JP2003106609A - Refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability in control by matching a controlled opening and an actual opening of an electric expansion valve, and to dispense with selecting the electronic expansion valve. SOLUTION: When an electric expansion valve 36 is controlled to a small opening near a minimum opening, the controlled opening is corrected to shift the controlled opening to the actual opening of the electric expansion valve 36 on the basis of a refrigerant condition at that time. This refrigeration unit comprises an opening correction part 85 for correcting the controlled opening to an opening side when the refrigerant condition that a degree of suction overheat of a compressor 30 is more than a predetermined value, and a pressure of a low-pressure refrigerant of the compressor 30 is less than a predetermined value, is continued in small opening of the electric expansion valve 36, and a closing correction part 86 for correcting the controlled opening to a closing side when the refrigerant condition that the degree of suction overheat of the compressor 30 is less than the predetermined value is continued in small opening of the electric expansion valve 36. Further when the opening correction part 85 corrects the controlled opening to the opening side, the electric expansion valve 36 is temporarily opened to a predetermined opening prior to the normal control.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a refrigerating apparatus,
In particular, the present invention relates to measures for controlling the opening of the expansion valve.

[0002]

2. Description of the Related Art Conventionally, an air conditioner is disclosed in Japanese Patent Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 0-132410, there is a configuration in which a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger are sequentially connected. The air conditioner includes an inverter circuit for driving and controlling the compressor, and changes the output frequency of the inverter circuit to control the operating capacity of the compressor. In addition, the air conditioner,
The opening degree of the expansion valve is controlled so that the suction superheat degree of the refrigerant of the compressor becomes a predetermined value.

[0003]

In the air conditioner described above, the opening degree of the expansion valve varies from one expansion valve to another. That is, the expansion valve sets the opening by moving the needle with respect to the valve body. The control opening is set with the movement amount of the needle as a command value, and the needle moves according to the control opening from the state where the expansion valve is completely closed, and the expansion valve opens and closes.

The control opening and the actual opening, which is the actual opening of the expansion valve, vary from one expansion valve to another, and a deviation may occur. As shown by the characteristic line A in FIG.
The flow rate of the expansion valve increases, that is, the amount of refrigerant increases as the opening degree increases. Conventionally, the average opening of each expansion valve is set as the control opening in consideration of variations in the opening of each expansion valve.

For example, when the expansion valve is completely closed to the fully open state and the control opening is set to 60 pulses, the refrigerant starts flowing through the expansion valve, and the expansion valve is controlled.

However, the opening of the expansion valve varies within the range of the characteristic lines B and C in FIG. As shown in FIG. 2, some expansion valves include a refrigerant that starts to flow when the control opening is 20 pulses, or a refrigerant that starts to flow when the control opening is 100 pulses.

Therefore, when the expansion valve is controlled in the vicinity of the minimum opening, the expansion valve is actually fully closed even though the expansion valve is opened at a small opening and the refrigerant is flowing in the control. The refrigerant may not flow. On the contrary, although the expansion valve has a minimum opening degree and a small amount of refrigerant flows in terms of control, the expansion valve may actually open greatly and a large amount of refrigerant may flow. As a result, there is a problem that the reliability of the expansion valve control is low.

Therefore, if the characteristic line B in the open state of any expansion valve is set to the control opening, the actual opening is large and a large amount of refrigerant is generated despite the minimum opening in control. There is a problem in that the flow of the compressor causes a damp operation and the compressor is damaged.

On the contrary, when the characteristic line C in the closed state of any expansion valve is set to the control opening, it is fully closed and the refrigerant does not flow although it is the minimum opening in control. However, there is a problem that various sensors cannot detect the state of the refrigerant, which causes failure of control.

Further, if the expansion valves are selected so as to reduce the variation in the opening, there is a problem that the expansion valve selection process is required, the yield is deteriorated, and the expansion valves are expensive.

The present invention has been made in view of the above point, and improves the reliability of control by matching the control opening of the expansion valve with the actual opening, and at the same time, selects the expansion valve. The purpose is not to need it.

[0012]

<Summary of the Invention> The present invention corrects the control opening of the expansion valve to match the actual opening.

<Solution> Specifically, as shown in FIG. 1, a first aspect of the present invention has a refrigerant circuit (20) having an expansion valve (36) whose opening degree is adjustable and performing a vapor compression refrigeration cycle. It is premised on a refrigeration system equipped with. Then, the control opening of the expansion valve (36) is corrected so that the control opening becomes the actual actual opening of the expansion valve (36).

The second aspect of the invention is premised on a refrigeration system having an expansion valve (36) whose opening degree is adjustable and having a refrigerant circuit (20) for performing a vapor compression refrigeration cycle. A valve control means (82) for controlling the opening of the expansion valve (36) is provided. In addition, the valve control means (82) has an expansion valve (36).
Is controlled to a small opening near the minimum opening, the control opening of the valve control means (82) becomes the actual opening of the expansion valve (36) based on the refrigerant state at the time of the control. A correction means (83) for correcting the control opening of the valve control means (82) is provided so as to shift.

The third aspect of the invention is premised on a refrigerating apparatus having an expansion valve (36) whose opening degree is adjustable and having a refrigerant circuit (20) for performing a vapor compression refrigeration cycle. A valve control means (82) for controlling the opening of the expansion valve (36) is provided. Further, when the valve control means (82) controls the expansion valve (36) to a small opening degree near the minimum opening degree, the suction superheat degree of the refrigerant of the compressor (30) in the refrigerant circuit (20) is increased. When the low-pressure refrigerant pressure on the suction side of the compressor (30) is equal to or higher than a predetermined value and the refrigerant state continues to be equal to or lower than the predetermined value, an open correction unit (85) that corrects the control opening of the valve control means (82) to the open side. Is equipped with. In addition, when the valve control means (82) controls the expansion valve (36) to a small opening degree near the minimum opening degree, the refrigerant intake superheat degree of the refrigerant of the compressor (30) in the refrigerant circuit (20). When the refrigerant state is equal to or less than a predetermined value, a closing correction unit (86) is provided to correct the control opening of the valve control means (82) to the closing side.

In a fourth aspect of the invention, in the third aspect of the invention, when the opening correction section (85) corrects the control opening to the open side, the expansion valve has priority over the control of the valve control means (82). (36)
Is provided with a forced opening means (84) for temporarily opening the valve to a predetermined opening.

That is, according to the present invention, the control opening of the expansion valve (36) is corrected to the actual opening. Specifically, in the second invention, the valve control means (82) includes the expansion valve (36).
Is controlled to a small opening degree near the minimum opening degree, the control opening degree of the valve control means (82) shifts to the actual actual opening degree of the expansion valve (36) based on the refrigerant state. (83) corrects the control opening of the valve control means (82).

According to the third aspect of the invention, when the expansion valve (36) is in a small opening degree, the suction superheat of the refrigerant in the compressor (30) in the refrigerant circuit (20) is equal to or higher than a predetermined value and the suction in the compressor (30). When the low-pressure refrigerant pressure on the side continues to be in the refrigerant state equal to or lower than the predetermined value, the open correction unit (85) corrects the control opening of the valve control means (82) to the open side. On the other hand, when the expansion valve (36) is slightly open, the refrigerant circuit (2
When the state of the refrigerant in which the suction superheat of the refrigerant in the compressor (30) in 0) continues to be equal to or less than a predetermined value, the closing correction unit (86) corrects the control opening of the valve control means (82) to the closing side.

In the fourth invention, the open correction unit (8
5) corrects the control opening to the open side, the forced opening means (8
4) has priority over the control of the valve control means (82), and the expansion valve (36)
To a predetermined opening and exit the abnormal area.

[0020]

Therefore, according to the present invention, since the control opening is corrected so as to become the actual actual opening of the expansion valve (36), variations in the opening of the expansion valve (36) are caused. It is possible to perform control in consideration. As a result, expansion valve (36)
The control reliability of can be improved.

In particular, when the expansion valve (36) is controlled in the vicinity of the strongest opening, the opening (30) becomes large even though the opening (30) is controlled, and the compressor (30) gets wet. It is possible to reliably prevent driving. On the contrary, it is possible to surely prevent the control from being damaged even if the opening is made small even though the opening is controlled to be large in the control.

Further, since it is not necessary to select the expansion valve (36), it is possible to prevent an increase in the number of manufacturing steps and prevent a decrease in yield, so that an increase in price can be suppressed.

Further, according to the fourth aspect of the invention, since the forced opening means (84) is provided, it is possible to quickly get out of the abnormal state when the actual opening is smaller than the control opening. As a result, it is possible to quickly shift to normal operation.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, the air conditioner (10) of the present embodiment applies the refrigeration system of the present invention and is configured to switch between cooling operation and heating operation.

The air conditioner (10) includes a refrigerant circuit (20) and a controller (80). The refrigerant circuit (20)
Is the outdoor circuit (21), indoor circuit (22), liquid side connecting pipe (2
3) and a gas side connecting pipe (24). The outdoor circuit (21) is provided in the outdoor unit (11), and the outdoor unit (11) is provided with an outdoor fan (12). On the other hand, the indoor circuit (22) is provided in the indoor unit (13),
An indoor fan (14) is provided in the indoor unit (13).

The outdoor circuit (21) includes a compressor (30), a four-way switching valve (33), an outdoor heat exchanger (34) and a receiver (35).
And an electric motor-driven expansion valve (36) which is an expansion valve, and a bridge circuit (40), a supercooling circuit (50), a liquid side closing valve (25) and a gas side closing valve (26). .
Further, a gas communication pipe (61) and a pressure equalizing pipe (63) are connected to the outdoor circuit (21).

The discharge port (32) of the compressor (30) is
It is connected to the first port of the four-way switching valve (33), and the second port of the four-way switching valve (33) is connected to one end of the outdoor heat exchanger (34). The other end of the outdoor heat exchanger (34) is connected to the bridge circuit (40). Further, the bridge circuit (40) is connected to the receiver (35), the electric motor-driven expansion valve (36), and the liquid side closing valve (25). The suction port (31) of the compressor (30) has a four-way switching valve (3
Connected to the 3rd port of 3), the above-mentioned four-way switching valve (33)
Is connected to the gas side shutoff valve (26).

The bridge circuit (40) includes a first conduit (4
1), second pipeline (42), third pipeline (43) and fourth pipeline (4
4) is connected in a bridge shape. The first to
The check valves (CV-1,
CV-2, CV-3, CV-4) are provided. The outlet end of the first pipeline (41) is connected to the outlet end of the second pipeline (42), and the inlet end of the second pipeline (42) is located at the outlet end of the third pipeline (43). Connected, and the inlet end of the third conduit (43) is connected to the fourth conduit (4
It is connected to the inlet end of 4) and the outlet end of the fourth pipeline (44) is connected to the inlet end of the first pipeline (41).

The other end of the outdoor heat exchanger (34) is connected to the inlet end of the first conduit (41) and the outlet end of the fourth conduit (44) of the bridge circuit (40). The bridge circuit (4
0) and the outlet end of the first pipeline (41) and the second pipeline (4)
The outlet end of 2) is connected to the upper end of the receiver (35). The lower end of the receiver (35) has an electric expansion valve (36).
Is connected to the inlet end of the third pipeline (43) and the inlet end of the fourth pipeline (44) of the bridge circuit (40). The inlet end of the second conduit (42) and the outlet end of the third conduit (43) of the bridge circuit (40) are connected to the liquid side closing valve (25).

An indoor heat exchanger (37) is provided in the indoor circuit (22). One end of the indoor circuit (22) is
It is connected to the liquid side closing valve (25) through the liquid side communication pipe (23). The other end of the indoor circuit (22) is connected to the gas side communication pipe (24).
It is connected to the gas side closing valve (26) via.

One end of the supercooling circuit (50) is connected between the lower end of the receiver (35) and the electric expansion valve (36), and the other end is connected to the suction port (31) of the compressor (30). Has been done. The supercooling circuit (50) includes a first electromagnetic valve (51) and a temperature automatic expansion valve (52) in this order from one end to the other end.
And a subcooling heat exchanger (54). The subcooling heat exchanger (54) is configured to exchange heat between the refrigerant flowing from the receiver (35) toward the electric expansion valve (36) and the refrigerant flowing through the subcooling circuit (50). The temperature sensing cylinder (53) of the temperature automatic expansion valve (52) is a supercooling circuit (50).
Is attached to the downstream portion of the subcooling heat exchanger (54).

One end of the gas communication pipe (61) is connected to the upper end of the receiver (35), and the other end is the electric expansion valve (36).
And bridge circuit (40). A second solenoid valve (62) is provided in the middle of the gas communication pipe (61).

One end of the pressure equalizing pipe (63) is connected between the second electromagnetic valve (62) and the receiver (35) in the gas communication pipe (61), and the other end is connected to the compressor in the outdoor circuit (21). It is connected between the discharge port (32) of (30) and the four-way switching valve (33). The pressure equalizing check valve (5
3) is provided.

The compressor (30) is a hermetically sealed high-pressure dome scroll compressor. The compressor (30)
The refrigerant sucked from the suction port (31) is directly introduced into the compression mechanism, and the compressed refrigerant is once discharged into the housing and then discharged from the discharge port (32).

Electric power is supplied to the electric motor of the compressor (30) through an inverter (not shown). When the output frequency of this inverter is changed, the compressor capacity changes. That is, the compressor (30) has a variable capacity.

The outdoor heat exchanger (34) is a cross-fin type fin-and-tube heat exchanger. The outdoor heat exchanger (34) is composed of two parts connected in series with each other. Outdoor air is supplied to the outdoor heat exchanger (34) by the outdoor fan (12).

The indoor heat exchanger (37) is composed of a cross-fin type fin-and-tube heat exchanger. Indoor air is supplied to the indoor heat exchanger (37) by an indoor fan (14).

The four-way switching valve (33) has a state in which the first port and the second port communicate with each other and the third port and the fourth port communicate with each other (state shown by a solid line in FIG. 1), The state is switched to a state in which the first port and the fourth port communicate with each other and the second port and the third port communicate with each other (a state indicated by a broken line in FIG. 1). By the switching operation of this four-way switching valve (33),
The circulation direction of the refrigerant in the refrigerant circuit (20) is reversed.

The air conditioner (10) is provided with a pressure sensor and a temperature sensor. The detection values of these sensors are input to the controller (80) and used for operation control of the air conditioner (10).

Specifically, the pipe connected to the suction port (31) of the compressor (30) has a low pressure detecting means for detecting the low pressure refrigerant pressure on the suction side of the compressor (30). A sensor (71) and a suction pipe temperature sensor (77) for detecting the suction refrigerant temperature of the compressor (30) are provided. The pipe connected to the discharge port (32) of the compressor (30) is provided with a discharge pipe temperature sensor (74) for detecting the discharge refrigerant temperature of the compressor (30).

The outdoor unit (11) is provided with an outdoor air temperature sensor (72) for detecting the temperature of outdoor air.
The outdoor heat exchanger (34) is provided with an outdoor heat exchanger temperature sensor (73) for detecting the temperature of the heat transfer tube.

The indoor unit (13) includes an indoor heat exchanger (3
An inside air temperature sensor (75) is provided to detect the temperature of the indoor air sent to (7). Indoor heat exchanger (3
The indoor heat exchanger temperature sensor (76) for detecting the heat transfer tube temperature is provided in 7).

The controller (80) controls the capacity of the compressor (30) by changing the output frequency of the inverter, while the superheat detection means (81), the valve control means (82) and the correction means (83). And a forced opening means (84).

The superheat degree detecting means (81) detects the low pressure equivalent saturation temperature based on the low pressure refrigerant pressure detected by the low pressure sensor (71) and the compressor (30) detected by the suction pipe temperature sensor (77). The suction superheat degree of the refrigerant of the compressor (30) is derived based on the suction refrigerant temperature.

The valve control means (82) controls the opening degree of the electric expansion valve (36) so that the intake superheat degree derived by the superheat detection means (81) becomes a predetermined value, for example, 5 ° C. There is.

The correction means (83) is a valve control means (82).
Is controlling the electric expansion valve (36) to a small opening degree near the minimum opening degree, the control opening degree of the valve control means (82) is changed to the electric expansion valve (36) based on the refrigerant state at the time of the control. ) The control opening of the valve control means (82) is corrected so as to shift to the actual opening. For example, the correction means (83) includes an open correction unit (8
5) and a closing correction unit (86).

The open correction section (85) includes an electric expansion valve (36).
When the opening degree is small, if the suction superheat degree derived by the superheat detection means (81) is equal to or higher than a predetermined value and the low pressure refrigerant pressure detected by the low pressure sensor (71) is equal to or lower than the predetermined value,
It is configured to correct the control opening of the valve control means (82) to the open side. Specifically, the suction superheat is higher than 5 ° C (SH> 5 ° C) and the low-pressure refrigerant pressure is lower than 3 Pa (Pe
When the state of <3 Pa) continues for 2 minutes, the open correction unit (85)
Increase the control opening by one pulse. The control opening is, for example, 0 when the electric expansion valve (36) is completely closed.
The pulse is set as a pulse, and the fully open state is set as 480 pulses.

The closing correction section (86) includes an electric expansion valve (36).
When the refrigerant state in which the intake superheat degree is equal to or less than the predetermined value continues at a small opening degree, the control opening degree of the valve control means (82) is corrected to the closing side. Specifically, inhalation superheat is 2 ℃
When the state of less than (SH <2 ° C.) continues for 2 minutes, the closing correction unit (86) reduces the control opening by one pulse.

The forced opening means (84) is provided with an opening correction section (8
5) corrects the control opening to the open side, valve control means (8
The electric expansion valve (36) is configured to be once opened to a predetermined opening in priority to the control of 2). Specifically, the forced opening means (84) once widens the electric expansion valve (36) by 20 pulses. After that, the process returns to the opening control of the valve control means (82).

<Operation> Next, the operation of the air conditioner (10) described above will be described. The air conditioner (10) switches between cooling operation by cooling operation and heating operation by heat pump operation.

-Cooling operation-During the cooling operation, the four-way switching valve (33) is switched to the state shown by the solid line in FIG. 1, the electric expansion valve (36) is adjusted to a predetermined opening, and the first solenoid valve ( 51) is opened and the second solenoid valve (62) is closed.

The refrigerant discharged from the compressor (30) passes through the four-way switching valve (33) and is condensed in the outdoor heat exchanger (34).
The condensed high-pressure liquid refrigerant flows through the first pipe line (41) and the receiver (35) of the bridge circuit (40), a part of the high-pressure liquid refrigerant flows into the supercooling circuit (50), and the rest is the supercooling heat. Exchanger (5
Inflow into 4).

The refrigerant in the subcooling circuit (50) is decompressed by the temperature automatic expansion valve (52) and flows into the subcooling heat exchanger (54). In the supercooling heat exchanger (54), the low pressure refrigerant from the automatic temperature expansion valve (52) is evaporated and the high pressure liquid refrigerant is cooled. This low-pressure refrigerant flows through the subcooling circuit (50) and returns to the compressor (30), while the high-pressure liquid refrigerant is fed by the electric expansion valve (36).
Then, the pressure is reduced. This depressurized low-pressure refrigerant is used for the third conduit (43) of the bridge circuit (40) and the liquid side communication pipe (23).
Through to the indoor heat exchanger (37).

The low-pressure refrigerant is evaporated in the indoor heat exchanger (37) to cool the indoor air, and low-temperature conditioned air is supplied into the room for cooling. The refrigerant evaporated in the indoor heat exchanger (37) is connected to the gas side communication pipe (24) and the four-way switching valve (33).
Flow back to the compressor (30). As described above, the cooling medium is circulated to perform the cooling operation.

-Heating operation-During heating operation, the four-way switching valve (33) is switched to the state shown by the broken line in FIG. 1, the electric expansion valve (36) is adjusted to a predetermined opening, and the first solenoid valve ( 51) and second solenoid valve (6
2) is closed.

The refrigerant discharged from the compressor (30) is
It is sent from the four-way switching valve (33) to the indoor heat exchanger (37) through the gas side communication pipe (24). In the indoor heat exchanger (37),
The refrigerant is condensed to heat the indoor air, and warm conditioned air is supplied to the room and used for heating.

The refrigerant condensed in the indoor heat exchanger (37) is supplied to the liquid side communication pipe (23) and the second pipe line (42) of the bridge circuit (40).
And the receiver (35), and after being decompressed by the electric expansion valve (36), they flow through the fourth pipe line (44) of the bridge circuit (40) to the outdoor heat exchanger (34) to be evaporated. The evaporated refrigerant flows through the four-way switching valve (33) and returns to the compressor (30).
As described above, the refrigerant circulates to perform the heat pump operation.

-Control operation of the electric expansion valve (36) -During the above-described cooling operation and heating operation, the valve control means (82) determines that the intake superheat degree derived by the superheat detection means (81) is a predetermined value, For example, the electric expansion valve (3
The opening of 6) is controlled.

When the valve control means (82) controls the electric expansion valve (36) to a small opening degree near the minimum opening degree, the correction means (83) causes the valve control means based on the refrigerant state. Correct the control opening of (82). For example, the control opening is set to 0 pulse when the electric expansion valve (36) is completely closed, 480 pulses when it is fully opened, and 32 pulses is set to the minimum opening.

The valve control means (82) is an electric expansion valve (36).
Is controlled near 32 pulses, the intake superheat is 5
Greater than ℃ (SH> 5 ℃) and low pressure refrigerant pressure is 3Pa
When the state of less than (Pe <3Pa) continues for 2 minutes, the open correction unit (85) increases the control opening by one pulse.

That is, the opening degree of the electric expansion valve (36) is
There are variations within the range of the characteristic lines B and C in FIG. Therefore, for example, as shown in FIG. 3, it is assumed that the electric expansion valve (36) is currently controlled with the characteristic line A as the control opening. In the state where the electric expansion valve (36) is controlled to the opening of point a of the characteristic line A, the intake superheat degree is larger than 5 ° C (SH
> 5 ° C) and low pressure refrigerant pressure is less than 3Pa (Pe <3Pa)
If the state of is continued for 2 minutes, the electric expansion valve (36) is actually opened with a small opening and the refrigerant is flowing with the control, but the electric expansion valve (36) is actually opened with a smaller opening. The refrigerant is almost not flowing. In this case, the opening correction unit (85) increases the control opening by one pulse so that the control opening moves to point b.

After that, when the opening correction section (85) of the correction means (83) corrects the control opening to the open side, the forced opening means (84) has priority over the control of the valve control means (82). The electric expansion valve (36) is once opened to a predetermined opening, for example, the electric expansion valve (36) is once opened by 20 pulses, and the current abnormal region is quickly exited. After that, the process returns to the opening control of the valve control means (82). By repeating this operation, for example, the control opening is corrected so as to become the characteristic line B in FIG.

On the other hand, when the valve control means (82) controls the electric expansion valve (36) in the vicinity of 32 pulses, the state where the intake superheat degree is less than 2 ° C. (SH <2 ° C.) continues for 2 minutes. Then,
The close correction unit (86) reduces the control opening by one pulse.

That is, for example, as shown in FIG. 4, the electric expansion valve (36) is currently controlled with the characteristic line A as the control opening. When the electric expansion valve (36) is controlled to the opening at point c of the characteristic line A, the intake superheat degree is 2
When the temperature below ℃ (SH <2 ℃) continues for 2 minutes, the electric expansion valve (36) is actually closed and no refrigerant flows, but the electric expansion valve (36) is actually closed. ) Is opened with a small opening and the refrigerant is flowing. in this case,
The closing correction unit (86) reduces the control opening by one pulse so that the control opening moves to point d. After that, the process returns to the opening control of the valve control means (82). By repeating this operation, for example, the control opening is corrected so as to become the characteristic line C in FIG.

<Effects of Embodiment> As described above, according to this embodiment, the control opening is corrected to the actual opening of the electric expansion valve (36). Control can be performed in consideration of variations in the opening of the valve (36). As a result, the reliability of control of the electric expansion valve (36) can be improved.

In particular, when performing control in the vicinity of the strongest opening of the electric expansion valve (36), even though the opening is controlled to be small in control, the opening becomes large and the compressor (30) is opened. It is possible to reliably prevent wet operation. On the contrary, it is possible to surely prevent the control from being damaged even if the opening is made small even though the opening is controlled to be large in the control.

Further, since the selection of the electric expansion valve (36) is not required, the manufacturing process is not increased and the yield can be prevented from decreasing, so that the price increase can be suppressed.

Further, since the forced opening means (84) is provided, the abnormal state when the actual opening is smaller than the control opening can be quickly eliminated. As a result, it is possible to quickly shift to normal operation.

[0070]

Other Embodiments of the Invention Although the air conditioner (10) capable of cooling and heating operation has been described in the above embodiment, the present invention may be a cooling only machine or a heating only machine.

The refrigerant circuit (20) is not limited to the embodiment.

Further, the correction means (83) has the open correction portion (85) and the close correction portion (86), but in the present invention, the open correction portion is used instead of the correction means (83). (85) and the closing correction section (86) may be provided.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram of the electric expansion valve showing the relationship between the opening degree and the flow rate of the electric expansion valve according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram of the electric expansion valve when the control opening is smaller than the actual opening.

FIG. 4 is a characteristic diagram of the electric expansion valve when the control opening is larger than the actual opening.

[Explanation of symbols]

20 Refrigerant circuit 30 compressor 34 Outdoor heat exchanger 36 Electric expansion valve (expansion valve) 37 Indoor heat exchanger 81 Superheat detection means 82 valve control means 83 Correction means 84 Forced opening means 85 Open compensation section 86 Closure correction section

Claims (4)

[Claims] 1. A refrigerating apparatus having an expansion valve (36) whose opening can be adjusted and having a refrigerant circuit (20) for performing a vapor compression refrigeration cycle, wherein the control opening of the expansion valve (36) is A refrigeration system characterized in that the control opening is corrected so that the actual opening of the expansion valve (36) is reached. 2. A refrigeration system having an expansion valve (36) whose opening degree is adjustable and having a refrigerant circuit (20) for performing a vapor compression refrigeration cycle, wherein the opening degree of the expansion valve (36) is controlled. Valve control means (82)
And, when the valve control means (82) controls the expansion valve (36) to a small opening degree near the minimum opening degree, the control of the valve control means (82) based on the refrigerant state at the time of the control. A refrigeration system comprising: a correction means (83) for correcting the control opening degree of the valve control means (82) so that the opening degree shifts to the actual actual opening degree of the expansion valve (36). . 3. A refrigeration system having an expansion valve (36) whose opening degree is adjustable and having a refrigerant circuit (20) for performing a vapor compression refrigeration cycle, wherein the opening degree of the expansion valve (36) is controlled. Valve control means (82)
When the valve control means (82) controls the expansion valve (36) to a small opening degree near the minimum opening degree, the suction superheat degree of the refrigerant of the compressor (30) in the refrigerant circuit (20) is increased. When the low-pressure refrigerant pressure on the suction side of the compressor (30) is equal to or higher than a predetermined value and the refrigerant state continues to be equal to or lower than the predetermined value, an open correction unit (85) that corrects the control opening of the valve control means (82) to the open side. When the valve control means (82) controls the expansion valve (36) to a small opening degree near the minimum opening degree, the suction superheat degree of the refrigerant of the compressor (30) in the refrigerant circuit (20) is increased. A refrigeration apparatus comprising: a closing correction unit (86) that corrects the control opening of the valve control means (82) to the closing side when the refrigerant state below a predetermined value continues. 4. The opening correction section (85) according to claim 3, wherein the control opening is corrected to the opening side,
A refrigeration system comprising a forced opening means (84) for temporarily opening the expansion valve (36) to a predetermined opening degree, prior to the control of the valve control means (82).