JP2003050071A - Operation control device for cooling system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent an increase in current at the start of operation in a refrigerator or a freezer, and to avoid an increase in size and cost of an electric motor and a power supply circuit. The speed of an electric motor for driving a compressor constituting a refrigeration cycle is controlled by an inverter circuit. The microcomputer 34 activates the inverter circuit 31 when the internal temperature Tx detected by the internal temperature sensor 35 is equal to or higher than a predetermined temperature (for example, 5 ° C. for a refrigerator and −18 ° C. for a freezer). Thus, the rotation speed of the electric motor 25 is suppressed to be low, and the current flowing through the electric motor 25 and the power supply circuit 40 is limited. Also, in this case, the rotation speed of the electric motor 21 is controlled to increase as the temperature Tx in the refrigerator decreases, so that an increase in current flowing through the electric motor 25 is suppressed, and the cooling speed of the refrigerator 10 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a cooling device which has a compressor driven by a speed-controlled electric motor and cools a storage such as a refrigerator or a freezer.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-11-1737.
As disclosed in Japanese Patent Publication No. 29 and Japanese Patent Application Laid-Open No. 60-188775, it is known to detect the temperature inside the refrigerator and control the speed of the electric motor using the detected temperature inside the refrigerator. In this case, the rotational speed of the electric motor is controlled so that the rotational speed of the electric motor increases as the detected internal temperature increases away from the set temperature, and the cooling capacity of the cooling device is increased to increase the internal temperature from the set temperature. Even if the temperature rises away, the inside temperature returns to the set temperature in a short time, and the inside temperature is kept substantially equal to the set temperature.

[0003]

However, in the above-mentioned conventional apparatus, when an extremely high inside temperature close to the outside air temperature is lowered to the set temperature as at the start of the operation of the cooling device, it is initially set. Since the internal temperature is extremely higher than the set temperature, the rotation speed of the electric motor is controlled to be extremely high. When the rotation speed of this electric motor is extremely high, a large current flows through the electric motor, and a large capacity electric motor and power supply circuit are required to allow this large electric current to flow. However, there is a problem that the manufacturing cost of them increases.

[0004]

SUMMARY OF THE INVENTION According to the present invention, the temperature inside the refrigerator rises greatly apart from the set temperature regardless of whether the object to be cooled is newly put in the refrigerator or when the cooled object is taken out of the refrigerator. This is because the temperature inside the refrigerator does not become extremely high except when the operation of the cooling device is started. Also, at the start of operation of this cooling device, it is not necessary to extremely increase the rotation speed of the electric motor to make the cooling capacity of the cooling device extremely high, and the cooling required when a new object to be cooled is newly put in the refrigerator. The cooling capacity of the equipment should be sufficient.

The present invention has been made on the basis of such a premise and has been made in order to solve the above problems. The purpose of the present invention is to increase the size of the electric motor and the power supply circuit and increase the manufacturing cost thereof. It is to provide an operation control device for a cooling device which is avoided.

In order to achieve the above object, a feature of the present invention is that a compressor driven by a speed-controlled electric motor,
In an operation control device for a cooling device including a refrigeration cycle including an evaporator that cools the inside of a storage by heat exchange with a refrigerant discharged from a compressor, a physical quantity that directly or indirectly represents the temperature inside the storage. A physical quantity detecting means for detecting, a storage temperature control means for controlling the rotation speed of the electric motor according to the detected physical quantity to keep the temperature in the storage at a desired set temperature, and the detected physical quantity being the set temperature. There is provided a rotation speed limiting means for limiting the rotation speed of the electric motor to a predetermined rotation speed or lower when the inside temperature is higher than the predetermined temperature.

In the above structure, it is preferable that the physical quantity detecting means is a temperature sensor provided in the storage for detecting the temperature in the storage. The physical quantity detecting means may be a temperature sensor that is provided in a passage of cooling air that is cooled by the evaporator and that cools the inside of the storage, and that detects the temperature of the cooling air. Further, the physical quantity detecting means may be a temperature sensor attached to the evaporator to detect the temperature of the evaporator. in this case,
In particular, place the temperature sensor in the vicinity of the refrigerant inlet of the evaporator,
It may be provided from the center of the evaporator to the rear, that is, between the center and the outlet. The physical quantity detecting means may be a pressure sensor that is provided in the refrigerant passage between the evaporator and the compressor and detects the pressure of the refrigerant flowing in the refrigerant passage. The temperature and pressure detected by these temperature sensor and pressure sensor are physical quantities that directly or indirectly represent the temperature inside the storage.

Further, the internal temperature control means changes the rotational speed of the electric motor so that the rotational speed of the electric motor increases as the detected physical quantity represents a large temperature difference between the internal temperature and the set temperature. It may be configured to control.
For example, a plurality of regions divided by the magnitude of the temperature difference between the internal temperature and the set temperature can be set in advance, and the rotation speed of the electric motor can be controlled to a different rotation speed for each region to which the temperature difference belongs. . Specifically, the rotation speed of the electric motor increases as the detected physical quantity represents the internal cold storage temperature higher than the set temperature and the internal cold storage temperature that belongs to a region where the temperature difference between the internal cold storage temperature and the set temperature becomes large. The rotational speed of the electric motor may be controlled so that the speed becomes faster. Further, a function or table showing the relationship between the temperature difference (or detected physical quantity) and the rotation speed, which is determined so that the rotation speed of the electric motor becomes faster as the temperature difference increases, is prepared in advance, and this function or table is stored. By using it, the detected physical quantity represents the internal temperature higher than the set temperature, and the internal temperature at which the temperature difference between the internal temperature and the set temperature becomes large. The rotation speed of the electric motor may be controlled so that

Further, the rotation speed limiting means may be configured to control the rotation speed of the electric motor based on the detected physical quantity regardless of the set temperature. For example,
In this case, the rotation speed of the electric motor may be limited to be equal to or lower than the rotation speed corresponding to the rated current flowing through the electric motor when the maximum cooling capacity is required during the steady operation.

According to this, even if the inside temperature rises slightly from the set temperature, for example, when the item to be cooled is newly put in the case, or when the cooled item is taken out from the case, This temperature rise in the cold storage is corrected by the cold storage temperature control means, and the cold storage temperature during the steady operation of the cooling device is kept substantially at the set temperature. Further, as in the case of starting the cooling device, in a situation where the temperature inside the refrigerator is close to the outside air temperature and is extremely higher than the set temperature and a large current flows for the same rotation speed of the electric motor, the rotation speed limiting means The rotation speed of the electric motor is limited to a predetermined rotation speed or less. Therefore,
Even under such a condition, a large current does not flow in the electric motor. In this case, the rate of decrease of the internal temperature does not increase so much, but it is normal that there is no object to be cooled at the time of starting the cooling device, which is not a problem. As a result, according to the present invention, without giving a big problem to the cooling of the inside by the cooling device,
It is possible to prevent an extremely large current from flowing through the motor,
It is possible to avoid increasing the size of the electric motor and the power supply circuit and increasing the manufacturing cost.

Another feature of the present invention is that the rotational speed of the electric motor is changed and controlled so that the rotational speed of the electric motor becomes faster as the detected physical quantity indicates a lower internal temperature. The rotation speed change control means is provided. In this case as well, for example, a plurality of regions divided by the height of the internal cold storage temperature are set in advance, and the rotation speed of the electric motor becomes higher as the detected physical quantity represents the internal cold storage temperature belonging to the low internal cold storage temperature region. The rotation speed of the electric motor may be controlled to increase the speed. In addition, a function or table indicating the relationship between the internal temperature (or the detected physical quantity) and the rotational speed, which is determined so that the rotation speed of the electric motor increases as the internal temperature decreases, is prepared in advance. By using, the rotation speed of the electric motor may be controlled so that the rotation speed of the electric motor continuously increases as the detected physical quantity indicates a low internal temperature.

According to this, when the temperature inside the refrigerator is close to the outside air temperature and much higher than the set temperature, such as when the cooling device is started, the current flowing through the electric motor can be suppressed to a predetermined current value or less. When the temperature inside the refrigerator begins to decrease due to cooling by the cooling device, the rotation speed of the electric motor is controlled to increase.In this state, the current flowing through the electric motor is suppressed to a predetermined current value or less, and then the cooling is performed. The cooling capacity of the device can also be increased. As a result, according to this other feature of the present invention, even when the cooling device is started, the temperature inside the refrigerator can be quickly lowered while suppressing the current flowing through the electric motor to a predetermined current value or less.

[0013]

DETAILED DESCRIPTION OF THE INVENTION a. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
3 schematically shows the entire cooling device 20 and the operation control device 30 for cooling the interior 10 of the refrigerator according to the first embodiment.

The cooling device 20 comprises a compressor 21, a condenser 22, a capillary tube 23 and an evaporator 24, and is provided with a refrigeration cycle for circulating a refrigerant. The compressor 21 is rotationally driven by a speed-controlled electric motor 25 to discharge a high-temperature high-pressure refrigerant gas. This electric motor 25
For example, a DC brushless motor can be used.
The high temperature and high pressure refrigerant gas discharged from the compressor 21 is
The condenser 22 provided with a cooling fan 26 radiates the heat to liquefy the heat, and the capillary tube 23 decompresses the heat.
It is evaporated and returned to the compressor 21. An internal fan 27 is arranged near the evaporator 24. The inside fan 27 accommodates a part or all of the evaporator 24 and is provided in a passage (cooling air passage) 10a communicating with the inside 10 of the inside of the inside to store the air cooled by the evaporator 24 inside the inside 1
It is circulated to 0 to cool the inside 10. The arrows in the figure indicate the flow of air.

The operation control device 30 includes an inverter circuit 31 for controlling the rotation speed of the electric motor 25, and fan drive circuits 32, 33 for controlling the operations of the cooling fan 26 and the internal fan 27. There is. In this embodiment, the rotation speed of the electric motor 25 is controlled by the inverter circuit 31 to be switched to five ranks of levels L1 to L5 as shown in Table 1 below. The rotation speed in Table 1 indicates the rotation speed of the electric motor 25 per second.

[0016]

[Table 1]

The inverter circuit 31 and the fan drive circuits 32 and 33 include the microcomputer 3
4 is connected. The microcomputer 34 executes a program corresponding to the flowcharts of FIGS. 3 and 4 to control the rotation speed of the electric motor 25. An internal temperature sensor 35 and a discharge refrigerant temperature sensor 36 are connected to the microcomputer 34 via an A / D converter 37, and an internal temperature setting device 38 is connected.

The inside temperature sensor 35 is used to detect the temperature T of the inside 10.
x is detected and an analog detection signal representing the temperature Tx in the same compartment is output to the A / D converter 37. Discharged refrigerant temperature sensor 3
6 detects the high-temperature high-pressure discharge refrigerant temperature Tc discharged from the compressor 21, and outputs an analog detection signal representing the discharge refrigerant temperature Tc to the A / D converter 37. The A / D converter 37 A / D-converts the analog detection signals respectively representing the inside temperature Tx and the discharged refrigerant temperature Tc, and outputs the analog detection signals to the microcomputer 34. The inside temperature setter 38 sets the temperature Ts of the inside 10 desired by the user,
It is operated by the user.

Further, the operation control device 30 includes a power supply circuit 40 for supplying electric power supplied from an external power supply line or the like to the inverter circuit 31 and the fan drive circuits 32 and 33. The power supply circuit 40 also supplies electric power to various circuits such as the microcomputer 34 and the A / D converter 37 as needed.

Before describing the operation of the embodiment configured as described above, each relationship between the cooling capacity of the cooling device 20 and the current flowing through the electric motor 25 with respect to the internal temperature Tx will be described. FIG. 2 shows a characteristic graph of the above two relationships, and a two-dot chain line in FIG. 2 shows a characteristic line of heat load with respect to the refrigerator internal temperature Tx. The heat load represents the total value of the amount of heat entering the inside of the refrigerator 10 from the outside and the amount of internal heat generation of the inside of the refrigerator 10. From this characteristic line, it can be understood that the heat load increases as the inside temperature Tx decreases.

Further, the solid line, the broken line and the alternate long and short dash line in the upper part of FIG. 2 indicate that the electric motor 25 is high speed, medium speed and low speed (for example, level L in Table 1 above) with respect to the internal temperature Tx.
5, L3, and L1), the respective change characteristics of the cooling capacity of the cooling device 10 when rotated are shown. According to this, it can be understood that the cooling capacity of the cooling device 10 becomes higher as the electric motor 25 is rotated at a higher speed, and becomes higher as the inside temperature Tx becomes higher. Further, the cooling power of the inside 10 is defined by the difference between the cooling capacity of the cooling device 10 and the heat load. The cooling power of the interior 10 is also the electric motor 2 as shown by the thick arrow in the figure.
The higher the rotation speed of 5, the higher the temperature, and the temperature T
It can be seen that the higher x is, the higher it is.

The solid line, broken line and alternate long and short dash line in the lower part of FIG. 2 indicate that the electric motor 25 is operated at high speed, medium speed and low speed (for example, level L in Table 1 above) with respect to the internal temperature Tx.
5, L3, L1), the motor 25
It shows the change characteristics of the magnitude of each current flowing through. According to this, it can be understood that the current flowing through the electric motor 25 becomes larger as the electric motor 25 is rotated at a higher speed, and becomes larger as the inside temperature Tx increases. The dotted line in FIG. 2 indicates the maximum permissible current Imax (rated current) of the electric motor 25 and the power supply circuit 40. When the rotation speed of the electric motor 25 is increased, the electric motor 25 is increased as the internal temperature Tx increases. It can be understood that there is a tendency that a current equal to or higher than the allowable current Imax flows. Therefore, the maximum allowable current (rated current) of the power supply circuit 40 may be determined so as to match the maximum allowable current Imax of the electric motor 25. In addition, the area with dots in FIG. 2 indicates an area (a prohibited area) where the cooling device 10 cannot exert the cooling power.

The operation of the refrigerator provided with the cooling device 20 having such characteristics will be described. After the user sets the set temperature Ts to a desired value using the internal temperature setting device 38,
When you start the operation with a switch not shown,
The microcomputer 34 starts executing the program in step 100 of FIG. When the program starts to be executed, the microcomputer 34 outputs an operation command to the fan drive circuits 32 and 33 to operate the cooling fan 26 and the internal fan 27.

After starting the execution of this program, step 1
02, the rank data RNK indicating the rank of the rotation speed of the electric motor 25 is set to the level L3, and the same rank data R
NK is output to the inverter circuit 31. The inverter circuit 31 rotates the electric motor 25 at a rotation speed corresponding to the level L3 represented by the supplied rank data RNK. The rotation speed of the electric motor 25 with respect to each level is as shown in Table 1 described above, and is a speed slow enough to suppress the current flowing through the electric motor 25 to the maximum allowable current Imax or less in relation to the internal temperature Tx.

The rotation of the electric motor 25 is transmitted to the compressor 21, and the compressor 21 starts to discharge the high temperature and high pressure refrigerant. That is, the cooling device 20 operates to start cooling the inside 10 in cooperation with the inside fan 27. After the process of step 102, in step 104, the internal temperature Tx detected by the internal temperature sensor 35 is input via the A / D converter 37, and the input internal temperature Tx is determined in advance. Also, it is determined whether or not the temperature is lower than a relatively high predetermined temperature T1 (for example, 10 ° C.).

Immediately after the operation of the cooling device 20 is started and the internal temperature Tx is higher than the predetermined temperature T1 depending on the outside air temperature, it is determined to be "NO" in step 104 and the steps 102 and 104 are executed. The cyclic processing is repeated. By this circulation processing, when the inside 10 is cooled and the inside temperature Tx becomes lower than the predetermined temperature T1, step 104
Then, the program is judged to be "YES" and the program is executed in step 106.
Continue below.

In step 106, the discharge refrigerant temperature Tc detected by the discharge refrigerant temperature sensor 36 is set to A /
It is input via the D converter 37, and it is determined whether or not the input discharge refrigerant temperature Tc is lower than a predetermined temperature T2 determined in advance. The predetermined temperature T2 is set to a value at which the temperature Tc of the refrigerant discharged from the compressor 21 is excessive in operation of the cooling device 20. If the discharged refrigerant temperature Tc is lower than the predetermined temperature T2, it is determined to be "YES" in step 106 and the program proceeds to step 108. In step 108, the rank data RNK is set to level L4.
(Or level L5) and set the same rank data RN
K is output to the inverter circuit 31. Inverter circuit 3
1 is the set level L4 (or level L5)
The electric motor 25 is rotated at a rotation speed corresponding to. In addition,
Although the rotation speed of the electric motor 25 corresponding to the level L4 (or the level L5) is higher than the rotation speed of the electric motor 25 corresponding to the level L3 shown in Table 1 described above, the rotation speed of the electric motor 25 and the power supply circuit 40 is increased. The speed is such that the flowing current is suppressed to the maximum allowable current Imax or less in relation to the internal temperature Tx. As a result, the current flowing through the electric motor 25 and the power supply circuit 40 is suppressed to the maximum allowable current Imax or less, and the cooling capacity of the cooling device 20 is enhanced.

After the processing of step 108, step 1
At 10, the inside temperature T input from the inside temperature sensor 35
It is determined whether x is lower than a predetermined temperature T3 (for example, 5 ° C.) lower than the predetermined temperature T1. Internal temperature Tx
Is higher than the predetermined temperature T3, in step 110, “N
It is determined to be “O”, and the circulation process including steps 106 to 110 is repeatedly executed. By this circulation processing, the inside 10 is continuously cooled. However, if the discharged refrigerant temperature Tc becomes equal to or higher than the predetermined temperature T2 during this circulation processing, it is determined as "NO" in step 106 and the program proceeds to step 112.

In step 112, the rank data RNK is returned to the level L3 and the same rank data RNK is output to the inverter circuit 31. Inverter circuit 31
Rotates the electric motor 25 at a rotation speed corresponding to the returned level L3. Therefore, the output of the compressor 21 is suppressed, and excessive operation of the cooling device 20 can be avoided. Then, as long as the discharged refrigerant temperature Tc is equal to or higher than the predetermined temperature T2, the circulation process including steps 106, 112, and 110 is continuously executed under the determination of “NO” in step 106 to protect the cooling device 20. Is planned.
On the other hand, if the discharge refrigerant temperature Tc becomes lower than the predetermined temperature T2 during the circulation process including steps 106, 112 and 110,
It is determined to be “NO” in step 106,
The circulation process including the steps 106 to 110 described above is repeatedly executed.

During the circulation process consisting of steps 106 to 110 or steps 106, 112 and 110,
If the internal temperature Tx is lower than the predetermined temperature T3, step 1
Step 1 of the program after judging "YES" at 10
Proceed to 14. In step 114, “1” is subtracted from the rank data RNK, and the subtracted rank data RNK is output to the inverter circuit 31. The inverter circuit 31 rotates the electric motor 25 at a rotation speed corresponding to the subtracted rank data RNK. Therefore,
The rotation speed of the electric motor 25 is reduced, and the compressor 21 is driven at this reduced rotation speed to cool the interior 10. That is, the cooling capacity of the cooling device 20 is switched to the lower side by one rank.

After the processing of step 114, the circulation processing of steps 116 and 118 of FIG. 4 is repeatedly executed. In step 116, it is determined whether the internal temperature Tx is equal to or higher than a predetermined temperature (upper limit temperature) T3 ′ (for example, 5.5 ° C.) higher than the predetermined temperature T3. Step 1
At 18, it is determined whether the internal temperature Tx is equal to or lower than the lower limit temperature Ts + ΔT11 obtained by adding a predetermined increment value ΔT11 to the set temperature Ts. The predetermined increment value ΔT11 is set to 2.5 ° C., and the set temperature Ts is 1 ° C., for example.
If the lower limit temperature Ts + ΔT11 is set to 3.
It is 5 ° C. Therefore, the internal temperature Tx is lower than the lower limit temperature Ts.
If it is between + ΔT11 and the upper limit temperature T3 ′, step 1
Both 16 and 118 continue to be determined as "NO", and the circulation processing including steps 116 and 118 is repeatedly executed. In this state, the cooling device 20 continues to be operated in a state where the cooling device 20 is switched to the lower side by one rank by the process of step 114.

If the internal temperature Tx becomes equal to or lower than the lower limit temperature Ts + ΔT11 by this cooling, at step 118, "YE
S ”is determined and the program proceeds to step 120 and subsequent steps. In step 118, “1” is subtracted from the rank data RNK, and the subtracted rank data RNK is output to the inverter circuit 31. Therefore, the electric motor 2
The rotation speed of 5 is reduced, and the compressor 21 is driven at this reduced rotation speed to cool the interior 10. That is, the cooling capacity of the cooling device 20 is switched to the lower side by one rank.

On the other hand, during the circulation processing in steps 116 and 118, when the internal temperature Tx becomes equal to or higher than the upper limit temperature T3 ', it is determined to be "YES" in step 116 and the program proceeds to step 122. In step 122, “1” is added to the rank data RNK, and the added rank data RNK is output to the inverter circuit 31. Therefore, the rotation speed of the electric motor 25 is increased,
The compressor 21 is driven at the increased rotation speed to cool the inside 10 of the refrigerator. That is, the cooling capacity of the cooling device 20 is switched to the higher side by one rank. After the processing of step 122, step 106 of FIG.
Return to the circulation process consisting of 110.

After the processing of step 120, step 1
The circulation process composed of 24 and 126 is repeatedly executed. In step 124, it is determined whether the internal temperature Tx is equal to or higher than the upper limit temperature Ts + ΔT12 obtained by adding the predetermined increment value ΔT12 to the set temperature Ts. The predetermined increment value ΔT12 is larger than the increment value ΔT11 and is set to 3.0 ° C., for example, and if the set temperature Ts is set to 1 ° C., the upper limit temperature Ts + ΔT12 is 4.0 ° C. is there. In step 126, it is determined whether the internal temperature Tx is lower than or equal to the lower limit temperature Ts + ΔT21 obtained by adding a predetermined increment value ΔT21 to the set temperature Ts. The predetermined increment value ΔT21 is smaller than the increment value T11 and is set to, for example, 1.0 ° C. If the set temperature Ts is set to 1 ° C., the lower limit temperature Ts + ΔT21 is 2.0 ° C. is there. Therefore, the internal temperature Tx is lower than the lower limit temperature Ts + ΔT21 and the upper limit temperature Ts + Δ.
If it is between T12, it is continuously determined as "NO" in both steps 124 and 126, and the circulation process including steps 124 and 126 is repeatedly executed. In this state, the cooling device 20 continues to be operated in the state in which it is switched to the lower side by one rank by the process of step 120.

If the internal temperature Tx becomes lower than or equal to the lower limit temperature Ts + ΔT21 by this cooling, in step 126, "YE
S "is determined and the program proceeds to step 128 and thereafter. In step 128, “1” is subtracted from the rank data RNK, and the subtracted rank data RNK is output to the inverter circuit 31. Therefore, the electric motor 2
The rotation speed of 5 is reduced, and the compressor 21 is driven at this reduced rotation speed to cool the interior 10. That is, the cooling capacity of the cooling device 20 is switched to the lower side by one rank.

On the other hand, during the circulation process of steps 124 and 126, if the internal temperature Tx becomes equal to or higher than the upper limit temperature T12, it is determined to be "YES" in step 124 and the process proceeds to step 130. In step 130, “1” is added to the rank data RNK, and the added rank data RNK is output to the inverter circuit 31. Therefore, the rotation speed of the electric motor 25 is increased, and the compressor 21 is driven at this increased rotation speed to cool the interior 10. That is, the cooling capacity of the cooling device 20 is switched to the higher side by one rank. Then, after the processing of step 130, the process returns to the circulation processing of steps 116 and 118 described above.

After the processing of step 128, step 1
The circulation processing consisting of 32 and 134 is repeatedly executed. In step 132, it is determined whether the internal temperature Tx is equal to or higher than the upper limit temperature Ts + ΔT22 obtained by adding the predetermined increment value ΔT22 to the set temperature Ts. The predetermined increment value ΔT22 is larger than the increment value ΔT21 and is set to, for example, 1.5 ° C. If the set temperature Ts is set to, for example, 1 ° C., the upper limit temperature Ts + ΔT22 is 2.5 ° C. is there. In step 134, it is determined whether or not the internal temperature Tx is lower than or equal to the lower limit temperature Ts + ΔT31 obtained by adding a predetermined increment value ΔT31 to the set temperature Ts. The predetermined increment value ΔT31 is smaller than the increment value ΔT21 and is set to, for example, −1.0 ° C. If the set temperature Ts is set to, for example, 1 ° C., the lower limit temperature Ts + ΔT31 is 0.0 ° C. Is. Therefore, the internal temperature Tx is lower than the lower limit temperature Ts + ΔT31 and the upper limit temperature T.
If it is between s + ΔT22, it is continuously determined as “NO” in steps 132 and 134, and steps 132 and 1
The circulation processing from 34 continues to be repeatedly executed. In this state, the cooling device 20 continues to be operated in the state where it is switched to the lower side by one rank by the process of step 128.

If the internal temperature Tx becomes equal to or lower than the lower limit temperature Ts + ΔT31 by this cooling, in step 134, "YE
S ”is determined and the process proceeds to step 138 and thereafter. Step 1
At 38, the operation of the electric motor 25 is stopped. When the operation of the electric motor 25 is stopped, the cooling device 20 stops the cooling operation.

On the other hand, during the circulation processing in steps 132 and 134, if the internal temperature Tx becomes equal to or higher than the upper limit temperature Ts + T22, it is determined to be "YES" in step 132 and the process proceeds to step 136. In step 136, “1” is added to the rank data RNK, and the added rank data RNK is output to the inverter circuit 31. Therefore, the rotation speed of the electric motor 25 is increased, and the compressor 21 is driven at this increased rotation speed to cool the interior 10. That is, the cooling capacity of the cooling device 20 is switched to the higher side by one rank. Then, the step 13
After the process of 6, the process returns to the circulation process including the steps 124 and 126 described above.

After the processing of step 138, step 1
At 40, the internal temperature Tx is increased by a predetermined increment value Δ to the set temperature Ts.
It is determined whether the temperature is equal to or higher than the upper limit temperature Ts + ΔT32 to which T32 is added. The predetermined increment value ΔT32 is the increment value ΔT3.
If it is set to be higher than 1 and is set to 0.5 ° C., for example, and the set temperature Ts is set to 1 ° C., the upper limit temperature Ts + ΔT 32 is 1.5 ° C. Therefore, if the internal temperature Tx is less than the upper limit temperature Ts + ΔT32, step 1
The determination is continued to be “NO” in step 40, and step 138,
The cyclic processing from 140 continues to be repeatedly executed. In this state, the operation of the electric motor 138 continues to be stopped, and the operation of the cooling device 20 also continues to be stopped.

On the other hand, during the circulation process of steps 138 and 140, if the internal temperature Tx becomes equal to or higher than the upper limit temperature T32, it is determined to be "YES" in step 140 and the process proceeds to step 142. In step 142, the electric motor 2
Restart the operation of 5. Then, steps 132 and 13
Returning to the circulation processing of 4, the cooling device 20 starts cooling the inside 10. In this case, the rank data RNK is kept set in step 128 described above, so that the rotation speed of the electric motor 25 is set in steps 132 and 134 described above.
It is kept the same as during the circulation process of.

As can be understood from the above description of the operation, according to the first embodiment, the inside temperature Tx is close to the outside air temperature as at the start of the operation of the refrigerator, that is, when the cooling device 20 is started, and the set temperature Ts is set. If the inside temperature Tx is equal to or higher than the predetermined temperature T1, if the temperature is extremely higher than
The ranks of the rotation speeds of the electric motors 25 are maintained at the level L3 by the processing of 2,104. If the internal temperature Tx is lower than the predetermined temperature T1 and is equal to or higher than the predetermined temperature T3,
The rank of the rotation speed of the electric motor 25 is maintained at the levels L3 to L5. That is, when the internal temperature Tx is close to the outside air temperature and is extremely higher than the set temperature Ts and a large current flows through the electric motor 25 and the power supply circuit 40, the rotation speeds of these are relatively low and the electric motor 25 and the power supply circuit 40 are relatively low. Since the current that flows in is suppressed below the maximum allowable current Imax,
It is possible to avoid an increase in the size of the electric motor 25 and the power supply circuit 40 and an increase in manufacturing cost. Further, by suppressing the load at the start of starting the refrigerator, that is, the compressor 21, it is possible to avoid unnecessarily increasing the capacity of the condenser 22 and to reduce the manufacturing cost of the condenser 22 at a low cost.

Further, in the processing of steps 102 to 110, as the internal temperature Tx becomes lower, the rotation speed of the electric motor 25 is switched to a higher rank, and the cooling capacity of the cooling device 20 becomes higher. Can be switched. Therefore, according to the first embodiment described above, it is possible to quickly reduce the internal temperature Tx while suppressing the current flowing through the electric motor 25 and the power supply circuit 40 to be equal to or less than the maximum allowable current Imax.

Further, in the steady operation state after the cooling device 20 is started, that is, in the state where the internal temperature Tx is lower than the predetermined temperature T3, the rotation speed of the electric motor 25 is increased as the internal temperature Tx rises, that is, cooling is performed. The cooling capacity of the device 20 is controlled to be high. Therefore, in the steady operation state of the refrigerator, when the object to be cooled is newly put in the inside 10 of the refrigerator, or when the cooled object is taken out of the inside 10, the inside temperature Tx is slightly different from the set temperature Ts. Even if the temperature rises, the temperature rise in the refrigerator 10 is corrected quickly and accurately, and the refrigerator temperature Tx during the steady operation of the cooling device 20 continues to be maintained at the set temperature Ts.

B. Second Embodiment Next, a second embodiment in which the present invention is applied to a freezer will be described. In the second embodiment, an alarm 39 is connected to the microcomputer 34 as shown by the broken line in FIG. In addition, in the second embodiment,
The microcomputer 34 executes a program corresponding to the flowcharts of FIGS. 5 and 6. Other configurations are similar to those of the refrigerator according to the first embodiment, and therefore description thereof will be omitted. The cooling device 20 of FIG.
The graph of FIG. 2 regarding the characteristics of the electric motor 25 also applies to the characteristics of the freezer according to the second embodiment, although the temperatures are different.

Next, the operation of the second embodiment will be described. Also in this case, upon the start of operation, the microcomputer 34 starts the program from step 200 of FIG. 5 and operates the cooling fan 26 and the internal fan 27. The processing of steps 202 to 210 and 218 of FIG. 5 is performed by steps 102 to 11 of FIG. 3 of the first embodiment.
This is substantially the same as the processing of 0,114. The difference is that
It is the rank of the rotation speed of the electric motor 25 set in steps 202, 208, and 218 and the temperature compared with the internal temperature Tx in step 210. That is, in the case of this freezer, in steps 202, 208, 218, the rank data RNK have levels L2, L3, respectively.
It is set to L4 (or L5). Also, step 21
The predetermined temperature T4 compared with the internal temperature Tx at 0 is
It is -5 ° C.

In addition, in the second embodiment, after the processing of step 218, a processing of determining whether or not the internal temperature Tx is lower than a predetermined temperature T5 (eg, -18 ° C.) is added in step 220. Has been done. Then, as long as the in-compartment temperature Tx is equal to or higher than the predetermined temperature T5, based on the determination of “NO” in step 220, steps 218 and
The cyclic process consisting of 20 is repeatedly executed. On the other hand, if the internal temperature Tx falls below the predetermined temperature T5, it is determined to be “YES” in step 220 and step 22 in FIG.
2 and subsequent normal operation control routines are proceeded to.

Therefore, in the second embodiment, from the state where the internal temperature Tx is extremely high immediately after the operation of the cooling device 20 is started to when the internal temperature Tx reaches 10 ° C.,
The rank of the rotation speed of the electric motor 25 is set to the level L2. Then, the rank of the rotation speed of the electric motor 25 when the internal temperature Tx is from 10 ° C to -5 ° C is set to level L3, and the rank of the rotational speed of the electric motor 25 when the internal temperature Tx is from -5 ° C to -18 ° C. Is set to level L4 or level L3. And these levels L2-L
Up to 5, as in the case of the first embodiment, the electric motor 2
5 and the current flowing through the power supply circuit 40 are the maximum allowable current Ima.
It can be kept below x.

As a result, also in the freezer according to the second embodiment, the temperature Tx inside the refrigerator is extremely close to the outside air temperature and is much higher than the set temperature, and under the situation where a large current flows through the electric motor 25 and the power supply circuit 40, these Since the rotation speed of the motor is kept relatively low, the motor 25 and the power supply circuit 40
It is possible to avoid an increase in size and an increase in manufacturing cost. Further, in a state where the inside temperature Tx before the freezer enters the steady operation state is equal to or higher than the predetermined temperature T5, the rotation speed of the electric motor 25 is switched to a higher rank as the inside temperature Tx becomes lower. Since the cooling capacity of the cooling device 20 is switched to the higher side, the internal temperature Tx can be quickly lowered while suppressing the current flowing through the electric motor 25 and the power supply circuit 40 to the maximum allowable current Imax or less. The capacity of the condenser 22 is also the same as that of the first embodiment.

Further, in the second embodiment, if it is determined in step 206 that "NO", that is, the discharge refrigerant temperature Tc is equal to or higher than the predetermined temperature T2 (for example, 60 ° C.), the processing of step 212 and subsequent steps is performed. To be executed. In step 212, the alarm device 39 is caused to output an alarm signal,
In step 214, the operation of the cooling device 20, such as the operation of the electric motor 25, the cooling fan 26 and the internal fan 27, is stopped, and the execution of this program is ended in step 216. After the completion of the execution of this program, unless the user starts the cooling device 20 again, the cooling device 2
0 is not activated. This is because in such a situation, there is a high possibility that an abnormality has occurred in any of the freezers, and the user needs to inspect each part of the refrigerator.

In the first embodiment, even when the discharge refrigerant temperature Tc is equal to or higher than the predetermined temperature T2, the processing of step 112 lowers the rank of the rotation speed of the electric motor 25 to operate the cooling device 20. I decided to continue.
However, also in the case of the refrigerator according to the first embodiment, steps 212 to 216 are performed, as in the case of the second embodiment.
You may make it stop the operation | movement of a refrigerator by performing the process which consists of.

Returning to the explanation of the operation of the freezer according to the second embodiment again, in step 220, the "YE
When it is determined to be "S", the microcomputer 34 executes the steady operation routine including steps 222 to 248 in FIG. The processing of these steps 222 to 248 is performed by the steps 116 to 142 of FIG. 4 of the first embodiment.
Substantially the same as the processing of. The difference is step 2
22,224,230,232,238,240,24
6 is a temperature compared with the in-compartment temperature Tx. That is, the predetermined temperature (upper limit temperature) T5 ′ that is compared with the internal temperature Tx in this step 222 is, for example, −17.5 ° C.
It is a low temperature. Also, steps 224 and 23
Set temperature Ts at 0,232,238,240,246
Increment value ΔT41, ΔT42, ΔT51, ΔT
52, ΔT61, ΔT62 are, for example, 0 ° C., 1 ° C., −, respectively.
It is set to 0.5 ° C, 0.5 ° C, -1 ° C, and 0 ° C.
Then, if the set temperature Ts is set to, for example, −20 ° C., steps 224, 230, 232, 238, 240, 246.
Upper limit or lower limit temperature Ts compared with the internal temperature Tx at
+ ΔT41, Ts + ΔT42, Ts + ΔT51, Ts + ΔT5
2, Ts + ΔT61 and Ts + ΔT62 are, for example, −
20 ° C, -19 ° C, -20.5 ° C, -19.5 ° C, -2
It becomes 1 ℃ and -20 ℃.

If it is determined in step 222 that "YES", that is, the internal temperature Tx is equal to or higher than the upper limit temperature T5 ', after the processing in step 226, step 2 in FIG.
It is returned to the circulation process consisting of 18,220.

As a result, also in the freezer according to the second embodiment, in the steady operation state after the cooling device 20 is started, that is, when the internal temperature Tx is lower than the predetermined temperature T5, the electric motor increases as the internal temperature Tx rises. The rotation speed of 25 is increased, that is, the cooling capacity of the cooling device 20 is increased. Therefore, in the steady operation state of the freezer, when the item to be cooled is newly put in the inside 10 or when the cooled item is taken out from the inside 10, the inside temperature Tx is slightly different from the set temperature Ts. Even if the temperature rises, the temperature rise in the refrigerator 10 is corrected quickly and accurately, and the refrigerator temperature Tx during the steady operation of the cooling device 20 continues to be maintained at the set temperature Ts.

C. Modified Example In the first and second embodiments, the discharge refrigerant temperature Tc and the predetermined temperature T2 are compared in step 106 of FIG. 3 and step 206 of FIG. But,
Instead of this, it is determined whether the pressure Pc of the high-temperature high-pressure refrigerant at the outlet of the compressor 21 is equal to or lower than a predetermined pressure, and the refrigerant pressure P
Steps 108 and 2 only when c is below a predetermined pressure
You may make it perform the process of 08. In this case, a pressure sensor that detects the pressure Pc of the refrigerant at the outlet of the compressor 21 is provided instead of the discharge refrigerant temperature sensor 36, and the output of the pressure sensor is guided to the microcomputer 34 via the A / D converter 37. You can do it like this.

Further, in the first and second embodiments, when the internal temperature Tx is equal to or higher than the predetermined temperatures T3 and T5, respectively, the steps 102 to 110, 114 and the steps 200 to 210, 218, 220 are performed. ,
Two and three regions divided by the height of the in-compartment temperature Tx are determined in advance, and the rotation speed of the electric motor 25 is set to increase as the region in which the in-compartment temperature Tx becomes lower.
However, the number of areas may be four or more.

Further, these steps 102 to 110,
114 and steps 200-210, 218, 220
In place of the process of (1), a table in which the rotation speed of the electric motor 25 is determined for each of the plurality of regions is prepared, and the rotation speed corresponding to the inside temperature Tx is derived by referring to the table,
The rotational speed of the electric motor 25 may be controlled by the derived rotational speed. Further, a table or a function that continuously indicates the rotation speed that increases as the inside temperature Tx decreases is prepared, and the rotation speed of the electric motor 25 decreases as the inside temperature Tx decreases by using these tables or functions. You may control so that it may become quick continuously.

Further, in the first and second embodiments, step 11 in the case where the internal temperature Tx is lower than the predetermined temperatures T3 and T5, that is, in the steady operation,
Also in the case of the processing of 6 to 142 and steps 222 to 248, three regions divided by the temperature difference between the in-compartment temperature Tx and the set temperature Ts are determined in advance, and the region where the in-compartment temperature Tx becomes higher becomes higher. The rotation speed of the electric motor 25 is increased, that is, the cooling capacity of the cooling device 20 is increased. However, the number of areas may be four or more.

Also in this case, steps 116 to
Instead of the processing of 142 and steps 222 to 248,
A table in which the rotation speed of the electric motor 25 is determined for each of the plurality of regions is prepared, and the rotation speed corresponding to the temperature difference between the inside temperature Tx and the set temperature Ts is derived by referring to the table, The rotation speed of the electric motor 25 may be controlled by the derived rotation speed. Also, the internal temperature T
A table or a function that continuously shows the rotation speed that increases as the temperature difference between x and the set temperature Ts increases is prepared, and using these tables or functions, the rotation speed of the electric motor 25 increases as the temperature difference increases. May be controlled to be continuously faster.

Further, in the first and second embodiments, the inside temperature Tx is directly detected by the inside temperature sensor 35. However, this internal temperature Tx
May be indirectly detected using another sensor. For example, as shown by a broken line in FIG. 1, a temperature sensor 41 may be provided in the passage 10a, and the passage temperature Tx ′ detected by the temperature sensor 41 may be used instead of the inside temperature Tx. The temperature sensor 41 may be arranged at any place in the passage 10a. Although the passage temperature Tx ′ detected by the temperature sensor 41 is different from the internal temperature Tx and also depends on the position where the temperature sensor 41 is arranged, the passage temperature Tx ′ is the temperature of the air circulating in the internal storage. Since the change tendency is the same as the internal temperature Tx, the internal temperature Tx
Will be indirectly represented.

Similarly, as shown by the broken line in FIG. 1, a temperature sensor 42 is fixed to the evaporator 24, and the temperature sensor 42 is fixed.
The evaporator temperature Tx "detected by the above may be used instead of the internal temperature Tx. In this case, the temperature sensor 42 is used between the inlet of the evaporator 24 into which the refrigerant flows and the central portion. It may be arranged at any position between the central portion and the outlet, and the evaporator temperature (same as the temperature of the passing refrigerant) Tx "detected by the temperature sensor 42 is also the internal temperature Tx. Although different, the tendency of change is the same as the internal temperature Tx due to the relationship of heat exchange with the air in the internal compartment 10.
The in-compartment temperature Tx is indirectly represented.

Similarly, as indicated by a broken line in FIG. 1, the pressure sensor 43 is provided in the refrigerant passage located downstream of the evaporator 24.
And the refrigerant pressure P detected by the pressure sensor 43.
x may be used instead of the internal temperature Tx. In this case, the pressure sensor 43 may be arranged at any position between the outlet of the evaporator 24 and the inlet of the compressor 21. Since the refrigerant pressure Px on the downstream side of the evaporator 24 has the same tendency to change as the inside temperature Tx due to the heat exchange relationship with the air in the inside 10 as in the case of the evaporator temperature Tx ″, It represents the temperature Tx indirectly.
The detection outputs of these sensors 41 to 43 are analog signals, and are guided to the A / D converter 37 as in the case of the in-compartment sensor 35 of the first and second embodiments.

When the temperature sensors 41 and 42 or the pressure sensor 43 are used instead of the inside temperature sensor 35 as described above, the passage temperature Tx ', the evaporator temperature Tx "or the refrigerant pressure Px.
A conversion table or conversion function for converting the inside temperature Tx to the inside temperature Tx is prepared. Then, using this conversion table or conversion function, the passage temperature Tx ′ and the evaporator temperature T detected by the temperature sensors 41 and 42 or the pressure sensor 43 are used.
x "or the refrigerant pressure Px is converted to the inside temperature Tx, and the converted inside temperature Tx is shown in FIG. 3 of the first and second embodiments.
To the program of No. 6 to the electric motor 25,
And control may be performed in the same manner as in the second embodiment.

Further, FIG. 3 of the first and second embodiments described above.
Predetermined temperatures T1, T3 to T5, T3 ', T5' and predetermined increment value ΔT, which are compared with the internal temperature Tx in the program of
Predetermined values obtained by converting 11 to ΔT61 and ΔT12 to ΔT62 into the passage temperature Tx ′, the evaporator temperature Tx ″ or the refrigerant pressure Px are prepared in advance, and these converted values are set to the predetermined temperature T1,
T3 to T5, T3 ', T5' and predetermined increment values ΔT11 to ΔT
61, ΔT12 to ΔT62 are installed in the program instead. Then, the temperature sensors 41, 42 or the pressure sensor 4
The passage temperature Tx ′, the evaporator temperature Tx ″ or the refrigerant pressure Px detected by 3 may be compared with the conversion value incorporated in the program when the program is executed. Regarding the set temperature Ts set by the inside temperature setter 38, the microcomputer 30
It is necessary to convert the passage temperature Tx ′, the evaporator temperature Tx ″, or the refrigerant pressure Px into the passage temperature Tx ′, the evaporator temperature Tx ″, or the refrigerant before or after the input. Since the pressure Px functions in the same manner as the internal temperature Tx, the same effect as that of the first and second embodiments can be expected.

In the first and second embodiments, when the internal temperature Tx is equal to or higher than the predetermined temperatures T3 and T5, that is, when the operation of the cooling device 20 is started, only the internal temperature Tx is determined. The rotation speed of the electric motor 25 is changed. However, in addition to or instead of the condition of the internal temperature Tx, the rotation speed of the electric motor 25 may be suppressed to a predetermined speed or less for a predetermined time after the operation of the cooling device 20 is started. Further, in addition to or instead of the condition of the internal temperature Tx, the rotation speed of the electric motor 25 is suppressed to a predetermined speed or less for a predetermined time from the start of operation of the cooling device 20 by an operation history of the cooling device 20 or an operation from the outside. It is also possible to do so.

Further, in the above-mentioned first and second embodiments, an example in which the present invention is applied to a refrigerator and a freezer has been described, but the present invention can also be applied to a freezer-refrigerator that also serves as a refrigerator and a freezer.

[Brief description of drawings]

FIG. 1 is a schematic block diagram schematically showing an entire cooling device for cooling the inside of a refrigerator, a freezer or the like and an operation control device thereof according to the first and second embodiments of the present invention.

FIG. 2 is a characteristic graph showing respective relations between the cooling capacity of the cooling device and the current flowing through the electric motor with respect to the temperature inside the refrigerator.

FIG. 3 is a flowchart showing a first half of a program executed by the microcomputer of FIG. 1 according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a second half of a program executed by the microcomputer of FIG. 1 according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a first half of a program executed by the microcomputer of FIG. 1 according to the second embodiment of the present invention.

FIG. 6 is a flowchart showing a second half of the program executed by the microcomputer of FIG. 1 according to the second embodiment of the present invention.

[Explanation of symbols]

Reference numeral 10 ... Inside the chamber, 10a ... Passage (cooling air passage), 20 ... Cooling device, 21 ... Compressor, 22 ... Condenser, 23 ... Capillary tube, 24 ... Evaporator, 25 ... Electric motor, 26 ... Cooling fan, 27 ... Internal fan, 30 ... Operation control device, 31
... Inverter circuit, 34 ... Microcomputer, 35
... In-compartment temperature sensor, 36 ... Discharge refrigerant temperature sensor, 38 ...
Internal temperature setting device, 41, 42 ... Temperature sensor, 43 ... Pressure sensor.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3L045 AA02 BA01 CA02 DA02 EA01                       LA06 LA12 LA17 MA02 MA06                       MA09 PA01 PA02 PA03

Claims (7)

[Claims] 1. A cooling device having a refrigeration cycle including a compressor driven by a speed-controlled electric motor and an evaporator for cooling the inside of a storage by heat exchange with a refrigerant discharged from the compressor. In the operation control device, the physical quantity detection means for detecting a physical quantity that directly or indirectly represents the temperature in the storage, and the rotation speed of the electric motor is controlled according to the detected physical quantity to obtain the temperature in the storage. In-compartment temperature control means for maintaining the set temperature of, and when the detected physical quantity represents an in-compartment temperature higher than a predetermined temperature higher than the set temperature, a rotation speed that limits the rotation speed of the electric motor to a predetermined rotation speed or less. An operation control device for a cooling device, which is provided with a limiting means. 2. An operation control device for a cooling device according to claim 1, wherein the physical quantity detecting means is a cooling device provided in a storage and configured to detect a temperature in the storage. Operation control device. 3. The operation control device for a cooling device according to claim 1, wherein the physical quantity detecting means is provided in a passage of cooling air that is cooled by the evaporator and cools the inside of the storage. An operation control device for a cooling device including a temperature sensor that detects the temperature of the cooling air. 4. An operation control device for a cooling device according to claim 1, wherein the physical quantity detection means is assembled to the evaporator,
An operation control device for a cooling device including a temperature sensor that detects the temperature of the evaporator. 5. The operation control device for a cooling device according to claim 1, wherein the physical quantity detecting means is provided in a refrigerant passage between the evaporator and the compressor, and the physical quantity detecting means is provided in the refrigerant passage. An operation control device for a cooling device, the operation control device including a pressure sensor that detects the pressure of a refrigerant flowing through the device. 6. An operation control device for a cooling device according to any one of claims 1 to 5, wherein the inside temperature control means controls the inside temperature to be the inside temperature and the inside temperature. As it shows a large temperature difference from the set temperature,
While being configured to change and control the rotational speed of the electric motor so that the rotational speed of the electric motor becomes faster, the rotational speed limiting means, regardless of the set temperature,
An operation control device for a cooling device configured to control a rotation speed of the electric motor based on the detected physical quantity. 7. The operation control device for a cooling device according to any one of claims 1 to 6, wherein the rotational speed limiting means indicates a low internal temperature of the detected physical quantity. According to the above, the operation control device for the cooling device is provided with rotation speed change control means for changing and controlling the rotation speed of the electric motor so that the rotation speed of the electric motor is increased.