JPH0875341A - Air cooling device with defrosting function - Google Patents

Abstract

PURPOSE: To expand a control temperature range and eliminate an auxiliary heater by a method wherein a heater is electrically energized during a defrosting operation and a non-defrosting operation of an evaporator and an amount of electrical energization is made larger at the defrosting time than that at the non-defrosting time. CONSTITUTION: During a defrosting time, an air blowing fan 16 and a condensor fan 23 are stopped, defrosting heaters 25 to 27 around an evaporator 7 are electrically energized or hot gas is fed into the evaporator 7 through a hot gas bypassing pipe 12 so as to remove frosts adhered to the evaporator 7. Under a normal operation, the heaters 25 to 27 around the evaporator 7 are electrically energized to be lower than that of the defrosting operation under a state in which a freezing cycle is being operated or a slight amount of hot gas is flowed to the evaporator 7 through the hot gas bypassing pipe 12 and its temperature is controlled under a state in which a certain load is applied to the evaporator 7. Also during the cooling operation, the heaters are partially operated to keep their set temperatures, so that a temperature of the refrigerator can be maintained at the set temperature without having any relation with a variation of surrounding air temperature and the control temperature range can be made wide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an air cooling device with a defrost function in a cooler used for cooling air or liquid.

[0002]

2. Description of the Related Art As a conventional defrosting method for an air cooling device, there are a method of defrosting every predetermined time based on a timer and a method of defrosting when the load of an evaporator is detected and the load becomes high. In any case, defrosting was performed by bypassing hot gas only when defrosting or by energizing a heater installed near the evaporator. However, no defrost heater is used during non-defrost.

[0003]

However, in such a conventional defrosting method, an auxiliary heating heater is indispensable for expanding the control temperature range, and a controller is required for temperature control, and a facility equipped with such equipment is required. Therefore, there is an inconvenience such as a large cost. Therefore, the present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide an air cooling device with a defrost function that can widen the control temperature range and does not need to provide an auxiliary heater.

[0004]

That is, according to the present invention, the invention of claim 1 is provided with an evaporator of a refrigeration cycle which is circulated and connected to a compressor, a condenser, an expansion valve, an evaporator, an evaporation pressure adjusting valve and the like. Air cooler, a blower fan installed on the air inlet side of the cooler, a temperature detecting means installed on the air outlet side of the cooler, a temperature t detected by the temperature detecting means and a set temperature t ₀ Comprising a controller for adjusting the opening of the evaporation pressure adjusting valve, a pressure switch for controlling the condenser fan provided in front of the condenser, and a defrost heater provided on the outer periphery of the evaporator, An air cooling device with a defrost function, wherein the heater is energized both during defrosting and non-defrosting of the evaporator, and the energization amount is greater during defrosting than during non-defrosting. Invention of An air cooler provided with an evaporator of a refrigeration cycle that is circulatively connected to a compressor, a condenser, an expansion valve, an evaporator, an evaporation pressure adjusting valve, and the like, and a blower fan installed on the air inlet side of the cooler. A temperature detecting means installed on the air outlet side of the cooler, a controller for comparing the detected temperature t by the temperature detecting means with a set temperature t _0, and adjusting the opening of the evaporation pressure adjusting valve; A pressure switch for controlling the condenser fan installed in front of the compressor, a hot gas bypass pipe connected between the compressor / condenser and the evaporator via a solenoid valve, and a hot switch connected between the compressor and the condenser. An air cooling device with a defrost function that opens and closes the solenoid valve so that the refrigerant flows through the hot gas bypass pipe during defrosting and the refrigerant flows through both the condenser and the hot gas bypass pipe during non-defrosting. is there.

[0005]

In the cooling device according to the present invention, when the defrosting is performed, the blower fan and the condenser fan are stopped and the defrost heater installed around the evaporator is energized, or the evaporator is connected via the hot gas bypass pipe. The evaporator is heated by blowing hot gas into it to remove frost from it. Next, in normal operation, with the refrigeration cycle activated, the heater installed around the evaporator is energized less than during defrosting, or a small amount of hot gas is passed through the hot gas bypass pipe to the evaporator. As a result, the temperature is controlled with the evaporator being loaded. That is, the temperature of the evaporator is controlled by adjusting the opening of the evaporation pressure adjusting valve in comparison with the temperature t detected by the temperature detecting means so as to maintain the set temperature t ₀ input to the controller. On the other hand, the condenser uses a condensing fan to condense the refrigerant sent from the compressor, but because the condenser fan control pressure switch is installed in front of the condenser, the condenser fan is
The load of the condenser is suppressed by stopping the fan when the refrigerant pressure is below a predetermined level or operating the fan when the pressure exceeds a predetermined level.

[0006]

1 shows a compressor 1, a solenoid valve 2, a condenser 4, a flow divider 5, expansion valves 6a, 6b and 6c, an evaporator 7a,
7b and 7c, a collector 8, an evaporating pressure adjusting valve 9, and an accumulator 10 in a refrigerating cycle that is circulated and connected between the compressor 1 and the solenoid valve 2 and between the evaporators 7a, 7b and 7c. The downstream side of the bypass pipe 12, which is connected via the bypass pipe 12, is branched by a flow divider 14 and connected to the evaporators 7a, 7b, 7c, respectively. A fan motor 16 is installed on the air inlet side of the cooler 15 in which the evaporators 7a, 7b, 7c of the refrigeration cycle are installed, and a temperature detecting means 18 is installed on the outlet side. Temperature detecting means 18
The detection result of is input to the controller 20, and the controller 2
0 adjusts the opening degree of the evaporation pressure adjusting valve 9 depending on whether the detected temperature t is higher than a preset temperature t ₀ input in advance. Two
Reference numeral 2 is a control device that turns on / off the fan motor 23 of the condenser and opens / closes the solenoid valves 2 and 3 based on the pressure detected by the evaporation pressure switch 21, and the control device 22 electromagnetically operates when the condenser 4 is defrosted. The valve 2 is closed and the solenoid valve 3 is fully opened. The solenoid valve 2 is opened and the solenoid valve 3 is slightly opened during cooling so that the refrigerating capacity of the evaporator 7 is lowered.

Next, FIG. 2 shows a second embodiment of the present invention, in which a refrigeration cycle evaporator 7 and a fan motor 16 are installed in a space partitioned by a casing 24 and a partition plate. The defrost heaters 25, 26 and 27 are installed around the outer periphery of the evaporator 7. The defrost heaters 25, 26 and 27 are energized in three phases during defrost as shown in FIG. At the time of control, it is connected so as to energize single phase. As a result, when each heater has 300 w, it has a total heater capacity of 900 w at the time of defrosting, but has 450 w of heater capacity when controlling the condenser fan. In the device according to the present embodiment having the above-described configuration, the following Table 1 is used.
And is controlled as shown in FIG.

[0008]

[Table 1]

In the apparatus according to the second embodiment having the above-mentioned configuration, the defrost control is performed as shown in FIG. That is, in the defrosted state, the fans 16 and 23
With the rotation of No. 2 stopped, a full-capacity current is passed through the defrost heater to remove the frost that has condensed on the evaporator 7. After defrosting, the defrost heaters 25, 2
The power of 6 and 27 is set to 450w, which is a half of the power, and the rotation of the condenser fan 23 is controlled to be turned on and off while the fan motor 16 is turned on. A pressure switch 21 is installed in front of the solenoid valve 2. For example, when the pressure of the switch is 19
When the pressure is over kg / cm ² , the fan 23 is turned on and the pressure is 12 kg.
The fan 23 is controlled so as to be turned off when it is less than / cm ² . In addition, the part that maintains the temperature at the set temperature is the cooler 15
The detected temperature t from the temperature detecting means 18 provided at the air outlet of the controller is input to the controller 20, and the controller 20 sets
The opening of the evaporation pressure adjusting valve 9 is changed depending on whether it is lower or higher than t ₀ to maintain the temperature. Further, in the case of the first embodiment of FIG. 1, instead of the heater capacities of 100% and 50% in FIG. 4, the solenoid valves 2 and 3 are opened and closed as described above to perform a similar operation. From the above, the apparatus according to the present embodiment can control the temperature in the range shown by the diagonal lines in FIG. 5, and as a result, can control the temperature in the range shown in FIG.

[0010]

As described above, the defrost control system according to the present invention is different from the conventional control system in that the heater (heating means) is partially operated during cooling to maintain the set temperature. The temperature inside the refrigerator can be maintained at the set temperature regardless of changes in the ambient temperature. As a result, the controlled temperature range is wider than that of conventional products, so that diversified products can be supplied. Further, in the device according to the present invention, the lower the ambient temperature, the more the load (heating) is applied to the evaporator, so that the amount of suction liquid in the compressor can be reduced, so that the life of the compressor can be extended.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a device according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view of an apparatus according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of an energization circuit for a heater of the device according to the second embodiment.

FIG. 4 is a flowchart showing control of the device according to the second embodiment.

FIG. 5 is a graph showing the relationship between ambient temperature and fan control of the device according to the second example.

FIG. 6 is a graph showing the relationship between the ambient temperature and the control temperature range of the device according to the second example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 3 Solenoid valve 4 Condenser 5 Flow divider 6 Expansion valve 7 Evaporator 8 Concentrator 9 Evaporation pressure control valve 10 Accumulator 12 Bypass pipe 14 Flow divider 16 Fan motor 18 Temperature detection means 20 Controller 21 Evaporation pressure Switch 22 Control device 23 Condenser fan 24 Casing 25, 26, 27 Defrost heater

Claims (2)

[Claims] 1. An air cooler in which an evaporator of a refrigeration cycle, which is circulatively connected to a compressor, a condenser, an expansion valve, an evaporator, an evaporation pressure adjusting valve, etc., is installed, and an air inlet side of the cooler. The blower fan, the temperature detecting means installed on the air outlet side of the cooler, and the temperature t detected by the temperature detecting means and the set temperature t ₀ are compared to adjust the opening degree of the evaporation pressure adjusting valve. It consists of a controller, a pressure switch for controlling the condenser fan provided in front of the condenser, and a defrost heater provided on the outer circumference of the evaporator.The defrost heater is provided to the heater both during defrosting and non-defrosting of the evaporator. An air cooling device with a defrost function, which is configured to be energized and have a larger amount of electricity when defrosted than when not defrosted. 2. An air cooler in which an evaporator of a refrigeration cycle, which is circulatively connected to a compressor, a condenser, an expansion valve, an evaporator, an evaporation pressure adjusting valve, etc. is installed, and an air inlet side of the cooler. The blower fan, the temperature detecting means installed on the air outlet side of the cooler, and the temperature t detected by the temperature detecting means and the set temperature t ₀ are compared to adjust the opening degree of the evaporation pressure adjusting valve. A controller, a pressure switch for controlling the condenser fan installed in front of the condenser, a hot gas bypass pipe connected between the compressor / condenser and the evaporator via an electromagnetic valve, the compressor and the condenser Consisting of a solenoid valve connected between
An air cooling device with a defrost function, characterized in that a solenoid valve is opened / closed so that a refrigerant flows through a hot gas bypass pipe during defrosting, and a refrigerant flows through both a condenser and a hot gas bypass pipe during non-defrosting.