JPH04366384A - Low temperature cabinet - Google Patents

Abstract

PURPOSE:To provide a low temperature box in which a malfunction of a con denser can be strongly urged to a user. CONSTITUTION:A compressor 8 is stopped at a predetermined abnormally high temperature of a condenser 12 based on an output of a condenser temperature sensor 19, and an alarm is displayed. When the temperature of the condenser 12 is lowered to a predetermined low temperature, the stop of the compressor 8 is released. The display of the alarm is continued until the temperature of the condenser 12 becomes below the low temperature.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature refrigerator that stops a compressor and issues an alarm due to an abnormal temperature rise in a condenser.

0002

[Prior Art] Conventionally, this type of low-temperature storage has a compressor, a condenser,
It consists of a cooling device in which a pressure reducer, a cooler, etc. are sequentially connected in a ring to form a refrigerant circuit, and an insulating box made of a heat insulating material. Provided for cold storage. At this time, the condenser functions as a radiator for the high-temperature, high-pressure gas refrigerant discharged from the compressor, and the refrigerant radiates heat here to condense and liquefy, reduce the pressure in the pressure reducer, and evaporate in the cooler.

[0003] As described above, since the condenser is used to dissipate heat from the high-temperature gas refrigerant, in order to improve its heat dissipation performance,
Cooling must be done by natural air cooling or forced air cooling using a blower. When dust etc. accumulates in the condenser due to the air cooling effect and it becomes clogged, air circulation is obstructed.
The temperature of the condenser increases abnormally, and the heat dissipation and condensation performance deteriorates significantly. When the condensing ability of the high-temperature, high-pressure gas refrigerant deteriorates, the cooling ability of the cooler deteriorates significantly, and the temperature of the compressor also increases, causing damage to equipment. Therefore, in general, when the temperature of the condenser rises abnormally, the operation of the compressor is temporarily stopped, and the compressor is started again after waiting until the temperature of the condenser falls.

[0004] However, even if the temperature of the condenser decreases due to the stoppage of the compressor, the condenser temperature will rise again because the condenser is not clogged. Therefore, conventionally, the operation of the compressor is stopped as the temperature of the condenser increases, and a predetermined alarm is issued to notify the user of the abnormality of the condenser.

[0005]

However, in the past, this alarm was issued at the same time as the compressor was stopped and the stop was released. In other words, in the past, an alarm was issued when the condenser temperature rose abnormally and compressor operation was stopped, and the alarm was canceled when the compressor resumed operation. As a result, it was often difficult to attract the user's attention.

An object of the present invention is to solve this problem and provide a low-temperature refrigerator that can strongly prompt the user to detect abnormalities in the condenser.

[0007]

[Means for Solving the Problems] The present invention provides a low-temperature refrigerator R equipped with a cooling device 7 consisting of a compressor 8, a condenser 12, a cooler 10, etc., which includes a sensor 19 for detecting the temperature of the condenser 12; a display section 48 that displays an alarm as an alarm section;
It consists of a control device (microcomputer) 46 that controls the operation of the compressor 8, and this control device 46 stops the compressor 8 at a predetermined abnormally high temperature of the condenser 12 based on the output of the sensor 19, and displays the When the temperature of the condenser 12 drops to a predetermined low temperature, the compressor 8 is stopped. It is designed to continue until the temperature drops to a low temperature.

[0008]

According to the present invention, if the condenser 12 becomes clogged and its temperature rises abnormally, the compressor 8 is stopped and a warning is displayed on the display section 48 at the same time. By stopping the compressor 8, the temperature of the condenser 12 decreases, and the operation of the compressor 8 is restarted at a predetermined low temperature, but the alarm display is not canceled until the temperature of the condenser 12 further decreases. Therefore, even if this abnormality is left unaddressed and the compressor 8 is repeatedly operated and stopped due to the abnormally high temperature of the condenser 12, the alarm display on the display unit 48 continues.

[0009]

Embodiments Next, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a block diagram of an electric circuit, and FIG. 2 is a longitudinal sectional view of the low-temperature refrigerator R. In this embodiment, the low-temperature storage R is a so-called cold roll box that is loaded on a delivery vehicle and used for cold delivery of low-temperature goods.

The low-temperature refrigerator R includes a main body 1 made of a heat-insulating box, a storage chamber 2 formed in the main body 1 for storing articles,
A door 3 that opens and closes the storage room 2, a cold storage room 4 that communicates with the storage room 2 via a duct 5, a cold storage agent 6 stored in the cold storage room 4, and a cooling device 7 that cools the cold storage agent 6. It is configured. Here, the cold storage agent 6 has a freezing and melting temperature Ts of -
Use one at 25°C.

The cooling device 7 includes a compressor 8, an accumulator 9, a cooler 10 arranged in the cold storage chamber 4 so as to be in close thermal contact with the cold storage agent 6, and a capillary tube 11 as a pressure reducer. It is composed of a condenser 12 and a condenser blower 13. Furthermore, the air cooled by the cool storage agent 6 is sent to the storage room 2 via the duct 5 by a DC fan motor 14 serving as a blowing means.

The air in the storage chamber 2 is supplied to the cold storage chamber 4 from the suction port 15.
The air from the cold storage chamber 4 is blown out from the outlet 16 of the duct 5 into the storage chamber 2. A cool storage agent temperature sensor 17 is attached to the cool storage agent 6 as a temperature detection means for detecting the temperature thereof. Further, the air outlet 16 is provided with an internal temperature sensor 1 that detects the temperature of the cold air blown into the storage room 2.
8 is provided. Furthermore, the temperature of the condenser 12 is detected by a condenser temperature sensor 19.

Casters 20 are attached to the bottom of the main body 1, and bumpers 21 are attached to the upper and lower ends of the outer peripheral surface of the main body 1. Further, a machine room 22 is formed in the rear corner of the lower part of the main body 1, and a compressor 8, a storage battery, etc., which will be described later, are housed therein. still,
In this embodiment, in order to obtain sufficient cooling capacity, two cooling devices 7 and two DC fan motors 14 each having the same size are installed.

In FIG. 1, a rectifier circuit 31 as a power supply circuit is connected to the a contact point of a switching relay 36, and the output of a storage battery 32 connected to a charging circuit 33 is connected to a relay coil Ry.
It is connected to the B contact of the switching relay 36 via the contact No. 6. The switching relay 36 functions as a switching means for switching the power source of a microcomputer (hereinafter referred to as a microcomputer) 46 constituting the control unit between an AC power source (200 VAC) and the storage battery 32. That is, the common contact c of the switching relay 36 is connected to the microcomputer 46, and the contact is closed to a contact when AC power is connected, and is closed to contact b when AC power is disconnected. As a result, the microcomputer 46 connects the AC power source to the AC power source, and disconnects the AC power source from the storage battery 32.
It works as a power source.

The storage battery 32 includes a resistor 3 as a current sensor.
4 are connected in series and output a voltage proportional to the charging current. Further, a voltage monitoring circuit 35 for monitoring the voltage of the storage battery 32 is connected to the common contact c of the switching relay 36.
The output is input to the microcomputer 46. The voltages generated by the cool storage agent temperature sensor 17, the internal temperature sensor 18, the condenser temperature sensor 19, and the resistor 34, which are composed of transistor sensors, are amplified by amplifier circuits 37, 38, 39, and 40, respectively, and are all sent to the microcomputer 46. is input. Furthermore, the microcomputer 46 also outputs the negative phase detection circuit 41 that detects the connection state of the connected three-phase AC power source (AC200V).
is input.

Compressor motor 42 of two compressors 8
, 43 and the reverse phase detection circuit 41, the relay coils 44 and 45 switch contacts (not shown) to bring the AC power supply into a normal connection state, and are respectively relay coils Ry2.
, Ry3, Ry4, and Ry5 to the AC power source. The DC fan motors 14, 14 are connected to a common contact c of a switching relay 36 via a contact of a relay coil Ry1. These relay coils Ry1, Ry2
, Ry3, Ry4, Ry5, and Ry6 are connected to the output of the microcomputer 46, and the microcomputer 46 opens and closes each contact by controlling energization of these, and controls the operation and stopping of the compressor 8 and DC fan motor 14 as described later. do. Similarly, the microcomputer 46 also controls switching between normal phase and negative phase, and discharge control of the storage battery 32.

Here, like the microcomputer 46, when the DC fan motor 14 is connected to an AC power source, it operates using the AC power source via the rectifier circuit 31 and the switching relay 36, and when the AC power source is disconnected, it operates using the storage battery 32 as a power source. . That is, during the cold storage operation to freeze the cold storage agent 6, the DC fan motor 14 uses the output of the rectifier circuit 31 as a power source, and the storage battery 32 and charging circuit 33 are not used.

Further, a switch input line from an operation panel 47 provided with input means for inputting signals to the microcomputer 46 and various display means and a display output line to the operation panel 47 are connected to the microcomputer 46 . Furthermore, the output of the rectifier circuit 31 is connected to the microcomputer 4 via a power signal line 49.
6, and based on this, the microcomputer 46 determines whether or not there is an AC power source.

Next, the operation will be explained. When the low-temperature refrigerator R is connected to an alternating current power source (AC200V) and the microcomputer 46 is powered on for the first time, the setting operation states of switches SW1 to SW4, which are input means provided on the operation panel 47, are read. Here, the operation panel 47 is provided with a refrigerator switch SW for instructing the start of internal cooling.
1. Temperature selection switch SW2 that selects the storage room 2 internal temperature to +5°C, which is the refrigeration temperature; temperature selection switch SW3, which selects the freezing temperature to 0°C; and -18°C, which is the freezing temperature.
Temperature selection switch SW4 to select from LED4 to LE
D6 is a display section 48 consisting of two 7-segment LEDs, and when any one of SW2 to SW4 is operated, the microcomputer 46 lights up LED4 to LED6 corresponding to the selected temperature. Also, microcomputer 46
detects that the low-temperature refrigerator R is connected to the AC power source by the output from the power signal line 49.

FIG. 3 shows temperature changes and operations of each part during operation, and FIGS. 4 and 5 show flowcharts of the control program of the microcomputer 46. At the delivery base, when the low-temperature warehouse R is connected to an alternating current power source (AC200V), charging of the storage battery 32 is started. Also, on the operation panel 47, S
It is assumed that W4 is operated and -18° C. is designated as the set temperature Tc. The microcomputer 46 has the switching relay 36 a.
Power is supplied from the rectifier circuit 31 through the contact, and starts at the same time as this power is supplied.In step 50, it is determined whether or not the cool storage agent temperature sensor 17 is short-circuited.If it is not short-circuited, the cool storage agent temperature is determined in step 51. It is determined whether the sensor 17 is disconnected this time. If there is no failure, it is determined in step 52 whether or not the compressor 8 is currently operating, and since it is stopped, in step 53 the temperature of the refrigerant 6 is -35°C.
It is determined whether or not the temperature is higher than that, and since the temperature is high at the start of operation, the compressor 8 is operated in step 54. As a result, the cool storage operation shown in FIG. 3 is started. Note that a short circuit or disconnection of the cool storage agent temperature sensor 17 can be determined by an abnormality in the output potential from the sensor.

If the compressor 8 is in operation in step 52, it is determined in step 55 whether the temperature of the refrigerant 6 is below -37°C, and if it is below, the compressor 8 is operated in step 56.
stop. As long as the cool storage agent temperature sensor 17 is normal and the AC power source (AC 200V) is connected, the compressor 8 is repeatedly operated and stopped under the above control.

In step 57, a subroutine for determining the completion of freezing of the cool storage agent 6 and the completion of charging of the storage battery 32 is executed. That is, there are two freezing determination conditions for the cold storage agent 6 here. One is that the temperature of the cold storage agent 6 based on the output of the cold storage agent temperature sensor 17 is -29 degrees Celsius lower than the freezing and melting temperature of -25 degrees Celsius. ℃ or below for more than 9 hours,
The other is -3, where the temperature of cold storage agent 6 is 7°C lower than -25°C.
This means that the temperature remained below 2°C for 10 minutes or more. If either one of these two conditions is satisfied, freezing of the cold storage agent 6 is considered to have been completed.

The charging state of the storage battery 32 is determined by inputting the voltage generated by the resistor 34 and calculating the charging current flowing through the storage battery 32 from that value. Consider it completed. When all of these steps are completed, the microcomputer 46 turns on the LED 2 to indicate that the cold storage operation is ready.

Next, in step 58, the refrigerator switch S
It is determined whether or not W1 has been pressed, and if it has not been pressed, it is determined in step 59 whether the freezing and charging have been completed, and since the power has just been turned on and neither freezing nor charging has been completed, step 64 is performed. The DC fan motor 14 is stopped.

The conventional cold storage operation will be explained based on FIG. 3. As the compressor 8 operates, the temperature of the cold storage agent 6 rapidly decreases, and approximately 3.5 hours after the start of operation, the temperature of the cold storage agent 6 reaches the freezing temperature Ts. It reaches -25°C. However, due to the supercooling phenomenon of the cool storage agent 6, the cool storage agent 6 does not freeze immediately, and its temperature continues to fall further. Then, the temperature of the cold storage agent 6 is about -
Freezing begins when the temperature reaches 31°C, and the temperature of the cold storage agent 6 is approximately -
Return to 25°C. While the cold storage agent 6 is frozen, its temperature is -25
The temperature remains constant at ℃, but once the freezing ends, the temperature starts to drop again and becomes lower than -32℃.

In the process of the above-described operation, when the freezing and charging completion determination conditions of step 57 are satisfied, the process proceeds from step 59 to step 60, where it is determined whether the DC fan motor 14 is currently operating, and since it is not, step 61 is performed. The temperature of the storage compartment 2 based on the internal temperature sensor 18 is the set temperature Tc.
It is determined whether the temperature is +1°C or higher, and since the temperature of the storage chamber 2 is high here, the DC fan motor 14 is operated in step 63.
The cool storage operation is ended and the refrigerator internal cooling operation is started. This DC
By operating the fan motor 14, the latent heat of fusion of the cool storage agent 6 or cold air cooled by the cooler 10 is circulated into the storage chamber 2, thereby cooling the storage chamber 2.

When the temperature of the storage chamber 2 based on the internal temperature sensor 18 reaches the set temperature Tc by this cooling, the process proceeds from steps 60 and 62 to step 64, and the DC fan motor 14 is stopped. In this way, DC fan motor 1
4 is repeatedly operated and stopped, and the temperature of storage room 2 is -18
Maintained around ℃.

Here, when the refrigerator switch SW1 is pressed during the cold storage operation, the cold storage agent 6 freezes or the storage battery 32 freezes.
Step 58
The process then proceeds to step 60, so that the cold storage operation is shifted to the internal cooling operation. This is performed when it is necessary to cool the food in the storage room 2 while freezing the cold storage agent 6.

[0029] Also, during the above-mentioned cold storage operation or refrigerator cooling operation, in step 50 or 51, the cold storage agent temperature sensor 17 is
If a failure is discovered, the process proceeds to step 65. In step 65, it is determined whether or not the DC fan motor 65 is in operation. If it is not in operation, in step 66, the temperature of the storage compartment 2 based on the internal temperature sensor 18 is set to the set temperature Tc + 1°C.
(i.e., -17°C) or higher, and if the temperature is higher than that, the compressor 8 and the DC fan motor 14 are
is operated, and when the temperature of the storage compartment 2 based on the internal temperature sensor 18 reaches the set temperature Tc due to this cooling, step 6
Step 5 and step 67 proceed to step 69, where the compressor 8 and DC fan motor 14 are stopped.

That is, if a failure such as a short circuit or disconnection occurs in the cold storage agent temperature sensor 17, it will be impossible to determine whether the freezing of the cold storage agent 6 is complete, but even in that case, instead of stopping the entire system, the compressor 8 and the DC fan motor 14 are automatically controlled by comparing the temperature of the storage compartment 2 based on the internal temperature sensor 18 and the set temperature Tc, that is, the control of general refrigerator operation is performed. The DC fan motor 14 is repeatedly operated and stopped, and the temperature of the storage chamber 2 is maintained at around -18° C., which is the set temperature Tc. Therefore, even if foods are stored in the storage chamber 2, at least the preservation of these foods can be achieved.

Here, when the microcomputer 46 is normal, it displays the temperature inside the storage chamber 2 and the set temperature Tc on the display section 48, but when a failure occurs in the refrigerant temperature sensor 17, E5 is displayed in the case of a disconnection, and E5 is displayed in the case of a short circuit. displays an alarm such as E6. This notifies the user of the occurrence of a failure.

Furthermore, in this type of cooling device 7, if the heat dissipation performance of the condenser 12 deteriorates due to a clogged filter of the condenser 12 or a failure of the condenser blower 13, the cooling capacity of the cooler 10 also decreases. Due to the risk of equipment damage, the condenser 1 is
If the temperature of the compressor 2 rises abnormally, the operation of the compressor 8 is interrupted.

That is, in step 95, the microcomputer 46 detects the temperature of the condenser 12 using the condenser temperature sensor 19, and
It is determined whether the temperature is above +58°C, and if the temperature is above +58°C, an alarm is output in step 96. This alarm output is sent to the operation panel 47 via a display output line, and an alarm such as E1 is displayed on the display section 48 to warn the user of an abnormality in the condenser 12. Next, step 9
At step 7, the interrupt flag is set, and at step 98, the condenser 12
It is determined whether the temperature of the condenser 12 is +55°C or higher, and if it is, it is then determined in step 99 whether the temperature of the condenser 12 is +52°C or higher, and if it is, the process returns to the original state. On the other hand, in steps 54 and 68 of the flowchart of FIG. 4, the setting and resetting of this interruption flag is actually monitored, and in step 54 or 68, the state of this interruption flag is checked, and the interruption flag is reset. In this case, the compressor 8 continues to operate, but if the interruption flag is set, the microcomputer 46 does not operate the compressor 8. As a result, if the temperature of the condenser 12 rises abnormally, the operation of the compressor 8 is stopped and the temperature of the condenser 12 is encouraged to decrease.

As the compressor 8 is stopped, the temperature of the condenser 12 gradually decreases, and when it becomes lower than +55°C,
The process proceeds from steps 95 and 98 to step 100 to reset the interruption flag. As a result, the suspension of operation of the compressor 8 is canceled and the operation starts again, but if the temperature of the condenser 12 does not fall below +52°C, steps 99 to 10
Since the process does not proceed to step 1, the alarm display is still performed. Condenser 12
If the abnormality is not resolved, the temperature of the condenser 12 will start to rise again as the compressor 8 starts operating again, so the temperature will rise to +58
When the temperature reaches above .degree. C., the process proceeds again from step 95 to step 96, where an interruption flag is set and the operation of the compressor 8 is interrupted.

Even when the abnormality of the condenser 12 is not resolved and the operation of the compressor 8 is started and interrupted intermittently, the alarm is displayed as long as the temperature of the condenser 12 does not fall below +52°C. Since this continues, the user's attention is strongly urged. When this abnormality is removed and the temperature of the condenser 12 becomes lower than +52° C., the alarm output is canceled in step 101 and the alarm display disappears.

After or during the cold storage operation and refrigerator cooling operation as described above, articles such as food are stored in the low-temperature refrigerator R, disconnected from the AC power source, and loaded onto a delivery vehicle. When the AC power supply to the low-temperature refrigerator R disappears (AC power is turned off)
Next, a cold storage operation is started in which the storage chamber 2 is cooled by the latent heat of fusion of the cold storage agent 6. During the cold storage operation, the microcomputer 46 and the DC fan motor 14 are supplied with power by discharging the storage battery 32 by switching the changeover switch 36 to the b contact. Further, the DC fan motor 14 is controlled by the microcomputer 46, and is operated when the temperature of the storage chamber 2 measured by the internal temperature sensor 18 rises to the set temperature Tc+1° C., and is stopped when the temperature falls to Tc. As a result, the inside of the storage chamber 2 is maintained at around -18°C. It is assumed that the contacts of the relay switch Ry6 are closed.

This cold storage operation ends 5 hours after the AC power supply is turned off, and thereafter the DC fan motor 14 is also completely stopped. These five hours are determined as enough time for the delivery vehicle to complete the delivery.

[0038] It goes without saying that the temperatures, times, etc. in the examples are not limited to these, and can be appropriately determined depending on the type, capacity, etc. of the equipment. Further, in the embodiment, the present invention is applied to a so-called cold roll box, but the present invention is not limited to this, but is also effective in ordinary refrigerator-freezers, showcases, etc.

[0039]

According to the present invention, if the condenser becomes clogged and its temperature rises abnormally, the compressor is stopped and at the same time an alarm is activated in the alarm section. In particular, this alarm operation continues even after the compressor is stopped and the temperature of the condenser drops and the compressor is restarted, so it strongly urges the user's attention and prompt response to abnormalities. can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an electric circuit.

FIG. 2 is a longitudinal cross-sectional view of the low-temperature refrigerator.

FIG. 3 is a characteristic diagram showing temperature changes and operations during operation.

FIG. 4 is a flowchart of a control program.

FIG. 5 is a flowchart of a control program.

[Explanation of symbols]

8 Compressor 12 Condenser 19 Condenser temperature sensor 46 Microcomputer 48 Display section R Low temperature storage

Claims (1)

[Claims] 1. A low-temperature warehouse equipped with a cooling device consisting of a compressor, a condenser, a cooler, etc., comprising: a sensor for detecting the temperature of the condenser; an alarm section for issuing an alarm; and a control device that stops the compressor at a predetermined abnormally high temperature of the condenser based on the output of the sensor, and performs an alarm operation in the alarm section to stop the condenser. When the temperature of the condenser drops to a predetermined low temperature, the stoppage of the compressor is canceled, and the alarm operation continues until the temperature of the condenser drops to a temperature even lower than the low temperature. and low temperature storage.