JPH0348434B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improvements in defrosting control means in a control device for a refrigeration system.

[Prior Art] A conventional defrosting device for removing frost that adheres to the inside of a refrigerated case used for food sales is configured to defrost by activating the defrosting device at every preset time using a timer. There is. Generally, defrosting devices are constructed by heating a refrigerant flow pipe in a show case with a heater or the like, or by using a hot gas defrost method.

[Problems to be Solved by the Invention] Conventional defroster devices operate at predetermined time intervals regardless of the presence or absence of frost.
To ensure safety, this time is usually set shorter than the time that frost actually forms. As a result, the number of operations of the defrosting device is greater than actually necessary, which causes power loss, and the temperature inside the show case increases while the defrosting device is operating, which may adversely affect the quality of the product. Therefore, it is an object of the present invention to solve these problems and eliminate unnecessary defrosting operations.

[Means for Solving the Problems] A control device for a refrigeration device of the present invention counts the number of pulse signal pulses of a reference time signal generator that emits a pulse signal of a predetermined period during operation of the refrigeration device, and calculates the counted value. A first calculation means for calculating the operating time of the refrigeration device by integrating the operation time, and a second calculation means for measuring the elapsed time from the end time of the previous defrosting operation to the present time, The time interval of operation is set by the defrost setting means, and when the quotient obtained by dividing the cumulative operating time by the elapsed time up to the current time is larger than a first predetermined value smaller than 1, the cumulative time is determined by the third calculation means. The defrosting operation is started when the time interval reaches the defrosting time interval, and when the integrated time is smaller than the first predetermined value, the time when the integrated time reaches the time equal to the product of the defrosting cycle and the second predetermined value larger than 1. It has a control means for causing defrosting operation.

[Operation] The preset defrosting time interval changes according to the cumulative operating time of the refrigeration device.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of a control device for a refrigerating device, such as a refrigerated case, which includes a defrosting device of the present invention. In the figure, temperature sensors 1a, 1b, . . . 1f installed in each of a plurality of storage cases are composed of, for example, thermistors, and the resistance value changes depending on the temperature. Resistors 2a, 2b, ... 2f are temperature sensors 1a,
1b,...1f are connected in series, respectively, and the resistors 3a, 3b,...3f are connected to the temperature sensors 1a, 1b,
... are each connected in parallel to 1f. These resistors compensate the temperature versus resistance characteristics of the temperature sensor. The multiplexer 4 connects each temperature sensor 1a,
It is a device that sequentially switches the detection signals of 1b, . The AD converter 6 converts voltage signals corresponding to the resistance values of the temperature sensors 1a, 1b, . The target temperature setting section 7 is composed of, for example, a digital switch, and is used to set the target temperature inside the storage case.
It can be set corresponding to each case of a, 1b, . . . 1f. If the temperature measured by the temperature sensors 1a, 1b, . 9b,...9f are turned on to perform cooling operation, and if the temperature is low, then the contacts 9a, 9 for opening and closing the solenoid valves are turned on.
Turn off b,...9f to stop the cooling operation.
The night setback temperature setting section 10 is a device for raising the target temperature of the target temperature setting section 7 by the set temperature during a predetermined time at night. The predetermined time at night is set by a timer (not shown), and a night setback signal, which is the output of the timer, is applied to the night setback signal input terminal 11. When the night setback signal is applied, the set temperature of the night setback temperature setting section 10 is read into the arithmetic processing section 5. The duty cycle setting section 12 is a device that sets the duty-off cycle, which is an operation to stop the refrigerator for a predetermined period of time, regardless of the control of the temperature control system including the temperature sensors 1a, 1b, . . . 1f. 5. The duty-off time setting section 13 is for setting the duty-off forced stop time, and its data is also read into the arithmetic processing section 5. The reference time signal generating section 14 outputs a pulse signal of a constant period that serves as a reference for the time signal, and the arithmetic processing section 5 measures time by counting the pulses. The override setting section 15 is for setting the maximum allowable temperature in the refrigerator during duty-off, and when this set value is exceeded, duty-off operation is stopped and temperature adjustment operation is started. The duty-off signal output terminals 16a and 16b output a contact signal of the duty-off contact 16 that is turned on during duty-off, and by inputting it to an external control device, other devices can be controlled. For example, when a duty signal is applied from an external control device to the external forced duty signal input terminal 17, the duty-off is performed while ignoring each set value of the duty-off time setting section 13 during the application period of this signal. The alarm contact 18 closes when the temperature inside the refrigerator exceeds the target temperature set by the target temperature setting section 7 for a certain period of time and generates a temperature alarm output at the alarm output terminals 18a and 18b. . The display unit 19 is composed of, for example, a pilot lamp or a digital display device, and displays an alarm when the alarm contact 18 is closed, displays the ON/OFF state of the contacts 9a, 9b, ... 9f for opening and closing the electromagnetic valve, and displays a duty cycle generator. 12 and duty-off time setting section 13 during duty-off, and a defrosting setting section 21 for setting defrosting conditions.
display during defrosting, and temperature sensors 1a, 1
b, . . . 1f, which shows the display of the internal temperature of each case, and the desired internal temperature of the case is selected and displayed by the call operation of the temperature call switch 20. The defrost setting section 21 is for setting a defrosting time interval for defrosting the inside of the refrigerator.
The arithmetic processing section 5 counts the number of reference pulses from the reference time signal generation section 14. When the time to start defrosting comes, the defrosting signal contact 22 is closed and a defrosting contact signal is given to a defrosting control circuit (not shown) connected to the defrosting signal output terminals 22a and 22b. When the defrosting is completed, a defrosting end signal is applied to the defrosting end signal terminal 23, inputted to the arithmetic processing section 5, and the defrosting signal contact 22 is opened.

Next, the operation will be explained. The arithmetic processing section 5 sequentially scans the multiplexer 4 using the reference pulse from the reference time signal generation section 14, and the temperature sensor 1
The detected temperatures of a, 1b, ... 1f are read in sequence. The read temperatures detected by the temperature sensors 1a, 1b, ... 1f are compared with the target temperature set by the target temperature setting unit 7, and if higher than the target temperature, the relay drive circuit 8 is driven to close the contact 9a for opening and closing the solenoid valve. ,9b,...
9f is closed and cooling operation is performed. On the other hand, if the temperature is lower than the target temperature, the relay drive circuit 8 is driven to open the contacts 9a, 9b, . . . 9f for opening and closing the solenoid valves, and the cooling operation is stopped. In this case, a predetermined temperature difference with respect to the target temperature is determined in advance to prevent hunting. For example, a temperature 1° C. higher than the target temperature is set as the temperature for opening the solenoid valve, and a temperature 1° C. lower than the target temperature is set as the temperature for closing the solenoid valve.

Next, when the store is closed at night, the door of the store case is not opened or closed, so the cold air inside the refrigerator does not escape, and the ambient temperature also drops, so if the temperature is controlled as is, the temperature inside the refrigerator will drop below the target temperature. It is known that people tend to get too cold.
To prevent this, the temperature is adjusted by raising the target temperature at night. For this purpose, a night setback temperature setting section 10 is provided for setting a temperature higher than the target temperature during the day. That is, at night, the temperature is adjusted by increasing the target temperature by the set temperature of the night setback temperature setting section 10.The set temperature of the night setback temperature setting section 10 is read into the arithmetic processing section 5, and the target temperature setting section Add to the target temperature in step 7. During the period when the night setback signal is applied to the night setback signal input terminal 11, the temperature inside the refrigerator is adjusted using this value as the target temperature.

Next, duty control for reducing the power consumption of the case and refrigerator will be explained.
The cycle set by the duty cycle setting section 12,
The forced stop time set by the duty-off time setting section 13 is read into the arithmetic processing section 5, and the duty cycle and duty-off time are stored in advance. In this state, the arithmetic processing section 5 counts the reference pulses from the reference time signal generation section 14, and each time the counted value reaches the duty cycle,
The relay drive circuit 8 is driven for the duty-off time, and the contacts 9a, 9b, . . . 9 for opening and closing the solenoid valve are
Turn off all f. Then, each time the counted value reaches the duty-off time setting value, the relay drive circuit 8 is driven again and the contacts 9a and 9 for opening and closing the solenoid valve are driven.
b,...9f are turned back on and temperature adjustment operation begins.

By the way, in general duty control, the duty cycle setting value of the duty cycle setting section 12 is compared with the count value of the reference pulse of the reference time signal generating section 14, and a certain period of time before the duty cycle setting value is reached, for example, one minute. Contact 9 for opening and closing the solenoid valve in front
A, 9b, . . . 9f are turned on one after another to perform cooling operation. Then, the state is continued until the duty cycle setting value is reached, and when the duty cycle setting value is reached, the contacts 9a, 9b, ... 9f are turned off immediately.
That is, the duty-off state is entered. This happens when you suddenly enter duty-off operation from temperature adjustment operation.
Since the internal temperature of the show case may rise too much and affect the quality of the product, it is recommended to cool the product before starting the duty-off operation and then start the duty-off operation to prevent abnormal temperature rises in the product. The purpose is to prevent

However, if the duty-off time is too long, there is a risk that the temperature inside the case will rise too much. For this purpose, the override setting section 15 sets the maximum allowable temperature inside the case. When the temperature during duty-off operation exceeds this set value, duty-off operation is stopped and temperature adjustment operation is started. For example, if the target temperature is -2°C and the override set value is +8°C, when the temperature inside the show case reaches +6°C, duty-off operation will be stopped and temperature adjustment operation will be performed.

During temperature adjustment operation, if the temperature inside the refrigerator rises abnormally due to some abnormality, exceeds the target temperature by a certain value, and continues in this state for a certain period of time, the alarm contact 18 is turned on. The alarm is notified to the outside and an alarm is displayed on the display unit 19.

The defrost setting section 21 sets the defrost time interval of the present invention. For example, the time interval is 4 hours, 6 hours, 8 hours.
hours or 12 hours, etc.

For example, the defrosting time interval mentioned above is represented by Z and the time is 4 hours (Z=4). Also, when the accumulated operating time of the refrigeration equipment is represented by X and the elapsed time from the end of the previous defrosting to the present time is represented by Y, if the quotient of X divided by Y is greater than 0.7 (X/Y>0.7) defrosts when the cumulative time X reaches the time interval Z. Also, if the quotient is smaller than 0.7, (X/Y
<0.7) Accumulated time X is 1.8 times the time interval Z (Z×
Defrost when the temperature reaches 1.8). Constant 0.7 above
and 1.8 are experimentally determined values, and other values may be selected.

In the operation of the above embodiment, the cumulative operation time X of the refrigeration device is measured, the elapsed time Y from the end of the previous defrosting to the present time is measured, and each of the above times X, Y,
Z is obtained by counting the number of reference pulses in the arithmetic processing section 5. Further, the above calculation is performed in the calculation processing section 5, and the constants are set in advance in the calculation processing section 5 by an input device (not shown).

[Effects of the Invention] According to the present invention, since the defrosting time interval of the refrigerated case is changed according to the cumulative operating time of the refrigerator, it is possible to avoid unnecessary defrosting operations even when no frost is present. Therefore, it is possible to prevent power loss and reduce the number of times the temperature of the product increases during defrosting.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the invention.

Claims (1)

[Scope of Claims] 1. A reference time signal generation unit that generates a pulse signal of a predetermined period, which counts the number of pulses of the pulse signal during operation of the refrigeration equipment, and integrates the counted value to control the operation of the refrigeration equipment. A first calculating means for calculating the operating time, a second calculating means for measuring the elapsed time from the end time of the previous defrosting operation to the present time, and a defrosting setting means for presetting the time interval of the defrosting operation of the refrigeration device. , a third calculation means for dividing the cumulative operating time by the elapsed time from the end time of the previous defrosting operation to obtain the quotient; and when the quotient is larger than a first predetermined amount smaller than 1, the cumulative operating time is The defrosting operation is performed when the defrosting time interval is reached, and when the integrated time is smaller than the first predetermined value, the integrated time is the time of the product of the defrosting time interval and the second predetermined value larger than 1. A control device for a refrigeration device, comprising: a control means for causing a defrosting operation when the temperature reaches the temperature.