JP4096862B2 - Refrigeration unit and refrigerator - Google Patents

Description

  The present invention relates to a refrigerator-freezer unit in which a compressor and a condenser of a cooling system are installed at the upper part of the gantry and an evaporator is installed in the lower part of the gantry, and a commercial refrigerator-freezer in which the refrigeration unit is provided in the upper part of the main body. The present invention relates to compressor operation control.

  In a conventional commercial refrigerator-freezer, particularly in a system for cooling a freezer compartment, a low boiling point refrigerant such as R22 or R404A that can provide a high refrigerating capacity even when the evaporation temperature is low is used.

  However, in recent years, from the viewpoint of preventing global warming, it has been desired to switch from chlorofluorocarbon refrigerants such as R22 and R404A, which have a high global warming potential, to natural refrigerants such as R290 and R600a, and to reduce CO2 emissions. For large-sized freezer refrigerators for business use with a large amount of electric power, it is desired to save energy as soon as possible.

  As a conventional commercial refrigerator, there is a commercial refrigerator (Patent Document 1) that controls the rotation speed of a compressor according to the outside air temperature.

  Hereinafter, the conventional refrigerator will be described with reference to the drawings.

  FIG. 3 is a circuit diagram of a conventional refrigerator, FIG. 4A is a diagram showing the relationship between the internal temperature and time, and FIG. 4B is a diagram showing the rotational speed control of the compressor, condenser fan, and evaporator fan. In FIG. 3, a variable speed compressor 1 is connected to a condenser 3, a capillary tube 5, and an evaporator 7 in a closed loop with a refrigerant pipe, and the condenser 3 is provided with a variable speed condenser fan 13. The evaporator 7 is also provided with a variable speed evaporator fan 17. The evaporator 7 is installed in a refrigerator or the like and cools the interior. Control is performed by the controller 19.

  About the refrigerator comprised as mentioned above, the operation | movement is demonstrated using FIG. 4 below.

  In FIG. 4A, the vertical axis indicates the temperature inside the refrigerator or the like, and the horizontal axis indicates the passage of time. Referring to FIG. 4A, in the present refrigeration apparatus, when the inside of the refrigerator is cooled after the operation is started and the inside temperature reaches the set temperature (thermo-off temperature) t1, the operation standby state (thermo-off) is entered, and this state continues. When the internal temperature reverses and rises and reaches the set temperature (thermo-on temperature) t2, the operation state (thermo-on) is entered, and this is normally repeated to maintain the internal temperature at a substantially constant range.

  The operating state of the refrigeration apparatus is first in the initial pull-down period (interval until the maximum torque peak (point P) is obtained) T1, in the period T2 from the initial pull-down period to the thermo-off period, in the period T3 from the thermo-off period to the thermo-on period, from the thermo-on period to the thermo-off period. It is divided into four operation states of the section T4.

  FIG. 2B shows the rotational speed control of the compressor 1, the condenser fan 13, and the evaporator fan 17.

In the section T4 from the thermo-on to the thermo-off, the following control is performed in relation to the outside air temperature. For example, when the outside air temperature is high (for example, 25 ° C. or higher), the rotation speeds of the compressor 1, the condenser fan 13 and the evaporator fan 17 are all uniformly controlled by the medium speed rotation M, which contributes to maintaining the internal temperature.

On the other hand, at a low outside air temperature (for example, less than 25 ° C.), the rotation speed of the compressor fan 1 and the condenser fan 13 is reduced while the rotation speed of the evaporator fan 17 is maintained at the medium speed rotation M, and the low speed rotation L To control. This is because the refrigerating capacity is not so required at low outside air temperature (for example, less than 25 ° C.).
JP 11-270914 A

  However, the conventional refrigerator has a low compression ratio, and it is easy to ensure the durability of the compressor 1. The refrigeration capacity per cylinder volume of the compressor 1 (hereinafter referred to as volume capacity) is high and high capacity can be achieved. There was a drawback that the theoretical efficiency and the effective efficiency of the compressor 1 were low.

  Further, while the compression ratio is low and the volume capacity is high, the characteristic that the efficiency is low is a common defect of low-boiling refrigerants having an evaporation temperature of −40 ° C. or lower, such as Freon refrigerants R404A and R22 and hydrocarbon refrigerant R290. Compression ratio, high pressure pressure, low pressure pressure, and theoretical efficiency at a condensing temperature of 40 ° C., an evaporation temperature of −30 ° C., a supercooling of 0 ° C., and an intake gas temperature of 332 ° C., which are general operating conditions of a commercial refrigerator at an ambient temperature of 30 ° C. (Table 1) shows the results of comparing the relative values of volume capacity with R134a and R600a, which are high-boiling refrigerants.

  As shown in (Table 1), it can be seen that R22, R290, and R404A, which are low-boiling refrigerants compared to the high-boiling refrigerants R134a and R600a, have a low compression ratio and a high volume capacity, but have a low theoretical efficiency. Moreover, R22, R290, and R404A, which are low boiling point refrigerants, have a relatively high high pressure and a large sliding loss of the compressor 1. The effective efficiency of the compressor 1 is further deteriorated compared to the theoretical efficiency, and the low pressure is low. There is also a disadvantage that the pressure is higher than the atmospheric pressure and the risk of refrigerant leakage into the freezer compartment 1 is high.

  The present invention solves the above-mentioned conventional problems, and suppresses an increase in the compression ratio while using R134a, R600a, etc., which are high-boiling refrigerants having high theoretical efficiency of the refrigerant and effective efficiency of the compressor. It aims at operating a compressor in the state of inside, and preventing breakage of a compressor.

The present invention uses a refrigerant whose evaporating pressure during refrigeration is a negative pressure, and in a refrigerator equipped with a variable speed compressor, condenser, throttle device, evaporator, external fan, and internal fan, Protection control means for suppressing the rotation speed of the compressor with variable rotation speed is provided , and the protection control is based on the temperature set in advance by the condensation temperature detected by the condensation temperature detection means for detecting the condensation temperature of the condenser. When it is high, control is performed to lower the upper limit number of rotations of the variable speed compressor from the upper limit number of rotations during normal operation set for each outside temperature to the upper limit number of rotations when the condensation temperature is high . It is possible to reduce the rotation speed of the compressor and to operate the compressor in a state where the compressor is used, thereby preventing the compressor from being damaged.

  The present invention provides a condensing temperature detecting means for detecting a condensing temperature in a refrigerator provided with a variable speed compressor, a condenser, a throttling device, an evaporator, an external fan, and an internal fan, and the condensing temperature detection When the condensing temperature detected by the means is higher than a preset temperature, the upper limit rotational speed of the variable speed compressor is lowered, a high temperature alarm is issued, and a refrigerant whose evaporating pressure during refrigeration is negative is reduced. When the condensing temperature is higher than the predetermined temperature, the compressor can be operated in a state where the compressor is used by reducing the compressor rotational speed by lowering the upper rotational speed of the compressor. In addition, the compressor can be prevented from being damaged, and a warning can be issued to quickly respond to the service.

The invention according to claim 1 of the present invention uses a refrigerant whose evaporation pressure during refrigeration is a negative pressure, and has a variable speed compressor, condenser, throttle device, evaporator, outside fan, and interior In the refrigerator including a fan, the refrigerator includes a protection control unit that suppresses the rotation speed of the variable speed compressor , and the protection control is performed by a condensation temperature detected by a condensation temperature detection unit that detects a condensation temperature of the condenser. When the temperature is higher than a preset temperature, the upper limit rotational speed of the variable speed compressor is changed from the upper limit rotational speed at normal operation set for each outside temperature to the upper limit rotational speed at the high condensation temperature. This is a control to lower the compressor, and by lowering the upper limit rotation speed of the compressor, the rotation speed of the compressor can be reduced, and the compressor can be operated within the compressor usage range, and the compressor is damaged. To prevent.

The invention according to claim 2 of the present invention further comprises condensation temperature detection means for detecting the condensation temperature and interior temperature setting means for setting the interior temperature, in addition to the invention according to claim 1, When the condensation temperature detected by the temperature detection means is higher than the preset temperature, the internal temperature setting means raises the preset temperature in the compartment to the preset temperature, and the condensation temperature is predetermined. If it is higher than the temperature, by raising the set temperature to a temperature that satisfies the specifications of the freezer temperature under high load conditions, the rotational speed of the compressor is reduced, and the compressor is operated within the compressor usage range, Prevent damage to the compressor.

The invention of the refrigerator according to claim 3 of the present invention further comprises outside temperature detection means for detecting the outside temperature in the invention according to claim 1 or 2 , and the condensation detected by the condensation temperature detection means. When the difference between the temperature and the outside temperature detected by the outside temperature detecting means is larger than the preset temperature difference, an alarm or warning is displayed, and an alarm or warning is given to prompt cleaning of the filter, etc. As a result, by reducing the compression ratio, the theoretical efficiency of the cycle is increased, and as a result, the power consumption is suppressed.

According to a fourth aspect of the present invention, there is provided a refrigerator according to any one of the first to third aspects, further comprising a suction temperature detecting means for detecting a suction temperature of the variable speed compressor. And when the suction temperature detected by the suction temperature detection means is lower than the temperature determined in advance by the outside air temperature detected by the outside temperature detection means, the defrost is performed to the evaporator. The amount of frost formation can be grasped indirectly, and defrosting can be performed under the optimum conditions, so that the temperature inside the chamber rises and the power consumption is reduced when not needed.

The invention of the refrigerator according to claim 5 of the present invention is the same as that of any one of claims 1 to 4 , wherein the variable speed compressor is determined in advance after the defrosting. If the difference between the outside temperature detected by the outside temperature detection means and the condensation temperature detected by the condensation temperature detection means is smaller than a predetermined temperature difference, The compressor with variable rotation speed is stopped, the outside fan and the inside fan are operated and a refrigerant leak warning is issued to give a warning and promptly respond to the service. It can be easily handled such as moving to a refrigerator.

The invention of the refrigerator according to claim 6 of the present invention is provided with the refrigerator-freezer unit according to any one of claims 1 to 5 at the upper part of the refrigerator body, and in particular, the cooling unit is arranged at the upper part. A reliable refrigerator can be provided with a protection control for compressors. The invention of claim 7 of the present application uses a flammable refrigerant as a refrigerant in the refrigeration unit or the refrigerator according to any one of claims 1 to 6.

  Hereinafter, embodiments of a refrigerator according to the present invention will be described with reference to the drawings. In addition, about the same structure as the past, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a block diagram of a refrigerator according to Embodiment 1 of the present invention. FIG. 2 is a control flowchart of the same embodiment.

  As shown in FIG. 1, in a refrigerator including a variable speed compressor 21, a condenser 22, an expansion device 23, an evaporator 24, an external fan 25, and an internal fan 26, the controller 27 detects the condensation temperature. Means 28, outside temperature detection means 29, suction temperature detection means 30, inside temperature setting means 31, compressor control means 32, alarm transmission means 33, defrost control means 34, inside fan control means 35, outside fan control Means 36;

  The operation of the refrigerator configured as described above will be described below with reference to the flowchart of FIG.

  First, in step 21, when the condensation temperature is detected by the condensation temperature detecting means 28 and it is determined that the detected condensation temperature is equal to or higher than a predetermined temperature (for example, 60 ° C.), rotation is performed in step 22. The upper limit number of revolutions of the variable number type compressor 21 is reduced from the upper limit number of revolutions during normal operation shown in (Table 2) to the upper limit number of revolutions when the condensation temperature is high, and the internal temperature setting means 31 is used to set the internal temperature setting The set temperature is increased to (for example, −18 ° C.).

  Next, in step 23, the outside temperature detection means 29 detects the outside temperature, calculates the temperature difference between the detected outside temperature and the condensation temperature, and the calculated temperature difference is a predetermined temperature set in advance. If it is determined that the difference is equal to or greater than 20K (eg, 20K), a filter clogging alarm is transmitted by the alarm transmission means 33 in step 24. If it is determined in step 23 that the temperature difference is less than a predetermined temperature difference (for example, 20 K) set in advance, a high temperature alarm is transmitted by the alarm transmission means 33 in step 25.

  If it is determined in step 21 that the detected condensing temperature is lower than a predetermined temperature (for example, 60 ° C.) set in advance, the process proceeds to the next step without issuing an alarm.

  As described above, the refrigerator using the refrigerator-freezer unit and the refrigerator-freezer unit according to the present embodiment reduces the upper limit rotation speed of the variable-speed compressor 21 and increases the load when the condensation temperature is high. By increasing the set temperature to a temperature that satisfies the specifications of the freezer compartment temperature, the rotational speed of the variable speed compressor 21 is reduced, and the compressor is in a state where the compressor is in a usable range and in an efficient state. Can be operated, the compressor can be prevented from being damaged, the amount of power consumption can be reduced, and a warning can be issued to quickly respond to the service.

  Also, if the difference between the condensation temperature and the outside temperature is larger than the preset temperature difference, the filter is likely to be clogged and a filter clogging alarm will be issued. As a result, by reducing the compression ratio, the theoretical efficiency of the cycle is increased, and as a result, the power consumption can be suppressed.

  In step 22, the upper limit number of rotations of the compressor 21 of variable speed type is reduced from the upper limit number of rotations during normal operation to the upper limit number of rotations when the condensation temperature is high, as shown in (Table 2). Although the set temperature is increased to 31 (e.g., -18 ° C) by 31, only one may be performed.

  Next, at step 26, after the defrost is completed or when a predetermined time (for example, 6 hours) preset in the initial pull-down has elapsed, at step 27, the intake temperature detecting means 30 detects the intake temperature and detects it. If it is determined that the sucked temperature is equal to or lower than a predetermined temperature (for example, 10 ° C.) set in advance, the defrost of the evaporator 24 is performed by the defrost control means 34 in step 28.

  In step 26, after defrosting, or when a predetermined time (for example, 6 hours) set in advance in the initial pull-down has not elapsed, or in step 27, a predetermined temperature (for example, 10) set in advance. If it is higher, the defrost is not performed.

As described above, in the refrigerator using the refrigeration unit of the present embodiment and the refrigerator refrigeration unit, when the evaporator is not frosted, the evaporator performs sufficient heat exchange and the evaporator outlet is in a gas state. If the evaporator is frosted, sufficient heat exchange is not performed in the evaporator, and the outlet of the evaporator becomes a two-phase refrigerant mixture of liquid and gas, and the intake temperature is lowered. Focusing on the fact that the intake temperature changes, the amount of frost formation on the evaporator can be indirectly grasped, and defrosting can be performed under optimum conditions. Can be suppressed.

  Next, in step 29, after the defrost is completed or in the initial pull-down, when the variable speed compressor 21 is continuously operated for a predetermined time (for example, 6 hours) set in advance, in step 30, When it is determined that the temperature difference between the outside temperature and the condensing temperature is equal to or less than a predetermined temperature difference (for example, 5K) set in advance, in step 31, the compressor control means 32 uses the variable speed compressor. 21, the internal fan control means 35 operates the internal fan 26, the external fan control means 36 operates the external fan, and the alarm transmission means 33 transmits a leak alarm.

  In step 29, after the defrost is completed or in the initial pull-down, the variable speed compressor 21 is not continuously operated for a predetermined time (for example, 6 hours) set in advance, or in step 30, If the temperature difference between the outside temperature and the condensation temperature is higher than a predetermined temperature difference (for example, 5K) set in advance, the operation proceeds to step 31 without performing the operation of step 31.

  As described above, the refrigeration unit of the present embodiment and the refrigerator using the refrigeration unit do not stop even after a predetermined time has elapsed by the variable speed compressor, and outside the refrigerator If the difference between the temperature and the condensation temperature is smaller than the predetermined temperature difference, it is determined that the refrigerant is leaking, the compressor with variable speed is stopped, and the external fan and internal fan are operated. At the same time, by issuing a leak alarm, it is possible to quickly deal with the service and to easily cope with moving the food in the refrigerator to another refrigerator.

  As described above, according to the present invention, when the condensing temperature is higher than the predetermined temperature, the upper limit rotational speed of the compressor is decreased, so that the compressor can be prevented from being damaged and warned and service can be performed promptly. Widely applicable to cooling equipment with a cycle.

Block diagram of Embodiment 1 of a refrigerator / freezer unit according to the present invention and a refrigerator using the refrigerator-freezer unit Control flowchart of the embodiment Circuit diagram of conventional refrigerator The figure which shows the internal temperature characteristic of the refrigerator of the conventional refrigerator

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Rotational speed variable compressor 22 Condenser 23 Throttle device 24 Evaporator 25 Outside fan 26 Inside fan 27 Controller 28 Condensing temperature detection means 29 Outside temperature detection means 30 Inlet temperature detection means 31 Inside temperature setting means 32 Compressor control means 33 Alarm transmission means 34 Defrost control means 35 Internal fan control means 36 External fan control means

Claims (7)

In a refrigerator that uses a refrigerant whose evaporating pressure during refrigeration is a negative pressure, and that includes a variable speed compressor, condenser, throttle device, evaporator, external fan, and internal fan, the variable rotational speed type Protection control means for suppressing the number of rotations of the compressor , the protection control is a case where the condensation temperature detected by the condensation temperature detection means for detecting the condensation temperature of the condenser is higher than a preset temperature, Refrigeration refrigeration characterized in that control is performed to reduce the upper limit rotational speed of a variable speed compressor from the upper limit rotational speed at normal operation set for each outside temperature to the upper limit rotational speed at a high condensation temperature. unit.   When the condensing temperature detecting means for detecting the condensing temperature and an in-chamber temperature setting means for setting the inside temperature are provided, and the condensing temperature detected by the condensing temperature detecting means is higher than a preset temperature, 2. The refrigeration unit according to claim 1, wherein the internal temperature setting means raises the set temperature in the cabinet to a preset temperature. An outside temperature detecting means for detecting the outside temperature is provided, and the difference between the condensation temperature detected by the condensation temperature detecting means and the outside temperature detected by the outside temperature detecting means is larger than a preset temperature difference. In the case, the refrigeration unit according to claim 1 or 2 , wherein a warning or warning display is issued. A suction temperature detecting means for detecting the suction temperature of the compressor with a variable speed is provided, and the suction temperature detected by the suction temperature detecting means after the defrosting is determined in advance by the outside air temperature detected by the outside temperature detecting means. The refrigeration unit according to any one of claims 1 to 3 , wherein defrosting is performed when the temperature is lower than a predetermined temperature. After completion of defrosting, the variable speed compressor does not stop even after a predetermined time has elapsed, and the outside air temperature detected by the outside temperature detection means and the condensation temperature detected by the condensation temperature detection means When the difference is smaller than a predetermined temperature difference, the variable speed compressor is stopped, the outside fan and the inside fan are operated, and a refrigerant leak warning is issued. Item 5. The refrigeration unit according to any one of Items 1 to 4 . A refrigerator comprising the refrigerator main body provided with the refrigeration unit according to any one of claims 1 to 5 . The refrigeration unit or refrigerator according to any one of claims 1 to 6, wherein the refrigerant is a combustible refrigerant.

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