JPH02122179A - Low temperature controller for low temperature goods storage case - Google Patents

Abstract

PURPOSE:To maintain a storage compartment at a specified temperature by a method wherein when one of two thermoregulation sensors is out of order, the reminder backs it up, and when the remainder is also out of order, it is backed up by duty control using a timer. CONSTITUTION:A thermoregulation sensor A 55 is installed in the vicinity of a cold air outlet 12 and a thermoregulation sensor B 56 in the vicinity of a cold air intake 13. A defrost reset sensor A 57 is installed on a first evaporator 20, and a defrost reset sensor B 58 on a second condenser 21. When two thermoregulation sensors 55 and 56 are in order, a refrigerant compressor is on-off operated so as to keep the average value of the output from the sensors within a specified range. When one of two sensors 55 and 56 comes out of order during that period, the temperature control is carried out only by the remaining normal sensor. When both the thermoregulation sensors A and B come out of order, the control is carried out by the defrost reset sensor on the evaporator in cooling operation. When a microcomputer 51 judges both the defrost reset sensors A and B are out of order, duty control takes place by which the refrigerant compressor is on-off operated by a timer 51A at pre-set time intervals.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to temperature control i of a low-temperature product storage case suitable for freezing or refrigerating products for sale, such as display storage of Western confectionery.
Regarding t.

2. Description of the Related Art In general, low-temperature product storage cases are provided with temperature control sensors in order to maintain the temperature inside the case at a predetermined temperature. Conventionally, when this temperature control sensor becomes abnormal, an alarm LED is simply turned on or an alarm is displayed on a display, and no further abnormality measures have been taken.

(c) Problems to be solved by the invention For this reason, in the conventional device described above, if the sensor for temperature control becomes abnormal, the cooling operation inside the case stops, which has a serious effect on the products inside the case. was there. Moreover, since the lifespan of the temperature sensor is not so long compared to other parts, such problems often occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a highly reliable temperature control device for a low temperature product storage case, that is, a fail-safe device that can normally control the temperature inside the case even if the temperature control sensor becomes abnormal.

(d) Means for Solving the Problems The first means of the present invention is to adjust the temperature inside a case for storing products at low temperature based on a detection signal from a temperature control sensor placed inside the case. In the temperature control method of a low-temperature product storage case, temperature control sensors are placed at two locations in the case, one at the cold air outlet and the other at the intake section, and when normal, the average output of the two temperature control sensors is means for controlling the temperature based on the value, means for determining whether the two temperature control sensors are abnormal, and based on the determination result, one of the two temperature control/roll sensors is abnormal. means for controlling the temperature based only on the normal temperature control sensor output, and
When both of the temperature control sensors become abnormal, the temperature is controlled by duty control that repeatedly operates and stops the refrigerant compressor constituting the cooling device in a certain time range based on a timer. This is what I did.

Further, as a second means of the present invention, the refrigerant compressor is operated and controlled during normal operation based on the two temperature control sensors and/or during abnormal operation based on the - one temperature control sensor.
It is equipped with a storage means for calculating and storing the average time of each stop, and when the two temperature control sensors become abnormal, the refrigerant compressor is operated or restarted according to the average time stored in the storage means. It employs duty control that performs stopping.

(e) Effect According to the first means, even if one of the temperature control sensors inside the low temperature product storage case becomes abnormal, the low temperature product storage case continues to operate normally using the other temperature control sensor. The inside of the case is maintained at a predetermined temperature, and sensor abnormalities are displayed, so the abnormal sensor can be replaced and the low temperature product storage case returned to its original state without affecting the stored products. Furthermore, even if both temperature control sensors become abnormal, temperature control close to normal can be performed in a duty cycle until the abnormal sensor is replaced.

According to the second means, during duty control, the refrigerant compressor is operated and stopped based on the average value when the refrigerant compressor was operated and stopped based on the temperature control sensor. , temperature control can be performed in substantially the same manner as temperature control based on a temperature control sensor.

(f) Embodiment FIG. 1 shows a low-temperature product storage case according to an embodiment of the present invention (
FIG. 2 shows an external perspective view of the low-temperature case 1, and FIG. 3 shows a perspective view of its cooling device.

In these figures, the low-temperature case 1 is a closed type suitable for cooling and preserving products such as fresh sweets, and its main body includes a storage chamber 2, a cooling chamber 3 located directly below the storage chamber 2, It consists of a machine room 4 located directly below this cooling room 3.

The storage room 2 has a curved transparent plate 5 arranged from the front to the top, a plurality of transparent doors 7 that slide in a left-right direction in a frame 6 arranged on the back, and arranged on both left and right sides, respectively. A detachable bottom plate 9 that also serves as a partition plate, a shelf 10, and a fluorescent lamp 11 are provided inside. The bottom plate 9 partitions the storage and cooling chambers 2 and 3 into upper and lower sections, and has an air outlet 12 along its rear edge and an inlet 13 along its front edge. Both cooling chambers 2 and 3 are configured to communicate with each other. The cooling chamber 3 is constituted by a heat insulating wall 14 with an open upper surface on which the storage chamber 2 is placed and supported, and the machine room 4 is formed below the heat insulating wall 14. The heat insulating wall 14 has a drainage port 15 on the bottom wall, and forms a base 17 together with a metal base leg 16.

Reference numeral 20.21 denotes a first and second evaporator arranged in the cooling chamber 3, and a partition plate 22 which also serves as a dew receiving plate is interposed so that the first evaporator 20 is located inside and the second evaporator 21 is located outside. They are arranged vertically overlapping each other and slanting low in the direction of the drain port 15. This first. The second evaporator 20.21 is a plate consisting of a large number of plate-shaped fins 23 arranged in parallel at equal intervals, both left and right tube plates 24, and a large number of refrigerant pipes 25 perpendicular to the fins and both tube plates. It is fin-shaped. Each of the fins 23 is coated with a water-repellent coating (1()) to increase moisture retention on the surface.The partition plate 22 has one end connected to the air inlet of the first and second evaporators 20 and 21. An extending portion 26 is formed that extends forward of the surface, that is, in the direction of the blower fan described later.This extending portion 26 includes a stepped portion 27 that collects dew from the first evaporator 20, and a stepped portion 27 that stores dew from the first evaporator 20. A plurality of small drainage holes 28 are formed to allow dew to drip downward.These drainage holes 28 are preferably formed in areas where the wind pressure of the blower fan described later is weak.

30.31 is always operated, and the 1st. Second evaporator 20
．． A pair of first and second blowing fans are used to forcibly circulate the cold air passing through the cooling chamber 3, the blowout hole 12, the storage chamber 2, the suction hole 13, and the cooling chamber 3 as shown by the arrows in Figure 1. Both are attached to a box-shaped fan case 33 provided with a partition plate 32. This first. Second blower fan 30
, 31 is the length of the low temperature case 1, in other words, the first . As the length of the second evaporator 20.21 increases, the number of the second evaporators 20.21 increases, for example, as shown in FIG. If the length of the second evaporators 20 and 21 is for 6 feet, two pairs are used. The rear edge of the first evaporator 34 is the front edge of the upper surface of the first evaporator 20 and the first evaporator 34 . Both left and right tube plates 2 of the second evaporator 20.21
The duct is arranged so as to overlap the front edge of the first tube plate 24 and is fixed to both tube plates 24 with fasteners such as screws. The air inlet surface of the second evaporator 20° 21 and the extension part 26 of the partition plate 22 are covered by this duct 34, and the inside of this duct is partitioned into inside and outside, that is, upper and lower parts by the extension part 26, and the first evaporator 20 It is divided into a first air passage 35 facing the evaporator 21 and an air passage 36 facing the second evaporator 21 .

This duct 34 is connected to the first duct. 2nd ventilation fan 30.31
This is to ensure that the cold air sent from the evaporators 20.21 to the corresponding evaporators 20.21 is diffused over the entire width of both evaporators 20.21, and a third
As shown in the figure, a first opening 37 facing the first air passage 35 and a second opening 38 facing the second air passage 36 are formed at appropriate positions in the lower half of the front surface. Reference numeral 39 denotes a rotating tool such as a hinge for attaching the fan case 33 to the duct 34 in a vertically rotatable manner. With the attachment of this rotating tool, the first blower fan 30 opens the first opening 37, the first air passage 35, and the like. The second blowing fan 31 corresponds to the inner route formed by the first evaporator 20, and the outer route formed by the second opening 38, the second air passage 36, and the second evaporator 31. , the return cold air from the storage chamber 2 is sent to the respective evaporators 20, 21. When the fan case 33 is opened, the duct 3 is opened as shown on the left side of FIG.
4, and in this state, the top surface of the extension part 26 or the soil surface of the bottom wall of the heat insulating wall 14 is cleaned through the first opening 37 or the second opening 38. From time to time, maintenance and inspection of the first and second blower fans 30, 31 is performed. Note that when opening the fan case 33, the bottom plate 9 is removed.

FIG. 4 shows the refrigerant circuit of the cooling device, in which the first and second evaporators 20, 21 are connected in parallel with each other, while the corresponding first evaporators 20, 21 are connected in parallel with each other. The second expansion valves 40, 41, the first. Second solenoid valve 42.
43 is connected in series. 44 is a refrigerant compressor, 45 is a condenser, 46 is a liquid receiver, 47 is a dryer, and the first
．． The second evaporator 20, 21, the first evaporator. Second expansion valve 40, 41
, 1st. Together with the second solenoid valve 42,43 it forms a cooling cycle. Note that the refrigerant compressor 44 and condenser 45 are arranged in the machine room 4.

FIG. 5 shows a control device, including a control board 50, a display board 60, and a display board 60 necessary for controlling the operation of the low temperature case 1.
It includes a power relay board 70 and the like.

A timer 51A is provided on the control board 50,
A microcomputer 51 that performs various calculation processes, an A/D converter 52 that performs signal conversion, a setting device 53 that performs various settings such as temperature, time, and differential (described later), an operational amplifier 54 that amplifies sensor output, etc. are provided. The operational amplifier 54 includes a temperature control A sensor (hereinafter referred to as temperature control A sensor) 55, a temperature control B sensor (hereinafter referred to as temperature control B sensor) 56, and a defrost return A
Various sensors such as a sensor 57, a Tefrost return B sensor 58, and a filter sensor 59 are connected. The temperature control A sensor 55 is located near the cold air Suita outlet 12 in FIG.
The sensor 56 is installed near the cold air intake port 13. Further, the defrost return A sensor 57 is connected to the first evaporator 20,
A defrost return B sensor 58 is installed in the second evaporator 21. The filter sensor 59 is provided on the filter of the condenser 45, and when the filter is clogged,
It is used as a means to issue an alarm when the temperature of No. 5 rises abnormally.

A switch section 61 for inputting various commands to the microcomputer 51 and a display section 62 for displaying various states based on instructions from the microcomputer 51 are provided on the display board 60 .

On the power supply relay board 70, the compressor 44, the first . Second
Solenoid valve 42, 43, fluorescent light 11, A, B heat H,,H
, etc., a power supply section 7 that supplies necessary power to the control board 50, display board 60, etc.
2nd class has been formed. Furthermore, the power supply section 72 is connected to the AClooV outlet via a transformer.

Next, operation control of the low-temperature case 1 configured as described above will be further explained with reference to flow charts and time charts shown in FIGS. 6 to 8.

Various sensors 55 to 59 obtained via operational amplifier 54
The output of the A/
The data is converted into HEX data by the D converter 52 and input to the microcomputer 51. The microcomputer 51 reads these data as necessary and controls cooling, defrosting, alarms, displays, etc.

Here, the temperature control set value set in the setting device 53 is m (°
C:], the differential setting value indicating the upper and lower limit width from the setting value is set to n['c], the cycle time setting value is set to t(h), and the temperature input from the temperature control A sensor 55 is set to a. [°C], the temperature input from the temperature control B sensor 56 is set to b(
'C), temperature input d from defrost return A sensor 57
['c), and the operation when the temperature input from the defrost return B sensor 58 is set to e['c] will be described.

First, the microcomputer 51 reads input data from various sensors as shown in FIG. 6, and determines sensor abnormality. As a result, if both temperature control A sensor and temperature control B sensor are judged to be normal (100, 101), calculate the average value (a+b)/2 of temperature control data a and b5 (103). Temperature control is based on

Inside the low-temperature case 1 is the first. Second two evaporators 20.2
1, the microcomputer 51 sets the cycle time t[h) set in the setting device 53 as one motocycle, and sets the cycle time t[h] to the seventh motocycle.
As shown in the figure, while the first evaporator 20 is in the cooling operation, the second evaporator 21 is in the defrosting operation (A mode). Further, in the next cycle, the evaporator 20 is in a defrost operation and the evaporator 21 is in a cooling operation (B mode). In this way, A
Operation control is performed alternately repeating mode and B mode.

Therefore, in the A mode, the microcomputer 51 outputs a command to the relay part 71 to turn on the solenoid valve 42 and turn off the solenoid valve 43. In addition, the microcomputer 51 monitors whether the temperature control data average value (a+b)/2 is between m10n/2 and m-n/2, and determines whether the upper and lower limits around the set value m are ±.
n/2) Turn on the refrigerant compressor 44 so that it falls within the range
, outputs a command to turn off to the relay part 71. As a result, the temperature control data average value (a+b)/2 moves up and down as the refrigerant compressor 44 is turned on and off, as shown in FIG. Temperature control data b and a of B fluctuate synchronously with a difference of ±n with respect to the average value (a+b)/2, and defrost return sensor outputs d and e similarly fluctuate with a difference of −y.

When this A mode reaches 30 minutes before the end, the microcomputer 5
1 issues a command to the relay part 71 to turn on the heaters H, H2 provided near the evaporator 20, 21. Then,
The defrost return sensor output d or e is monitored, and when the return temperature reaches 5.03 or higher, the heater is turned off. Next, the cycle time is checked, and when T[h] has elapsed, the A mode is switched to the B mode.

At the time of this mode switching, as shown by the * mark in Fig. 7, in one evaporator, the heater is turned ON to 30
If the defrost recovery sensor output does not reach the recovery temperature even after 30 minutes have passed, the other evaporator will switch from cooling operation to defrost operation after 30 minutes, but the defrost recovery sensor output will return to the one evaporator side. Do not switch to cooling operation until the temperature has been reached.

When the two temperature control sensors 55 and 56 are both normal as in case B, the refrigerant compressor 44 is turned on and off so that the average sensor output value (a+b)/2 falls within a predetermined range. During this time, only one of the two evaporators is in cooling operation, and the other is in defrost operation using only air blowing, and the moisture removed from the evaporator is transported to storage chamber 2, adding moisture to the interior. Prevent the product from drying out. Further, the two evaporators can always be operated in a frost-free state during cooling operation, and cooling operation can be carried out efficiently.

If one of the temperature control sensors 55, 56 becomes abnormal during this time, temperature control is performed using only the normal temperature control sensor.

In other words, as shown in Figure 6, the temperature control A sensor is normal (10
0), when the temperature control B sensor is abnormal (101), the input data is only from the temperature control A sensor (103), and when the temperature control B sensor is normal (104), the input data is only from the temperature control B sensor. (
105), perform temperature control. When controlling the temperature using only the temperature control sensor A, the temperature inside the refrigerator will be higher than the normal temperature by the temperature difference,
If the temperature is controlled only by the temperature control B sensor, the temperature will be lowered by the difference in temperature. However, this temperature difference is not that large, so even if it is ignored, the temperature inside the refrigerator can be maintained close to normal.

Next, what to do when both temperature control sensors A and B become abnormal is to perform temperature control using the defrost return sensor on the evaporator side during cooling operation (106). The temperature difference y in this case is quite large, so if it is not taken into account, the temperature inside the refrigerator will rise by y [°C], which will be quite different from when the sensor is normal. Therefore, considering the temperature difference y, turn on the compressor when the temperature d or e+y of the defrost return sensor becomes m+n/2.
Then, turn off the compressor when it reaches m - n / 2.
do. That is, at this time, the microcomputer 51 first determines whether or not the driving mode is in A mode (107), and if it is in A mode, it adopts the value (d+y) obtained by adding y to the defrost return sensor output d (108). . On the other hand, in B mode, the value (e
+y) (109), and temperature control is performed based on this data. By performing such operational control, it becomes possible to keep the temperature inside the refrigerator constant.

On the other hand, during such operation control, the display on the display unit 62 shows (a+b)/as the case internal temperature when the sensor is normal.
Display 2. Further, when either one of the temperature controllers 55, 56 becomes abnormal, the sensor abnormality is displayed and the temperature read by the normal temperature controller is displayed.

Also, the microcomputer 51 determines that both or each of the defrost return sensors A and B are abnormal (110).
If (111) is performed, duty control (112) is performed because temperature control using a sensor becomes impossible. This duty control turns on the relay part 71 to operate the refrigerant compressor 44 during the duty-on time set by the timer 51A built into the microcomputer 51, and turns off the relay part 71 to operate the refrigerant compressor 44 during the duty-off time.
4 and perform temperature control.

This duty control has one cycle of duty on time and duty off time, and there is a relationship of duty on time > duty off time, and each time is determined by the cooling capacity of the cooling device and the outside air (inside the store) set in advance. Air) determined by the relationship with temperature, temperature control A sensor and temperature control B
Temperature control close to the sensor's normal state can be performed.

Furthermore, FIG. 9 is a flowchart in which the function of performing temperature control using the defrost return sensor (106) in FIG. 104), duty control (112) is performed.

The output of the operation/stop of the refrigerant compressor 44 by this duty control (112) is the operation/stop time of the refrigerant compressor 44 stored in the microcomputer 51 when the temperature control A sensor and the temperature control B sensor are normal. Each average value is taken out and applied to the timer 51A, and duty-on and duty-off are repeated based on the average value. According to this operation, duty control that incorporates temperature correction due to changes in the amount of products stored in the storage chamber 2 and the outside air temperature can be performed, so that temperature control can be performed in substantially the same manner as in normal times.

The table below summarizes the above operations.

Table 1 However, t t2 is time.

In addition, in the embodiment described above, an example was shown in which two evaporators were provided, but the number of evaporators is not limited to this.

It goes without saying that the number of temperature sensors and defrost return sensors and the duty on and off times can be set arbitrarily.

(g) Effects of the invention The present invention described above produces the following effects.

■ If one of the two temperature control sensors becomes abnormal, the remaining one will provide backup, and if the remaining one also becomes abnormal, backup will be performed using duty control using a timer to operate the low-temperature product storage case. Since it is possible to continue the process, there is a double fail-safe.
A storage room can be maintained at a predetermined temperature without affecting stored products due to sensor abnormality.

■During duty control, the average value of the operation and stop times of the refrigerant compressor stored in the microcomputer during normal operation is taken out as the output, and the temperature is corrected as it becomes the duty-on time and duty-off time. Temperature control can be performed taking into account changes in the amount of stored products and changes in outside air temperature, which are required, and control that is approximately equivalent to temperature control using a temperature control sensor can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a side (A-A) sectional view of a low temperature product storage case according to an embodiment of the present invention, Fig. 2 is an external perspective view thereof, Fig. 3 is a perspective view of its cooling device, and Fig. 4 is its The refrigerant circuit diagram of the cooling system, Figure 5 is the configuration diagram of its control device, and Figure 6 is the diagram of the control device.
Figure 7 is a diagram of the relationship between the operating modes of the two evaporators and the defrost return temperature, Figure 8 is a time chart of each sensor output during temperature control, and Figure 9 is a diagram of the process flow of the microcomputer in Figure 6. FIG. 3 is a flow diagram of another embodiment corresponding to FIG. 20.21... Evaporator, 42.43... Solenoid valve,
44... Refrigerant compressor, 50... Control board, 51... Microcomputer, 51A... Timer,
55-58...sensor, 62...display section,
71...Relay section. 'mouth-

Claims (1)

[Scope of Claims] 1. A temperature control device for a low-temperature product storage case that controls the temperature inside a case for storing products at a low temperature based on a detection signal from a temperature control sensor disposed in the case. Temperature control sensors are disposed at two locations, a cold air blowout section and a suction section, respectively, and a means for controlling the temperature based on the average value of the outputs of those two temperature control sensors during normal operation; means for determining whether the temperature control sensor is abnormal, and means for controlling the temperature based only on the normal temperature control sensor output when one of the two temperature control sensors becomes abnormal based on the determination result; , when both of the two temperature control sensors become abnormal, means for controlling the temperature by duty control that repeatedly operates and stops a refrigerant compressor constituting the cooling device in a certain time range based on a timer; A temperature control device for a low-temperature product storage case, comprising: 2. It is equipped with a storage means for calculating and storing the average time of operation and stop of the refrigerant compressor during normal operation based on the two temperature control sensors and/or during abnormal operation based on one of the temperature control sensors. A temperature control device for a low-temperature product storage case, characterized in that when a temperature control sensor becomes abnormal, a refrigerant compressor is operated or stopped according to an average time stored in the storage means.