JPH0539974A - Cooling device - Google Patents

Abstract

PURPOSE:To control the rate of rotation of a blower for evaporator to suppress the reduction of airflow rate and deterioration of cooling capacity due to frost on the evaporator with the temperature difference between a storage room and evaporation. CONSTITUTION:Temperature sensors 8, 9 are provided at an outlet pipe section of an evaporator 4 and adjacent to materials to be stored in a storage room. And a controller 10 to periodically receive signals generated from these temp. sensors 8, 9, is provided, and at each time of reception, the temp. difference between both signals is calculated and the rate of rotation of a blower 6 for evaporator is controlled corresponding to the extent. Thus, the reduction of airflow rate and deterioration of cooling capacity due to frost in a cooling operation can be suppressed, and the start of defrosting is delayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cooling device used in a refrigerator.

[0002]

2. Description of the Related Art FIG. 5 is a refrigerant circuit diagram of a conventional cooling device disclosed in, for example, Japanese Patent Application Laid-Open No. 62-196581. In the figure, 1 is a compressor, 2 is a condenser, 3 is an expansion valve, and 4 is an evaporator for exchanging heat with the inside air of a refrigerator (not shown) blown by an evaporator blower 6 to cool the inside air. Then, a refrigeration cycle is configured by sequentially connecting these with refrigerant pipes. Reference numeral 7 is a bypass pipe for bypassing the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 to the evaporator 4, and 7 A is a solenoid valve provided in the middle of the bypass pipe 7.

Next, the operation will be described. During cooling operation,
The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 exchanges heat with a cooling fluid such as outside air in the condenser 2 to be condensed and liquefied. Then, the pressure is reduced by the expansion valve 3 to become a low temperature, low pressure liquid refrigerant. Thereafter, the liquid refrigerant enters the evaporator 4, heat-exchanges with the inside air of the refrigerator blown by the blower 6 for the evaporator, and the inside air is cooled, whereby the inside of the refrigerator (not shown) is cooled. When the above cooling operation is continued, frost 11 adheres to the evaporator 4 as shown in FIG. 6, the static pressure applied to the fan 5 of the evaporator blower 6 increases, and the rotation speed of the fan 5 decreases. As a result, the air volume is reduced, and the performance of the evaporator 4 is reduced from Q ₂ to Q ₁ as shown by the chain double-dashed line in FIG. Therefore, the defrosting timer (not shown) regularly defrosts. When a defrosting timer (not shown) operates, the electromagnetic valve 7A is opened, and the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 is guided to the evaporator 4 through the bypass pipe 7 and the electromagnetic valve 7A. Then, the frost 11 attached to the evaporator 4 is defrosted by being melted by the high temperature gas refrigerant. Then, the refrigerant returns from the evaporator 4 to the compressor 1.

[0004]

Since the conventional cooling device is constructed as described above, defrosting occurs because the amount of air blown by the evaporator blower decreases due to the effect of frost on the evaporator, resulting in a decrease in cooling capacity. Has to be increased, and if the frequency of defrosting is increased, there is a problem in that the temperature inside the refrigerator increases due to the influence of the high-temperature gas refrigerant flowing into the evaporator during defrosting.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to suppress a decrease in the cooling capacity due to a decrease in the air volume of the evaporator blower due to frost formation on the evaporator and to reduce the number of defrosting times. An object of the present invention is to obtain a cooling device that can be reduced in amount and has a small influence on the temperature inside the high-temperature gas refrigerant flowing in the evaporator during defrosting.

[0006]

A cooling device according to the present invention detects the evaporation temperature of a refrigerant in an evaporator for exchanging heat with the air in a refrigerator blown by an evaporator blower to cool the air in the refrigerator. And a second temperature sensor for detecting the temperature inside the refrigerator, and the first temperature sensor
And the number of revolutions of the evaporator blower is controlled according to the temperature detected by the second temperature sensor.

[0007]

In the cooling device according to the present invention, the number of revolutions of the evaporator blower is controlled according to the evaporation temperature of the evaporator and the internal temperature of the refrigerator detected by the first and second temperature sensors, and the frost is formed on the evaporator. The decrease in the air volume and the decrease in the cooling capacity due to are suppressed, the cooling operation time becomes longer until the defrosting starts, and the number of defrosting decreases.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A refrigerant circuit diagram of a cooling device according to an embodiment of the present invention shown in FIG. 1 will be described below. 1 is different from FIG. 5 in that the first temperature sensor 8 for detecting the evaporation temperature of the refrigerant in the evaporator 4 is provided in the outlet pipe of the evaporator 4 and near a stored product of a refrigerator (not shown). A second temperature sensor 9 for detecting the temperature inside the storage compartment, etc. is provided in the vicinity of the stored goods inside the storage compartment, and the temperatures detected by the first and second temperature sensors 8 and 9 are periodically input. The point is that the controller 10 is provided to control the number of rotations of the evaporator blower 6 that blows air to the evaporator 4 depending on the detected temperature.

Next, the operation will be described with reference to FIGS. 2 is a flowchart showing the operation of the controller shown in FIG. 1, and FIG. 3 is a diagram showing the relationship between the cooling capacity Q of the evaporator and the temperature difference TD (TD = internal temperature RT−evaporation temperature ET), FIG. 4 is a diagram showing the relationship between the cooling capacity Q of the evaporator and the time T. The cooling operation is performed in the same manner as the conventional one, and the inside air is cooled by heat exchange with the evaporator 4, and the inside of the refrigerator (not shown) is cooled. The performance of the evaporator 4 in the non-frosting state is the temperature difference TD (TD = internal temperature RT−evaporation temperature E) with the cooling capacity Q ₂ as shown by the one-dot chain line in FIG.
(Defined as T) becomes TD ₁ , and when frost forms, the static pressure of the evaporator 4 increases due to the frost, the rotation speed of the evaporator blower 6 decreases, and the air volume also decreases. Since it also decreases, the two-dot chain line shows, the cooling capacity Q decreases to Q ₁ , and the temperature difference TD becomes TD ₂ . These temperature differences TD ₁ and TD ₂ are set in the controller 10 as reference values. And the controller 10 has a first
And the evaporator 4 detected by the second temperature sensors 8 and 9.
The evaporation temperature ET of the refrigerant and the internal temperature RT of the refrigerator in step 10-1 are input at step 10-1 periodically, for example, every 10 seconds, and the temperature at that time is based on the input evaporation temperature ET and internal temperature RT. The difference TD is calculated in step 10-2, and the calculated temperature difference TD is compared with the set temperature difference TD ₂ to determine the temperature difference TD.
If it is ₂ or more, the rotation speed of the evaporator blower 6 is increased by a predetermined rotation speed. As the rotation speed increases, the amount of air blown from the evaporator blower 6 to the evaporator 4 increases, the cooling capacity increases, and the temperature difference TD also becomes TD ₁ <TD <TD ₂ and the one-dot chain line and the two-dot chain line in FIG. Enter the proper range between. In addition, the limit of the increase in the air volume at this time is set in advance so that the air volume does not affect the stored goods in the refrigerator. If the temperature difference TD is less than or equal to the temperature difference TD ₂ , step 10-3
The process proceeds, is compared with the temperature difference TD ₁ at step 10-3, as small as a predetermined rotational speed a rotational speed of the evaporator blower 6 if the temperature difference TD ₁ or less. As a result, the amount of air blown to the evaporator 4 is reduced, and both the cooling capacity Q and the temperature difference TD are within proper ranges. Also in comparison with the temperature difference TD _1, if the temperature difference TD ₁ or more, since that will be the temperature difference TD, cooling capacity both proper range, the rotational speed of the evaporator blower 6 is maintained. The above operation is the temperature sensor 8,
It is repeated every time the detected temperature of 9 is input, and the rotation speed of the evaporator blower 6 is controlled according to the temperature difference TD. Therefore, the decrease in the air volume and the decrease in the cooling capacity due to the frost on the evaporator 4 are suppressed. When the rotation speed control of the blower for the evaporator is performed as indicated by the one-dot chain line in FIG. 4, the cooling operation time up to the start of defrosting becomes longer than when the rotation speed control indicated by the solid line is not performed. Then, a defrosting timer (not shown) is set with a cooling operation time until the defrosting is started, for example, 6 hours, and by this set time, defrosting is regularly performed in the same manner as in the past and the number of defrosting is reduced. .

[0010]

As described above, according to the present invention, the number of revolutions of the evaporator blower is controlled according to the temperature difference between the evaporation temperature of the refrigerant in the evaporator and the internal temperature of the refrigerator. It is possible to suppress the decrease in air volume and cooling capacity due to frost during operation, it is possible to extend the cooling operation time until the start of defrosting, the number of defrosting is reduced, and the temperature rise in the refrigerator is suppressed. Has the effect of.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a cooling device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the controller shown in FIG.

FIG. 3 is a diagram showing a relationship between a cooling capacity Q of an evaporator and a temperature difference TD.

FIG. 4 is a diagram showing a relationship between a cooling capacity Q of an evaporator and time.

FIG. 5 is a refrigerant circuit diagram of a conventional cooling device.

FIG. 6 is a diagram showing a frosted state on the evaporator.

FIG. 7 is a diagram showing a relationship between a cooling capacity Q of an evaporator and a temperature difference TD.

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Expansion valve 4 Evaporator 5 Fan 6 Blower for evaporator 8 1st temperature sensor 9 2nd temperature sensor 10 Controller

Claims (1)

[Claims] 1. A compressor, a condenser, a decompression device, and an evaporator for exchanging heat with the inside air of a refrigerator blown by a blower for an evaporator to cool the inside air by a refrigerant pipe. In a cooling device including a refrigeration cycle including the above, a first temperature sensor that detects an evaporation temperature of a refrigerant in the evaporator, a second temperature sensor that detects an internal temperature of the refrigerator, and the first and the second temperature sensors. And a controller for controlling the number of revolutions of the evaporator blower according to the temperature detected by the temperature sensor (2).