JPH08219604A - Control type refrigerating device with expansion mechanism - Google Patents

Abstract

PURPOSE: To improve safety or a compressor at the time of switching to a non-frosting operation, suppress a drop of the refrigerating capability, and reduce a turbulance in the control. CONSTITUTION: A refrigerating device have an evaporator 11 which constitutes a refrigerating circuit 1, electronic expansion valve 12, evaporation pressure- regulating valve 13 and electromagnetic valve 14 which are provided in parallel, compressor 15, condenser 16, etc., and a control unit 2 which controls respective apparatus, and evaporation temperature sensor 3, etc., and is provided on, e.g. an environmental test device. When the electromagnetic valve 14 is switched from being open to close for a non-frosting operation, the operation unit of a control unit 2 performs a control to fully open the electronic expansion valve 12 first, and stops the control when the evaporation temperature reaches a specified temperature, and returns to a normal control state. By this method, when the electromagnetic valve is closed, the evaporation pressure ascends at an early stage, a refrigerant circulation quantity is recovered, a flow rate to the compressor is recovered, the ascent of a discharging gas temperature is suppressed, and safety of the device is ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an expansion mechanism on the upstream side of an evaporator, the opening degree of which can be adjusted, and a refrigeration circuit on which an evaporation state adjusting valve and an on-off valve are arranged side by side. Refrigeration equipment.

[0002]

2. Description of the Related Art As a conventional refrigeration circuit, there is a refrigeration circuit in which an evaporation pressure adjusting valve is provided on the downstream side of an evaporator and an opening / closing valve such as an electromagnetic valve is provided in parallel with the evaporation pressure adjusting valve. In such a refrigeration circuit, the evaporation pressure adjusting valve is set to a high pressure, and when the electromagnetic valve is closed, the evaporation pressure and the evaporation temperature become high, and the non-frosting operation can be performed. However, even if the open / close valve is switched from open to closed, the pressure in the evaporator does not rise suddenly, and the evaporation pressure adjusting valve maintains the closed state, so that the refrigerant does not flow to the downstream side thereof.
As a result, the suction pressure of the compressor decreases, the compression ratio increases, and the discharge gas temperature rises.
In addition, the differential pressure across the expansion valve decreases as the evaporation pressure increases,
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 problems in the prior art, and when switching to non-frosting operation,
An object of the present invention is to provide a refrigerating apparatus in which the safety of the compressor is improved, the reduction of the refrigerating capacity is suppressed, and the control is less disturbed.

[0004]

In order to solve the above-mentioned problems, the present invention according to claim 1 is provided with an expansion mechanism whose opening degree can be adjusted on the upstream side of the evaporator and also on the downstream side of the evaporator. In a refrigerating apparatus having a refrigeration circuit in which an evaporation state adjusting valve and an on-off valve are installed side by side, switching detection means for detecting that the on-off valve has been switched from an open state to a closed state, and the switching detection means is in the closed state. And an opening enlargement control means for controlling the opening of the expansion mechanism so as to increase the opening of the expansion mechanism. A detection means for detecting a state value, and a control stop means for stopping the control of the opening degree enlargement control means when the operating state value detected by the detection means reaches a preset predetermined value, Invention of 3 is a request In addition to the characteristics of the second aspect of the invention, time detection means for detecting the time until the operating state value reaches the predetermined value after the opening degree expansion control means starts control, and the time detection means detects the time. And a notifying means for notifying that the time is longer than a predetermined time set in advance.

[0005]

The invention of claim 1 is directed to a refrigerating apparatus provided with an expansion mechanism whose opening degree can be adjusted, an evaporation state adjusting valve and an opening / closing valve which are arranged in parallel. Here, the evaporation state adjustment valve is
Evaporation pressure control valve, evaporation temperature control valve, etc.The on-off valve means a valve that opens and closes by being controlled by a solenoid valve, an air actuated valve, etc. It explains as a valve. In such a refrigeration system, when the solenoid valve is open, the refrigerant sufficiently flows through the solenoid valve, so the pressure on the upstream side is lower than the set pressure of the pressure control valve, and the pressure control 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 equipped with a refrigeration system. For example, in the case of an expansion mechanism of a refrigeration system used in an environmental testing device, its opening is controlled by operating conditions such as temperature and humidity of the environmental testing device. Therefore, even if the state of the refrigerating circuit itself of the refrigerating apparatus changes, the opening degree of the expansion mechanism does not directly follow this. Therefore, even if the electromagnetic valve is switched from open to closed and the flow rate of the refrigerant on the downstream side is reduced, the opening degree of the expansion mechanism is not affected by that.

However, according to the invention of claim 1,
Since the switching detection means and the opening degree expansion control means are provided,
When the solenoid valve is switched from the open state to the closed state, the switching detection means detects this, and the opening degree expansion control means controls to increase the opening degree of the expansion mechanism. As a result, a larger amount of refrigerant flows through the evaporator, and the lowered pressure quickly rises and reaches the set pressure of the pressure control valve. And
The pressure regulating valve opens early, the refrigerant flows to the downstream side, and the pressure on the downstream side also recovers. As a result, the rise of the discharge gas temperature of the compressor is suppressed to a low level, and the reduction of the refrigerating capacity is also suppressed. Further, the control disturbance is reduced by the early recovery of the refrigerant circulation amount and the refrigerating capacity. Since the control for increasing the opening degree of the expansion mechanism is a transient control, it is stopped at an appropriate time, for example, by setting a time.

According to the second aspect of the present invention, the detection means for detecting the operating state value of the refrigeration circuit and the control stop means for stopping the control of the opening degree expansion control means when the detected value reaches a predetermined value are provided. To be Here, the operating state value of the refrigeration circuit refers to the temperature or pressure of the refrigerant in the evaporator or in the vicinity thereof, the opening of the pressure adjusting valve, the flow rate of the refrigerant downstream thereof, or the like. Further, the predetermined value refers to the above-mentioned operating state value during steady-state operation with the solenoid valve closed or a value close thereto. Therefore, by such detecting means and control stopping means, transient control for forcibly increasing the opening degree of the expansion mechanism is performed when the refrigeration system reaches the steady operation state when the pressure control valve is closed or in the vicinity thereof. Since it is stopped, the refrigeration system returns to the normal operation at an appropriate time.

According to the invention of claim 3, the time detection means for detecting the time until the operating state value reaches the predetermined value after the opening enlargement control means starts the control, and the detected time are preset. An informing unit is provided to inform the user when the time is longer than the predetermined time. When the opening degree expansion control means controls the expansion mechanism to fully open, this predetermined time is the time until the evaporation temperature returns to the value during steady operation when the solenoid valve is closed, for example, after the expansion mechanism is fully opened. Is obtained in advance by calculation, actual trial operation, etc., and a certain margin is added to the time. Therefore, if the notification means notifies that the time has exceeded the predetermined time, it means that the refrigerator does not return to the normal operation as expected due to some abnormality. From this notification, the driver can know the occurrence of such an abnormality. The notifying means means a visual or audible alarm such as an alarm lamp or a bell.

[0009]

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

The environment test device is provided in the heat insulating casing 51, the test chamber 52, the air conditioning chamber 53, and the air conditioning chamber, and the refrigeration circuit 1 is provided.
The evaporator 11, the humidifier 54, the heater 55, the blower 56, the temperature sensor 57, and the humidity sensor 5 which are also constituent devices of
8. A control device 59, etc., which incorporates the control unit 2 of the refrigeration circuit 1 and totally controls the environmental testing device, is provided. The control device 59 includes an operation part and a control part (not shown), and the temperature or temperature and humidity set in the operation part and the temperature sensor 57 or the temperature sensor 57 and the humidity sensor 58.
Compare the temperature or temperature and humidity measured in
5 and the capacity of the refrigeration circuit 1 or in addition to this, the capacity of the humidifier 54 is adjusted to perform control to maintain the temperature inside the test chamber 52 or the temperature and humidity set therein.

FIG. 3 shows a control unit 2 of the refrigeration system.
Shows the configuration of. 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 is provided with an electromagnetic valve drive output unit 22 for turning on / off, 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 testing device.
Through the test room set temperature, set humidity, temperature sensor 57
Also, the temperature signal and the humidity signal from the humidity sensor 58, the count of the timer 24, and the like are input. And the arithmetic processing unit 2
Reference numeral 6 appropriately combines these signals for calculation, and supplies the drive signals to the drive output units 22 and 23.

In controlling the solenoid valve 14, the arithmetic processing unit 26 determines the operating state of the environmental testing device from the set temperature and the set humidity, and opens the solenoid valve 14 during low temperature operation or low dew point operation. A signal is given to the valve drive output section 22, and when not in such an operating state, a signal for closing the solenoid valve 14 is given. When the solenoid valve is open, the evaporator 11 is in a low pressure / low temperature state. The evaporation pressure adjusting valve 13 is
Because of the non-frosting operation, the evaporation temperature is set to a high pressure such as a high temperature of, for example, about 1 ° C., so that it is closed under such a low-pressure operating condition. Solenoid valve 14
When is closed, the pressure in the evaporator portion rises, the evaporation pressure adjusting valve 13 operates, the evaporation pressure is controlled so that the evaporation temperature becomes about 1 ° C, and the non-adhesion that prevents the condensation of the evaporator is prevented. Frost operation is performed.

The solenoid valve 1 is used to control the electronic expansion valve 12.
In the normal operation other than the switching of the open / closed state of 4, the arithmetic processing unit 26
Controls the set temperature / humidity, the measured temperature / humidity, the heating / humidifying output, etc., determines the optimum opening degree of the electronic expansion valve 12, and gives the signal to the expansion valve drive output unit 23. The electronic expansion valve 12 is driven by, for example, a stepping motor, and a pulse is given to the motor from the expansion valve output unit 23 to have an opening degree corresponding to the number of pulses. As a result, a required cooling capacity is generated in the evaporator 11, and the environmental testing device is operated in energy saving mode.

When the solenoid valve 14 is switched from the open state to the closed state, the electronic expansion valve 12 is subjected to control prior to the above-mentioned normal control. Therefore, a switching detection means for detecting that the electromagnetic valve 14 has been switched from open to closed, and an opening expansion control means for controlling the opening of the electronic expansion valve 2 to be increased by this switching are provided. In the present embodiment, the arithmetic processing unit 26 serves as a switching detection unit and an opening degree expansion control unit. That is, a signal provided by the arithmetic processing unit 26 to the electromagnetic valve drive output unit is used to detect the switching of the electromagnetic valve 14 from open to closed. Further, the arithmetic processing unit 26 gives a signal for fully opening the electronic expansion valve 12 to the expansion valve drive output unit 23 by this switching detection. As the switching detecting means, other means such as an opening / closing switch provided on the solenoid valve 14 and the opening / closing signal thereof can be used.

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

Further, in the present embodiment, as described above, in the control unit 2, the arithmetic processing unit 26 has the electronic expansion valve 1.
After the control to fully open 2 is started, the timer 24 as a time detecting means for detecting the time until the measured value of the temperature sensor 3 reaches a predetermined value, for example, about 0 ° C, and the time detected by this An alarm bell 25 is provided as an informing means for informing that the time has become longer than a predetermined time set in advance. This predetermined time is a time for judging abnormality of the refrigeration circuit, and 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 required to reach a certain level plus an appropriate margin. This time is unique to the characteristics of the actual refrigeration system and the environment test equipment equipped with the refrigeration system, and is determined by calculation and actual measurement in the trial run of the system.

FIG. 4 shows an example of a processing flow when the electromagnetic 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 end of the process of opening the electromagnetic valve 14 from the open state to the closed state, respectively.

First, the end of this process is judged by the flag 2 (S-1). If this process has already been completed, the process proceeds to the next process for performing normal opening degree control of the electronic expansion valve 12, and if not completed, the flag 1 is confirmed (S-2). When the flag 1 has become 1 and this process has already been started, the process proceeds to the determination of the evaporation temperature (S-3).
If this process is not started, the electromagnetic valve 14 is closed, the flag 1 is set to 1 and set to the start state, and then the timer 24 is started to fully open the electronic expansion valve 12 (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 judge 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. To 0 in the unstarted state and 1 in the finished state,
The timer 24 is reset (S-5), this process is terminated, and the process proceeds to the next process. When the evaporation temperature has not reached the predetermined temperature, the count of the timer 24 is compared with the predetermined time set in advance to determine the abnormal state of the refrigeration circuit (S-6). When the state in which the evaporation 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). Proceed to alarm processing such as ringing the alarm bell 25. When the evaporation 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 opened state and the process proceeds to the next process.

FIG. 5 shows a change state of the refrigeration circuit when the solenoid valve 14 is switched from open to closed. FIG. 5A shows the electronic expansion valve 12 fully opened when the solenoid valve 14 is opened and closed by applying the present invention. In the case of control, (b) is a case where such control is not performed and the electronic expansion valve 12 is left in the state of opening control during steady state. The set evaporation pressure is a pressure corresponding to an evaporation temperature of about 1 ° C. The amount of refrigerant circulation is determined by the electronic expansion valve 12
Is the flow rate of the refrigerant passing through and is determined by the valve opening and the magnitude of the differential pressure across the valve. When the solenoid valve 14 is open, the resistance of the refrigerant passing through the solenoid valve 14 is small, so that both the evaporation pressures 1 and 2 are sufficiently lower than the set pressure.

When the electromagnetic valve 14 is closed from the open state, the evaporation pressure adjusting valve 13 is also closed. Therefore, 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 of 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 refrigerant circulation amount increases, so that the evaporation pressure 1 rises more rapidly than in the case of (b) as shown in FIG. To do. As a result, the evaporation pressure 1 reaches the set pressure in a shorter time, the evaporation pressure adjusting valve 13 opens, and the evaporation pressure 2 recovers early. Further, the drop in the refrigerant circulation amount is reduced and the normal refrigerant circulation amount is quickly recovered.

FIG. 6 shows the effect obtained when the control for maximizing the opening degree of the electronic expansion valve 12 is terminated by detecting the evaporation temperature. If the control for maximizing the opening degree 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 indicated by, the refrigerant circulation amount becomes the amount during steady operation when the solenoid valve 14 is closed and is stabilized.

[0022]

As described above, according to the present invention, in the invention of claim 1, since the opening degree of the expansion mechanism is increased when the on-off valve is switched from the open state to the closed state, it is often used in the evaporator. Of the refrigerant, the pressure of the evaporator portion is quickly raised to reach the set pressure of the evaporation pressure adjusting valve, and the evaporation pressure adjusting valve is actuated to recover the downstream pressure and the refrigerant flow rate at an early stage. Further, it is possible to suppress a decrease in the refrigerant circulation amount passing through the expansion mechanism and to secure an appropriate refrigerant circulation amount at an early stage. As a result, it is possible to reduce the deterioration of the refrigerating capacity and suppress the rise of the discharge gas temperature of the compressor to improve the safety of the refrigerating apparatus. Further, the fluctuation of the refrigerant circulation amount and the refrigerating capacity passing through the expansion mechanism is reduced, so that the controllability of the refrigerating apparatus can be improved. Therefore, the switching to the non-frosting operation can be performed extremely smoothly and safely, and the reliability of the device can be improved.

According to the second aspect of the invention, when the operating state value of the refrigeration circuit such as the evaporation temperature reaches a predetermined value, the above-described opening degree expansion control of the expansion mechanism is stopped, so the refrigeration system is appropriately timed. Can be returned to the normal operating state. Then, it is possible to prevent the refrigerant circulation amount and the refrigerating capacity from becoming excessive. According to the third aspect of the present invention, further, since it is notified when a predetermined time or more elapses before the operating state value reaches the predetermined value after the opening degree expansion control of the expansion mechanism is started, the on-off valve, the evaporation pressure adjustment When an abnormality occurs in the valve, the control means, etc., the driver can know this, and the safe operation of the refrigeration system can be secured.

[Brief description of drawings]

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

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

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

FIG. 4 is a flowchart showing an example of a control flow of the refrigeration system.

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

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 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 Electromagnetic valve (open / close valve) 24 Timer (time detection means) 25 Alarm bell ( Informing means) 26 Arithmetic processing section (opening degree expansion control means, control stop means)

Claims (3)

[Claims] 1. A refrigeration system comprising an expansion mechanism having an opening degree adjustable on the upstream side of an evaporator, and a refrigeration circuit having an evaporation state adjusting valve and an on-off valve arranged side by side on the downstream side of the evaporator. A switching detection means for detecting that the valve has been switched from the open state to the closed state, and an opening degree expansion control for increasing the opening degree of the expansion mechanism when the switching detection means detects the switching to the closed state. A refrigeration apparatus comprising: a control unit. 2. A detection means for detecting an operating state value of the refrigeration circuit, and a control stop for stopping the control of the opening degree enlarging control means when the operating state value detected by the detecting means reaches a preset predetermined value. The refrigerating apparatus according to claim 1, further comprising means. 3. A time detection means for detecting a time until the operating state value reaches the predetermined value after the opening enlargement control means starts control, and a time detected by the time detection means is set in advance. The refrigerating apparatus according to claim 2, further comprising a notifying unit that notifies the user of the time when the predetermined time has elapsed.