JP3033260B2 - Defrosting control device for refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting control device for a refrigerating device such as a refrigerator mounted on a vehicle, a mobile refrigerator or a stationary refrigerator.

[0002]

2. Description of the Related Art Conventionally, in a refrigerator, for example, in order to prevent a decrease in refrigeration capacity due to frost formation on a cooler due to a freezing operation, a defrosting operation for removing frost from the cooler by appropriately suspending the freezing operation has been performed. I have. As described above, as a refrigerator that suspends the freezing operation and performs the defrosting operation, a refrigerator that suspends the freezing operation and performs the defrosting operation every time a predetermined time elapses by a timer, or an optical sensor provided near the cooler When the frost formation amount detected by the frost formation sensor configured as described above reaches the set frost formation amount, the refrigeration operation is interrupted and the defrosting operation is performed (
-31273 gazette).

[0003]

However, although the former refrigerator has a simple structure, it is difficult to keep the defrosting operation interval at an optimum value. That is, in the former refrigerator, as shown in the graph of FIG. 6, even when the amount of frost is small, the defrosting operation is performed after a certain period of time. descend.
Further, as shown in the graph of FIG. 7, since the defrosting operation is not started until a certain time has elapsed even if the amount of frost becomes too large, frost formation progresses and an excessive decrease in refrigeration capacity occurs. There were problems such as an increase in the temperature in the refrigerator. further,
The latter refrigerator has a complicated structure, and even when the chiller is not so frosted, when the frost is formed on the optical sensor, it is erroneously determined that the amount of frost is large and the defrosting operation is started. For example, it is difficult to maintain the defrosting operation interval at an optimum value. Therefore, the conventional refrigerator has a problem that it is difficult to keep the defrosting operation interval at an optimum value despite having a complicated structure. An object of the present invention is to provide a defrosting control device for a refrigeration system that can optimize a defrosting operation interval.

[0004]

SUMMARY OF THE INVENTION The present invention provides a refrigerating operation and a refrigerating operation.
Refrigerator that performs frost operation and detection that detects temperature outside the refrigerator
And a calculation unit for calculating the operation rate of the refrigerator.
The temperature outside the refrigerator detected by the detection unit and the calculation unit
The target of the defrosting operation interval is calculated from the calculated operation rate of the refrigerator.
Value and control the refrigerator based on the target value.
Control means, the target value of the defrosting operation interval,
The lower the outside temperature detected by the detector, the lower the temperature during defrosting operation.
The interval is set to be short, and the refrigerator is
Set so that the higher the operation rate, the shorter the defrost operation interval
Adopt the technical means to be done. Further, the refrigerator is provided with
The high-temperature refrigerant discharged from the medium compressor passes through the pressure reducing means.
And then flow to the refrigerant evaporator and return to the refrigerant compressor.
1 Refrigerant circulation circuit, high-temperature cold discharged from the refrigerant compressor
The medium is passed to the refrigerant evaporator after bypassing the pressure reducing means.
A second refrigerant circuit for flowing and returning to the refrigerant compressor; and
Disconnect the first refrigerant circuit and the second refrigerant circuit.
Switching means for switching, wherein the control means is
During the freezing operation of the refrigerator, the circulation circuit switching means is controlled.
To the first refrigerant circuit, and removes the refrigerator.
During the frost operation, the second circuit is controlled by controlling the circulation circuit switching means.
It is characterized by switching to a refrigerant circuit.

[0005]

According to the present invention, the target value of the defrosting operation interval is determined by paying attention to the fact that the refrigeration capacity decreases as the amount of frost increases and the operating rate of the refrigerator increases. Note that the target value of the defrosting operation interval is a value obtained indirectly from the outside temperature detected by the detection unit and the operation rate of the refrigerator calculated by the calculation unit, and thus has high reliability. Then, by controlling the defrosting operation interval of the refrigerator based on the target value of the defrosting operation interval, the defrosting operation interval of the refrigerator is maintained at an optimum value.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A defrosting control device for a refrigeration system according to the present invention will be described based on one embodiment shown in FIGS. Here, FIG.
(A) is a diagram showing a refrigeration cycle of a mobile refrigerator,
FIG. 1B is a diagram illustrating a defrosting control device for a mobile refrigerator. The mobile refrigerator defrost control device 1 includes a refrigeration cycle 2 and a computer 3. Refrigeration cycle 2
Is a refrigerator of the present invention, which has a known structure of a refrigerant compressor (compressor) 4, a refrigerant condenser (condenser) 5, a receiver 6, an expansion valve (decompression means) 7, a refrigerant evaporator (evaporator) 8, It comprises an accumulator 9 and a refrigerant pipe 10 for connecting them in a ring shape. Then, the refrigeration cycle 2 passes the high-temperature refrigerant discharged from the discharge port of the refrigerant compressor 4 through the refrigerant condenser 5 and the receiver 6, passes through the expansion valve 7, flows into the refrigerant evaporator 8, and passes through the accumulator 9 A first refrigerant circulation circuit that returns to the suction port of the compressor 4 and a high-temperature refrigerant discharged from the discharge port of the refrigerant compressor 4 (used as a refrigerant passage by stopping the electric fan 14)
5, a second refrigerant circuit, which flows through the bypass pipe 11 through the receiver 6, flows into the refrigerant evaporator 8, returns to the suction port of the refrigerant compressor 4 through the accumulator 9, a first refrigerant circuit, and a second refrigerant. It has a defrost valve 13 as a circulation circuit switching means for switching between the circuit and the circulation circuit.

[0007] A bypass pipe 11 bypassing the expansion valve 7 is connected between the receiver 6 and the refrigerant evaporator 8.
The coil 12 is energized (on) in the bypass pipe 11.
A defrost valve 13 is provided, which opens when it is pressed, and closes when the energization of the coil 12 is stopped (turned off). Also, the refrigerant condenser 5 and the refrigerant evaporator 8 are equipped with electric fans 14 and 15 for blowing air to them, respectively.

The computer 3 is a control means of the present invention, and includes an outside air temperature sensor 16 as a detecting unit for detecting the outside temperature of the refrigerator, an inside temperature sensor 17 for detecting the inside temperature of the refrigerator, and refrigerant evaporation. Based on the defrost release sensor 18 that detects the surface temperature of the heater 8, the operation mode such as the freezing operation mode, the cold-holding operation mode, and the defrosting operation mode is selected as shown in Table 1 below. Accordingly, the refrigeration operation relay 19 and the defrost operation relay 20 are turned on and off.

Further, the computer 3 is provided with an arithmetic unit 21 for obtaining the operation rate of the refrigeration cycle 2 from the on / off time of the refrigeration operation relay 19, and the outside temperature from the outside air temperature sensor 16 and the refrigeration cycle 2 from the arithmetic unit 21. The setting unit 22 sets the target value of the defrosting operation interval of the refrigeration cycle 2 by fuzzy control together with the operation rate of the refrigeration cycle 2 as shown in Table 2.
Built-in. Here, 23 is a power supply for applying an operating voltage to the computer 3.

[0010]

[Table 1]

In Table 1, * indicates that the setting unit 22 changes the start time of the defrosting operation mode according to the target value of the defrosting operation interval obtained from the outside temperature and the operation rate of the refrigeration cycle 2.

When the refrigeration operation relay 19 is turned on, the refrigerant compressor 4 and the electric fans 14, 15 are energized (ON).
When the power is turned off, the energization of the refrigerant compressor 4 and the electric fans 14 and 15 is stopped (OFF). When turned on, the defrosting operation relay 20 energizes the refrigerant compressor 4 and the defrosting valve 13 (O
N) Then, when turned off, the refrigerant compressor 4 and the defrost valve 13
Is stopped (OFF).

The operation of this refrigerator defrost control device 1 is shown in FIG.
A description will be given with reference to FIG. FIG. 2 is a flowchart showing an example of a main program of the computer. When the operating voltage is applied to the computer 3 from the power supply 23, the internal temperature Ti is first input from the internal temperature sensor 17 (step S1), and the internal temperature Ti is set to the set value Ts.
It is determined whether the temperature has risen (for example, 0 ° C.) or more (step S2). When the in-compartment temperature Ti is higher than the set value Ts (Yes), the refrigeration operation relay 19 is turned on as shown in Table 1 (step S3). As a result,
The refrigerant compressor 4 and the electric fans 14 and 15 are energized, and a low-temperature and low-pressure refrigerant flows into the refrigerant evaporator 8 to cool the air in the refrigerator. A so-called refrigeration operation is performed. Then, the determination in step S1 is repeated.

In step S2, when the internal temperature Ti has not risen above the set value Ts (No),
When the internal temperature Ti falls below the set value Ts, Table 1
As described above, the refrigeration operation relay 19 is turned off (step S4). As a result, the energization of the refrigerant compressor 4 and the electric fans 14 and 15 is stopped, and the cooling operation is performed. Note that the cold keeping operation and the freezing operation may be performed with a certain hysteresis.

After performing the control in step S4, the outside temperature To is input from the outside temperature sensor 16 (step S4).
5) The operation unit 21 calculates the operation rate of the refrigeration cycle 2 from the ON / OFF time of the refrigeration operation relay 19 (step S6). Then, the setting unit 22 sets the target value of the defrosting operation interval of the refrigeration cycle 2 by fuzzy control by combining the outside temperature To and the operation rate of the refrigeration cycle 2 from the calculation unit 21 (step S7).

Here, the setting of the target value of the defrosting operation interval of the refrigeration cycle 2 will be described with reference to FIG.

[0017]

[Table 2]

FIGS. 3A to 3C are graphs showing membership functions of the outside temperature, the operation rate of the refrigeration cycle 2, and the defrosting operation interval, respectively. For example, when the outside temperature is 25 ° C. and the operation rate of the refrigeration cycle 2 is 0.45, the middle grade of the outside temperature is 0.33 as shown in FIG. As shown in (B), the middle grade of the operation rate of the refrigeration cycle 2 is 0.75. Then, the grade in which the defrosting operation interval is medium according to the defrosting operation interval control rule shown in Table 2 below is min.
(0.33, 0.75). Similarly, in other cases, when the max calculation is performed, the shaded portion shown in FIG. 3C is obtained, and the value of the center of gravity of 2.3 is obtained as the target value of the defrosting operation interval.

After performing the calculation in step S7, the setting unit 22 starts counting the operation timer.
Then, it is determined whether or not the target value (for example, 2.3 hours) of the defrosting operation interval set in the step has elapsed (step S8). When the target value of the defrosting operation interval has not elapsed (No), the control in step S1 is performed. That is, the defrosting operation is not performed.

In step S8, when the target value of the defrosting operation interval has elapsed (Yes), the defrosting operation relay 20 is turned on (step S9). As a result, an instruction to start the defrosting operation is output, so that the refrigerant compressor 4 and the defrosting valve 13 are energized. At this time, the state in which the energization of the electric fans 14 and 15 is stopped is continued.

For this reason, the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 4 passes through the refrigerant condenser 5 without heat exchange and flows into the receiver 6. And this receiver 6
The high-temperature and high-pressure refrigerant flowing out of the refrigerant flows into the refrigerant evaporator 8 through the bypass pipe 11 because the defrost valve 13 is open. Therefore, the frost and ice adhering to the surface of the refrigerant evaporator 8 are melted and removed to be defrosted.

After performing the control in step S9, the surface temperature TE of the refrigerant evaporator 8 is input from the defrost release sensor 18 (step S10), and the surface temperature TE of the refrigerant evaporator 8 is set to a set value TSE (for example, 3 ° C.). ) It is determined whether or not it has risen above (step S11). When the surface temperature TE of the refrigerant evaporator 8 has not risen above the set value TSE (No),
The control of step S10 is performed.

In step S11, the surface temperature TE of the refrigerant evaporator 8 has risen above the set value TSE (Ye).
At s), it is determined that the defrosting operation has ended, the defrosting operation relay 20 is turned off (step S12), the operation timer is reset, and the count is started from 0 (step S13). Thereafter, the control in step S1 is performed.

As described above, when the amount of frost is large, FIG.
As shown in the time chart, since the amount of frost is indirectly estimated from the relationship between the outside temperature of the refrigerator and the operation rate of the refrigeration cycle 2, the target value of the defrosting operation interval is set to an appropriate value. Therefore, the defrosting operation is performed at the optimal time. Therefore,
Since the formation of frost is prevented from progressing, an excessive decrease in refrigeration capacity can be prevented. On the other hand, when the amount of frost is small, as shown in the time chart of FIG. 5, the defrosting operation is not performed, the temperature in the refrigerator is stabilized, and a decrease in energy loss can be prevented. That is, it is possible to provide the refrigerator defrosting control device 1 having a simple configuration and high reliability.

(Modification) In this embodiment, the present invention is applied to a defrosting control device for a mobile refrigerator (cold roll box). It may be used for a frost control device, and may be used for a defrost control device of a cooler incorporated in a cooling device. In the present embodiment, the fuzzy control is used in obtaining the target value of the defrosting operation interval. However, the target value of the defrosting operation interval may be obtained using a method other than the fuzzy control. Note that a method of turning on only the electric fans 14 and 15 during defrosting may be used.

[0026]

According to the present invention, since the defrosting operation interval of the refrigerator can be controlled to an optimum value, an increase in energy loss and a decrease in refrigeration capacity can be prevented. Further, since the amount of frost formation can be obtained indirectly, the reliability of the target value of the defrosting operation interval is high.

[Brief description of the drawings]

FIG. 1A is a configuration diagram illustrating a refrigeration cycle of a refrigerator according to the present invention, and FIG. 1B is an electric circuit diagram illustrating a defrost control device of the refrigerator according to the present invention.

FIG. 2 is a flowchart showing an example of a main program of a computer according to the present invention.

FIG. 3 is a graph showing a membership function adopted for fuzzy control according to the present invention.

FIG. 4 is a time chart of the internal temperature when the amount of frost is large in the present invention.

FIG. 5 is a time chart of the internal temperature when the amount of frost is small in the present invention.

FIG. 6 is a time chart of the internal temperature when the amount of frost is large in the conventional technique.

FIG. 7 is a time chart of the internal temperature when the amount of frost is small in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigerator defrost control device (refrigeration device defrost control device) 2 Refrigeration cycle (refrigerator) 3 Computer (control means) 16 Outside air temperature sensor (detection part) 21 Operation part

Claims (2)

(57) [Claims] 1. A refrigerator comprising: (a) a refrigerator for performing a freezing operation and a defrosting operation; (b) a detecting unit for detecting a temperature outside the refrigerator; and a computing unit for computing an operation rate of the refrigerator. Control means for obtaining a target value of the defrosting operation interval from the outside temperature detected by the detection unit and the operation rate of the refrigerator calculated by the calculation unit, and controlling the refrigerator based on the target value e Bei the door, the target value of the defrosting operation interval detected by the detecting unit
The lower the outside temperature, the shorter the defrost operation interval
And the higher the operating rate of the refrigerator, the shorter the defrosting operation interval.
Control device for a refrigeration system,
Place. 2. A control device for a refrigeration system according to claim 1.
In the refrigerator, the high-temperature refrigerant discharged from the refrigerant compressor,
After passing through the decompression means, it flows into the refrigerant evaporator,
A first refrigerant circulation circuit returning to the medium compressor, from the refrigerant compressor
After the discharged high-temperature refrigerant, bypassing the decompression means
The second refrigerant flowing to the refrigerant evaporator and returned to the refrigerant compressor
A medium circulation circuit, and the first refrigerant circulation circuit and the second cooling medium.
Has a circulation circuit switching means for switching between medium circulation circuit, wherein, during the freezing operation of the refrigerator, the circulation
Controls circuit switching means to switch to the first refrigerant circuit
The circulation circuit switching means during the defrosting operation of the refrigerator.
To switch to the second refrigerant circuit.
Control device for refrigeration system.