JPH0823457B2 - Refrigeration system operation controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to an operation control device for a refrigeration system provided in a prefabricated cold storage or the like.

2. Description of the Related Art Conventionally, as an operation control device of this type of refrigeration system, there is, for example, Japanese Utility Model Laid-Open No. Sho 58-188554, which discloses a plurality of refrigeration cycles each having a variable capacity compressor and the compressors. One inverter circuit for driving the drive motor, and a plurality of switches for selectively forming a power supply path from the inverter circuit to each of the drive motors or a power supply to each of the drive motors A refrigeration cycle apparatus including a control unit that controls the switches and the inverter circuit according to the magnitude of the load is disclosed.

Problems to be Solved by the Invention When the refrigeration cycle device according to the related art is used, for example, in a prefabricated freezer or the like, an indoor side forming a part of the refrigeration cycle is accompanied by a cooling operation by 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, hot gas refrigerant of high temperature and high pressure is made to flow from the compressor to the heat exchanger, and defrosting is performed by the latent heat of this hot gas refrigerant. Defrosting by the hot gas defrost method is started.
However, when the driving power from the inverter circuit during the cooling operation is low, that is, when the operating capacity of the compressor is low and the cooling operation is switched to the defrosting operation, the operating capacity of the compressor is low. The defrosting operation will be started at this time, the amount of hot gas refrigerant flowing to the heat exchanger will be small, and the defrosting time will be longer than when the compressor operating capacity is high, and the higher the time, the higher the defrosting time. There was a problem that the temperature inside the chamber would rise. Especially when the state of frost is not constant over the entire heat exchanger, and when there is a strong or weak frost, there will be a portion where ice frost is melted and a portion where it is not melted, and the refrigerant pipe can be in direct contact with air. If defrosting is continued for a long time, there is a problem in that the temperature inside the refrigerator is significantly increased. In addition, when the drive frequency control by PID control is performed even if the temperature inside the chamber is greatly increased at the end of defrosting, the compressor after defrosting is compared with the capacity of the compressor immediately before the start of defrosting operation. The increase in the capacity of the refrigerator will be zero or slight, and it will take a considerable amount of time to stabilize the temperature inside the refrigerator by lowering it to the set temperature. There is a problem in that the product may be exposed to adverse conditions and the quality of the product may be impaired.

Therefore, the present invention is to limit the operating frequency during the defrosting operation regardless of the operating frequency before the defrosting operation, and after the defrosting operation, based on the relationship between the internal temperature and the set temperature, the frequency It is an object of the present invention to provide an operation control device which performs frequency control by piecewise limited frequency control and PID control so that a signal is divided into three areas and changed.

[Structure of the Invention] Means for Solving the Problems A refrigeration system operation controller according to the present invention includes two refrigeration cycles each including a compressor, a condenser, an evaporator, a flow path switching valve, and the like. Inside temperature detecting element that detects the inside temperature and outputs the inside temperature signal, and outputs the switching signal that switches the flow path of the flow path switching valve at predetermined time intervals and based on the inside temperature signal, and the inside temperature A controller that outputs a frequency signal that is increased or decreased between the lowest frequency and the highest frequency based on the signal, and an inverter that inputs the frequency signal from this controller and increases or decreases the power supplied to the compressor, Is a defrosting operation, outputs a switching signal that makes one side of the refrigeration cycle a cooling operation and the other one is a defrosting operation, and is the highest frequency or the highest frequency regardless of the operation frequency signal before the start of defrosting. Ri slightly outputs defrosting operation frequency signal set to a lower frequency, or, after defrosting, temperature inside the predetermined temperature than any settable set temperature p
If the temperature inside the refrigerator is lower than the first preset temperature and higher than the second preset temperature which is higher than the preset temperature by a constant temperature q (<p), the frequency signal of the highest frequency is output. A frequency signal having a value higher than the operating frequency signal immediately before the start of frost by a set frequency is output, and when the internal temperature is equal to or lower than the second set temperature, the frequency signal is output by PID control.

When performing defrosting, one of the two refrigeration cycles (11) (12) provided with two systems is set to the cooling operation and the other is set to the defrosting operation, and the first in this refrigeration cycle (11) (12)
Based on the defrosting operation frequency signal output from the controller (45), the compressor (5A) and the second compressor (5B)
Driven independently of the frequency signal before defrosting, the defrosting capacity is kept at a maximum or a constant value close to the maximum, and cooling is performed in parallel with defrosting, and the temperature inside the refrigerator is accompanied by defrosting. Controls the rise. Also, by determining the set temperature S that can be set arbitrarily, the first set temperature (t ₁ ) and the second set temperature are automatically set.
Set the set temperature (t ₂ ) so that these two temperatures
At t _1, t _2, a high temperature region (first region) than t _1, a high temperature region (second region) than t ₂ at t ₁ below, t ₂ the following temperature region three of (third region) The temperature signal is divided into temperature regions, and the frequency signal output from the controller (45) is different for each region. That is, the frequency signal with the highest frequency in the first region, the frequency signal with a value higher by the set frequency ΔHz than the frequency immediately before the start of defrost in the second region, and the frequency signal just before the start of defrost in the third region. The cooling capacity of the compressors (5A) and (5B) is determined by outputting the frequency signals of PID control through the frequency signals of the same frequency as the above.

Embodiments Embodiments of the present invention will be described below with reference to FIGS. 1 to 7.

(1) is a prefabricated refrigerator, and a refrigerating device (2) is provided on one side wall of the prefabricated refrigerator (1).
This refrigeration system (2) comprises an outside unit (3) and an inside unit (4), and the outside unit (3) is a partition plate (3).
The upper heat exchange chamber (3C) and the lower machine room (3D) by B)
Condensers (6A) (6B) that are part of the refrigeration cycle and share fins in the heat exchange chamber (3C)
And an axial-flow type condenser blower (7) and the like. Further, the machine room (3D) is provided with first and second compressors (5A) (5B) and the like which form a part of the refrigeration cycle. Further, the in-compartment unit (4) is provided with the first and second evaporators (8A) (8B) and the first and second evaporator blowers (9A) (9B) which constitute a part of the refrigeration cycle. Then, by operating the respective blowers (7), (9A), and (9B), the air inside and outside the refrigerator circulates in the refrigeration system (2) as shown by the arrows. still,
(4A) is a drain pan and (4B) is a drain pipe.

3 and 4 show the first and second refrigeration cycle (11).
In the refrigerant circuit of (12), FIG. 3 shows the flow of the refrigerant when both refrigeration cycles (11) and (12) are in the cooling operation, and FIG. 4 shows the second refrigeration cycle (12). The flow of the refrigerant when the cooling operation and the first refrigeration cycle (11) perform the defrosting operation is shown. The first refrigeration cycle (11) 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), and an accumulator. (14) With pipes connected in a ring,
(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. The second refrigeration cycle (12) is the first
It has the same structure as the refrigeration cycle (11) and has a second compressor (5
B), the second four-way valve (13B) as the second flow path switching valve, the second
A condenser (6B), a second evaporator (8B), an accumulator (14), and the like are connected in an annular pipe, and the same reference numerals as those of the first refrigeration cycle (11) indicate the same parts. Next, a schematic circuit configuration of the operation control device of the refrigeration system of the present invention will be described. (20) is a three-phase AC power supply, (21) is a three-layer full-wave rectifier (hereinafter referred to as a bridge circuit), (22) and (23) are smoothing capacitors and choke coils, and (24) is a controller (45) described later. It is an inverter that converts the DC power that has passed through the bridge circuit (21) into AC power based on the frequency signal from. Here, the inverter (24) is composed of a plurality of transistors and diodes. In addition, (25
S) and (26S) are first and second magnet switches provided between the inverter (24) and the first and second compressors (5A) and (5B), respectively.

Further, (31a) and (31b) are first and second power supply lines connected to the three-phase AC power supply (20), (32) is a motor provided in the condenser blower (7), and (25C) (26C). ) Is the first, respectively
The first and second exciting coils paired with the second magnet switch, (33) (34) are respectively the first and second exciting coils (25C) (2
6C) to control the energization. First and second compressor operation relays (hereinafter referred to as first and second relays), (35) is a first four-way valve coil, (36) is a motor (9A) provided in the first evaporator blower (9A) ( Hereinafter, the first motor) and (37) are defrosting / cooling switching relays (hereinafter referred to as third relays) of the first refrigeration cycle (11), and the first four-way valve coil (35) is the third relay (37). Connected to the defrost side contact (37a) of the first motor (3
6) is connected to the cooling side contact (37b) of the third relay (37). Also, (38) is the second four-way valve coil, and (39) is the second
A motor (hereinafter referred to as a second motor) provided in the evaporator blower (9B), (41) is a defrosting / cooling switching relay (hereinafter referred to as a fourth relay) of the second refrigeration cycle (12), and is a second
The four-way valve coil (38) and the second motor (39) are respectively the defrosting side contact (41a) and the cooling side contact (41b) of the fourth relay (41).
It is connected to the. Also, (42) is a triac, (43)
Is a heater such as a heating wire for heating air in the refrigerator, the energization of which is controlled by the triac (42).

Further, (45) is a controller composed of a microcomputer. (46) is a first evaporator (8A) itself or a first defrosting end temperature detection element arranged near the evaporator such as a refrigerant outlet pipe, for example, a negative characteristic defrosting thermistor (hereinafter referred to as a first sensor), ( 47) is a second evaporator (8B) itself or a second defrosting end temperature detecting element arranged in the vicinity thereof, for example, a negative defrosting thermistor (hereinafter referred to as a second sensor), and (48) is an air suction port ( P) or an in-compartment temperature detecting element disposed in the vicinity thereof, for example, a thermistor for in-compartment with negative characteristics (hereinafter referred to as a third sensor), each sensor (46) (47) (48) being a controller (45). It is connected to the. First relay (33), second relay (34)
Is turned on / off based on a control signal from the controller (45), and the connection terminals of the third relay (37) and the fourth relay (41) are switched based on a switching signal from the controller (45). Further, the conduction angle of the triac (42) increases or decreases based on the conduction angle control signal from the controller (45). still,
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 based on this PID control to the inverter (24). However, the frequency signal by this PID control is controlled between the highest frequency, for example 60 Hz, and the lowest frequency, for example 30 Hz. Then, based on the frequency signal, the first compressor (5A) and the second compressor (5A)
The power supplied to the compressor (5B) varies. Further, the controller (45) sends a defrost signal for defrosting one of the first evaporator (8A) and the second evaporator (8B) every predetermined time, for example, every two hours after the start of the cooling operation. Output. At this time, the evaporator which has been defrosted once defrosts alternately so that it will be defrosted four hours later.

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

First, after the power is turned on, both the first and second relays (33) and (34) are turned on by the control signal and the switching signal from the controller (45), and the third and fourth relays (37) (41) Will be described as being both at the cooling side contacts (37b) (41b). At this time, the first and second exciting coils (25C) (26C) are both energized, and the first and second magnet switches (25S) (26S)
S) are both turned on. Therefore, the first compressor (5A)
And the second compressor (5B) are both in the drive ready state. On the other hand, the 3rd and 4th relays (37) (41) are the cooling side contacts (37b)
Since it is located at (41b), the first and second four-way valve coils (35)
(38) is de-energized and the first and second four-way valves (13A) (13B)
Both serve as cooling flow paths, and the first and second motors (36) and (39) are both energized to provide the first and second blowers (9A).
Both (9B) are in operation. The triac (42) is non-conductive and the heater (43) is not energized. Here, the controller (45) outputs a frequency signal by PID control based on the internal temperature signal from the third sensor (48), and passes through the inverter (24) to the first and second compressors (5A).
Change the power supplied to (5B). Then, as shown by the solid line arrow in FIG. 3, the refrigerant circulates in the first and second refrigeration cycles (11) and (12), and the refrigerant is generated by the first evaporator (8A) and the second evaporator (8B). The air in the refrigerator is cooled.

Now, assuming that the controller (45) outputs a frequency signal of a certain frequency, for example 40 Hz, and that both compressors (5A) (5B) are operating, the time set in advance in the controller (45) after the start of cooling operation ( For example, when 2 hours have elapsed (see time T _{1 in} FIG. 5), the controller (45) causes the third relay (37) to start the defrosting operation of one of the evaporators, for example, the first evaporator (8A). ), The third relay (37) is switched to the defrosting side contact (37a). Therefore, the first motor (36) is de-energized, the first evaporator blower (9A) is stopped, and at the same time, the first four-way valve coil (35) is energized, and the flow path of the first four-way valve (13A) is changed. The refrigerant is switched to the defrosting flow path, and by operating the first compressor (5A), the refrigerant circulates in the first refrigeration cycle (11) as shown by the dotted arrow in Fig. 4, and the first compressor (5A) The high-temperature and high-pressure hot gas refrigerant discharged from the tank flows to the first evaporator (8A) and exchanges heat with ice frost for defrosting. Here, at the same time that the third relay (37) is switched to the defrosting side, the controller (45) outputs a frequency signal of a defrosting operating frequency, for example, 50 Hz, which is set to be slightly lower than the maximum frequency (60 Hz in this embodiment) in advance. Inverter (2
4), and the inverter (24) outputs three-phase AC power (hereinafter referred to as power) corresponding to a frequency of 50 Hz, and this power drives both compressors (5A) (5B). At this time, the first refrigeration cycle (11) performs defrosting operation by the reverse hot gas defrost method in the refrigerant flow path of the first four-way valve (13A), and the second refrigeration cycle (12) continues cooling operation. To do. Incidentally, although an example in which immediately start the defrosting operation be in time T _1, it may be allowed to start the defrosting operation with a slight delay from the time T _1. Further, although the defrosting operation frequency is set slightly lower than the maximum frequency, it may be set to the maximum frequency, and the point is that the frequency is the maximum frequency or a frequency close to the maximum frequency. Then, with the continuation of the defrosting operation, the ice frost of the first evaporator (8A) is gradually melted, and the radiant heat from the first evaporator (8A) cools the inside temperature of the second refrigeration cycle (12). It rises gradually while driving. Then, the first evaporator (8
The first sensor (4) indicates that the ice frost of (A) has melted and the temperature of the first evaporator (8A) has risen to reach the defrost end temperature, for example, 4 ° C.
6) senses (see time T _{2 in} FIG. 5), the controller (45) outputs a signal for ending the defrosting and starting the cooling operation based on the temperature signal from the first sensor (46), Three
Switch the relay (37) to the cooling contact (37b). Therefore, the first four-way valve coil (35) is de-energized, the first four-way valve (13A) is switched to the cooling flow path, and the first compressor (5
By the operation of A), the refrigerant circulates in the first refrigeration cycle (11) as shown by the solid arrow in FIG.

On the other hand, the temperature inside the refrigerator, which rises with the defrosting operation, is detected by the third sensor (48), and the set temperature S (for example, -1
When the temperature inside the refrigerator is higher than the first set temperature (t ₁ ) (0.5 ° C. in this example) which is higher than the predetermined temperature P (for example, 1.5 ° C.) by the predetermined temperature P (see FIG. 5, time T ₂ ). , The controller (45) outputs a frequency signal of the highest frequency (60 Hz in this case) to the inverter (24), and the inverter (24) sends electric power corresponding to the frequency of 60 Hz to both compressors (5
A) (5B) is operated at maximum output. In addition, when shifting from the defrosting operation to the cooling operation, the blower for the first evaporator (9A)
If the operation start of (1) is delayed by a delay means such as a timer for a predetermined time (about 1 minute), it is possible to prevent the warm air filled in the inside unit (4) from being discharged into the inside during defrosting.

Due to the maximum output of both compressors (5A) and (5B), the cooling operation continued, the internal cold storage temperature slightly increased and then quickly decreased, and the internal cold storage temperature fell below the first preset temperature (t ₁ ). Is detected by the third sensor (48) (see time T _{3 in} FIG. 5),
The controller (45) uses a frequency signal (40 Hz in this example) immediately before the start of defrosting for a preset frequency ΔHz, for example 10
Output a frequency signal with a high value of Hz (which means 50 Hz). If the frequency signal immediately before defrosting starts is 50Hz or more, the value obtained by adding 10Hz to the frequency is 60Hz.
However, the maximum frequency signal is 60Hz. Then, based on this frequency signal, the inverter (24) outputs electric power that is lower than the previous electric power, reduces the operating capacity of the first and second compressors (5A) (5B), and reduces the first refrigeration cycle ( 11) and the cooling capacity of the second refrigeration cycle (12) are reduced. After that, as the cooling operation is continued by this cooling capacity, the internal temperature gradually decreases, and the second preset temperature (t ₂ in this example, −t ₂ which is higher than the preset temperature S by a constant temperature q (smaller than P) (for example, 0.5 ° C.) − When the 3rd sensor (48) detects that the temperature has dropped below 0.5 ° C (which is the time shown in Fig. 5).
T reference _4), the controller (45) outputs a defrosting start immediately preceding frequency signals (40 Hz in this example). Then, the inverter (24) uses the same electric power as before the defrosting starts, and the first and second compressors (5A)
Drive (5B). After that, the controller (45) detects the PID based on the internal temperature signal from the third sensor (48).
It controls and changes the frequency signal. For this reason, the internal temperature gradually decreases, and eventually reaches the set temperature S at time T ₅ , and then the PID control is continued so as to maintain the set temperature S (the above is the description of the case of the transition of D ₁ ). ).

By the way, when the amount of stored material in the storage is large and the latent heat becomes large, the rise in the storage temperature during defrosting changes in a gentle curve and changes as shown by the dotted line in Fig. 5 (D ₂ the transition of), when the defrost is finished at time T _2, the inside temperature is between the first predetermined temperature (t ₁₎ and the second set temperature (t _2), the controller (45) Outputs a 50Hz frequency signal, which is 10Hz higher than the frequency signal immediately before the start of defrosting. Then, based on this frequency signal, the inverter (24) supplies electric power corresponding to the frequency of 50 Hz to the first and second compressors (5A) (5B). Further, the first four-way valve (13A) is switched to the cooling flow path with the completion of defrosting, the refrigerant circulates to the first refrigeration cycle (11) as shown by the solid arrow, and the second refrigeration cycle (12). The cooling operation is performed as in (1).
When the third sensor (48) senses that the internal cold storage temperature has dropped to the second preset temperature (t ₂ ) due to the continued cooling operation (see time T _{6 in} FIG. 5), the controller (45) starts defrosting. It outputs the same frequency signal (40Hz) as the previous one, and the inverter (24) supplies power corresponding to the frequency signal. Based on this electric power, the operating capacities of the first and second compressors (5A) and (5B) change, and the internal temperature gradually decreases to the set temperature S,
After that, PID control is continued so as to maintain the set temperature.

If the preset time (2 hours) elapses from the start of defrosting, whether in the D ₁ transition or the D ₂ transition, the second
In order to start the defrosting operation of the evaporator (8B), the controller (45) outputs a switching signal to the fourth relay (41), causing the fourth relay (41) to move from the cooling side contact (41b) to the defrosting side contact. (41a)
Switch to. The controller (45) outputs a signal of the defrosting operation frequency (50 Hz), and the inverter (24) outputs electric power corresponding to this frequency. Both compressors (5A) (5B) are operated by this electric power, but the second four-way valve coil (38) is energized by the fourth relay (41), and the second four-way valve (13B) is defrosted. The first refrigeration cycle (11) continues to perform the cooling operation and the second refrigeration cycle (12) performs the defrosting operation because the flow path is switched to the working flow path. After that, the second refrigeration cycle (12) is cooled from defrosting in the same transition order as in the case of transition from the defrosting operation of the first evaporator (8A) of the first refrigeration cycle (11) described above to the cooling operation. Then, the frequency signal from the controller (45) is changed so as to quickly decrease the internal temperature to the set temperature and maintain the set temperature.

In addition, after 2 hours have passed since the defrosting of the second evaporator (8B) was started, the defrosting of the first evaporator (8A) is performed again, and then the evaporators alternate with the passage of time. The defrosting operation is performed to prevent the cooling capacity from deteriorating due to long-term use.

Next, for example, when the ambient temperature is low in winter, or when there are few stored items in the refrigerator, the refrigeration load is small, so
The cooling operation of only one of the first and second refrigeration cycles (11) and (12) is performed, and the defrosting operation at this time will be described (this state is referred to as E ₁ transition).

Now, for example, by the output from the controller (45),
It is assumed that the second relay (34) is off. Therefore, the second excitation coil (26C) is not energized and the second magnet switch (26S) is off, so the second compressor (5B)
Is not energized, and the cooling operation of the second refrigeration cycle (12) is stopped. On the other hand, the first relay (33) is turned on by the output from the controller (45), the first compressor (5A) is in operation, and the first refrigeration cycle (11) is in cooling operation. At this time, at time T ₇ (see FIG. 6) set by the controller (45) to be read and set, the controller (45) stops the second refrigeration cycle (12) until then.
Outputs a signal for defrosting the second evaporator (8B). Then, this signal causes the fourth relay (41) to switch from the cooling side contact (41b) to the defrosting side contact (41a). Therefore, the operation of the second evaporator blower (9B) is stopped and the second four-way valve (13B) is switched to the defrosting flow path.

On the other hand, the controller (45) has a frequency lower than 30 Hz, which is the lowest frequency for PID control operation, such as 28
Output a frequency signal of Hz. Due to this frequency signal, the power supplied from the inverter (24) to the first compressor (5A) gradually decreases, and when it decreases to the power corresponding to 28 Hz (about 25 seconds during this period), the controller (45) becomes zero. A Hz frequency signal is output and a signal for turning off the first relay (33) is output. Therefore, the power supply to the first compressor (5A) is cut off, and the first compressor (5A) temporarily stops its operation. On the other hand, the power output from the inverter (24) gradually decreases until it reaches the power corresponding to zero Hz (
About 50 seconds), the controller (45) outputs the ON signal of the first and second relays (33) and (34) to turn ON both the first and second magnet switches (25S) and (26S), Then, the second compressors (5A) and (5B) are brought into an operable state. Then, the controller (45) outputs a frequency signal of the defrosting operation frequency (50 Hz), gradually increases the power of the inverter (24) to the power corresponding to 50 Hz, and performs the cooling operation in the first refrigeration cycle (11). The second refrigeration cycle (12) is made to perform defrosting operation.

By the above operation, 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 ( (Refer to FIG. 4, but FIG. 4 is the reverse of this state.) In the second evaporator (8B), hot gas refrigerant of high temperature and high pressure flows to perform defrosting. Second by continuing this defrosting
The ice frost in the evaporator (8B) gradually melts, and the internal temperature gradually increases due to radiation heat from the second evaporator (8B). The defrosting of the second evaporator (8B) progresses, and this second
That the temperature of the evaporator (8B) becomes defrosting ending temperature (4 ° C.), the second sensor (47) senses (see FIG. 6 time T _8), the controller (45) and the second refrigeration cycle The signal for starting the cooling operation in (12) is output. With this signal, the fourth relay (41) switches from the defrosting side contact (41a) to the cooling side contact (41b), the second four-way valve (13B) switches to the cooling flow path, and the second evaporator Blower (9
B) starts operation. The blower for the second evaporator (9
The operation of B) may be delayed for a predetermined time by the operation of a timer or the like after the second four-way valve (13B) is switched.

On the other hand, when the internal temperature is higher than the first set temperature (t ₁ ) when the second sensor (47) senses the defrosting end temperature, the controller (45) outputs a frequency signal of the highest frequency, that is, 60 Hz. . Therefore, when defrosting the second evaporator (8B), the first and second compressors (5A) (5B), which were supplied with 50Hz power from the inverter (24), had the highest frequency during the cooling operation. Power corresponding to 60Hz is supplied. Therefore,
In the first and second refrigeration cycles (11) and (12), the cooling operation is performed with the maximum cooling capacity, and the internal temperature slightly rises and then rapidly decreases. Then, when the third sensor (48) detects that the temperature inside the refrigerator has become equal to or lower than the first set temperature (t ₁ ) (see time T _{9 in} FIG. 6), the controller (45) controls the frequency immediately before the start of defrosting. It outputs a frequency signal of 45 Hz, which is 10 Hz higher than the signal (for example, 35 Hz). Therefore, the inverter (24) outputs electric power corresponding to the frequency of 45 Hz, and the first and second compressors (5A) (5
The operation capacity of B) decreases and becomes between the cooling capacity up to time (T ₉ ) and the cooling capacity before the start of defrosting. After that, the cooling operation is performed with this cooling capacity, and the internal temperature gradually decreases. Then, when the third sensor (48) detects that the temperature inside the refrigerator has reached the second set temperature (t ₂ ) due to continued cooling (see time T _{10 in} FIG. 6), the controller (45) defrosts. The frequency signal of the frequency (35 Hz) immediately before the start is output, and the inverter (24) outputs the power corresponding to the frequency 35 Hz. After that, the controller (45) inputs the temperature signal from the third sensor (48) and performs PID control to output a frequency signal based on the temperature inside the refrigerator, and the inverter (24) outputs electric power based on the frequency signal. Output. Further, the controller (45) outputs a frequency signal of 35 Hz and, at the same time, outputs an off signal to the first relay (33) to turn off the first relay (33). Then, the first exciting coil (25C) is de-energized, the first magnet switch (25S) is turned off,
The power supply to the first compressor (5A) is cut off, and the first compressor (5A)
A) stops driving. After that, only the second compressor (5B) is operated by the frequency-controlled electric power from the inverter (24), and the internal cold storage temperature 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, and outputs a frequency signal based on the temperature inside the refrigerator, and the second compressor (5B) is the inverter (24). Driven by frequency-controlled power from
The temperature inside the refrigerator is maintained at a substantially set temperature. On the other hand, when the second evaporator (8B) is defrosted, the temperature of the second evaporator (8B) rises, and when the second sensor (47) detects the defrosting end temperature, the temperature inside the refrigerator changes. When the temperature is higher than the second set temperature (t ₂ ) and equal to or lower than the first set temperature (t ₁ ), 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. After that, the controller (45) outputs the frequency signal immediately before the start of defrosting when the temperature inside the refrigerator reaches the second set temperature (t ₂ ) as in the operation after the above defrosting, and thereafter the PID based on the temperature inside the refrigerator is output. Outputs a frequency signal under control. In the above description, when only the first compressor (5A) is operated and the second compressor (5B) is stopped, the second evaporator (8B) is defrosted and after defrosting is completed. The cooling operation of the first evaporator (8A) when the first compressor (5A) is stopped and only the second compressor (5B) is operating is described above. The 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 such as Hokkaido and the ambient temperature is low, the cooling operation is performed by either one of the first and second refrigerating devices (11) (12). , If the temperature inside the refrigerator tends to be lower than the set temperature despite the operation based on the lowest frequency signal of either one of them, the controller (45) outputs a conduction angle control signal to the triac (42). To do. The conduction angle control signal controls the triac (42) and the heater (4) is turned on only when the triac (42) is on.
In 3), electricity is generated and heat is generated, and the air in the refrigerator is heated. still,
At this time as well, one of the compressors continues to operate based on the lowest frequency signal (this state is called the E ₂ transition). Hereinafter, the operation of the defrosting and the cooling operation after defrosting when the first compressor (5A) performs the operation based on the lowest frequency signal and the heater (43) is energized to control the temperature inside the refrigerator Will be described. Now, at time T ₁₁ (see FIG. 7) preset by the controller (45), the controller (45) is used to defrost the second evaporator (8B) which has been stopped until then. Output a signal. Then, by this signal, the fourth relay (41) switches from the cooling side contact (41b) to the defrosting side contact (41a). Therefore, the operation of the second evaporator blower (9B) is stopped, and the second four-way valve (13B) is switched to the defrosting flow path.

On the other hand, the controller (45) has a frequency lower than 30 Hz, which is the lowest frequency for PID control operation, such as 28 Hz.
The frequency signal of is output. Due to this frequency signal, the power supplied from the inverter (24) to the first compressor (5A) gradually decreases, and when it decreases to the power corresponding to 28 Hz (about 25 seconds during this period), the controller (45) becomes zero. A frequency signal of Hz is output and a signal for turning off the first relay (33) is output. Therefore, the power supply to the first compressor (5A) is cut off, and the first compressor (5A) temporarily stops its operation. On the other hand, when the power output from the inverter (24) gradually decreases to a power corresponding to zero Hz (about 50 seconds during this time), the controller (45) causes the first and second relays (33) (34) to Is output to turn on both the first and second magnet switches (25S) and (26S) to put the first and second compressors (5A) and (5B) in an operable state. Then, the controller (45) outputs a frequency signal of the defrosting operation frequency (50 Hz), gradually increases the power of the inverter (24) to the power corresponding to 50 Hz, and performs the cooling operation in the first refrigeration cycle (11). The second refrigeration cycle (12) is made to perform defrosting operation.

Then, at the same time when the defrosting operation is started, the controller (45) stops the conduction angle control signal to the triac (42) and stops the energization of the heater (43). Melt Korishimo gradually of the second evaporator by the continuation of the defrosting operation (8B), when the defrost is complete (see Fig. 7 time T _12), a signal for the controller (45) to start the cooling operation Output.
Based on this signal, similar to the operation after defrosting of E ₁ transition, the inside temperature of the defrosting end, when higher than the first set temperature (t _1), the first inverter (24), The second compressor (5A) (5B) is supplied with electric power of the highest frequency, that is, 60 Hz. Therefore, the first and second refrigeration cycle (11) (12)
Performs the cooling operation at the maximum cooling capacity. After that, when the cooling by the maximum cooling capacity continues and the temperature inside the refrigerator decreases to the first set temperature (t ₁ ) (see time T _{13 in} FIG. 7), the controller (45) causes the frequency signal ( 30Hz) to 10Hz
It outputs a high frequency signal of 40Hz. Therefore, the inverter (24) supplies electric power corresponding to a frequency of 40 Hz to the first and second compressors (5A) and (5B), and the operating capacity of each compressor decreases, and the first and second refrigeration cycles The cooling capacity of (11) and (12) is between the cooling capacity up to time T ₁₃ and the cooling capacity before the start of defrosting.

When the temperature inside the refrigerator decreases to the second set temperature (t ₂ ) due to the cooling operation by this cooling capacity (see time T _{14 in} FIG. 7), the controller (45) causes the frequency signal (30 Hz) immediately before the start of defrosting. The inverter (24) outputs electric power corresponding to a frequency of 30 Hz. Further, the controller (45) simultaneously outputs an off signal to the first relay (33) to turn off the first relay (33). Therefore, the first exciting coil (25
C) is de-energized, the first magnet switch (25S) is turned off, and the first compressor (5A) is stopped. The second compressor (5B) continues to operate. In addition, the controller (4
5) outputs a conduction angle control signal to the triac (42),
The heater (43) is energized to cool and heat the inside air at the same time. After that, the frequency signal from the controller (45) changes from 30 Hz immediately before the start of defrosting based on the temperature inside the refrigerator, and the cooling by the second refrigeration cycle (12) and the heater (4
The heating by 3) is performed at the same time, and the internal temperature reaches the set temperature S.

After that, the cooling by the second refrigeration cycle (12) and the heating by the heater (43) are performed at the same time, and the temperature inside the refrigerator is maintained at the substantially set temperature S. Then, when the next defrost time preset in the controller (45) comes, the first
The defrosting of the evaporator (8A) is performed similarly to the defrosting of the second evaporator (8B).

As described above, when defrosting the first evaporator (8A) or the second evaporator (8B), the controller (45) is set to the maximum frequency of operation or a preset defrost operation frequency close to the maximum frequency. A frequency signal is output, and electric power based on this frequency signal is output from the inverter (24).
At this time, the controller (45) outputs a signal for switching the refrigerant flow path so that one evaporator is in a defrosting state and the other evaporator is in a cooling state. Then, since the first compressor (5A) and the second compressor (5B) are operated at the defrosting operation frequency based on the electric power from the inverter (24), regardless of the operation frequency signal immediately before the start of defrosting, The operating capacity of both compressors (5A) and (5B) can be increased in a short time compared to the change time by PID control, and this operating capacity can perform defrosting and cooling at the same time, and the defrosting time can be shortened. At the same time, the degree of increase in the temperature inside the refrigerator due to defrosting of one evaporator can be suppressed as much as possible by cooling by the other evaporator.

In addition, the first set temperature (t ₁ ) which is higher than the set temperature S set by the user by the predetermined temperature p and the constant temperature q which is higher than the set temperature S.
(P> q) higher second set temperature (t ₂ ) is stored in the controller (45) according to the setting of the set temperature S, and the frequency signal immediately before defrosting is stored, and the defrosting operation ends. After that, the controller (45) outputs a signal for switching the refrigerant flow paths so that both evaporators (8A) and (8B) are used for cooling. When the temperature inside the refrigerator after the defrosting is higher than the first set temperature (t ₁ ), the controller (45) outputs the frequency signal of the highest frequency, and outputs both the compressors ( By operating 5A) and (5B) with the maximum operating capacity and giving the maximum cooling capacity to both refrigeration cycles (11) and (12), the internal temperature rise after defrosting operation is slightly suppressed and The temperature can be lowered quickly. On the other hand, when the temperature inside the refrigerator is lower than the first set temperature (t ₁ ) and higher than the second set temperature (t ₂ ), the controller (45) outputs a frequency signal higher than the frequency immediately before the start of defrosting by the preset frequency ΔHz. Is output, and both compressors (5A) and (5B) are operated through the inverter (24) to have an operating capacity higher than the capacity immediately before defrosting, so that the degree of decrease in the internal room temperature is made larger than that immediately before defrosting. The internal temperature is made to drop closer to the set temperature sooner. On the other hand, when the temperature inside the refrigerator is equal to or lower than the second set temperature (t ₂ ), the controller (45) outputs the frequency signal immediately before the start of defrosting, and thereafter, based on the temperature inside the refrigerator.
By changing the operating capacity of the compressor via the inverter (24) by outputting the frequency signal by PID control, the overshoot phenomenon in the temperature change from the second set temperature (t ₂ ) to the set temperature S As a result, the required power can be saved and the temperature can be precisely controlled with respect to the set temperature. Therefore, it is possible to slightly suppress the rise in the temperature inside the refrigerator due to defrosting, reduce it to the set temperature in a short time, maintain the set temperature, and perform the cooling operation for a long time. The quality of internal storage can be maintained for a long period of time, and precise temperature control is possible.

[Effect of the Invention] As described in detail above, according to the present invention, during defrosting, one of the refrigeration cycles provided with two systems performs cooling operation, the other performs defrosting operation, and the maximum frequency is preset. Since the compressor of each system is driven by the frequency signal set in the vicinity, the operating capacity can be determined regardless of the operating frequency immediately before the start of defrosting, and the high capacity can be achieved in a shorter time, thus reducing the defrosting time. In addition to being able to achieve it, it is possible to suppress the temperature increase in the refrigerator due to defrosting. Then, with the determination of the set temperature, the first
Set the set temperature and the second set temperature so that
Area higher than the first set temperature at one temperature (first area)
And a cooling operation after defrosting, which is divided into three temperature areas, that is, an area (second area) below the first set temperature and higher than the second set temperature, and an area below the second set temperature (third area). Based on the temperature inside the refrigerator, the controller outputs the frequency signal of the highest frequency in the first region, the frequency signal of (frequency immediately before defrost start + set frequency) in the second region, and the PID in the third region. Since the frequency signals of the control frequency are output, the internal temperature that rises due to defrost can be reduced efficiently in a short time, and the cooling operation that minimizes the overshoot phenomenon with respect to the set temperature Can be done. Further, in combination with the effect of suppressing the temperature rise in the refrigerator in the above defrosting, an operation control device suitable for use in the field of cooling in which precise temperature control is required, particularly for ice cooling, is provided. be able to.

[Brief description of drawings]

Each drawing shows an embodiment of the present invention, FIG. 1 is a schematic electric circuit diagram of an operation control device of a refrigerating apparatus, FIG. 2 is a schematic vertical sectional view of a prefabricated refrigerator, and FIGS. In the refrigerant circuit diagram of the cycle, FIG. 3 shows the flow of the refrigerant in the case of both cooling operations, and FIG. 4 shows the flow of the refrigerant in the case of one cooling operation and the other one defrosting operation. 7 to FIG. 7 are transition diagrams showing changes in the in-compartment temperature before defrosting, during defrosting, and after defrosting, and changes in the refrigeration operation control state, and FIG. 5 is a transition in the operation state of FIG. FIG. 7 shows a transition in an alternate cooling operation state with only one refrigeration cycle, and FIG. 7 shows a transition in an operation state with alternate minimum cooling operation and heater energization only in one refrigeration cycle. (1) …… Prefabricated refrigerator, (2) …… Refrigerator, (5
A) …… 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 second four-way valve, (24) ……
Inverter, (33) …… first relay, (34) …… second relay, (37) …… third relay, (41) …… fourth relay,
(42) …… Triac, (45) …… Controller,
(46) …… First sensor, (47) …… Second sensor, (48)
...... Third sensor.

Claims (1)

[Claims] 1. A refrigeration cycle of two systems each comprising a compressor, a condenser, an evaporator, a flow path switching valve, etc., and an internal temperature detection element for detecting an internal temperature and outputting an internal temperature signal. When,
A frequency signal that outputs a switching signal for switching the flow path of the flow path switching valve at predetermined time intervals and based on the internal temperature signal and that is increased or decreased between the minimum frequency and the maximum frequency based on the internal temperature signal. In the operation control device of the refrigerating apparatus, which includes a controller that outputs a signal, and an inverter that inputs a frequency signal from the controller to increase or decrease the power supplied to the compressor, the controller is in defrosting, and A defrosting operation that outputs a switching signal that makes one of the refrigeration cycle a cooling operation and the other a defrosting operation and that is set to the maximum frequency or a frequency slightly lower than the maximum frequency regardless of the operation frequency signal before the start of defrosting When the frequency signal is output and the defrosting is performed, and the internal temperature is higher than the first preset temperature which is higher by a predetermined temperature p than the preset temperature that can be arbitrarily set, Outputs a frequency signal of higher frequency, the inside temperature is constant than the set temperature by more than the first set temperature Temperature q
When the temperature is higher than the second set temperature, which is higher than (<p), a frequency signal having a value higher than the operating frequency signal immediately before the start of defrosting by a set frequency is output, and when the internal temperature is equal to or lower than the second set temperature, PID control is performed. An operation control device for a refrigerating device, which outputs a frequency signal.