JP3046740B2 - Expansion mechanism added control type refrigeration system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a refrigerating circuit having an expansion mechanism capable of adjusting the opening on the upstream side of an evaporator and having an evaporation state adjusting valve and an on-off valve arranged downstream of the evaporator. It relates to a refrigeration system.

[0002]

2. Description of the Related Art As a conventional refrigeration circuit, there is a circuit in which an evaporation pressure regulating valve is provided downstream of an evaporator, and an on-off valve such as a solenoid valve is provided in parallel with the evaporating pressure regulating valve. In such a refrigeration circuit, the evaporating pressure regulating valve is set to a high pressure, and when the electromagnetic valve is closed, the evaporating pressure and the evaporating temperature are increased so that the frost-free operation can be performed. However, even if the on-off valve is switched from open to closed, the pressure in the evaporator does not suddenly increase, so that the evaporating pressure regulating valve maintains the closed state, so that no refrigerant flows downstream thereof.
As a result, there arises a problem that the suction pressure of the compressor decreases, the compression ratio increases, and the discharge gas temperature increases.
Also, as the evaporating pressure rises, the differential pressure across the expansion valve decreases,
There is a problem that the amount of refrigerant circulating through the expansion valve is reduced, and the refrigeration capacity is reduced.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and when switching to non-frosting operation,
An object of the present invention is to provide a refrigeration apparatus in which the safety of a compressor is improved, a decrease in refrigeration capacity is suppressed, and control disturbance is small.

[0004]

In order to solve the above-mentioned problems, the present invention has an expansion mechanism capable of adjusting an opening on the upstream side of the evaporator and a downstream side of the evaporator. Frost-free transport when the on-off valve and the on- off valve are closed
In a refrigerating apparatus having a refrigerating circuit in which an evaporating state adjusting valve set to be rotatable is provided in parallel, a switch detecting means for detecting that the on-off valve is switched from an open state to a closed state, An opening expansion control unit that controls the opening of the expansion mechanism to be increased when the detection unit detects the switch to the closed state, wherein the invention according to claim 2 further includes: Detecting means for detecting an operation state value of the refrigeration circuit, and control stop means for stopping control of the opening degree expansion control means when the operation state value detected by the detection means reaches a predetermined value set in advance. It is characterized by.

[0005]

The invention of claim 1 is directed to a refrigerating apparatus including an expansion mechanism capable of adjusting an opening degree, and an evaporation state adjusting valve and an on-off valve arranged in parallel. Here, the evaporation state adjustment valve is
Evaporation pressure adjustment valve, evaporation temperature adjustment valve, etc., and on-off valve means a valve that opens and closes under the control of an electromagnetic valve, an air-operated valve, etc. Explanation will be given as a valve. In such a refrigerating apparatus, when the solenoid valve is open, the refrigerant flows sufficiently through the solenoid valve, so that the pressure on the upstream side is lower than the set pressure of the pressure regulating valve, and the pressure regulating valve is almost closed. It has become. On the other hand, the expansion mechanism is usually controlled by the operating state of a mechanical device or the like equipped with the refrigeration device. For example, in the case of an expansion mechanism of a refrigerating device used in an environmental test device, its opening is controlled by operating conditions such as temperature and humidity of the environmental test device. Therefore, even if the state of the refrigeration circuit itself of the refrigeration apparatus changes, the opening degree of the expansion mechanism does not directly follow the change. Therefore, even if the solenoid valve is switched from the open state to the closed state and the flow rate of the refrigerant on the downstream side decreases, the opening degree of the expansion mechanism is not affected by the fact.

However, according to the first aspect of the present invention,
Since switching detection means and opening degree expansion control means are provided,
When the solenoid valve is switched from the open state to the closed state so as to perform the frost-free operation , the switch detection unit detects this, and the opening degree expansion control unit controls the expansion mechanism to increase the opening degree. As a result, more refrigerant flows into the evaporator, and the reduced pressure quickly increases to reach the set pressure of the pressure regulating valve capable of performing the frost-free operation . Then, the pressure regulating valve opens earlier, the refrigerant flows downstream of the valve, and the pressure on the downstream side also recovers. As a result, an increase in the discharge gas temperature of the compressor is suppressed low, and a decrease in the refrigerating capacity is also suppressed. Furthermore,
Due to the early recovery of the refrigerant circulation amount and the refrigeration capacity, control disturbance is reduced. Since the control for increasing the opening degree of the expansion mechanism is a transient control, the control is stopped at an appropriate time, for example, by setting time.

According to the second aspect of the present invention, there are provided a detecting means for detecting an operation state value of the refrigeration circuit, and a control stopping means for stopping the control of the opening expansion control means when the detected value reaches a predetermined value. Can be Here, the operating state value of the refrigeration circuit refers to the temperature or pressure of the refrigerant in or near the evaporator, the opening of the pressure regulating valve or the flow rate of the refrigerant downstream of the evaporator. In addition, the predetermined value refers to the above-mentioned operation state value at the time of steady operation in a state where the solenoid valve is closed or a value close thereto. Therefore, by such a detecting means and a control stopping means, the transient control for forcibly increasing the opening of the expansion mechanism is performed when the refrigeration system reaches or near the steady operation state when the pressure regulating valve is closed. Since the operation is stopped, the refrigeration system returns to the normal operation at an appropriate time.

In the above case, a time detecting means for detecting a time until the operating state value reaches a predetermined value after the opening degree expansion control means starts the control, and a detecting time for detecting the time until the operating state value reaches a predetermined value. If longer and informing means for informing this
Can be provided. When the opening degree expansion control means controls the expansion mechanism to fully open, the predetermined time is the time from when the expansion mechanism is fully opened until, for example, the evaporation temperature returns to the value at the time of steady operation when the solenoid valve is closed. Is obtained in advance by calculation, actual test operation, or the like, and is a time obtained by adding a certain margin to the time. Therefore, if the notification unit notifies that the time has become longer than the predetermined time, it means that some abnormality has occurred in the refrigeration apparatus and the operation has not returned to the normal operation as scheduled. Then, this notification allows the driver to know the occurrence of such an abnormality. Note that the notification means means a visual or audible alarm such as an alarm lamp or a bell.

[0009]

FIG. 1 shows a configuration of a refrigeration apparatus according to an embodiment, and FIG.
Fig. 1 shows a configuration of an environmental test device which is an example of a mechanical device equipped with such a refrigeration device. The refrigerating device is an evaporator 11
An electronic expansion valve 12 as an expansion mechanism capable of adjusting the opening degree is provided on the upstream side, and an evaporation pressure adjustment valve 13 as an evaporation state adjustment valve and an electromagnetic valve 14 as an on-off valve are arranged downstream of the evaporator 11. Refrigeration circuit 1 provided. The refrigeration apparatus further includes a compressor 15 that constitutes the refrigeration circuit 1 and compresses the refrigerant gas, a condenser 16 that liquefies the compressed gas, a control unit 2 that controls each component of the refrigeration apparatus, and controls the temperature of the expanded and vaporized refrigerant. A temperature sensor 3 and the like for detection are provided.

The environmental test apparatus includes a heat insulating casing 51, a test room 52, an air conditioning room 53, and a refrigeration circuit 1 provided in the air conditioning room.
Evaporator 11, humidifier 54, heater 55, blower 56, temperature sensor 57, humidity sensor 5
8. A control unit 59 for controlling the environmental test apparatus by incorporating the control unit 2 of the refrigeration circuit 1 is provided. The control device 59 includes an operation portion and a control portion (not shown), and the temperature or temperature and humidity set by the operation portion, and the temperature sensor 57 or the temperature sensor 57 and the humidity sensor 58
The temperature or the temperature and humidity measured in the above are compared with each other, and the heater 5
5 and the capacity of the refrigeration circuit 1 or the capacity of the humidifier 54 in addition thereto, and control is performed to maintain the inside of the test chamber 52 at the set temperature or the set temperature and humidity.

FIG. 3 shows a control unit 2 of the refrigeration system.
Is shown. The control unit 2 includes an A / D converter 21 to which a signal from the temperature sensor 3 is input, a solenoid valve 1
4 includes an electromagnetic valve drive output unit 22 for turning on / off the 4, an expansion valve drive output unit 23 for adjusting the opening degree of the electronic expansion valve 12, a timer 24 and an alarm bell 25 described later, an arithmetic processing unit 26, and the like. The arithmetic processing unit 26 includes an A / D converted temperature signal of the temperature sensor 3 and a control device 59 of the environmental test device.
Set temperature, set humidity, temperature sensor 57
And a temperature signal and a humidity signal from the humidity sensor 58, a count of the timer 24, and the like. And the arithmetic processing unit 2
The arithmetic unit 6 performs an operation by appropriately combining these signals and gives a drive signal to the drive output units 22 and 23 and the like.

In the control of the solenoid valve 14, the arithmetic processing unit 26 determines the operating state of the environmental test apparatus from the set temperature and the set humidity, and controls the solenoid valve 14 to open at the time of low temperature operation or low dew point operation. A signal is supplied to the valve drive output section 22, and a signal for closing the solenoid valve 14 is provided when the operation state is not such. When the solenoid valve is open, the evaporator 11 enters a low pressure / low temperature state. The evaporating pressure adjusting valve 13 is
Since the evaporation temperature is set to a high pressure so that the evaporation temperature becomes a high temperature of, for example, about 1 ° C., the operation is closed under such low pressure operation conditions. Solenoid valve 14
Is closed, the pressure in the evaporator increases, the evaporating pressure regulating valve 13 is operated, and the evaporating pressure is controlled so that the evaporating temperature becomes about 1 ° C. A frost operation is performed.

The control of the electronic expansion valve 12 includes the solenoid valve 1
In the case of the steady operation other than the switching operation of the opening / closing operation 4, the arithmetic processing unit 26
Calculates the set temperature / humidity, the measured temperature / humidity, the heating / humidification output, etc., determines the optimal opening of the electronic expansion valve 12, and provides the expansion valve drive output unit 23 with the signal. The electronic expansion valve 12 is driven by, for example, a stepping motor, and a pulse is given from the expansion valve output unit 23 to the motor, and the motor has an opening corresponding to the number of pulses. As a result, the necessary cooling capacity is generated in the evaporator 11, and the environmental test apparatus is operated with energy saving.

When the solenoid valve 14 is switched from the open state to the closed state, the electronic expansion valve 12 is controlled so as to take precedence over the above-described normal control. Therefore, there are provided switching detection means for detecting that the electromagnetic valve 14 has been switched from open to closed, and opening expansion control means for controlling the electronic expansion valve 2 to increase the opening by this switching. In the present embodiment, the arithmetic processing unit 26 serves as switching detection means and opening degree expansion control means. That is, a signal given by the arithmetic processing unit 26 to the solenoid valve drive output unit is used to detect the switching of the solenoid valve 14 from the open state to the closed state. Further, the arithmetic processing section 26 gives a signal to the expansion valve drive output section 23 to fully open the electronic expansion valve 12 by detecting the switching. As the switching detecting means, other means such as providing an open / close switch on the electromagnetic valve 14 and using the open / close signal can be used.

Since the above-described full opening control of the electronic expansion valve 12 is a transient control, the control must be stopped when it is no longer necessary. This control stop may be automatically stopped for a certain period of time from the start of the full-open control, for example. In this embodiment, a temperature sensor 3 shown in FIGS. 1 and 3 is provided as detecting means for detecting the evaporation temperature of the refrigerant at the evaporator inlet as an example of the operation state value of the refrigeration circuit 1. When the predetermined value reaches, for example, about 0 ° C. as a predetermined value, the control for expanding the opening of the electronic expansion valve 2 is stopped. The arithmetic processing unit 26 also has a function as such a control stop unit.

Further, in the present embodiment, as described above, the control unit 2 includes the arithmetic processing unit 26 in which the electronic expansion valve 1
After starting the control to fully open 2, a timer 24 as time detecting means for detecting a time until the measured value of the temperature sensor 3 reaches, for example, about 0 ° C. as a predetermined value, and a time detected by the timer 24. An alarm bell 25 is provided as notification means for notifying that the time is longer than a predetermined time set in advance. The predetermined time is a time for judging abnormality of the refrigeration circuit. When the solenoid valve 14 is switched from open to closed and the electronic expansion valve 12 is fully opened, the evaporation pressure increases and the evaporation temperature becomes 0 ° C. This is the time obtained by adding an appropriate margin to the time required to reach the degree. This time is a unique time determined from the characteristics of the actual refrigeration system and the environmental test device equipped with the refrigeration system, and is determined by calculation or actual measurement in a test run of the device.

FIG. 4 shows an example of a processing flow when the solenoid valve 14 is opened to closed by the control unit as described above. In the figure, flags 1 and 2 are flags for judging the start and the end of the process of switching the electromagnetic valve 14 from open to closed, respectively.

First, the end of this processing is determined by the flag 2 (S-1). If this process has already been completed, the process proceeds to the next process of performing normal opening control of the electronic expansion valve 12, and if not completed, the flag 1 is confirmed (S-2). If the flag 1 is set to 1 and this process has been started, the process proceeds to the determination of the evaporation temperature (S-3).
If this process has not been started, the solenoid valve 14 is closed, the flag 1 is set to 1 and the start state is set, the timer 24 is started, and the electronic expansion valve 12 is fully opened (S-4). . In the determination of the evaporation temperature, the evaporation temperature measured by the temperature sensor 3 is compared with a predetermined temperature set in advance to determine the state of the refrigeration circuit. If the evaporation temperature is higher than the predetermined temperature, the flag 1 and the flag 2 are determined. Are set to 0 for an unstarted state and 1 for an end state, respectively.
The timer 24 is reset (S-5), and this process ends to proceed to the next process. If the evaporation temperature has not reached the predetermined temperature, the count of the timer 24 is compared with a predetermined time set in advance for judging an abnormal state of the refrigeration circuit (S-6). If the state in which the evaporating temperature does not reach the predetermined temperature exceeds the predetermined time, the flag 1 and the flag 2 are set to 0 in the unstarted state and the unfinished state, respectively, and the timer 24 is reset (S-7). The process proceeds to alarm processing such as sounding the alarm bell 25. If the evaporating temperature does not reach the predetermined temperature and the timer 24 is within the predetermined time, the electronic expansion valve 12 is maintained in the fully open state and the process proceeds to the next processing.

FIG. 5 shows how the refrigeration circuit changes when the solenoid valve 14 is switched from open to closed. FIG. 5A shows the application of the present invention, in which the electronic expansion valve 12 is fully opened when the solenoid valve 14 is switched between open and closed. In the case where the electronic expansion valve 12 is controlled, (b) does not perform such control, and the electronic expansion valve 12 is left in a state of the opening control in a steady state. The set evaporation pressure is a pressure corresponding to an evaporation temperature of about 1 ° C. The amount of circulating refrigerant is determined by the electronic expansion valve 12.
, And is determined by the valve opening and the magnitude of the differential pressure across the valve. When the electromagnetic valve 14 is open, the evaporation pressures 1 and 2 are sufficiently lower than the set pressure because the resistance of the refrigerant passing through the electromagnetic valve 14 is small.

When the solenoid valve 14 is closed from the open state, the evaporation pressure control valve 13 is also closed, so that the upstream evaporation pressure 1 gradually increases and the downstream evaporation pressure 2 decreases. Then, since the differential pressure of the electronic expansion valve 12 decreases due to the increase in the evaporation pressure 1, the refrigerant circulation amount also decreases. In this case, according to the present invention, since the opening degree of the electronic expansion valve 12 is maximized, the amount of circulating refrigerant increases, so that the evaporation pressure 1 rises more rapidly than in the case of (b) as shown in FIG. I do. As a result, the evaporation pressure 1 reaches the set pressure in a shorter time, the evaporation pressure adjustment valve 13 opens, and the evaporation pressure 2 recovers earlier. In addition, the fall of the refrigerant circulation amount is reduced, and the refrigerant circulation amount is quickly restored to the normal refrigerant circulation amount.

FIG. 6 shows the effect of the control in which the control for maximizing the opening of the electronic expansion valve 12 is terminated by detecting the evaporation temperature. If the control for maximizing the opening of the electronic expansion valve 12 is not stopped, the refrigerant circulation amount 1 becomes excessive as shown by the two-dot chain line in the figure. As shown by, the amount of circulating refrigerant becomes stable during the steady operation when the solenoid valve 14 is closed.

[0022]

As described above, according to the present invention, the opening degree of the expansion mechanism is increased when the on-off valve is switched from the open state to the closed state according to the first aspect of the present invention. And the pressure of the evaporator is quickly increased to reach the set pressure of the evaporating pressure regulating valve, and the evaporating pressure regulating valve is operated to quickly recover the downstream pressure and the refrigerant flow rate. Further, it is possible to suppress a decrease in the amount of circulating refrigerant passing through the expansion mechanism and to secure an appropriate amount of circulating refrigerant at an early stage. As a result, a decrease in the refrigerating capacity can be reduced, and a rise in the discharge gas temperature of the compressor can be suppressed, thereby improving the safety of the refrigerating apparatus. Further, the controllability of the refrigerating apparatus can be improved by reducing the fluctuations in the amount of circulating refrigerant passing through the expansion mechanism and the refrigerating capacity. Therefore, the switching to the frost-free operation can be performed extremely smoothly and safely, and the reliability of the device can be improved.

According to the second aspect of the present invention, when the operating state value of the refrigeration circuit, such as the evaporation temperature, reaches a predetermined value, the control for expanding the opening of the expansion mechanism as described above is stopped. Can be returned to the normal operation state. And it can prevent that a refrigerant | coolant circulation amount and refrigeration capacity become excessive. This case, if the operating state value from the start of the opening enlargement control of the expansion mechanism informs this when older than a predetermined time to reach a predetermined value,
When an abnormality occurs in the on-off valve, the evaporating pressure regulating valve, the control means, or the like, the driver can know this, and the safe operation of the refrigeration apparatus can be ensured.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a refrigeration apparatus according to an embodiment.

FIG. 2 is an explanatory diagram of an environmental test apparatus equipped with the refrigeration apparatus.

FIG. 3 is a block diagram showing a configuration of a control unit of the refrigeration apparatus.

FIG. 4 is a flowchart illustrating an example of a control flow of the refrigeration apparatus.

FIG. 5 is a curve diagram showing a change state of a refrigeration circuit when an electromagnetic valve is changed from an open state to a closed state, wherein (a) shows a case where the present invention is applied and (b) shows a case where it is not applied.

FIG. 6 is a curve diagram showing a change in the amount of circulating refrigerant passing through the expansion valve after switching the solenoid valve from open to closed.

[Explanation of Signs] 1 Refrigeration circuit 3 Temperature sensor (detection means) 11 Evaporator 12 Electronic expansion valve (expansion mechanism) 13 Evaporation pressure adjustment valve (evaporation state adjustment valve) 14 Solenoid valve (open / close valve) 24 Timer (time detection means) 25 alarm bell (notification means) 26 arithmetic processing unit (opening expansion control means, control stop means)

Claims (2)

(57) [Claims] 1. A closing valve and the downstream of the evaporator with the upstream side of the evaporator comprises a possible expansion mechanism of the opening regulating
Defrosting operation is possible when the on-off valve is closed.
In a refrigerating apparatus having a refrigerating circuit in which a set evaporation state adjusting valve is juxtaposed, switch detection means for detecting that the on-off valve has been switched from an open state to a closed state, and the switch detection means is in the closed state. And an opening expansion control means for controlling so as to increase the opening of the expansion mechanism when the switching to the expansion mechanism is detected. 2. A detecting means for detecting an operating state value of the refrigeration circuit, and a control stop for stopping the control of the opening expansion control means when the operating state value detected by the detecting means reaches a predetermined value set in advance. The refrigeration apparatus according to claim 1, further comprising means.