JPS63210570A - Operation controller for refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] Industrial Field of Use The present invention relates to an operation control device for a refrigeration system installed in a prefabricated low-temperature refrigerator or the like.

2. Description of the Related Art A conventional operation control device for this type of refrigeration equipment is disclosed in Japanese Utility Model Application No. 58-188554, which discloses a plurality of refrigeration cycles each having a variable capacity compressor, and one inverter circuit for driving a drive motor; a plurality of switches that selectively form an energization path from the inverter circuit to each of the drive motors or from a power source to each of the drive motors; A refrigeration cycle device is disclosed that includes a control section that controls each of the switches and an inverter circuit according to the magnitude of the load.

Problems to be Solved by the Invention When the refrigeration cycle device according to the above-mentioned conventional technology is used, for example, in a prefabricated freezer, etc., as the refrigeration cycle performs cooling operation, the indoor side forming a part of the refrigeration cycle Frost forms on the heat exchanger. Therefore, in order to defrost this heat exchanger, the refrigerant flow path of the four-way valve is switched, high temperature and high pressure hot gas refrigerant is flowed from the compressor to the heat exchanger, and defrosting is performed using the latent heat of this hot gas refrigerant. Defrosting using the hot gas defrost method begins. However, if you switch from cooling operation to defrosting operation when the drive power from the inverter circuit is low during cooling operation, that is, when the compressor operating capacity is low, the compressor operating capacity will be low. The amount of hot gas refrigerant flowing to the heat exchanger is small, and the defrosting time is longer than when the compressor operating capacity is high. There was a problem that the internal temperature rose. In particular, if the frost formation is not constant throughout the heat exchanger and the frost formation is strong or weak, there will be areas where the ice has melted and areas where it has not yet melted, causing the refrigerant pipes to come into direct contact with the air. There was a problem in that if defrosting was continued for a long time, the temperature inside the refrigerator would rise significantly.

In addition, even though the temperature inside the refrigerator has risen significantly at the end of defrosting, if the driving layer wave number side is controlled by PID control, the capacity of the compressor after the end of defrosting will be lower than the capacity of the compressor immediately before the start of defrosting operation. The increase in the capacity of the compressor will be zero or slight, and it will take a considerable amount of time to lower and stabilize the temperature inside the refrigerator to the set temperature. However, there is a problem in that the product is exposed to adverse conditions for a long period of time, which may impair the quality of the product.

Therefore, in the present invention, the operating frequency during defrosting operation is limited regardless of the operating frequency before the start of defrosting, and after the defrosting operation is finished, based on the relationship between the internal temperature and the set temperature,
The present invention provides an operation control device that performs frequency control using piecewise limited frequency control and PID control so that the frequency signal is divided into three areas and changed.

[Structure of the Invention: Means for Solving the Problems] The operation control device for a refrigeration system of the present invention has a compressor and a compressor, respectively.
A two-system refrigeration cycle consisting of a condenser, an evaporator, a flow path switching valve, etc., an internal temperature detection element that detects the internal temperature and outputs an internal temperature signal, and an internal temperature detection element that detects the internal temperature and outputs an internal temperature signal. A controller that outputs a switching signal that switches the flow path of a flow path switching valve based on the signal, and also outputs a frequency signal that can be increased or decreased between the lowest frequency and the highest frequency based on the internal temperature signal, and a frequency signal from this controller. and an inverter that inputs a signal to increase or decrease the power supplied to the compressor, and the controller outputs a switching signal to set one of the refrigeration cycles to cooling operation and the other to defrost operation during defrosting, and Regardless of the operating frequency signal before the start of defrosting, a defrosting operating frequency signal set to the highest frequency or a frequency close to the highest frequency is output, and after defrosting, the internal temperature is lower than the predetermined set temperature that can be set arbitrarily. When the temperature is higher than the first set temperature which is higher by the temperature p, the frequency signal of the highest frequency is output, and when the internal temperature is lower than the first set temperature and higher than the second set temperature which is higher than the set temperature by a constant temperature q (< p), the frequency signal of the highest frequency is output. , outputs a frequency signal with a value higher by a set frequency than the operating frequency signal immediately before the start of defrosting, and outputs a frequency signal under PID control when the internal temperature is below the second set temperature.

For functional defrosting, two refrigeration cycles (1
1) and (12) are used for cooling operation and the other for defrosting operation, and the first compressor (5A) and second compressor (5B) in this refrigeration cycle (11) and (12) are controlled by a controller ( By driving based on the defrosting operation frequency signal output from 45), regardless of the frequency signal before defrosting, the defrosting capacity is maintained at a maximum or a constant value close to the maximum,
Furthermore, cooling is performed simultaneously and in parallel with defrosting to suppress the rise in temperature inside the refrigerator due to defrosting. In addition, by determining the set temperature S that can be set arbitrarily, the first set temperature (t,) is automatically set.
and the second set temperature (t2) are determined, and these two
At two temperatures i1+t, a temperature region higher than tl (first
region), temperature region below t8 and higher than t2 (second region)
, t.

The temperature range is divided into three temperature ranges (third range) as shown below, and the frequency signal output from the controller (45) is different for each range. That is, in the first region, a frequency signal with the highest frequency, in the second region, a frequency signal with a value higher than the frequency immediately before the start of defrosting by the set frequency ΔHz, and in the third region, immediately before the start of defrosting. The cooling capacity of the compressors (5A) and (5B) is determined by outputting frequency signals under PID control via frequency signals having the same frequency as those of the compressors (5A) and (5B).

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7.

(1) is a prefab refrigerator, and this prefab refrigerator (1)
A refrigeration device (2) is provided on the - side wall of.

This refrigeration system (2) consists of an external unit (3) and an internal unit (4), and the external unit (3) has a partition plate (3).
B) connects the upper heat exchange room (3C) and the lower machine room (3C).
D), and the heat exchange chamber (3C) is divided into a condenser (6A) that forms part of the refrigeration cycle and uses fins in common.
) (6B), an axial flow type condenser blower (7), etc. are installed. Further, in the machine room (3D), there is a first refrigeration cycle which constitutes a part of the refrigeration cycle. Second compressor (5A) (5B)
etc. are arranged. Moreover, the first refrigerator unit (4) which constitutes a part of the NiHa refrigeration cycle. Second evaporator (8A) (
8B) and 1st. Second evaporator blower (9A) (9B
) are arranged, and by operating the respective blowers (7) (9A>(9B), the air inside the refrigerator and outside the vehicle circulates through the refrigeration system (2) as shown by the arrow. Note that (4A) The drain pan (4B) is a drain vibe.

FIG. 3 and FIG. Second refrigeration cycle (11)
(12), Fig. 3 shows the flow of refrigerant when both refrigeration cycles (11) and (12) perform cooling operation, and Fig. 4 shows the refrigerant flow when the second refrigeration cycle (12) It shows the flow of refrigerant when the first refrigeration cycle (11) performs a defrosting operation. 1st refrigeration cycle (1
1) includes a first compressor (5A), a first four-way valve (13A) as a first flow path switching valve, a first condenser (6A), a first evaporator (8A), an accumulator (14), etc. The piping is connected in an annular manner, and (15) and (16) are a first check valve and a first capillary tube, respectively, and (17 and 18) are a second check valve and a second capillary tube, respectively. Also, the second
The refrigeration cycle (12) is configured in the same manner as the first refrigeration cycle (11), and includes a second compressor (5B), a second four-way valve (13B>) as a second flow path switching valve, and a second condenser (6B). , a second evaporator (8B), an accumulator (14), etc., are connected in a ring with piping, and the same numbers as the first refrigeration cycle (11) indicate the same parts.Next, the refrigeration cycle of the present invention The schematic circuit configuration of the device's operation control device will be explained. (
20) is a three-phase AC power supply, (21> is a three-phase full-wave rectifier (hereinafter referred to as a bridge circuit), (22) and (23) are smoothing capacitors, respectively, and choke plug (24) is a power supply from a controller (45), which will be described later. This is an inverter that converts DC power that has passed through a bridge circuit (21) into AC power based on a frequency signal.Here, the inverter (24) is composed of a plurality of transistors, diodes, etc. ) are the inverter (24) and
1st. The first compressor provided between the second compressor (5A) (5B). This is the second magnetic switch.

In addition, (31a) and (31b> are the first and second power lines connected to the three-phase AC power supply (20), (32) are the motors installed in the condenser blower (7), and (25C) (26C
) are the first and second magnetic switches, respectively.
．． The second excitation coils (33) and (34) are the first excitation coils, respectively. Second
Controls energization to the excitation coils (25C) (26C).

1st. The relay for operating the second compressor (hereinafter referred to as the first and second relay), (35) the first four-way valve filter, and (36) the motor (hereinafter referred to as the first motor) installed in the first evaporator blower (9A). ), (37) is the first refrigeration cycle (11
) defrosting/cooling switching relay (hereinafter referred to as the 3rd relay)
The first four-way valve coil (35) is connected to the defrosting side contact (3711) of the third relay (37), and the first four-way valve coil (36)
) is connected to the cooling side contact (37b) of the third relay (37). Further, (38) is the second four-way valve coil, (39
) is the motor (
(hereinafter referred to as the second motor), (41) is a defrosting/cooling switching relay (hereinafter referred to as the fourth relay) of the second refrigeration cycle (12), and the second four-way valve coil (38) and the second motor (
39) are the defrosting side contacts (41a) of the fourth relay (41), respectively.
) and the cooling side contact (41b). or,(
42) is a triac, (43) is this triac (
42) is a heater such as a heating wire for heating the air inside the refrigerator.

Furthermore, (45) is a controller configured by a microcomputer. (46) is the first evaporator (8A>
A first defrosting end temperature sensing element, such as a negative characteristic defrosting thermistor (hereinafter referred to as the first sensor), which is placed near the evaporator or a refrigerant outlet vibrator, (47) is the second evaporator (8B) itself. Or a second one placed near it.
Defrosting end temperature sensing element, for example, a negative characteristic defrosting thermistor (hereinafter referred to as the second sensor and the respective sensors (46), (47), and
8) is connected to the controller (45). The first relay (33) and the second relay (34) are connected to the controller (4).
The third relay (37) and the fourth relay (41) are turned on and off based on the control signal from the controller (45).
The connection terminals are switched based on the switching signal from. or,
The conduction angle of the triac (42) is determined by the controller (45)
It increases or decreases based on the conduction angle control signal from. The controller (45) performs proportional, integral, and differential control, that is, PID control, based on the temperature signal input from the third sensor <48), and outputs a frequency signal resulting from this PID control to the inverter (24). However, the frequency signal under PID control is controlled between a maximum frequency of, for example, 60 Hz and a minimum frequency of, for example, 30 Hz. and,
The power supplied from the inverter (24) to the first compressor (5A) and the second compressor (5B) changes based on the frequency signal. Further, the controller (45) controls the first evaporator (8A),
A defrosting signal is output for causing one of the second evaporators (8B) to perform a nitrogen removal operation. At this time, defrosting is performed alternately such that the evaporators that have been defrosted once are defrosted the next time after 4 hours.

Next, the operation of the operation control device based on the above configuration will be explained.

First, after the power is turned on, the first. 2nd relay (33),
(34) are both on, and the third. 4th relay (37
) (41) are both located at the cooling side contacts (37b) (41b>. At this time, both the first and second excitation coils (25C) (26C) are energized, and the first and second magnets The network switches (255) and (265) are both turned on.Therefore, the first compressor (5A), the second compressor (5B), and D are both in the preparation state.Meanwhile, the third and fourth compressors relay(
37)<41) is at the cooling side contact (37b) (4th), so the first. Second four-way valve coil (35) (38)
is not energized, and the first. Second four-way valve (13A) (13B
> are both cooling channels, and the first. The second motors (36) and (39) are both energized, and the first. Both the second blowers (9A) and (9B) are in operation. Further, the triac (42) is non-conductive and no electricity is supplied to the heater (43). Here, the controller (45) controls the third sensor (
Based on the temperature signal in the refrigerator from 1. Change the power supplied to the second compressor (5A) (5B).

Then, as shown by the solid arrow in Fig. 3, the refrigerant enters the first
．． The second refrigeration cycle (11) (12) is circulated, and the first
The air inside the refrigerator is cooled by the evaporator (8A) and the second evaporator (8B).

Now, the frequency at which the controller (45) is located is, for example, 40H.
z frequency signal, and assuming that the circular compressors (5A) and (5B) are fully operational, the controller (
45) When the preset time (for example, 2 hours) has elapsed (see time T1 in FIG. 5), in order to start the defrosting operation of one of the evaporators, for example, the first evaporator (8A),
The controller (45) outputs a signal to the third relay (37), and this third relay (37) is connected to the defrosting side contact (37a).
Switch to . Therefore, the first motor (36) is de-energized, the first evaporator blower (9A) is stopped, and at the same time the first motor
The four-way valve coil (35) is energized, and the first four-way valve (13)
A) flow path is switched to the defrosting flow path, and the first compressor (5
By operation A), the refrigerant circulates through the first refrigeration cycle (11) as shown by the dotted line arrow in Figure 4, and the refrigerant circulates through the first compressor (5).
The high-temperature, high-pressure hot gas refrigerant discharged from A) flows to the first evaporator (8A), where it exchanges heat with the ice and frost to perform defrosting. Here, at the same time as the third relay (37) switches to the defrosting side, the controller (45) sends a frequency signal of a defrosting operation frequency, for example, 50 Hz, which is set in advance to be slightly lower than the highest frequency (60 Hz in this embodiment). Inverter (24)
Three-phase AC power (hereinafter referred to as power) corresponding to the frequency of 50) 1z is output from the inverter (24), and both compressors (5A) (5B> are operated by this power. At this time, In the refrigerant flow path of the first four-way valve (13A), the first refrigeration cycle (11) performs defrosting operation using a reverse hot gas debrost method, and the second refrigeration cycle (11)
2) continues the cooling operation.

Although an example has been shown in which the defrosting operation is started immediately at time T, the defrosting operation may be started with a slight delay from time T. Further, although the defrosting operation frequency is set slightly lower than the maximum frequency, it may be set at the maximum frequency, and in short, it is sufficient as long as it is the maximum frequency or a frequency close to the maximum frequency. As the defrosting operation continues, the frost in the first evaporator (8A) gradually melts, and the temperature inside the refrigerator is reduced by the radiant heat from the first evaporator (8A), which is cooled by the second refrigeration cycle (12). It gradually increases even though I am driving. Then, the first sensor (46) detects that the ice and frost in the first evaporator (8A) has melted and the temperature of the first evaporator (8A) has risen to reach the defrosting end temperature, for example, 4°C.
When the controller (see time T in Figure 5) senses the
45) outputs a signal to end defrosting and start cooling operation based on the temperature signal from the first sensor (46), and switches the third relay (37) to the cooling side contact (37b). Therefore, the first four-way valve coil (35) is de-energized,
The first four-way valve (13A) switches to the cooling flow path, and the first four-way valve (13A) switches to the cooling flow path.
By operating the compressor (5A), the refrigerant circulates through the first refrigeration cycle (11) as shown by solid arrows in FIG.

On the other hand, the third sensor (48) detects the temperature inside the refrigerator that increases due to the defrosting operation, and the set temperature S (for example, -1°
C) by a predetermined temperature P (for example, 1.5°C).
When the temperature inside the refrigerator is higher than the set temperature (1,) (0.5°C in this example) (see time T! in Figure 5)
In this case, the controller (45) outputs a frequency signal of the highest frequency (60Hz in this case) to the inverter 24),
The power corresponding to this 60Hz frequency is transferred to an inverter (2
4) is sent and both compressors (5A) (5B) are operated at maximum output. In addition, when shifting from defrosting operation to cooling operation, if the start of operation of the first evaporator blower (9A) is delayed by a predetermined time (about 1 minute) using a delay means, such as a timer, the internal unit ( 4) Warm air filled inside can be prevented from being discharged into the refrigerator.

Due to the continuation of the cooling operation with the maximum output of both compressors (5A) (5B>), the temperature inside the refrigerator rose slightly but quickly decreased, and the temperature inside the refrigerator fell below the first set temperature (1,). When the third sensor (48) senses this (see time T in Figure 5), the controller (45) adjusts the preset frequency ΔH from the frequency signal (40 Hz in this example) immediately before the start of defrosting.
For example, a frequency signal whose value is higher by 10Hz (50H
z) is output. In addition, when the frequency signal immediately before the start of defrosting is 50 Hz or more, the value obtained by adding 10 Hz to that frequency becomes 60 Hz or more, but the frequency signal is up to 60 Hz. Then, based on this frequency signal, the inverter (24) outputs power lower than the previous power. 2nd g# compressor <5A
)(5B>'s operating capacity is reduced, and the first refrigeration cycle (
11) and the second refrigeration cycle (12).

Thereafter, by continuing the cooling operation using this cooling capacity, the temperature inside the refrigerator gradually decreases, and the second set temperature (for example, 0,5'C) is higher than the set temperature S by a constant temperature q (less than P).
11. When the third sensor (48) detects that the temperature has dropped below 105°C (see time T4 in Figure 5), the controller (45) changes the frequency immediately before the start of defrosting. A signal (40Hz in this example) is output. Then, the inverter (24) operates at the same power as before starting defrosting.
Drive the second compressor (5A) (5B>. After this,
Based on the internal temperature signal from the third sensor (48), the controller (45) performs PID control and changes the frequency signal. Therefore, the temperature inside the refrigerator gradually decreases and eventually reaches the set temperature S at time T, and thereafter PID control is continued to maintain the set temperature S.

This is an explanation of the case where there is a transition).

By the way, when there is a large amount of stored items in the refrigerator and the latent heat becomes large, the temperature rise in the refrigerator during defrosting draws a gentle curve and changes as shown by the dotted line in Figure 5 (D
, transition), when defrosting is completed at time T, the internal temperature changes between the first set temperature (Ll) and the second set temperature (Ll).
t, ), and the controller (45) outputs a frequency signal of 50 Hz, which is 10 Hz higher than the frequency signal immediately before the start of defrosting. Then, based on this frequency signal, the inverter (24) converts the power corresponding to the frequency of 50Hz into the first. It is supplied to the second compressor (5A) (5B). Additionally, as the defrosting is completed, the first four-way valve (13A) switches to the cooling flow path, and the refrigerant circulates to the first refrigeration cycle (11) as shown by the solid arrow, and the refrigerant circulates to the second refrigeration cycle (12). ) Cooling operation is performed in the same way as in Then, when the third sensor (48) detects that the temperature inside the refrigerator has decreased to the second set temperature (t, ) due to the continuation of the cooling operation (see time T6 in Figure 5).
, the controller (45) outputs the same frequency signal (40 Hz) as immediately before the start of defrosting, and the inverter (24) supplies power in response to the frequency signal. Based on this power, the first
．． The operating capacity of the second compressor (5A) (5B) changes,
The internal temperature gradually decreases to the set temperature S, and thereafter PID control is continued to maintain the set temperature.

When a preset time (2 hours) has elapsed after the start of defrosting, whether the D1 transition or not, the controller (45) starts the defrosting operation of the second evaporator (8B). outputs a switching signal to the fourth relay (41),
The fourth relay (41) is switched from the cooling side contact (41b) to the defrosting side contact (41a). Also, the controller (45
) outputs a signal at the defrosting operating frequency (50 Hz), and the inverter (24) outputs power corresponding to this frequency. The compressors (5A) (5B) are operated by this electric power, and the second four-way valve coil (38) is connected to the fourth relay (41).
) is energized and the second four-way valve (13B) switches to the defrosting flow path, so the first refrigeration cycle (11) continues to perform cooling operation, and the second refrigeration cycle (12,) Perform defrosting operation. Thereafter, the second refrigeration cycle (12) is switched to the first evaporator (8A) of the first refrigeration cycle (11) described above.
), the controller moves from defrosting to cooling in the same transition order as the transition from defrosting to cooling, quickly lowers the temperature inside the refrigerator to the set temperature, and maintains it at the set temperature. The frequency signal from (45) changes.

Moreover, after 2 hours have elapsed since defrosting of the second evaporator (8B) was started, defrosting of the first evaporator (8A) is performed again, and thereafter, as time passes, the evaporator is Perform defrosting operation to prevent the cooling capacity from decreasing due to long-term use.

Next, for example, when the ambient temperature is low in winter or when there are few items stored in the refrigerator, the refrigeration load is small, so the first
．． The cooling operation of only one of the second refrigeration cycles (11) and (12) is performed, and the defrosting operation at this time will be explained (this state is referred to as E, transition).

Now, for example, due to the output from the controller (45),
It is assumed that the second relay (34) is off.

Therefore, the second excitation coil (26C) is de-energized and the second magnet switch (265) is off, so the second
The compressor (5B) is de-energized and the second refrigeration cycle (12)
has stopped cooling operation. On the other hand, the controller (45
), the first relay (33) is turned on, the first compressor (5A) is operated, and the first refrigeration cycle (
11) is performing cooling operation. At this time, at time T, which has been set in advance in the controller (45) (see Fig. 6), the controller (45) activates the second evaporator (8B) of the second refrigeration cycle (12), which had been stopped until then. )
Outputs a signal for defrosting. This signal causes the fourth relay (41) to connect to the cooling side contact (41b).
The contact is switched from to the defrosting side contact (41a). For this reason, the second
The evaporator blower (9B) stops operating, and the second
The four-way valve (13B> is switched to the defrosting flow path.

On the other hand, the controller (45) outputs a frequency signal having a frequency much lower than 30Hz, which is the lowest frequency of PID control operation, for example, 2B)1z. This frequency signal causes the inverter (24) to connect to the first compressor (5A).
The power supplied to Outputs a signal to

Therefore, the power to the first compressor (5A) is cut off, and the first compressor (5A) temporarily stops operating. On the other hand, the power output from the inverter (24) gradually decreases to zero Hz.
When the power decreases to the corresponding level (during this time for about 50 seconds)
, the controller (45> is the first and second relay (33)
(34) and outputs the ON signal of the first. Turn on both the second magnetic switches (255) and (265), and turn on the first magnetic switch. The second compressor (5A) (5B) is made ready for operation. Then, the controller (45) controls the defrosting operation frequency (50Hz
), the power of the inverter (24) is gradually increased to the power corresponding to 50Hz, the first refrigeration cycle (11> is in cooling operation, the second refrigeration cycle (11) is in cooling operation,
2) performs defrosting operation.

Through the above operations, the refrigerant circulates in the first refrigeration cycle (11) as shown by the solid arrow, and the refrigerant circulates in the second refrigeration cycle (12) as shown by the dotted arrow ( (See FIG. 4, but this state is reversed in FIG. 4). A high-temperature, high-pressure hot gas refrigerant flows through the second evaporator (8B) to perform defrosting. As this defrosting continues, the ice and frost in the second evaporator (8B) gradually melts, and the internal temperature gradually rises due to radiant heat from the second evaporator (8B). Defrosting of the second evaporator (8B) progresses,
The temperature of this second evaporator (8B) is the defrosting end temperature (4°C
), when the second sensor (47) detects that (
(See time T8 in FIG. 6), the controller (45) outputs a signal for starting the cooling operation of the second refrigeration cycle (12). By this signal, the fourth relay (41) switches from the defrosting side contact (41a) to the cooling side contact (41b), and the second four-way valve (13B) switches to the cooling flow path, and the second evaporator The blower (9B) starts operating.

Note that the operation of the second evaporator blower (9B) may be delayed for a predetermined period of time after the second four-way valve (13B) is switched, for example, by operating a timer or the like.

On the other hand, when the second sensor (47) senses the defrosting end temperature and the internal temperature is higher than the first set temperature (1,), the controller (45) outputs a frequency signal of the highest frequency, that is, 60 Hz. . For this reason, the second evaporator (8B)
During defrosting, the 1st. The second compressors (5A) (5B) can be fully supplied with electric power corresponding to the highest frequency 60)1z during cooling operation. Therefore, the first. Second refrigeration cycle (1
1) (12) performs cooling operation at the maximum cooling capacity, and the internal temperature rises slightly and then rapidly drops. Then, when the temperature inside the refrigerator falls below the first set temperature (Ll), a third
When the sensor (48) senses (see time T in Figure 6),
The controller (45) outputs a frequency signal of 45 Hz, which is 10 Hz higher than the frequency signal (for example, 35 Hz) immediately before the start of defrosting. Therefore, the inverter (24)
Outputs power corresponding to 5Hz, and outputs power corresponding to 5Hz. The operating capacity of the second compressor <5A) (5B) decreases and the time (T,
) and the cooling capacity before the start of defrosting. Thereafter, cooling operation is performed using this cooling capacity, and the temperature inside the refrigerator gradually decreases. Then, when the third sensor (48) detects that the temperature inside the refrigerator has reached the second set temperature (t2) due to continued cooling (see time T1° in Figure 6),
The controller (45) sets the frequency (35H) immediately before the start of defrosting.
The inverter (24) outputs power corresponding to the frequency 35)1z. After that, the controller (45) inputs the temperature signal from the third sensor <48>, performs PID control, and outputs a frequency signal based on the temperature inside the refrigerator, and the inverter (24) outputs a frequency signal based on the frequency signal. Output. Also, controller (45)
outputs a 35Hz frequency signal, and at the same time outputs an off signal to the first relay (33〉).
turn off. Then, the first excitation coil (25C) is de-energized, the first magnet switch (255) is turned off, the power to the first compressor (5A) is cut off, and the first compressor (5A) is turned off. Stop driving. After that, the second compressor (5
Only B) is operated by frequency-controlled power from the inverter (24), and the temperature inside the refrigerator gradually decreases to the set temperature S. After that, the controller (45) inputs the temperature signal from the third sensor (48) and performs PID control, outputs a frequency signal based on the internal temperature, and the second compressor (5B) is connected to the inverter (24). The temperature inside the refrigerator is maintained at approximately the set temperature. On the other hand, the second evaporator (8B) is defrosted, and the second evaporator (8B) is defrosted.
When the temperature of the evaporator (8B) rises and the second sensor 7 (47) senses the defrosting end temperature, the internal temperature is higher than the second set temperature (t,) and the first set temperature <1. ．． ) In the following cases, the controller (45) outputs a frequency signal of 45 Hz, which is 10 Hz higher than the frequency signal (35 Hz) immediately before the start of defrosting. Thereafter, in the same way as the operation after the defrosting is completed, when the temperature inside the refrigerator reaches the second set temperature (t,), the controller (45
) outputs a frequency signal just before the start of defrosting, and thereafter outputs a frequency signal under PID control based on the temperature inside the refrigerator.

In addition, in the above description, defrosting of the second evaporator (8B) when only the first compressor (5A) is operated and the second compressor (5B) is stopped, and after the defrosting is completed. We have explained the cooling operation of the first evaporator (8A) when the first compressor (5A) is stopped and only the second compressor (5B) is operating. Control of the cooling operation after the end of frost is performed in the same manner.

Next, if the prefabricated refrigerator (1) is installed in a cold region, for example, Hokkaido, and the ambient temperature is low, cooling operation is performed by either the first or second refrigeration device (11) or (12). However, if the temperature inside the refrigerator tends to be lower than the set temperature despite operation based on the lowest frequency signal of one of the compressors, the controller (
45) outputs a conduction angle control signal to the triac (42>.The conduction angle control signal causes the triac (42>) to output a conduction angle control signal.
42> is controlled, and only when the try book (42) is on, the heater (43> is energized and generates heat, and the air in the refrigerator is heated completely. At this time, one of the compressors continues to operate at the minimum temperature. It operates based on the frequency signal (this state is referred to as E, transition). Hereinafter, the first compressor (5A) operates based on the lowest frequency signal, and the heater (43) The operation of defrosting and post-defrosting cooling operation when electricity is applied and the temperature inside the refrigerator is controlled will be explained.Now, at the time T, □ (see Fig. 7) set in advance by the controller (45), ), the controller (45) switches the second evaporator (8B) which had been stopped until then.
Outputs a signal for defrosting. This signal causes the fourth relay (41) to close the cooling side contact (41b).
The second evaporator blower (9B) stops operating, and the second four-way valve (13B) switches to the defrosting flow path.

On the other hand, the controller (45) outputs a frequency signal of 28 Hz, for example, a frequency even lower than 30) 1z, which is the lowest frequency of PID control operation. Due to this frequency signal, the power that can be supplied from the inverter (24> to the first compressor 5A) gradually decreases, and when it drops to the power corresponding to 28Hz (during about 25 seconds), the controller (45) returns to zero Hz. It outputs a frequency signal and also outputs a signal to turn off the relay (33). Therefore, the power supply to the first compressor (5A) is completely cut off, and the first
The compressor (5A) temporarily stops operating. On the other hand, the power output from the inverter (24) gradually decreases, and when it drops to the power corresponding to zero Hz (during about 50 seconds),
The controller (45) is a first controller. 2nd relay (33) (
34) and outputs the ON signal of 1.34). Both the second magnetic switches (255) (2εS) are turned on, and the first magnetic switch (255) (2εS) is turned on. Second
The compressors (5A) (5B) are made ready for operation. The controller (45) then controls the defrosting operation frequency (50Hz).
The power of the inverter (24) is increased by 5.
The power is gradually increased to the level corresponding to 0Hz, and the first refrigeration cycle (11) is operated for cooling, and the second refrigeration cycle (12) is operated.
) to perform defrosting operation.

Then, at the same time as the defrosting operation is started, the controller (45) stops the conduction angle control signal to the triac (42) and stops energizing the heater (43). Defrosting operation! The ice and frost in the second evaporator (8B) is gradually melted by the IR, and when defrosting is completed (see time TI2 in FIG. 7), the controller (45) outputs a signal to start cooling operation. Based on this signal, the internal temperature at the end of defrosting will be
When the temperature is higher than the first set temperature (t,), the inverter (
24> to 1st. Power at the highest frequency, that is, 60 Hz, is supplied to the second compressors (5A) (5B). Therefore, the first.
The second refrigeration cycle (11) (12) performs cooling operation at the maximum cooling capacity.

Thereafter, cooling continues with the maximum cooling capacity, and when the temperature inside the refrigerator decreases and reaches the first set temperature (1,) (time T1 in Figure 7).
), the controller (45) outputs a frequency signal of 40 Hz, which is 10 Hz higher than the frequency signal (30 Hz) immediately before the start of defrosting. Therefore, the inverter (24) converts the power corresponding to the frequency of 40Hz into the first. Second compressor (5A) (
5B), the operating capacity of each compressor decreases, and the operating capacity of each compressor decreases. The cooling capacity of the second refrigeration cycle (11) (12) is between the cooling capacity up to time T'+s and the cooling capacity before the start of defrosting.

When the temperature inside the refrigerator decreases due to the cooling operation using this cooling capacity and reaches the second set temperature (t, ) (see time T in Figure 7), the hunt roller (45) outputs the frequency signal (30Hz) just before the start of defrosting. ), and the inverter (24) outputs power corresponding to a frequency of 30 Hz.

Also, the controller (45) simultaneously connects the first relay (33).
outputs an off signal to turn off the first relay (33). Therefore, the first excitation coil (25C> is de-energized, the first magnet switch (255) is turned off, and the first
The compressor (5A) stops. Note that the second compressor (5B) continues to operate. Furthermore, the controller (45) outputs a conduction angle control signal to the triac (42), and the heater (43) is energized to simultaneously cool and heat the air in the refrigerator. Thereafter, the frequency signal from the controller (45) changes from 30Hz just before the start of defrosting based on the temperature inside the refrigerator, and cooling by the second refrigeration cycle (12) and heating by the heater (43) are performed simultaneously, The temperature becomes the set temperature S.

Thereafter, cooling by the second refrigeration cycle (12) and heater (
43) is performed at the same time, and the temperature inside the refrigerator is maintained at approximately the set temperature S. Then, when the next defrosting time that has been preset in the controller (45) comes, the first evaporator (8A) is defrosted in the same way as the second evaporator (8B).

As mentioned above, the first evaporator (8A) or the second evaporator
8B), the controller (45)
outputs a frequency signal of the highest frequency of operation or a preset defrosting operation frequency close to the highest frequency, and the inverter (24) outputs electric power based on this frequency signal. At this time, the controller (45) outputs a signal to switch the refrigerant flow path so that one evaporator can be placed in a defrosting state and the other evaporator can be placed in a cooling state. Then, based on the electric power from the inverter (24), the first compressor (5A
) and the second compression Ja (5B) at the defrosting operating frequency, the operating capacity of both compressors (5A) (5B) is controlled by PID control regardless of the operating frequency signal immediately before the start of defrosting. This operating capacity allows defrosting and cooling to be performed at the same time, shortening the defrosting time and reducing the temperature rise in the refrigerator due to defrosting of one of the evaporators. The degree of this can be suppressed as much as possible by cooling with the other evaporator.

Also, a first set temperature (tl) higher than the set temperature S set by the user by a predetermined temperature p, and a constant temperature q than the set temperature S.
A second set temperature (t,) which is higher by (p>q) is stored in the controller (45) along with the setting of the set temperature S,
In addition, the controller (45) can memorize the frequency signal immediately before defrosting, and after the defrosting operation is finished, sends a signal to switch the refrigerant flow path so that both evaporators (8A) (8B> are used for cooling).
outputs. When the internal temperature after defrosting is higher than the first set temperature (tl), the controller (45
) outputs the highest frequency signal and connects the inverter (
By operating both compressors (5A) and (5B) at maximum operating capacity via The rise in temperature can be suppressed slightly, and the temperature inside the refrigerator can be quickly lowered. On the other hand, when the temperature inside the refrigerator is lower than or equal to the first set temperature (t,) and higher than the second set temperature (t,), the controller (45) operates at a preset frequency ΔH.
A frequency signal higher than the frequency immediately before the start of defrosting by z is output, and the peripheral compressor (5A) (5
B> is set as an operating capacity higher than the capacity immediately before defrosting, so that the degree of decrease in the temperature inside the refrigerator is greater than that immediately before defrosting, and the humidity inside the refrigerator is lowered to near the set temperature more quickly. On the other hand, when the temperature inside the refrigerator is equal to or lower than the second set temperature (1,), the controller (45) outputs a frequency signal immediately before the start of defrosting, and thereafter outputs a frequency signal by PID control based on the temperature inside the refrigerator. In this way, the inverter (24)
By changing the operating capacity of the compressor via Temperature control is possible. Therefore, it is possible to slightly suppress the rise in temperature inside the refrigerator due to defrosting, lower the temperature to the set temperature in a short time, and maintain the set temperature, allowing long-term cooling operation. The quality of the internal storage can be maintained over a long period of time, and precise temperature control is possible.

[Effect of the invention] As detailed above, according to the present invention, during defrosting,
Of the refrigeration cycles equipped with two systems, one performs cooling operation and the other performs defrosting operation, and the compressor of each system is driven by a frequency signal set in advance near the highest frequency, so the time immediately before defrosting starts. Since the operating capacity can be determined regardless of the operating frequency and a high capacity can be achieved in a short time, the defrosting time can be shortened and the temperature rise in the refrigerator due to defrosting can be suppressed. Then, the first set temperature and the second set temperature are determined in accordance with the determination of the set temperature, and at these two temperatures, there is a region higher than the first set temperature (first region) and a region below the first set temperature. The temperature is divided into three temperature ranges: a region higher than the second set temperature (second region) and a region lower than the second set temperature (third region), and the cooling operation after defrosting is performed based on the internal temperature. , the controller transmits a frequency signal of the highest frequency during the first region, a frequency signal of (frequency + set frequency immediately before the start of defrosting) during the second region, and a frequency signal of the frequency determined by PID control during the third region. Since the temperature inside the refrigerator increases due to defrosting, it is possible to reduce the internal temperature in a short time and efficiently, and furthermore, it is possible to perform a cooling operation with a slight overshoot phenomenon with respect to the set temperature.

In addition, together with the effect of suppressing the rise in temperature inside the refrigerator during defrosting, the present invention provides an operation control device suitable for use in the field of cooling that requires precise temperature control, especially for ice temperature cooling. be able to.

[Brief explanation of the drawing]

Each figure shows an embodiment of the present invention. Figure 1 is a schematic electrical circuit diagram of an operation control device for a refrigeration system, Figure 2 is a schematic vertical sectional view of a prefabricated refrigerator, and Figures 3 and 4 are each refrigeration system. In the refrigerant circuit diagram of the cycle, Fig. 3 shows the refrigerant flow when both are in cooling operation, Fig. 4 shows the refrigerant flow when one is in cooling operation and the other is in depletion operation, and Fig. Figures 7 to 7 are transition diagrams showing changes in the internal temperature before, during and after defrosting, as well as changes in the refrigeration operation control state. FIG. 6 shows the Nu transition in an alternate cooling operation state using only one refrigeration cycle, and FIG. 7 shows the Nu transition in an operation state in which only one refrigeration cycle performs alternate minimum cooling operation and heater energization. (1)...Prefabricated refrigerator, (2)...Freezing device, (5A)...First compressor, (5B)...Second
Compressor, (8A)...first evaporator, (8B)...
・Second evaporator, (11)...first refrigeration cycle,
(12)...Second refrigeration cycle, (13A)...First four-way valve, (13B)...Second four-way valve, (24)
...Inverter, (33)...First relay,
(34>...Second relay, (37)...Third relay, ri41)...Fourth relay, (42)...Triac, (45)...Controller, (46)...
...First sensor, (47)...Second sensor, <48
>...Third sensor.

Claims (1)

[Claims] 1. Two systems of refrigeration cycles, each consisting of a compressor, condenser, evaporator, flow path switching valve, etc.; an internal temperature detection element that detects the internal temperature and outputs an internal temperature signal; It outputs a switching signal for switching the flow path of the flow path switching valve every hour and based on the temperature signal inside the refrigerator, and also outputs a frequency signal that increases or decreases between the lowest frequency and the highest frequency based on the temperature signal inside the refrigerator. In the operation control device for a refrigeration system, the controller includes a controller that outputs a frequency signal, and an inverter that inputs a frequency signal from the controller to increase or decrease the power supplied to the compressor. Outputs a switching signal that sets one of the cycles to cooling operation and the other to defrosting operation, and also outputs a defrosting operation frequency signal set to the maximum frequency or a frequency close to the maximum frequency regardless of the operation frequency signal before the start of defrosting. output,
After defrosting, when the internal temperature is higher than the first set temperature, which is higher than the arbitrarily settable set temperature by a predetermined temperature p,
The frequency signal with the highest frequency is output, and when the internal temperature is lower than the first set temperature and higher than the second set temperature, which is higher than the set temperature by a constant temperature q (< p), the set frequency is higher than the operating frequency signal immediately before the start of defrosting. 1. An operation control device for a refrigeration system, which outputs a frequency signal with a higher value than the second set temperature, and outputs a frequency signal based on PID control when the internal temperature is below a second set temperature.