JPH07122541B2 - Temperature control device for low temperature product storage case - Google Patents

Description

TECHNICAL FIELD The present invention relates to a temperature control device for a low temperature product storage case suitable for freezing or refrigerating storage of sold products such as display storage of Western confectionery.

(B) Conventional Technology In general, a low temperature product storage case is provided with a temperature control sensor in order to keep the temperature inside the case at a predetermined temperature. In the past, when the temperature control sensor became abnormal, the alarm LED was only displayed on the illuminated display, and no further measures against the abnormality were taken.

(C) Problem to be Solved by the Invention Therefore, in the above-mentioned conventional device, if the temperature control sensor becomes abnormal, the cooling operation in the case is stopped, and the products in the case are seriously affected. was there. Moreover, since the life of the temperature sensor is not so long as that of other products, there is a problem that such a problem occurs frequently.

Therefore, 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, in which the temperature control in the case is normally performed even if the temperature control sensor becomes abnormal.

(D) Means for Solving the Problem The present invention is directed to the temperature of a low temperature product storage case in which the temperature in a case for storing a product at a low temperature is controlled based on a detection signal from a temperature control sensor arranged in the case. In the control device, temperature control sensors are respectively arranged at two locations in the case, namely, a cool air blowing portion and a suction portion, and at the time of normal operation, means for controlling the temperature based on an average value of these two temperature control sensor outputs, Means for judging abnormality of the two temperature control sensors, and based on the judgment result, when either one of the two temperature control sensors becomes abnormal, only normal temperature control sensor output is output. When both the means for controlling the temperature based on the temperature control sensor and the two temperature control sensors become abnormal, the defrost recovery sensor When both the means for controlling the temperature based on the output and the two temperature control sensors are abnormal and the defrost recovery sensor is also abnormal, the refrigerant compressor constituting the cooling device is configured with a certain time width based on the timer. It is provided with a means for controlling the temperature by duty control for repeatedly operating and stopping.

(E) Action According to the above means, even if one of the temperature control sensors in the low temperature product storage case becomes abnormal, the low temperature product storage case continues to operate normally by the other temperature control sensor, Since the inside of the case is maintained at a predetermined temperature and the sensor abnormality is displayed, it is possible to replace the abnormality sensor and return it to the original state of the low temperature product storage case without affecting the stored goods at all. In addition, even if both of the two temperature control sensors become abnormal, the defrost return sensor keeps the inside of the case at a predetermined temperature, and even if the defrost return sensor also becomes abnormal, the abnormal sensor is replaced. Until then, the temperature control can be performed with a duty cycle close to the normal time.

(F) Embodiment FIG. 1 is a side sectional view of a low temperature product storage case (hereinafter referred to as a low temperature case) 1 according to an embodiment of the present invention, FIG. 2 is an external perspective view of the low temperature case 1, and FIG. The perspective view of a cooling device is shown.

In these figures, the low temperature case 1 is a closed type that is suitable for cold storage of fresh confectionery and the like, and its main body is a storage chamber 2 and a cooling chamber 3 located directly below the storage chamber 2. It is composed of a machine room 4 located directly below the cooling room 3. The storage chamber 2 has a curved transparent plate 5 arranged from the front surface to the upper surface, and a frame 6 arranged on the back surface.
It is composed of a plurality of transparent doors 7 that slide in the left-right direction in a pulling manner in the left-right direction, and transparent side plates 8 arranged on the left and right side surfaces, respectively.
Removable bottom plate 9 that also serves as a partition plate, shelf 10 and fluorescent lamp
11 are provided. The bottom plate 9 is both the storage and cooling chambers.
A part that divides 2, 3 into upper and lower parts.
2. A suction port 13 is formed along the front edge, and the storage and cooling chambers 2 and 3 communicate with each other through the blowout and suction ports 12 and 13. The cooling chamber 3 is constituted by a heat insulating wall 14 having an open upper surface for mounting and supporting the storage chamber 2, and the machine chamber 4 is formed below the heat insulating wall 14. The heat insulating wall 14 has a drainage port 15 on the bottom wall, and constitutes a base 17 together with a metal base leg 16.

20 and 21 are first and second evaporators arranged in the cooling chamber 3,
The first evaporator 20 is located inside, and the second evaporator is located outside, with the partition plate 22 also serving as a dew receiving plate being overlapped vertically to form the drainage port.
It is arranged with a low inclination in 15 directions. The first and second evaporators 20 and 21 have a large number of plate-like fins 23 arranged in parallel at equal intervals.
And the left and right tube plates 24, and the fins and a large number of refrigerant tubes 25 orthogonal to the tube plates form a plate fin shape. Each of the fins 23 is coated with a water-repellent coating material as a coating film (H) that enhances the water retention of the surface. The partition plate 22 has an extension 26 whose one end extends in front of the air inlet surfaces of the first and second evaporators 20 and 21, that is, in the direction of a blower fan described later. The extending portion 26 is provided with a paragraph 27 for accumulating the dew from the first evaporator 20 and a plurality of small drain holes 28 for allowing the dew of the paragraph 27 to drip downward. The drain hole 28 is preferably formed in a portion of the blower fan, which will be described later, where the wind pressure is weak.

The cooling air passing through the first and second evaporators 20 and 21 is cooled by a cooling chamber 3-a blowout port 12-a storage chamber 2-a suction port 13-a cooling chamber 3 as shown by arrows in FIG. Forced circulation paired first
Both the first and second blower fans are attached to a box-shaped fan case 33 having a partition plate 32 in the center. This first 1,
The number of the second blower fans 30 and 31 increases as the length of the low temperature case 1, in other words, the length of the first and second evaporators 20 and 21 increases. For example, as shown in FIG. If the lengths of the second evaporators 20 and 21 are for 6 shaku, two pairs are used. The rear edge of 34 is the top edge of the upper surface of the first evaporator 20 and the first and second evaporators 20 and 2.
A duct which is arranged so as to overlap the front edges of both the left and right tube plates 24 and is fixed to the tube plates 24 with a fastener such as a screw. With this fixing, the first and second evaporators 20 are attached. The ducts 34 cover the air inlet surfaces of the inlets 21 and 21 and the extending portion 26 of the partition plate 22, while the inside of the duct is partitioned by the extending portion 26 into the inside and outside, that is, the upper and lower portions. It is divided into an air passage 35 and an air passage 36 facing the second evaporator 21. The duct 34 is connected to the evaporators 20 and 21 corresponding to the first and second blower fans 30 and 31, respectively.
This is to ensure that the cool air sent toward the air diffuser is spread over the entire width of both evaporators 20 and 21, and is located in the appropriate place in the upper half of the front face thereof as shown in FIG. The first opening 37 is provided, and the second air passage 36 is provided at an appropriate position in the lower half of the front surface.
And second openings 38 facing each other. Reference numeral 39 is a rotating tool such as a hinge for mounting the fan case 33 on the duct 34 so as to be rotatable in the vertical direction. With the mounting of the rotating tool, the first blower fan 30 causes the first opening 37, the first air passage 35 and Corresponds to the inner route formed by the first evaporator 20, and the second
The blower fan 31 includes the second opening 38, the second air passage 36, and the second evaporator.
Will correspond to the outer route formed by 31
The return cold air from the storage chamber 2 is sent to the corresponding evaporators 20 and 21, respectively. When the fan case 33 is opened, it is placed on the upper surface of the duct 34 as shown on the left side in FIG. 3, and in this state, the extension portion is inserted through the first opening 37 or the second opening 38. 26 While the top surface is cleaned or the bottom surface of the heat insulating wall 14 is cleaned, sometimes the first and second blower fans are used.
30,31 maintenance inspections will be carried out. The bottom plate 9 is removed when the fan case 33 is opened.

FIG. 4 shows a refrigerant circuit of a cooling device, in which the first and second evaporators 20 and 21 are connected in parallel with each other while corresponding first and second expansion valves 40 and 41, first and second expansion valves are provided. The solenoid valves 42 and 43 are connected in series. 44 is a refrigerant compressor, 45 is a condenser, 46 is a receiver, 47 is a dryer, and the first and second evaporators 20 and 21, the first and second expansion valves 40 and 41, the first and second A cooling cycle is formed with the second solenoid valves 42, 43. The refrigerant compressor 44 and the condenser 45 are arranged in the machine room 4.

FIG. 5 shows a control device, which is provided with a control board 50, a display board 60, a power supply relay board 70, etc. necessary for executing the operation control of the low temperature case 1.

A timer 51A is provided on the control board 50, a microcomputer 51 that executes various arithmetic processes, an A / D converter 52 that performs signal conversion, temperature, time, and differential (described later).
A setting device 53 for performing various settings such as, and an operational amplifier 54 for amplifying the sensor output are provided. The operational amplifier 54 has an A sensor for temperature control (hereinafter referred to as a temperature A sensor) 5
5, various sensors such as a temperature control B sensor (hereinafter referred to as temperature control B sensor) 56, a defrost return A sensor 57, a defrost return B sensor 58, and a filter sensor 59 are connected. The temperature control A sensor 55 is installed near the cool air outlet 12 in FIG. 1, and the temperature control B sensor 56 is installed near the cold air inlet 13. The defrost return A sensor 57 is installed in the first evaporator 20, and the 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, i.e., the condenser
It is used as a means to give an alarm when the temperature of 45 rises abnormally.

On the display substrate 60, a switch unit 61 for inputting various commands to the microcomputer 51, and a display unit 62 for displaying various states based on commands from the microcomputer 51 are provided.

On the power relay board 70, the compressor 44, the first and second solenoid valves 4 in the low temperature case 1 are received based on a command from the microcomputer 51.
2, 43, the fluorescent lamp 11, the A, B heaters H ₁ , H _2, etc., a relay section 71 for turning on and off, a control board 50, a power supply section 72 for supplying necessary power to the display board 60, etc. are formed. . Further, the power supply unit 72 is connected to a 100V AC outlet via a transformer.

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

The outputs of various sensors 55 to 59 obtained through the operational amplifier 54 and various data set in the setting device 53 are converted into HEX data by the A / D converter 52 and input to the microcomputer 51. The microcomputer 51 appropriately reads these data as needed, and controls cooling, defrosting, alarming, display and the like.

Here, the temperature control set value set in the setter 53 is set to m [° C],
The differential set value indicating the upper and lower limit control width from the set value is set to n [° C.], the cycle time set value is set to t [h], and the temperature input from the temperature control A sensor 55 is set to a.
[° C], operation when temperature input from temperature control B sensor 56 is b [° C], temperature input from defrost return A sensor 57 is d [° C] temperature input from defrost return B sensor 58 is e [° C] I will describe.

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

Since the first and second evaporators 20 and 21 are provided in the low temperature case 1, the microcomputer 51 sets the cycle time [h] set in the setter 53 as one mode cycle and is shown in FIG. In this way, when the first evaporator 20 is in the cooling operation, the second evaporator 21 is in the defrost operation (A mode). In the next cycle, the evaporator 20 is defrosted and the evaporator 21 is cooled (B mode). In this way, the A mode and the B mode are alternately repeated to perform the operation control.

Therefore, the microcomputer 51 turns on the solenoid valve 42 in the A mode,
A command to turn off the solenoid valve 43 is output to the relay unit 71. Further, the microcomputer 51 monitors whether or not the temperature control data average value (a + b) / 2 is between m + n / 2 and m−n / 2, and the set value m
To be within the upper and lower limits (± n / 2) centered around
A command to turn on / off the refrigerant compressor 44 is output to the relay unit 71. As a result, the temperature control data average value (a + b) / 2 is
As shown in the figure, it moves up and down as the refrigerant compressor 44 turns on and off. At this time, the temperature control data b, a fluctuates synchronously with a difference of ± n with respect to the average value (a + b) / 2, and the defrost return sensor outputs d, e fluctuate similarly with a difference of -y.

When the A mode reaches 30 minutes before the end, the microcomputer 51 issues a command to the relay unit 71 to turn on the heaters H ₁ and H ₂ provided near the evaporators 20 and 21. Next, the output d or e of the defrost return sensor is monitored, and when the return temperature exceeds 5 [° C.], the heater is turned off. Next, the cycle time is examined, 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, if the defrost recovery sensor output does not reach the recovery temperature for 30 minutes after turning on the heater in one of the evaporators, 30 minutes have passed. Therefore, the other evaporator side is switched from the cooling operation to the defrost operation, but the one evaporator side is not switched to the cooling operation until the output of the defrost recovery sensor reaches the recovery temperature.

In this way, when both of the two temperature control sensors 55 and 56 are normal, the refrigerant compressor 44 is turned on and off so that the sensor output average value (a + b) / 2 falls within a predetermined range. During this time,
By operating only one of the two evaporators for cooling operation, the other one is for defrosting operation by only blowing air, and the water removed from the evaporator is carried to the storage chamber 2 to add moisture to the interior of the product. Prevents drying. In addition, the two evaporators can always be operated in a frost-free state during the cooling operation, and the cooling operation can be efficiently performed.

When either one of the temperature control sensors 55, 56 becomes higher than the above, the temperature control is performed only by the normal temperature control sensor. That is, as shown in FIG. 6, when the temperature control A sensor is normal (100) and the temperature control B sensor is abnormal (101), only the temperature control A sensor input data (103) indicates that the temperature control B sensor is normal. At the time of (104), the temperature control is performed (105) with only the input data of the temperature control B sensor. When only the temperature control A sensor is used for temperature control, the temperature inside the refrigerator is higher than the normal temperature by the temperature difference h, and when only the temperature control B sensor is used for temperature control, the temperature difference is decreased by the temperature difference h. However, since this temperature difference h is not so large, even if it is neglected, it is possible to maintain the inside temperature close to the normal time.

Next, when both the temperature control sensors A and B become abnormal, the temperature is controlled by the defrost return sensor on the evaporator side during the cooling operation (106). Since the temperature difference y in this case is quite large, the temperature inside the chamber will increase by y [° C.] if not taken into consideration, and the temperature will differ greatly from that when the sensor is normal. Therefore, considering the temperature difference y, the temperature input d or e + of the defrost recovery sensor
Turn on the compressor when y becomes m + n / 2, and turn off the compressor when y becomes m−n / 2. That is, at this time, the microcomputer 51 first determines whether or not the operation mode is the A mode (107), and if it is in the A mode, adopts the value (d + y) obtained by adding y to the defrost return A sensor output d ( Ten
8). On the other hand, in the b mode, the value (e + y) obtained by adding y to the defrost return sensor output e is adopted (109),
Temperature control is performed based on this data. By performing such operation control, it becomes possible to keep the internal temperature constant.

On the other hand, the display on the display unit 62 during such operation control displays (a + b) / 2 as the case internal temperature when the sensor is normal. When any one of the temperature adjustments 55 and 56 becomes abnormal, the sensor abnormality is displayed and the temperature read by the temperature adjustment sensor on the normal side is displayed.

Further, the microcomputer 51 determines that the defrost recovery sensors A and B are abnormal both and / or individually (110) (11).
In the case of 1), the duty control (112) is performed because the temperature control using the sensor cannot be performed. This duty control is performed by the timer 51A built in the microcomputer 51.
The relay unit 71 is turned on during the duty-on time set by to operate the refrigerant compressor 44, and the relay unit is operated during the duty-off time.
71 is turned off to stop the refrigerant compressor 44 and control the temperature. This duty control has one cycle of the duty-on time and the duty-off time, and there is a relation of duty-on time> duty-off time, and each time is the cooling capacity of the cooling device and the preset outside air (inside the store). Air temperature) Determined in relation to temperature, temperature control A sensor and temperature control B
The temperature can be controlled in a manner similar to that when the sensor is operating normally.

The table below summarizes the above operations.

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

It goes without saying that the set number of the temperature sensor and the defrost return sensor and the duty ON / OFF time can be arbitrarily set.

(G) Effect of the Invention According to the present invention described above, even if one of the temperature control sensors in the low temperature product storage case becomes abnormal, the low temperature product storage case continues to operate normally by the other temperature control sensor. Since the inside of the case is kept at a predetermined temperature and the sensor abnormality is displayed, it is possible to replace the abnormality sensor and return the low temperature product storage case to the original state without affecting the stored goods at all. And 2
Even if both of the temperature control sensors become abnormal, the defrost return sensor keeps the inside of the case at the specified temperature, and even if the defrost return sensor also becomes abnormal, replace the abnormal sensor. In the meantime, there is an effect that the temperature control can be performed with a duty cycle close to the normal time.

[Brief description of drawings]

FIG. 1 is a side (AA) sectional view of a low temperature commodity 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. Refrigerant circuit diagram of the cooling device, FIG. 5 is a block diagram of its control device, and FIG.
FIG. 7 is a process flow chart of the microcomputer in the figure, FIG. 7 is a relationship diagram between the operation modes of the two evaporators and the defrost return temperature, and FIG. 8 is a time chart of each sensor output during temperature control. 20,21 …… Evaporator, 42,43 …… Solenoid valve, 44 …… Refrigerant compressor, 50 …… Control board, 51 …… Microcomputer, 51A…
… Timer, 55-58 …… Sensor, 62 …… Display, 71 …… Relay.

Claims (1)

[Claims] 1. A temperature control device for a low temperature product storage case, which controls the temperature of a case for storing a product at a low temperature based on a detection signal from a temperature control sensor arranged in the case. While the temperature control sensors are respectively arranged at the blow-out portion and the suction portion, the means for controlling the temperature based on the average value of these two temperature-control sensor outputs in the normal state, and the two temperature-control sensors. Means to judge abnormalities,
Based on the determination result, when either one of the two temperature control sensors becomes abnormal, a means for controlling the temperature based only on the normal temperature control sensor output, and the two temperature control sensors. When both of them become abnormal, the means for controlling the temperature based on the output of the defrost recovery sensor and the two temperature control sensors are both abnormal, and the defrost recovery sensor also becomes abnormal. A temperature control device for a low temperature product storage case, comprising: a temperature control unit that performs temperature control by duty control for repeatedly operating and stopping a refrigerant compressor that constitutes a cooling device in a time width.