JPH048637B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for controlling the operation of a variable frequency compressor during a refrigeration cycle.

(b) Prior Art A conventional method for controlling the operation of a refrigeration cycle of this kind is configured as proposed in, for example, Japanese Utility Model Application No. 57-142185. Here, a conventional example will be explained with reference to this publication. In Fig. 1, 1 is a multi-refrigerator equipped with three compressors 2, 3, and 4, 5 is a condenser, 6 is a pressure reducing device, and 7 is an evaporator.
These are sequentially connected via piping to form a refrigeration cycle. 8 is the three compressors 2 of the multi-refrigerator 1,
This is a control circuit that performs capacity control operation by combining 3 and 4. Reference numeral 9 denotes a first timer circuit for controlling the capacity of the multi-refrigerator 1 by the control circuit 8 for a certain period of time. 10, after performing capacity control operation by the first timer circuit 9, all the compressors 2,
This is a second timer circuit that stops timers 3 and 4. 11
The second timer circuit 10 causes all the compressors 2,
This is a third timer circuit that forces all compressors 2, 3, and 4 to operate for a certain period of time after stopping compressors 3 and 4.

In the operation control method of the refrigeration cycle with this structure, the set time of the first timer circuit 9, the three compressors 2,
After performing capacity control operation by combining 3 and 4, the second
The timer circuit 10 forcibly stops all compressors 2, 3, and 4, and after a certain period of time, the third timer circuit 11
All the compressors 2, 3, and 4 are forced to operate for a set period of time, so that the oil stagnant in the piping of the refrigeration cycle during capacity control operation is forcibly returned to the compressors 2, 3, and 4.

However, depending on the load conditions, if all the compressors 2, 3, and 4 were forcibly stopped for a certain period of time using the second timer circuit 10, there was a risk that the temperature inside the refrigerator, which is cooled by the evaporator 7, would become too high. .

(c) Purpose of the Invention In view of the above points, this invention changes the stop time of the duty cycle device depending on the operating state of the variable frequency compressor, and prevents the temperature inside the refrigerator from rising during this stop time. The purpose is to prevent.

(d) Structure of the Invention This invention involves connecting a compressor, a condenser, a pressure reducing device, an evaporator, etc. whose operation is controlled at variable speed by an inverter to piping, and after the compressor is forced to operate for a predetermined period of time. , a method for controlling the operation of a refrigeration cycle having a duty cycle device that stops the duty cycle device for a predetermined period of time, comprising: an operation timer means for forcibly operating a compressor of the duty cycle device for a predetermined period of time;
stop timer means for forcibly stopping the compressor for a predetermined time after the operation timer time has elapsed; and integration timer means for determining the stop time of the stop timer means by integrating the total operating time of the compressor at low frequency; The compressor is constructed of a reset timer means for resetting the integration timer means and the operation timer means when the continuous operation time of the compressor at a high frequency continues for a certain period or more.

By configuring this invention as described above,
The setting of the stop time of the stop timer means of the duty cycle device is changed depending on the operating state of the compressor, thereby enabling energy-saving operation of the compressor without causing a temperature rise on the load side.

(E) Embodiment The present invention will be explained based on the embodiment shown in FIGS. 2 to 5. 20 is a compressor, 21 is a condenser, 22 is a pressure reducing device, and 23 is an evaporator, which are sequentially connected to each other. The pipes are connected to form a refrigeration cycle. A pressure sensor 24 detects the pressure on the outlet side of the evaporator 23, and this pressure sensor changes the operating frequency setting of the inverter device 25 in accordance with the detected pressure. Compressor 20 is driven at the operating frequency of inverter device 25 . 26 is a duty cycle device that generates a forced stop signal to the inverter device 25 based on the output frequency of the inverter device 25. The inverter device 25 is 25
Compressor 20 is operated at a frequency between Hz and 75Hz. The duty cycle device 26 includes an operation time timer 27 that forcibly operates the inverter device 25 for 32 minutes;
A stop time timer 28 that forcibly stops the inverter device 25 after the time set by the operation time timer has elapsed.
, an integration timer 29 that determines the stop time of the stop time timer, and a reset timer 30 that resets the integration timer and the operating time timer. The integration timer 29 is the operating time timer 27.
The operation signals of 35 Hz or less output from the inverter device 25 are integrated within the set time at . For example, 35
If the operation below Hz is 4 minutes, the stop time is 1 minute.
Thereafter, the stop time is increased by 1 minute every time the cumulative time by the cumulative timer 29 increases by 2 minutes. The stop time is set at a maximum of 6 minutes. The reset timer 30 activates the operation time timer 2 when the operation signal of 50Hz or more output from the inverter device 25 continues for more than 1 minute.
7 and the integration timer 29 are reset. FIG. 4 shows a signal output circuit for the frequency increase/decrease signal and the override signal, and 31 is a comparator that compares the voltage signal of the lower limit setter 32 and the low pressure signal of the pressure sensor 24. A down signal is generated that lowers the output frequency. A comparator 33 compares the voltage signal from the upper limit setter 34 with the low pressure signal from the pressure sensor 24. An up signal for increasing the output frequency of the inverter device 25 is generated from this comparator. 35 is a comparator that compares the voltage signal amplified by the amplifier 36 to a value 1.8 times higher than the set value of the upper limit setter 34 and the low pressure signal of the pressure sensor 24, and the duty cycle device 26 is stopped from this comparator. timer 28 with time
An override signal is generated that stops the inverter 25 and forces the inverter device 25 into operation. This override signal is transmitted when a duty cycle is applied to the inverter device 25.

In the method for controlling the operation of a refrigerator configured as described above, the compressor 20 is driven by an inverter device 25. This inverter device has pressure sensor 2
4, the low pressure of the refrigeration cycle is sensed and the frequency is variable controlled. Depending on the operating state of the compressor 20, the duty cycle device 26 is switched to the inverter device 2.
5 forced stop time can be changed.

Here, the flowchart of the duty cycle shown in FIG. 5 will be explained. The operating frequency transmitted from the inverter device 25 is detected while the compressor 20 is operating, and if the operating frequency is 50 Hz or more, the reset timer 30 adds up the continuous operating time at 50 Hz or more. If the cumulative time of this reset timer is 1 minute or more, the operating time timer 27 and cumulative timer 2
9 is reset, and the inverter device 25 is continuously operated for the newly set time of the operating time timer. At this time, the reset timer 30 is also reset. Thereafter, when the operating time timer 27 passes the set time, the stop time timer 28 starts operating.
Inverter device 25 stops. This stop time is
Timer 2 that integrates the operating time at an operating frequency of 35Hz or less
It can be decided by adding up in 9. If the low pressure increases due to an increase in load during this stop time, the override signal stops the stop time timer 28 and then resets the operating time timer 27 and integration timer 29. The compressor 20 is then driven by an inverter device 25. Further, when the set time of the stop time timer 28 has elapsed, the compressor similarly resets the operation time timer 27 and the integration timer 29 and is driven. Inverter device 25 to 50
If the compressor 20 is operated continuously for more than 1 minute at an operating frequency of Hz or higher, the load may increase, and the compressor 20 is forced to operate again for the set time of the operating time timer 27. This prevents the temperature inside the refrigerator from rising due to shutdown. Furthermore, since the stop time of the stop time timer 28 is determined according to the load by integrating the operating time at an operating frequency of 35 Hz or less, the temperature change inside the refrigerator can be reduced during the stop. During low frequency operation where the amount of refrigerant circulation is reduced, oil stagnates in the refrigeration cycle. However, this oil is recovered by the compressor 20 at startup when the amount of refrigerant circulation increases.

Furthermore, the override signal that forces the compressor 20 to operate during the stop time set by the stop time timer 28 is sent by detecting the low pressure of the refrigeration cycle, which shortens the distance from the detection unit to the signal and requires wiring. I try not to make it longer than that.

(F) Effects of the Invention As described above, according to the present invention, the compressor, condenser, and
In the operation control method of a refrigeration cycle, the refrigeration cycle has a duty cycle device in which a pressure reducing device, an evaporator, etc. are connected via piping, and the compressor is forcibly operated for a predetermined time and then stopped for a predetermined time. The device includes an operation timer means for forcibly operating the compressor for a predetermined time, a stop timer means for forcibly stopping the compressor for a predetermined time after the elapse of the operation timer time, and a total operation time of the compressor at a low frequency. an integration timer means which integrates and determines the stop time of the stop timer means; and a reset timer means which resets the integration timer means and the operation timer means when the continuous operation time of the compressor at high frequency continues for a certain period or more. Therefore, the operation timer means integrates the operating time at the lower frequency of the operating frequencies of the compressor operated for a predetermined period of time, and when the operating time at the low frequency is long, the stop time is increased, The stop time is shortened when the low frequency operation time is short, and the temperature inside the refrigerator can be prevented from rising abnormally while the compressor is stopped. Moreover, in this invention, when the continuous operation time of the compressor at a high frequency continues for a certain period of time, the reset timer means resets the operation timer means and the integration timer means so that the compressor can continue to operate for a predetermined period of time. .

[Brief explanation of drawings]

Fig. 1 is a conventional refrigeration cycle diagram, Figs. 2 to 5 show the present invention, Fig. 2 is a refrigeration cycle diagram, Fig. 3 is a block diagram of a duty cycle device, and Fig. 4 is a transmission circuit. FIG. 5 is a flowchart. 20... Compressor, 21... Condenser, 22... Pressure reducing device, 23... Evaporator, 25... Inverter device, 26... Duty cycle device.

Claims (1)

[Claims] 1. A compressor, a condenser, a pressure reducing device, an evaporator, etc. whose operation is controlled at variable speed by an inverter are connected to piping, and after the compressor is forced to operate for a predetermined time, In a method for controlling the operation of a refrigeration cycle having a duty cycle device that stops the operation for a certain period of time,
The duty cycle device includes an operation timer means for forcibly operating the compressor for a predetermined time, a stop timer means for forcibly stopping the compressor for a predetermined time after the elapse of the operation timer time, and a compressor operating at a low frequency. an integration timer means that determines the stop time of the stop timer means by integrating the total operation time of the compressor, and resets the integration timer means and the operation timer means when the continuous operation time of the compressor at high frequency continues for a certain period or more. 1. A method for controlling the operation of a refrigeration cycle, comprising a reset timer means. 2. The method of controlling the operation of a refrigeration cycle according to claim 1, characterized in that the variable frequency compressor, which is currently in operation, is forced into operation using an override signal.