of the compressor updated in the second period is equal to the capacity (F ′) of the compressor updated in the first period and the second evaporation temperature deviation (ΔTe ^*). The refrigeration apparatus according to any one of claims 1 to 6, wherein the refrigeration apparatus is obtained by the following equation:
F ′ ^* = F ′ (1 + K′ΔTe)
However, K ′ is a constant.

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