JPH04332362A - Controlling device for operation of refrigerating plant - Google Patents

Abstract

PURPOSE:To reduce a non-required defrosting operation time and perform an accurate defrosting operation. CONSTITUTION:An operation control device is comprised of a suction gas temperature sensing means for sensing a suction gas temperature of a compressor and a defrosting operation means 21 for use in controlling a defrosting operation. In addition, it is further comprised of an operating time accumulation means 22 for accumulating an actual operation time of the compressor, a defrosting operation timer for counting a defrosting operation time, and the second defrosting completing means 25 for completing the defrosting operation as the accumulated operation time of the compressor is less than the predetermined time during the defrosting operation and the defrosting continues for more than the predetermined period of time and the suction gas temperature exceeds more than the second predetermined temperature. In addition, in the case that the accumulated operating time of the compressor is less than the predetermined time, as the suction gas temperature is more than the third predetermined temperature higher than the second predetermined temperature, the third defrosting completing means 26 for completing forcedly the defrosting operation is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a refrigeration system, and more particularly to a measure for detecting the end of a defrost operation.

0002

2. Description of the Related Art Generally, in this type of refrigeration system, a compressor, a condenser, an expansion valve, and an evaporator are connected in order to refrigerant pipes, as disclosed in Japanese Patent Application Laid-Open No. 59-197764. There are things that are connected and configured by. In this refrigeration system, when the continuous operation time reaches a certain value according to the defrost timer, hot gas is flowed to the evaporator to perform defrost operation, and when the intake gas temperature of the compressor reaches a predetermined temperature, the defrost operation is terminated. However, this defrost operation removes frost from the evaporator and prevents a decrease in refrigerating capacity.

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional refrigeration apparatus has the following problems.

That is, as shown in FIG. 5, when the outside air temperature is high, the defrost operation ends in a relatively short time (see time T2 in the solid curve in the figure). However, when the outside temperature is low, the amount of heat released from the refrigerant circuit to the outside air is reduced by detecting whether the defrost operation has finished by checking whether the intake gas temperature of the compressor has fallen below a predetermined value. Since the amount of heat is large, the amount of heat supplied for defrosting is reduced, and the rate of increase in intake gas temperature is reduced. Therefore, the defrosting operation time will take longer than necessary (see the broken line curve in the figure).

On the other hand, when the outside temperature is low, when the refrigeration system is installed in a refrigerated container, the amount of moisture generated inside the container is small and ventilation is not performed, so the amount of frost formation is generally small. However, when the defrost operation is performed for a long time as described above, the heat released during the defrost operation is consumed not only by melting the frost on the evaporator and drain pan but also by increasing the temperature of the frame, etc. Additional energy is required to cool down the elevated frame, etc. again.

[0006] The above-mentioned problems are particularly serious in the freezing mode. That is, in the freezing mode, usually
This is because the temperature of frost, ice, and the temperature of the frame are low, and therefore there is a large temperature difference between the set temperature of the defrost completion thermometer that detects the end of the defrost operation and the frost temperature.

[0007] Therefore, when the outside air temperature is low, there is a risk that the defrost operation will be performed more than necessary, leading to an increase in power consumption, and the temperature of the cargo will also rise due to an excessive rise in the internal temperature.

[0008] Furthermore, conventionally, no backup means has been provided for detecting the end of the defrost operation.
If an abnormality occurs in the control board or the like, there is a problem in that the defrost operation continues, causing the intake gas temperature to rise abnormally and damaging the compressor.

[0009] The present invention has been made in view of the above points, and aims to reduce unnecessary defrost operation time, save power consumption and prevent excessive temperature rise, and also reduce the amount of time the defrost operation ends. The purpose is to ensure that the process is carried out accurately.

0010

[Means for Solving the Problems] In order to achieve the above object, the means taken by the present invention is to estimate the outside air temperature based on the operating time of the compressor and shorten the defrosting operating time.
The defrost operation is terminated when the compressor intake gas temperature rises abnormally.

Specifically, as shown in FIG. 1, the means taken by the invention according to claim 1 first include a compressor (11), a condenser (12), an expansion mechanism (EV), and an evaporator. Vessel (14)
This assumes a refrigeration system equipped with a refrigerant circulation circuit (1) in which the following are connected in sequence.

and suction gas temperature detection means (Th5) for detecting the temperature of suction gas to the compressor (11);
A defrost operating means (21) outputs a defrost signal at fixed time intervals in the in-range in the freezing mode to control the defrosting operation, and during the defrosting operation of the defrosting operating means (21), the intake gas temperature detecting means (Th5 ) becomes equal to or higher than the first predetermined temperature,
A first defrost termination means (24) is provided for terminating the defrost operation. Furthermore, an operating time integrating means (22) for integrating the actual operating time of the compressor (11) in the in-range in the refrigeration mode, and a defrosting time calculating means (23) for counting the defrosting operating time of the defrosting operating means (21). ) and the above defrost operating means (
21) During the defrost operation, if the cumulative operating time of the operating time integrating means (22) is less than the predetermined time, the defrosting time calculating means (23) counts the predetermined time and the intake gas temperature detecting means (Th5) detects the Second defrost terminating means (25) is provided for terminating the defrost operation in place of the first defrosting terminating means (24) when the temperature reaches a second predetermined temperature or higher, which is lower than the first predetermined temperature. . In addition, during the defrost operation of the defrost operating means (21), if the cumulative operating time of the operating time integrating means (22) is equal to or less than a predetermined time, the temperature detected by the suction gas temperature detecting means (Th5) is set to a second value. In addition to the second defrost termination means (25), a third defrost termination means (26) for forcibly terminates the defrost operation when the temperature reaches a third predetermined temperature higher than the predetermined temperature.

[0013]

[Operation] With the above configuration, in the invention according to claim 1,
The refrigerant circulates through the refrigerant circulation circuit (1), cools the air sucked into the evaporator (14), and blows out the cooled air.

On the other hand, when the continuous operation time reaches a certain time,
A defrost operation control means (21) controls the defrost operation and removes frost from the evaporator (14). Further, while the operating time integrating means (22) calculates the actual operating time of the compressor (11) between this defrosting operation and the previous defrosting operation, the intake gas temperature detecting means (Th
5) detects the intake gas temperature of the compressor (11), and the defrost time calculation means (23) calculates the defrost operation time.

[0015] If the cumulative operating time of the operating time integrating means (22) exceeds a predetermined time, it is assumed that the outside air temperature is high and the detected temperature of the suction gas temperature detecting means (Th5) is higher than the first one.
When the temperature reaches a predetermined temperature or higher, the first defrost termination means (2
4) ends the defrost operation.

Further, if the cumulative operating time of the operating time integrating means (22) is less than a predetermined time, it is assumed that the outside temperature is low.
When the defrost time calculation means (23) calculates a predetermined time and the temperature detected by the intake gas temperature detection means (Th5) becomes equal to or higher than the second predetermined temperature, the second defrost termination means (25) terminates the first defrost. The defrost operation is ended in place of the means (24).

[0017] Furthermore, during defrosting operation when the cumulative operating time of the operating time integrating means (22) is less than a predetermined time, if the detected temperature of the suction gas temperature detecting means (Th5) exceeds a third predetermined temperature; In addition to the second defrost terminating means (25), a third defrost terminating means (26) forcibly terminates the defrost operation. As a result, even if there is an abnormality in the defrost time calculation means (23), the defrost operation is reliably completed.

[0018]

[Effect of the invention] Therefore, according to the invention according to claim 1,
When defrosting operation is performed at regular intervals in the in-range in the freezing mode, the defrosting operation is normally performed until the intake gas temperature reaches the first predetermined temperature, while the integration of the compressor (11) in the in-range in the freezing mode When the operating time is less than the predetermined time, the defrost operation is ended when the predetermined time has elapsed and the intake gas temperature reaches the second predetermined temperature, so the defrost operation time can be shortened, reducing consumption. Since electric power can be saved and unnecessary defrost operation can be prevented, it is possible to prevent the temperature of cargo items and the like from rising excessively.

Furthermore, even if the defrost operation continues abnormally, the intake gas When the temperature reaches a third predetermined temperature, the defrost operation is terminated.
Since it is possible to reliably prevent the intake gas temperature from rising abnormally, it is possible to reliably prevent damage to the compressor (11) and improve reliability in the event of an abnormality.

[0020]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, (1) is a refrigerant circulation circuit of a refrigeration system installed in a refrigerated container, which cools the inside of a container body (not shown).

[0022] The refrigerant circulation circuit (1) has a capacity of 100%.
A compressor (11) that can be adjusted to a maximum capacity of 67%, a medium capacity of 67%, and a minimum capacity of 33%, a condenser (12), a receiver (13), and an electric expansion valve (EV )and,
An evaporator (14), an accumulator (15), and a suction solenoid valve (SV) having a bleed port are connected in order by a refrigerant pipe (16) to form a closed circuit. The condenser (12) is provided with an external fan (12a).
), the evaporator (14) is provided with an internal fan (14a), while the compressor (11) and condenser (1
2), a three-way solenoid valve (TV) is interposed between the two. The three-way solenoid valve (TV) has a hot gas bypass path (17
) is connected to the hot gas bypass path (17).
The other end is connected between the electric expansion valve (EV) and the evaporator (14), and a drain pan heater (17a) is formed. And the hot gas bypass path (
17) is the hot gas compressor (11) during defrost operation.
) to the evaporator (14) to melt the frost in the evaporator (14) and a drain pan (not shown).

[0023] The above-mentioned refrigeration system is also provided with various sensors, (HPS) is a high-pressure sensor that detects the high-pressure refrigerant pressure on the discharge side of the compressor (11), and (Th1) is a high-pressure sensor that detects the high-pressure refrigerant pressure on the discharge side of the compressor (11). (Th2) is a gas pipe temperature sensor that detects the gas pipe temperature on the outlet side of the evaporator (14). (Th3) is a gas pipe temperature sensor that detects the gas pipe temperature on the outlet side of the evaporator (14).
4) is a suction temperature sensor that detects the intake air temperature on the air suction side, (Th4) is a blowout temperature sensor that detects the blowout air temperature on the air blowout side of the evaporator (14), and (Th5) is a compressor (11). This is a suction pipe temperature sensor serving as suction gas temperature detection means for detecting the suction gas temperature on the suction side of the suction pipe.

[0024] Each of the above sensors (HPS), (Th
The detection signals of 1) to (Th5) are input to the controller (2), while the controller (2) is connected to the compressor (1).
1), electric expansion valve (EV), suction solenoid valve (SV), and 3
The controller is configured to control a solenoid valve (TV), etc. That is, the controller (2) controls the electric expansion valve (E
V) is PID controlled according to the degree of superheating based on the detection signals of the liquid pipe temperature sensor (Th1) and gas pipe temperature sensor (Th2) in the freezing mode, and the blowout is controlled based on the detection signal of the blowout temperature sensor (Th4) in the refrigeration mode. While performing PID control based on air temperature, the intake solenoid valve (SV) is controlled to close when the evaporation temperature decreases, for example, when a predetermined opening degree of an electric expansion valve (EV) continues for a certain period of time.

The controller (2) also includes a defrost operation control means (21) and an operating time integration means (2).
2), a defrost operation timer (23) which is a defrost time calculation means, a first defrost end means (24), a second defrost end means (25), and a third defrost end means (26). is provided. When the operation such as freezing continues for a predetermined period of time, for example, 12 hours, the defrost operation means (21) outputs a defrost signal, switches the three-way solenoid valve (TV), and directs the hot gas to the hot gas bypass path ( 17) to the evaporator (14) to control the defrost operation. In addition, the operating time accumulating means (22)
is configured to calculate the actual operating time of the compressor (11) in the in-range refrigeration mode between the end of the previous defrost operation and the current defrost operation.

On the other hand, the defrost operation timer (23)
is configured to calculate the defrost operation time. Further, the first defrost terminating means (24) is configured to adjust the temperature detected by the suction pipe temperature sensor (Th5) to a first predetermined temperature, for example, when the cumulative operating time of the operating time integrating means (22) exceeds a predetermined time. , the defrost operation is terminated when the temperature reaches 40° C. or higher. Also,
The second defrost terminating means (25) is configured to cause the defrost operation timer (23) to count a predetermined time when the cumulative operating time of the operating time accumulating means (22) is less than a predetermined time, and for example, when 45 minutes have elapsed. , and the temperature detected by the suction pipe temperature sensor (Th5) is a second predetermined temperature, for example, 0.
The defrost operation is configured to end when the temperature exceeds ℃. Furthermore, when the temperature detected by the suction pipe temperature sensor (Th5) reaches a third predetermined temperature higher than the second predetermined temperature, the third defrost termination means (26)
For example, when the temperature exceeds 35° C., the defrost operation is forcibly terminated separately from the second defrost termination means (25). That is, the second defrost terminating means (25) and the third defrosting terminating means (26)
) is equipped with an AND circuit (27) and an OR circuit (28), as shown in FIG. 2 predetermined temperature signal S1 and a time signal S2 of 45 minutes counted by the defrost operation timer (23) are input,
The OR circuit (28) is configured to receive the output signal of the AND circuit (27) and a third predetermined temperature signal S3 of 35° C. or higher detected by the suction pipe temperature sensor (Th5). The circuit (28) is the defrost operation end signal S
4 is output.

Next, the control operation of the defrost operation in the freezing mode of this refrigeration system will be explained based on the flowchart of FIG.

First, in step ST1, the operating time integrating means (22) operates the compressor (1) in the in-range in the freezing mode.
When the actual operating time in step 1) is integrated and the defrost operation means (21) outputs a frost operation command signal in step ST2, the defrost operation is started in step ST3,
Switch the three-way solenoid valve (TV) to supply hot gas to the evaporator (14) via the hot gas bypass path (17),
Controls defrost operation. Subsequently, in step ST4, it is determined whether the cumulative operating time T1 of the compressor (11) is longer than a predetermined set time α (for example, about 3 hours). Then, if T1>α, step ST5
Step ST6 inputs the suction gas temperature t detected by the suction pipe temperature sensor (Th5), and waits until the suction gas temperature t reaches the first predetermined temperature t1 (for example, a temperature of 40° C.). When the temperature reaches the first predetermined temperature t1 or higher, in step ST7, the first defrost termination means (24)
ends defrost operation.

On the other hand, if it is determined in step ST4 that the cumulative operating time T1 of the compressor (11) is smaller than the set time α, the process moves to step ST8, and the defrost operation timer (23) having a predetermined time starts counting. is started, and in step ST9, the intake gas temperature t is input, and in step ST10, the process returns to step ST9 until the intake gas temperature t becomes 0° C. or higher. Then, when the intake gas temperature t becomes 0° C. or higher, the process moves to step ST11, moves to step ST12 until the intake gas temperature t becomes 35° C. or higher, and returns to step ST9 until the defrost operation timer (23) counts up. Thereafter, when the intake gas temperature t becomes 0° C. or higher and the defrost operation timer (23) counts up (45 minutes), the second defrost ending means (25) ends the defrost operation in step ST13.

Further, in step ST11, when the intake gas temperature becomes 35° C. or higher, the process moves to step ST13, where the third defrost termination means (26) forcibly terminates the defrost operation. In other words, the defrost operation time is 45 minutes or more, and the intake gas temperature is 0℃ or higher.
Alternatively, the defrost operation is simply terminated when the intake gas temperature becomes 35° C. or higher.

Therefore, as shown in FIG. 5, when the outside air temperature is high, the intake gas temperature t also rises quickly, and a relatively short time (for example, about 30 minutes) has passed since the start time T0 of the defrost operation. The defrost operation ends at time T2 (see the solid curve in the figure), but when the outside temperature is low, the amount of heat radiated to the outside air is large, so the amount of heat supplied for defrosting the evaporator (6) decreases. Since the increase in the intake gas temperature t is reduced, the defrost operation time may become very long (for example, about 90 minutes, see the broken line curve in the figure). On the other hand, when the outside temperature is low, the amount of moisture in the refrigerator is relatively small, and there is no need to perform the defrost operation for such a long time. As a result, the evaporator (6) and drain pan heater section (1
In addition to melting the frost described in 1), the temperature of the frame etc. is increased, and an extra amount of heat is supplied, which may lead to an increase in power consumption.

Therefore, the operating time accumulating means (22) integrates the actual operating time of the compressor (11) in the in-range in the freezing mode, and the first defrost ending means (24) calculates the accumulated operating time of the compressor (11). When T1 is less than the predetermined time α, the defrost operation is performed until the predetermined time elapses and the intake gas temperature t becomes 0° C. or higher. That is, as shown in FIG. 5, the defrost operation ends when the set time Ts has elapsed, making it possible to shorten the defrost operation, reduce power consumption, and eliminate unnecessary defrost operations. By preventing the operation, it is possible to prevent an excessive rise in the temperature inside the warehouse, that is, an excessive rise in the temperature of cargo items. Furthermore, in the above defrost operation, even if a predetermined period of time has passed after the start of the defrost operation, the defrost operation continues until the intake gas temperature t reaches 0°C, so the evaporator (6) is not defrosted. However, the defrost operation never ends.

Furthermore, even if the defrost operation continues abnormally, such as when the defrost operation timer (23) becomes abnormal or when the operation time accumulating means (22) incorrectly calculates the operation time, the intake gas temperature Since the defrost operation is ended when t reaches a third predetermined temperature,
Since it is possible to reliably prevent the intake gas temperature from rising abnormally, it is possible to reliably prevent damage to the compressor (11) and improve reliability in the event of an abnormality.

[0034] In this embodiment, the first predetermined temperature (40°C)
and the third predetermined temperature (35°C) were set to different values,
The temperature may be the same.

The present invention also provides a refrigerant circulation circuit (
The present invention is not limited to 1), nor is it limited to what is provided in a refrigerated container.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention.

FIG. 2 is a refrigerant circuit diagram.

FIG. 3 is a circuit diagram of a second defrost terminating means and a third defrosting terminating means.

FIG. 4 is a control flow diagram of defrost operation.

FIG. 5 is a characteristic diagram of intake gas temperature versus time.

[Explanation of symbols]

1 Refrigerant circulation circuit 2 Controller 11 Compressor 12 Condenser 14 Evaporator 21 Defrost operation control means 22 Operating time integration means 23 Defrost operation timer (defrost time calculation means) 24 First defrost termination means 25 Second defrost termination means 26 Third Defrost termination means

Claims (1)

[Claims] Claim 1: A refrigeration system comprising a refrigerant circulation circuit (1) in which a compressor (11), a condenser (12), an expansion mechanism (EV), and an evaporator (14) are connected in order. , suction gas temperature detection means (Th5) for detecting the temperature of the suction gas to the compressor (11), and defrost operation means for controlling defrost operation by outputting a defrost signal at fixed time intervals in the in-range in refrigeration mode. (21) During the defrost operation of the defrost operation means (21), when the temperature detected by the intake gas temperature detection means (Th5) becomes equal to or higher than the first predetermined temperature, the first defrost operation is terminated. means (24), operating time integrating means (22) for integrating the actual operating time of the compressor (11) in the in-range in the freezing mode, and a defrosting time for counting the defrosting operating time of the defrosting operating means (21). During the defrosting operation of the calculation means (23) and the defrost operation means (21), if the cumulative operating time of the operating time accumulating means (22) is less than a predetermined time, the defrost time calculating means (23) counts the predetermined time. In addition, when the detected temperature of the suction gas temperature detection means (Th5) reaches a second predetermined temperature lower than the first predetermined temperature, a second defrost operation is terminated in place of the first defrost termination means (24). defrost termination means (25);
During the defrost operation of the defrost operating means (21), if the cumulative operating time of the operating time integrating means (22) is less than or equal to a predetermined time, the suction gas temperature detecting means (Th5
), when the detected temperature reaches a third predetermined temperature higher than the second predetermined temperature, a third defrost terminating means (26) for forcibly terminating the defrost operation separately from the second defrost terminating means (25); An operation control device for a refrigeration system, characterized by comprising: