JPH074797A - Refrigeration equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] If the cooling operation that is switched after defrosting is abnormal is abnormal, this is promptly detected to suppress the temperature rise in the freezer and maintain the quality of stored products. [Structure] When the defrost finish thermo 27 detects that the defrost has finished, a temperature signal from the internal temperature thermo 28 detects whether or not the cooling operation is normally performed. If the cooling operation is not normally performed, it is possible to notify the user by stopping the operation of the device or by warning the abnormality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system in which the evaporator section is defrosted by hot gas.

[0002]

2. Description of the Related Art After a cooling operation has been carried out for a predetermined time, it is automatically switched to a defrosting operation, and when the defrosting is completed, the cooling operation is resumed and a refrigerating apparatus for repeating this operation is disclosed in JP-B-60-
This is a known technique disclosed in Japanese Patent No. 15235. The technical content disclosed in the above publication aims to eliminate unnecessary anxiety of the user by temporarily suspending the display of the temperature inside the refrigerator from the start of defrosting to the end of one cycle of the cooling operation performed thereafter. It is a thing.

In this known technique, a timer for switching between a cooling operation and a defrosting (defrosting) operation and a thermostat for detecting the completion of defrosting are normally operating under the precondition. There is an advantage that the display interruption time can be obtained without interrupting the lighting of the lamp indicating an abnormality and giving unnecessary uneasiness during defrosting, and further, irrespective of load fluctuation during defrosting.

[0004]

According to the above-mentioned known technique, the cooling operation is performed by the refrigeration cycle, while the defrost operation is performed by the electric heater for defrosting which is a system different from the refrigeration cycle. Even if the switching to the cooling operation after completion is not normally performed and the cooling operation and the electric heater are operated at the same time, it is possible to suppress the abnormal increase of the internal temperature. For example, when the defrost completion thermostat does not operate normally and the defrost operation continues for a long time, the abnormal temperature is not displayed at all even though the temperature inside the storage chamber rises, and the storage inside the storage chamber continues. There is a problem that adversely affects the quality of the articles to be processed. Such a problem is particularly remarkable in the case of a refrigeration apparatus that defrosts by hot gas in the refrigeration cycle.

For example, a four-way switching valve is operated to switch,
In the prior art in which the refrigeration cycle is switched to the reverse cycle to perform defrosting, and operation control is performed based on the flowchart shown in FIG. 3, it is necessary to switch to the cooling operation of step m1 after the end of defrosting.
Since the refrigerant pressure is used as the pilot pressure in the switching operation of the four-way switching valve, when the refrigerant is insufficient,
It does not work properly. If the four-way switching valve does not operate normally, the defrost operation, which is the heating cycle, continues even though the command to switch to the cooling operation is issued, so the internal temperature thermostat (not shown) In step m2, an abnormality in the internal cold storage temperature is detected, and a timer (not shown) measures the cooling operation time in the abnormal state in step m3. That is, the temperature inside the refrigerator is in a high temperature abnormal state, which is higher than the set temperature by 7 ° C or more, and the set time is 1
Detect that it has continued for more than time.

When this abnormal state is detected,
Then, in step m4, an alarm is output, a buzzer sounds, and an alarm is displayed, for example, a lamp is displayed. On the other hand, moving to the next step m5, the current cooling operation of the refrigeration system is continued. As a result, the refrigeration system continues to perform the heating operation in the reverse cycle, and the temperature of the stored goods in the refrigerator rises, making it impossible to protect the quality deterioration.

The four-way switching valve often does not switch from the defrost (reverse cycle) side to the cooling side due to a gas shortage phenomenon in which the refrigerant is insufficient. That is, a slide valve type four-way switching solenoid valve is often used as the four-way switching valve,
The pilot solenoid valve is usually non-excited and on the cooling operation side,
It becomes the heating (defrost) operation side by excitation, and normally switches according to switching between non-energization and energization. On the other hand, the four-way switching valve on the main body side is a bowl-shaped slide valve that slides in the main body so that the pressure difference between the high-pressure chamber outside the bowl and the low-pressure chamber inside the bowl becomes a set value of, for example, 2 kg / cm ² or more. If it doesn't work smoothly. If an abnormal operating condition such as gas shortage occurs due to refrigerant accumulation in the evaporator during defrost operation, the pressure difference will be small and the valve body will move to the cooling side even if the pilot solenoid valve is switched. Without doing so, defrost (heating) operation will remain. If the pressure difference becomes greater than 2 kg / cm ² ,
The four-way switching valve automatically switches to the cooling side.

It is an object of the present invention to detect an abnormal rise in temperature by promptly detecting even if the temperature inside the refrigerator rises due to an abnormal cooling operation performed after defrosting. Hold down to maintain quality,
It is to maintain the safe driving by notifying the user of an abnormal condition as necessary.

[0009]

The present invention comprises a compressor 1, a condenser 3, a cooling pressure reducing device 5, an evaporator 6, and a control valve 2 which is switched between a cooling operation and a defrosting operation, and the control valve 2 is switched. In a refrigerating apparatus in which a cooling operation and a defrosting operation by hot gas are switched by an operation, a defrost detection means 27 for detecting the end of defrost, and a switching operation of the control valve 2 after the defrost detection means 27 detects the end of defrost The refrigerating apparatus is characterized by including an operation switching detecting means 28 for detecting whether the cooling operation is switched to the cooling operation.

The present invention is also a refrigeration system in which the operation switching detection means includes temperature detection means 28, 29 for detecting a temperature that changes in response to a temperature change in the inside of the refrigerator in which the evaporator 6 is provided.

The present invention is also a refrigeration system in which the operation switching detecting means includes temperature detecting means 30 and 31 for detecting a temperature that changes in accordance with a temperature change on the condenser 3 side.

The present invention is also the refrigeration system in which the operation switching detecting means includes a pressure detecting means for detecting the pressure in the refrigerant pipeline in which the refrigerant pressure changes when the control valve 2 is switched.

Further, according to the present invention, the operation switching detecting means 2 is provided.
8 is characterized in that the detection operation is performed after a predetermined time has passed after the completion of defrosting.

[0014]

According to the present invention, the defrost detection means 27 detects that the defrost operation by the hot gas has ended. After the end of the defrost is detected, the operation switching detection means 28 operates to detect whether the cooling operation has been switched. At the end of defrost,
For example, when the control valve 2 such as the four-way switching valve is not normally switched to the cooling operation side because the pressure difference in the refrigeration cycle is not so large in the gas shortage operation, the operation switching detection means 28 This abnormal state is detected. By detecting the abnormal state, for example, the cooling operation can be stopped or / and the alarm output can be performed.

When the cooling operation is stopped, the hot gas flow into the evaporator 6 is stopped, so that the temperature rise inside the refrigerator is prevented. Further, by outputting an alarm at the same time when the cooling operation is stopped, the user is notified of an abnormal state, and necessary measures such as operation stop or manual forced switching of the control valve 2 are taken to maintain the quality of the stored goods in the refrigerator. it can.

[0016]

FIG. 1 is a device circuit diagram of a refrigerating machine according to an embodiment of the present invention. The embodiment shown in FIG. 1 includes an outdoor unit A installed in a machine room or outdoors, and an indoor unit B installed in a refrigerator or freezer room. The outdoor unit A includes a compressor 1, a control valve 2 realized by a four-way switching valve, a condenser 3 of air type, a capillary tube 9 and a check valve 11 which are connected in parallel and are formed as a defrosting pressure reducing device. 4, an accumulator 7, a compressor accumulator 8, a dryer 21, a closing valve 22 and a closing valve 23 are provided. The indoor unit B includes a temperature-sensitive expansion valve 10 and a check valve 12
Cooling decompression device 5 formed by connecting in parallel, evaporator 6, check valve 13, check valve 14, fan guard heater 1
5, a drain pan heater 16 and a filter 20 are provided.

In the outdoor unit A, the compressor 1 has a discharge port connected to the high-pressure port of the four-way switching valve 2 by a gas line, and an intake port connected to the outlet of the accumulator 7 by a gas line equipped with a compressor accumulator 8. Connected. The low pressure port of the four-way switching valve 2 is connected to the inlet of the accumulator 7 by a gas pipeline. One switching port is connected to the gas side end of the coil of the condenser 3 by the gas pipeline, and the other switching port serves as the gas pipeline 33.
Is connected to the gas side shutoff valve 22. The condenser 3 is
It is composed of an air-to-air coil equipped with a fan 17, and a liquid side end port of the coil is connected to a defrosting low-pressure side outlet of the defrosting pressure reducing device 4 by a liquid line. The defrosting decompression device 4 has a defrosting high-pressure side inlet connected to the liquid-side shutoff valve 23 by a liquid pipe having a dryer 21.

In the in-compartment unit B, the cooling decompression device 5 has a cooling high-pressure inlet side connected to the liquid-side closing valve 23 via the filter 20, and a cooling low-pressure side outlet connected to the coil of the evaporator 6 by a liquid line. Is connected to the liquid side end port of. Evaporator 6
Consists of an air-to-air coil with a fan 18, the gas side end of which is connected via a check valve 13 to a gas side closing valve 22. The evaporator 6 is provided with a fan guard heater 15 and a drain pan heater 16 to form a series refrigerant circuit of the check valve 14, the fan guard heater 15 and the drain pan heater 16, and this circuit is connected to the check valve. It is connected in parallel with 13 and formed so that the refrigerant is guided only during the defrost operation.

In the embodiment shown in FIG. 1, a high pressure switch 26 for protecting the discharge gas pressure of the compressor 1 from being higher than a set pressure and a high pressure switch for detecting the high pressure during defrosting. And a device 25 are provided in the outdoor unit A, while a defrost end thermometer 27 for detecting the coil temperature of the evaporator 6 to know the completion of the defrost operation is provided in the indoor unit B, and further detects the temperature in the freezer. An internal temperature thermostat 28 is attached to control the cooling operation and the defrosting operation.

In the above embodiment, the four-way switching valve 2 is switched to perform the cooling operation and the defrost operation alternately. In the case of the cooling operation, the compressor 1, both fans 17 and 18 are operated, and the four-way switching valve 2 is in a non-excited state,
The refrigerant becomes the flow indicated by the solid arrow in FIG. 1, and the condenser 3 radiates the condensation latent heat to the outside air, and the evaporator 6 cools the inside of the warehouse by heat exchange between the evaporation latent heat and the inside air. Be seen. This cooling operation is continued for 3 hours by the timer control, and during that time, the start / stop control of the compressor 1 is automatically performed so that the inside temperature is kept constant by the inside temperature thermo 28. Further, the opening degree of the temperature-sensitive expansion valve 10 is adjusted according to the degree of superheat of the refrigerant detected by the temperature-sensitive cylinder 24.

When the cooling operation is continued for 3 hours, the cooling operation is switched to the defrost operation by the timer control.
In the case of the defrost operation, the compressor 1 continues to operate, both fans 17 and 18 are stopped, and the four-way switching valve 2 is excited and switched. The refrigerant becomes a flow indicated by a broken line arrow in FIG. 1, and hot gas sequentially flows through the fan guard heater 15, the drain pan heater 16, and the coil of the evaporator 6, and the check valve 1
After passing through 2, the operation that flows to the outdoor unit A side is performed, so that the frost adhering to the evaporator 6 is melted by the retained heat of the hot gas. The end of defrost
It is detected by the defrost detecting means. In this defrost detection means, the coil temperature detected by the defrost end thermo 27 provided in the evaporator 6 becomes 25 ° C. or the hot gas pressure becomes 21 kg / cm ² and the high pressure switch 25 operates. Either outputs the defrost end signal. When the guard timer measures the defrost operation time and the defrost detection means does not output the defrost end signal even after one hour has passed, the defrost is forcibly ended, and the defrost end signal is output. Is issued, the defrost operation is switched to the cooling operation.

FIG. 2 is a flow chart showing a mode of operation control in the control circuit 19 provided in the embodiment shown in FIG. Such a control circuit 19 is realized by including a microcomputer and the like. When the defrost detecting means outputs the defrost end signal in step n1, the process immediately proceeds to step n2, and the defrost operation is switched to the cooling operation. Simultaneously with this switching of the cooling operation, the process proceeds to step n3, the cooling operation time t is measured, and when a predetermined time t1 that is predetermined, for example, 5 minutes is reached, the process proceeds to the next step n4, and the inside temperature is kept. The temperature T in the refrigerator is checked by the thermo 28. When the inside of the refrigerator is set to 0 ° C., for example, the inside set temperature Tx is set to 10 ° C. When the inside of the refrigerator is set to −20 ° C., for example, the inside set temperature Tx is It is set at 0 ° C. When the temperature T in the refrigerator is lower than the set temperature Tx after 5 minutes have passed from the start of the cooling operation, the process proceeds to step n6, and the cooling operation time t
Is measured, and even when a predetermined time t2, for example, 5 minutes has elapsed and a total of 10 minutes has elapsed, if T <Tx, it is determined that the switching to the cooling operation is normally performed.
The process proceeds to step n7 and the cooling operation is continued as it is.

On the other hand, whether t1 = 5 minutes has elapsed from the start of the cooling operation and whether the internal temperature T is equal to or higher than the set temperature Tx, or even if T <Tx at that time, t2 = 5 minutes still elapses. If either T ≧ Tx by the time
Moving to step n5, the cooling operation is stopped, and at the same time, the buzzer sounds or the warning light is ignited to notify the abnormality. Thus, when the first 5 minutes have passed, or a total of 1
The fact that the temperature in the freezer does not drop below the set temperature Tx by the time it reaches 0 minutes means that the four-way switching valve 2 does not switch normally due to some circumstances, and normal cooling operation is not performed. . Therefore, it is necessary to stop the operation by determining that the operation is abnormal. In this case, the operation of steps n3, n4 and n6 corresponds to the operation of the operation switching detection means, and the operation of step n5 corresponds to the operation of the control means.

In the above-described embodiment, the operation switching detecting means for detecting whether the cooling operation is switched to the normal cooling operation by the switching operation of the control valve 2 after the detection of the defrost end detects the temperature inside the storage. Although it is configured by the inside temperature detecting means having the temperature thermo 28 as an element, the present invention also includes an operation switching detecting means in addition to the outside unit A.
It is of course possible to consider various modified examples such as a method of detecting the temperature on the side and a method of detecting the change of the temperature or pressure of the refrigerant in the refrigeration cycle.

In another embodiment of the present invention, in the apparatus shown in FIG. 1, as shown by a broken line, the blown air temperature thermostat 30 for detecting the temperature of the air blown from the condenser 3 of the outdoor unit A or the condenser. A coil temperature thermostat 31 for detecting the coil temperature of the container 3 is provided, and step n4 in FIG.
It is possible to detect that temperature and judge that the cooling operation is normally performed if the temperature is higher than the preset reference temperature.

In still another embodiment, as shown by a broken line in the apparatus shown in FIG. 1, the temperature of the refrigerant pipe 33 connecting the switching port of the four-way switching valve 2 and the gas side closing valve 22 is controlled. A refrigerant gas temperature thermostat 32 for detection is provided,
Alternatively, a thermo 29 for detecting the coil temperature of the evaporator 6 is provided, the temperature is detected in step n4 in FIG. 2, and if the cooling operation is normally performed, the temperature becomes low corresponding to the low pressure refrigerant, When the heating operation is performed, the temperature rises corresponding to the high-pressure refrigerant. Therefore, it is possible to easily and surely determine whether or not the cooling operation is performed by the change in the temperature.
This determination can also be made easily and surely by detecting the pressure in the refrigerant conduit 33.

As still another embodiment, the apparatus shown in FIG. 1 adopting the method of detecting the pressure in the liquid pipe connecting the condenser 3 and the defrosting depressurizing apparatus 4 is adopted. In this case, a high value is detected at a high pressure in the cooling operation, and a low value is detected at a low pressure in the defrost operation. Therefore, the operation switching state can be detected by detecting the pressure change in step n4 in FIG. Is possible. In the case where such a pressure detection method is adopted, the condition of time measurement by the timer in the flowchart shown in FIG. 2 may be shorter than that in the case of the temperature detection method, for example, t1 = t2≈20 seconds is sufficient. is there.

In each of the above embodiments, the defrosting operation is realized by the device that performs the refrigerant circulation cycle in the opposite direction to the cooling cycle. However, the present invention defrosts the heat held by the refrigerant of the device itself. Other examples may be used as long as they can be used as a heat source. For example, it is also applied to a simple hot gas defrosting method in which hot gas is guided to an evaporator by bypassing a condenser coil and a cooling decompression device. It is preferable to use the device of the present invention because opening / closing operation may not occur due to "bite", and such modified examples are naturally included in the scope of the present invention.

[0029]

As described above, according to the present invention, when the defrosting operation by the hot gas is finished and the operation is switched to the cooling operation, the operation switching detecting means 28 performs the cooling operation such as the inside temperature, the refrigerant pressure and the temperature. A phenomenon that changes depending on whether or not the operation is normally performed can be detected, and if the normal cooling operation is not switched, the operation can be stopped or an alarm can be output. Therefore, when the control valve 2 such as the four-way switching valve does not operate normally and the defrost operation is continued even though the switching command is issued, it is necessary to quickly respond to the normalization. Therefore, it is possible to prevent the quality deterioration of the goods stored in the refrigerator.

[Brief description of drawings]

FIG. 1 is a device circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation control circuit 1 in the embodiment shown in FIG.
9 is a flowchart showing a control mode of No. 9.

FIG. 3 is a flowchart showing a mode of operation control of a refrigeration system which is a prior art.

[Explanation of symbols]

 1 Compressor 2 Control valve 3 Condenser 4 Defrosting depressurizer 5 Cooling depressurizer 6 Evaporator 9 Capillary tube 10 Temperature-sensitive expansion valve 19 Control circuit 27 Defrost end thermo 28 Storage temperature thermo 29 Evaporator coil temperature Thermo 30 Condensation Air temperature thermostat 31 Coolant temperature of condenser coil 32 Thermostat of refrigerant gas temperature 33 Refrigerant pipeline

Claims (5)

[Claims] 1. A compressor 1, a condenser 3, a cooling pressure reducing device 5,
An evaporator 6, a control valve 2 that switches between a cooling operation and a defrost operation, and a refrigeration apparatus that switches between a cooling operation and a defrost operation by hot gas by the switching operation of the control valve 2 detects that defrost has ended. A refrigeration system including defrost detection means 27 and operation switching detection means 28 for detecting whether or not the cooling operation is switched by the switching operation of the control valve 2 after the defrost detection means 27 detects the end of defrost. . 2. The operation switching detection means 28 includes temperature detection means 28, 29 for detecting a temperature that changes in accordance with a temperature change in a refrigerator in which the evaporator 6 is installed. The refrigeration system described. 3. The refrigerating apparatus according to claim 1, wherein the operation switching detecting means 28 includes temperature detecting means 30 and 31 for detecting a temperature that changes corresponding to a temperature change on the condenser 3 side. . 4. The refrigerating apparatus according to claim 1, wherein the operation switching detecting means 28 includes a pressure detecting means for detecting the pressure in the refrigerant pipe line in which the refrigerant pressure changes when the control valve 2 is switched. . 5. The refrigerating apparatus according to claim 2, 3 or 4, wherein the operation switching detecting means 28 is adapted to perform a detecting operation after a lapse of a predetermined time after the completion of defrosting.