JP2000055486A - Refrigeration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration device capable of restricting deterioration of an evaporator air amount and refrigeration capacity upon frosting with stable control. SOLUTION: First, an initial air volume (air volume upon non-frosting in a refrigerant evaporator) of an air fan 1 is set to an air volume where effective refrigeration capacity of a refrigeration machine is maximum. Thereafter, when a blowoff air speed from a refrigerant evaporator 5 is lowered, an air blowing level (revolutions of a motor) of the air fan 1 is increased stepwise until it reaches a previously set maximum air volume level. When the air blowing level of the air fan 1 reaches the maximum air volume level, the air blowing level (the maximum air volume level) is kept intactly for a predetermined time, and then when the blowoff air speed from the refrigerant evaporator 5 is lowered to a blowoff air speed previously set, defrosting operation is executed. Hereby, cooling-down time is reduced, and the evaporator air volume and the refrigeration capacity are prevented from being lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus used for a cool box or the like.

[0002]

2. Description of the Related Art As a prior art, Japanese Patent Application Laid-Open No. 5-39974 is disclosed.
There is a cooling device disclosed in Japanese Patent Publication No. This cooling device
By controlling the number of rotations of the evaporator blower according to the magnitude of the temperature difference between the evaporator outlet pipe and the vicinity of the storage items in the refrigerator, it is possible to suppress a decrease in the evaporator air volume and a decrease in cooling capacity due to frost formation. Things.

[0003]

However, when the compressor is driven by the vehicle engine, the rotation speed of the compressor fluctuates due to the fluctuation of the engine speed, and the temperature of the evaporator outlet pipe also fluctuates. Therefore, there arises a problem that the temperature difference between the evaporator outlet pipe portion and the vicinity of the stored goods in the storage fluctuates and stable control cannot be performed. For this reason, it is difficult to suppress a decrease in the evaporator air volume and a decrease in the cooling capacity due to frost formation during the freezing (cooling) operation.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a refrigeration apparatus capable of suppressing a decrease in an evaporator air volume and refrigeration capacity during frost formation by stable control.

[0005]

According to the present invention, the amount of air blown to the refrigerant evaporator when the effective refrigeration capacity of the refrigeration system is maximized is set as the initial air flow of the blower, and the refrigerant evaporates. The number of rotations of the blower is controlled so that the amount of blown air blown out through the fan becomes substantially equal to the initial amount of air. In this case, since it is not necessary to control the rotation speed of the blower based on the temperature of the evaporator outlet pipe unlike the related art, stable control can be performed irrespective of fluctuations in the engine rotation speed.
Note that the effective refrigerating capacity of the refrigerating apparatus is obtained by subtracting the power consumption of the blower from the refrigerating capacity of the refrigerating apparatus.

In addition, by setting the amount of air blown to the refrigerant evaporator when the effective refrigeration capacity of the refrigeration system is maximized as the initial air flow of the blower, the inside of the refrigerator can be most efficiently cooled down (rapid cooling). , Can reduce its cooldown time. Furthermore, at the time of frost formation of the refrigerant evaporator, the rotation speed of the blower is increased to increase the amount of air blown to the refrigerant evaporator so that the amount of air blown out through the refrigerant evaporator is substantially equal to the initial air amount of the blower. By doing so, it is possible to suppress a decrease in the evaporator air volume and the refrigeration capacity.

When the refrigerant evaporator is frosted, the wind speed of the air blown from the refrigerant evaporator is detected by a wind speed sensor, and the wind speed detected by the wind speed sensor is substantially equal to the wind speed of the blower at the time of the initial air flow. The number of rotations of the blower is controlled to be equal.
Thereby, even at the time of frost formation, the amount of air blown from the refrigerant evaporator can be made substantially equal to the initial amount of air from the blower.

(3) The defrosting operation is performed when the wind speed detected by the wind speed sensor decreases to the preset wind speed after the rotational speed of the blower reaches the preset maximum revolution speed. . By this control, the defrosting operation can be performed efficiently. After the rotation speed of the blower has reached a preset maximum rotation speed, the maximum rotation speed may be maintained for a certain period of time, and then the defrosting operation may be performed.

[0009]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a refrigeration cycle diagram of the refrigeration apparatus. The refrigeration apparatus of the present embodiment is applied to, for example, a cool box that stores food items and the like, and includes a refrigeration cycle S that is a cooling unit for cooling (or freezing) the inside of the cool box.
Control means (described later) for controlling the operation of the blower 1 used for the refrigeration cycle S is provided.

The refrigeration cycle S has a refrigerant compressor 2, a refrigerant condenser 3, an expansion valve 4, and a refrigerant evaporator 5, and is constituted by connecting these functional components by a refrigerant pipe 6. In the refrigeration cycle S, a bypass passage 7 for bypassing the refrigerant condenser 3 and the expansion valve 4 and guiding the high-temperature refrigerant discharged from the refrigerant compressor 2 to the refrigerant evaporator 5 is provided. An electromagnetic valve 8 that opens and closes is provided.

The blower 1 blows the air in the cool box to the refrigerant evaporator 5 and circulates the air. The fan 1A and the motor 1
B. The control unit outputs to the motor controller 9 a motor controller 9 for varying the motor rotation speed of the blower 1 and a control signal for instructing an increase in the air volume of the blower 1 when the blowing air speed of the refrigerant evaporator 5 decreases. And a wind speed calculator 10. The wind speed calculator 10 has a built-in microcomputer (not shown), and the blower 1
An arithmetic expression, a control program, and the like necessary for operation control of the computer are input.

[0012] The above "blowing wind speed of refrigerant evaporator 5"
Is the wind speed of the air blown from the blower 1 passing through the refrigerant evaporator 5 and detected by the wind speed sensor 11 arranged downstream of the refrigerant evaporator 5 on the air side (blowing side). You.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. First, the blowing level (initial air volume) of the blower 1 is determined (S10). Here, the initial air volume of the blower 1 (the air volume when the refrigerant evaporator 5 is not frosted) will be described.

In the refrigeration system, the refrigeration capacity increases as the amount of air blown to the refrigerant evaporator 5 increases. However, when it increases to a certain extent, as shown in the graph of FIG. 3, the increase in the refrigerating capacity reaches a plateau (trace amount) with the increase in the air flow. on the other hand,
As shown in the graph of FIG. 3, the motor power consumption of the blower 1 increases in a quadratic curve with an increase in the air volume.

As a result, the effective refrigeration capacity (the amount of heat exhausted from the cool box) obtained by subtracting the motor power consumption from the refrigeration capacity of the refrigeration system is, as shown in the graph of FIG. It increases while the rate of increase in power is smaller, but decreases when the rate of increase in motor power consumption is greater than the rate of increase in airflow.

In other words, the effective refrigeration capacity is maximum (FIG. 3
At point A) and the motor power consumption. Therefore, if the air volume when the refrigerant evaporator 5 is not frosted is set to the air volume (motor power consumption) at which the effective refrigeration capacity is maximized, the cool down time can be reduced and the energy saving effect can be obtained. For the above reasons, the initial air volume of the blower 1 is set to the air volume at which the effective refrigeration capacity of the refrigeration system is maximized.

After the initial air volume of the blower 1 is determined, the sensor value of the wind speed sensor 11 is read (S20). continue,
Based on the read sensor value, it is determined whether or not the blowing wind speed of the refrigerant evaporator 5 is decreasing (S30). here,
The sensor value of the wind speed sensor 11 is compared with the wind speed of the blower 1 at the time of the initial air flow. If the sensor value is lower than the wind speed at the time of the initial air flow by a predetermined value or more, the blowing air speed of the refrigerant evaporator 5 decreases. Judge that there is.

If the result of the determination in S30 is NO, that is, if the blowing air speed of the refrigerant evaporator 5 has not decreased, it can be determined that the refrigerant evaporator 5 is not frosted.
Return to If the result of the determination in S30 is YES, that is, if the blowing speed of the refrigerant evaporator 5 is decreasing, the blowing level (motor rotation speed) of the blower 1 is increased by one step (S4).
0).

Subsequently, the air blowing level of the air blower 1 is set to a preset maximum air volume level (maximum rotation speed of the motor 1B).
Is determined (S50). If this determination result is NO, that is, if the air blowing level of the blower 1 has not reached the maximum air volume level, the process returns to S20 again. If the result of the determination in S50 is YES, that is, if the air blowing level of the blower 1 has reached the maximum air volume level, the air blowing level (maximum air volume level) is maintained for a predetermined time (S60).

After a lapse of a predetermined time, it is determined whether or not the sensor value of the wind speed sensor 11 has decreased to a preset blowing wind speed (S70). If the result of this determination is YES, that is, if the sensor value has dropped to the preset blowout wind speed, the blowing level of the blower 1 cannot be raised any more, so the defrosting operation is executed (S80). This defrosting operation is performed by opening the solenoid valve 8 provided in the bypass passage 7 of the refrigeration cycle S. After executing the defrosting operation, the process returns to S10 and sets the initial air volume of the blower 1 again.

(Effect of this embodiment) In this embodiment, the air flow when the effective refrigeration capacity of the refrigeration system is maximized is determined by the blower 1
Is set as the initial air volume, and the blowing air speed of the refrigerant evaporator 5 is compared with the air speed at the initial air volume to determine the frost formation of the refrigerant evaporator 5. In this case, since there is no need to control the rotation speed of the blower 1 based on the temperature of the evaporator outlet pipe unlike the related art, stable control can be performed regardless of fluctuations in the engine rotation speed.

Further, by setting the air flow when the effective refrigeration capacity of the refrigeration system is maximized as the initial air flow of the blower 1, the inside of the refrigerator can be most efficiently cooled down (rapid cooling). Can be shortened, and an energy saving effect can be obtained.

Further, at the time of frost formation of the refrigerant evaporator 5, the motor rotation speed of the blower 1 is increased so that the blown air velocity of the refrigerant evaporator 5 becomes substantially equal to the wind velocity at the time of the initial air flow. , The decrease in the evaporator air volume and the refrigerating capacity can be suppressed. This will be described with reference to FIG.
Comparing the case where the frost is formed from the air volume A and the case where the frost is formed from the air volume B which is larger than the air volume A, the refrigeration capacity when the frost is reduced to the same effective refrigeration capacity C and D is larger than the air volume A. Since the amount of frost is greater when frost is formed from above, it can be said that the refrigeration capacity is higher by that much.

Thus, in the present embodiment, in order to shorten the cool down time, the air volume A when the effective refrigerating capacity of the refrigerating device is maximized is set as the initial air volume of the blower 1. Since the airflow level of the blower 1 is increased in accordance with the frost formation, the effect of suppressing the decrease in the refrigerating capacity is obtained from the above description, in addition to the effect of shortening the cool down time.

(Modification) In the above-described embodiment, the blower 1
Although the control example in which the air blowing level is increased by one stage has been described, the air volume level of the air blower 1 may be increased in accordance with the degree of decrease in the blowing air speed. After the motor rotation speed of the blower 1 reaches a preset maximum rotation speed, the state is maintained for a predetermined time, and then the blowing wind speed of the refrigerant evaporator 5 is determined. (S60) may be omitted.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram of a refrigeration apparatus.

FIG. 2 is a flowchart illustrating a control procedure of the refrigeration apparatus.

FIG. 3 is a graph showing an effective refrigeration capacity of the refrigeration apparatus.

FIG. 4 is a graph showing an effective refrigeration capacity of the refrigerant evaporator when frost is formed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 blower 5 refrigerant evaporator 9 motor controller (control means) 10 wind speed calculator (control means) 11 wind speed sensor

Claims (3)

[Claims] 1. A refrigeration system comprising: a refrigerant evaporator for cooling blast air by heat exchange with a low-temperature refrigerant flowing inside; a blower for blowing the refrigerant evaporator; and control means for controlling the rotation speed of the blower. The apparatus, wherein the control means sets an air flow rate to the refrigerant evaporator when the effective refrigeration capacity of the refrigeration apparatus is maximized as an initial air flow rate of the blower, and blows out through the refrigerant evaporator. A refrigeration system, wherein the number of rotations of the blower is controlled such that a blown air volume to be blown is substantially equal to the initial air volume. 2. The apparatus according to claim 1, further comprising: a wind speed sensor for detecting a wind speed of air blown by the air blown from the blower through the refrigerant evaporator, wherein the control means detects a wind speed detected by the wind speed sensor. ,
The rotation speed of the blower is controlled to be substantially equal to the wind speed of the blower at the time of the initial air flow.
The refrigeration apparatus described in 1. 3. The defrosting operation is performed when the wind speed detected by the wind speed sensor decreases to a preset wind speed after the revolution speed of the blower reaches a preset maximum revolution speed. The refrigeration apparatus according to claim 2, wherein