JPH0810087B2 - Air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating cycle and a control device for an air conditioner, and in particular to expanding the operating range of an air conditioner using a compressor whose compression capacity can be adjusted. It is about.

[Conventional technology]

A conventional device of this type is shown in FIG.
In the figure, (1) is a compressor, (2) is an oil separator,
(3) is a four-way valve, (4) is an outdoor heat exchanger, (5) is a decompression device, (6) is an indoor heat exchanger, (7) is an accumulator, (11) is a flow rate control device (8) (hereinafter Called a capillary tube)
From the bottom of the oil separator (2) through the compressor (1)
The first bypass passage connected to the suction pipe of (2) is connected to the second bypass pipe (12) connected to the inflow pipe of the accumulator (7) from the bottom of the oil separator (2) through the solenoid valve A (9). It is a bypass road. In the figure, the solid arrows indicate the refrigerant flow direction during the cooling operation, and the broken arrows indicate the refrigerant flow direction during the heating operation.

Next, the operation during the cooling operation will be described. The compressor (1) compresses the gas refrigerant, and the discharged high-temperature and high-pressure gas refrigerant and refrigerating machine oil flow into the oil separator (2) to separate refrigerating machine oil, and the high-temperature and high-pressure gas refrigerant is a four-way valve ( While flowing into the outdoor heat exchanger (4) via 3) and radiating heat to the outdoor air, the refrigerant condenses into a high-pressure liquid refrigerant and is decompressed by the decompression device (5) to form a low-pressure gas-liquid mixed refrigerant. And is supplied to the indoor heat exchanger (6). In the indoor heat exchanger (6),
While collecting heat from the room air to cool it, the refrigerant evaporates into a low-pressure gas refrigerant and flows into the accumulator (7) through the four-way valve. In the accumulator (7), the liquid refrigerant and the gas refrigerant that have not completely evaporated in the indoor heat exchanger (6) are separated and sucked into the compressor (1). Next, the operation during the heating operation will be described. The high-temperature and high-pressure gas refrigerant that has been compressed by the compressor (1) and discharged is passed through the oil separator (2) and the four-way valve (3) to the indoor heat exchanger (6).
And is radiated to indoor air to heat the refrigerant, the refrigerant condenses into high-pressure liquid refrigerant. This liquid refrigerant is decompressed by the decompression device (5) to become a low-pressure gas-liquid mixed refrigerant, which is supplied to the outdoor heat exchanger (4), takes heat from the outdoor air, becomes a low-pressure gas refrigerant, and becomes a four-way valve (3). ) And the accumulator (7) to the compressor (1).

Further, the refrigerating machine oil separated by the oil separator (2) is constantly returned to the suction pipe of the compressor (1) through the capillary tube (8), so that an appropriate amount of oil in the compressor (1) is secured. Further, the solenoid valve A (9) provided in the second bypass passage (12) is opened to suppress the pressure rise when there is a rise in the high pressure due to the change in the indoor / outdoor air temperature. In addition, the operation of the compressor (1) can be continued.Furthermore, when the compressor (1) is started or during heating operation, it is switched to a cooling cycle to melt the frost adhering to the outdoor heat exchanger (4). During the defrost operation, a large amount of refrigerating machine oil flows out from the compressor (1), so that the electromagnetic valve A (9) is opened to quickly collect the refrigerating machine oil in the accumulator (7).

[Problems to be Solved by the Invention]

As described above, in the conventional air conditioner, since the second bypass passage (12) is connected to the inflow pipe of the accumulator (7) from the bottom of the oil separator (2), the high pressure increases as the pressure increases. When the solenoid valve A (9) is opened, the refrigerating machine oil separated by the oil separator (2) flows into the accumulator (7), so that it is diluted with the excess refrigerant liquid in the accumulator (7), resulting in In addition, there is a problem that the oil return to the compressor (1) is delayed.

In the case of a multi-chamber air conditioner in which the compressor (1) used in the air conditioner is of a variable capacity type and the indoor heat exchanger (6) is plural, the opening / closing control of the solenoid valve A (9) is performed. It is highly necessary to continue the operation of the compressor (1) due to the above, and as the capacity control range is expanded, the number of times the electromagnetic valve A (9) is opened and closed increases, and there is a problem that reliability decreases.

The present invention has been made to solve such a problem, and an air conditioner which has a high reliability and a wide capacity control range while ensuring a sufficient oil return amount even when the pressure is increased or the capacity is decreased. The purpose is to get.

[Means for solving the problem]

An air conditioner according to the present invention includes a compressor, an oil separator,
In a refrigerant circuit in which a four-way valve, an outdoor heat exchanger, a pressure reducing device, an indoor heat exchanger, and an accumulator are connected by piping, the first part connected from the bottom of the oil separator to the suction pipe of the compressor via a flow rate adjusting device. A bypass line and a second bypass line connected from the bottom of the oil separator to the inflow pipe of the accumulator via a solenoid valve, and a outflow pipe of the oil separator to the inflow pipe of the accumulator via a solenoid valve. The third bypass passage and the pressure detecting means for detecting the high pressure side pressure of the refrigerant circuit during the heating operation and the low pressure side pressure during the cooling operation, and the operation control means and the compressor for controlling the operating capacity of the compressor. When it is necessary to continue the operation after the operating capacity of 1 is minimized, the solenoid valve provided in the third bypass passage is opened first, and then the solenoid valve provided in the second bypass passage is opened. Open the circuit It is provided with a electromagnetic valve control means. Further, the solenoid valve control means controls the opening and closing of the solenoid valve provided in the second bypass passage for a predetermined time after the compressor is started. Further, based on the temperature detection signal from the discharge temperature detection means, the solenoid valve control means controls opening / closing of the solenoid valves provided in the second and third bypass passages when the discharge gas temperature becomes equal to or higher than a predetermined temperature.

[Work]

In this invention, after the compressor operating capacity is minimized,
When the operation of the compressor is continued, the solenoid valve provided in the third bypass path is opened, so that the refrigerating machine oil separated by the oil separator does not flow into the accumulator and is supplied to the compressor. Sufficient oil return can be secured. Furthermore, when it is necessary to continue the operation of the compressor after the solenoid valve of the third bypass passage is opened, the solenoid valve provided in the second bypass passage can be opened to continue the operation. The range can be widened.

〔Example〕

FIG. 1 is an overall configuration diagram of an air conditioner according to one embodiment of the present invention. In the figure, (1) to (9) and (11) and (12) are the same as those of the conventional air conditioner shown in FIG. 4, and (13) is an oil separator (12) and a four-way valve ( 3)
The third bypass passage connected to the inflow pipe of the accumulator (7) through the solenoid valve B (10) from the middle of the pipe connecting the, and (14) is the four-way valve (3) and the indoor heat exchanger (6). Pressure detecting means for detecting the pressure of the refrigerant gas provided in the connection pipe, (15) discharge temperature detecting means for detecting the temperature of the refrigerant gas provided in the discharge pipe of the compressor (1), and (16) the above Operating capacity control means for controlling the operating capacity of the compressor (1) based on the pressure detected by the pressure detecting means (14), (17)
Is a solenoid valve control means for controlling the opening and closing of the solenoid valves A (9) and B (10) provided in the second and third bypass passages (12) and (13), and is the compressor (1). It also has the function of measuring the time from the start of. The solid arrows in the figure indicate the refrigerant flow directions during the cooling operation and the defrost operation, and the broken arrows indicate the refrigerant flow directions during the heating operation. The compressor (1) has a variable compression capacity by changing the operating frequency by an inverter (not shown).

The operation on the refrigerant side during the cooling operation and the heating operation is exactly the same as that of the conventional air conditioner shown in FIG. 4, and therefore its explanation is omitted, and the operation capacity control of the compressor (1) and the solenoid valve A are omitted.
The operation of B (9) and (10) will be described.

FIG. 2 is a flowchart showing the control states of the operating capacity control means (16) and the solenoid valve control means (17) during heating operation. When the heating operation is started in step (21), it is determined in step (22) whether the pressure P _c detected by the pressure detection means (14) is within a certain range with respect to the target pressure P ₀ , and the stable range is determined. If so, the operating frequency of the compressor (1) is maintained. If the detected pressure P _c is higher than the stable pressure upper limit (P ₀ +1) in step (22), step (23)
Then, it is determined whether the current operating frequency of the compressor (1) is the minimum, and if it is not the minimum frequency, the process proceeds to step (32) to reduce the frequency. If the frequency is the minimum value in step (23), the process proceeds to step (24), and the detected pressure P _c is the solenoid valve B (10) provided in the third bypass passage (13). It is judged whether the control pressure is higher than the control pressure P _{1 of the} above, and if it is lower than steps (26), (2
7), the solenoid valve B (10) maintains the closed state, and the process proceeds to step (28). In step (28), it is determined whether the detected pressure P _c is higher than the control pressure P _{2 of} the solenoid valve A (9) provided in the second bypass passage (12). Since the relationship between the control pressure set values P ₁ and P ₂ is (P ₁ <P ₂ ), the process proceeds from step (28) to steps (30) and (31). When the detected pressure P _c is higher than the control pressure P ₁ in step (24), the process proceeds to step (25) to open the solenoid valve B (10),
After the solenoid valve B (10) is opened, it is judged in step (26) whether or not the detected pressure P _c is reduced. If it is reduced, the solenoid valve B (10) is closed in step (27). If it is not decreased, the process proceeds to step (28) to determine whether the detected pressure P _c is higher than the control output P ₂ , and if it is higher, the electromagnetic valve A (9) is determined in step (29). , And proceed to step (30).

When the detected pressure P _c is lower than the stable pressure lower limit (P ₀ -1) in step (22), the process proceeds to step (33) to turn on the solenoid valve A (9) and the solenoid valve B (10). After closing the circuit, the process proceeds to step (34) to determine whether the operating frequency of the compressor (1) is the maximum frequency. If it is not the maximum frequency, the process proceeds to step (35) to increase the operating frequency. Have control. During the cooling operation, the pressure detection means (14)
The detected pressure P _c becomes a low pressure, and the operating frequency is controlled by the operating capacity control means (16) so that the low pressure becomes constant, and when the operating frequency becomes the minimum, the detected pressure P _c further decreases. If so, the solenoid valve B (10) and the solenoid valve A (9) are controlled to open.

Next, the control state of the solenoid valve control means (17) by the discharge temperature detection means (15) will be described with reference to FIG. In the figure, T _c is the temperature detected by the discharge temperature detecting means (15), T ₁ and T ₂ are the control temperatures of the solenoid valve B (10) and solenoid valve A (9), and (T ₂ > T ₁ ). Is set. In step (40), it is determined whether the detected temperature T _c is higher than the control temperature T ₁ , and if it is lower, steps (42), (43), (44),
Go to (46) and (47), solenoid valve B (10) and solenoid valve A.
(9) maintains the closed state. When the detected temperature T _c is higher than the control temperature T _{1 in} step (40), the process proceeds to step (41), the solenoid valve B (10) is opened, the high pressure is reduced, and the rise of the discharge temperature is controlled. . Further, when the detected temperature T _c is high, the process proceeds to steps (42) and (44), and the solenoid valve A
It is determined whether the temperature is higher than the control temperature T _{2 in} (9), and if it is higher, the process proceeds to step (45) to open the electromagnetic valve A (9) to suppress the rise in the discharge temperature. Due to the opening operation of the solenoid valve A (9) and the solenoid valve B (10), the discharge temperature decreases and the detection temperature T _c decreases, and the control temperature (T ₁ -10) or (T ₂ -1
If it is lower than 0), step (42) or (4
Proceeding to 6), the solenoid valve A (9) and the solenoid valve B (10) are controlled to be closed.

Further, when the solenoid valve A (9) is opened for a predetermined time after the compressor (1) is started, a large amount of refrigerating machine oil due to the forming associated with the start of the compressor (1) generates an oil separator (2). ) Even if it flows into the accumulator (7)
The oil can be returned to the compressor (1) via the.

〔The invention's effect〕

Since the present invention is configured as described above,
The following effects are achieved. When it is necessary to continue operation when the compressor operating capacity becomes the minimum, the solenoid valve provided in the third bypass passage is opened first, so the refrigeration oil separated by the oil separator is stored in the accumulator. The compressor can continue to operate in good condition without any inflow and without delaying the return of oil to the compressor. In addition, when it is necessary to continue operation even when the solenoid valve is closed in the third bypass passage, the solenoid valve provided in the second bypass passage is opened, so that the operating range of the air conditioner can be expanded. Is possible.

Further, when the solenoid valve provided in the second bypass passage is opened at the time of starting the compressor, it is possible to efficiently recover the outflow of refrigerating machine oil due to the forming inside the compressor that occurs at the time of starting the compression. The reliability of the machine can be improved. Further, the discharge gas temperature of the compressor is detected, and when the discharge gas temperature rises, the solenoid valve provided in the third bypass path or the second bypass path is opened regardless of the compressor operating capacity. In this case, the discharge pressure can be lowered, the discharge gas temperature can be suppressed as a result, the reliability of the compressor can be improved, and the operating range of the air conditioner can be expanded. You can

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an air conditioner showing an embodiment of the present invention, FIG. 2 is a flowchart for heating and heating by the operating capacity control means of the compressor, and FIG. 3 is similarly discharge temperature detection means. FIG. 4 is a flowchart of the electromagnetic valve control means according to FIG. 4, and FIG. 4 is an overall configuration diagram of a conventional air conditioner. In the figure, (1) is a compressor, (2) is an oil separator, (3) is a four-way valve, (4) is an outdoor heat exchanger, (5) is a decompression device,
(6) is an indoor heat exchanger, (7) is an accumulator,
(8) is a flow rate control device, (9) and (10) are solenoid valves,
(11) is the first bypass path, (12) is the second bypass path, (13) is the third bypass path, (14) is pressure detection means, (15) is discharge temperature detection means, (16) Is an operating capacity control means, and (17) is a solenoid valve control means. In the drawings, the same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Setsu Nakamura 6-5-66 Tehira, Wakayama, Wakayama Sanryo Electric Co., Ltd. Wakayama Works (56) Reference JP 63-163749 (JP, A) JP 62-147265 (JP, A) Actual development 59-145673 (JP, U)

Claims (3)

[Claims] 1. A compressor having an adjustable compression capacity, an oil separator, a four-way valve, an outdoor heat exchanger, a pressure reducing device, a refrigerant circuit to which an indoor heat exchanger and an accumulator are connected by pipe, and a flow rate from the bottom of the oil separator. A first bypass passage connected to the suction pipe of the compressor via the adjusting device, a second bypass connected to the inflow pipe of the accumulator or the accumulator from the bottom of the oil separator via a solenoid valve. Passage, the top of the oil separator, or the third bypass passage connected to the inflow pipe of the accumulator or the accumulator via the solenoid valve from the middle of the pipe connecting the oil separator and the four-way valve, heating operation At the time of detecting the high pressure side pressure of the refrigerant circuit, during cooling operation pressure detection means for detecting the low pressure side pressure, operating capacity control means for controlling the operating capacity of the compressor, and The rolling capacity control means to open the solenoid valve provided in the third bypass passage when it is necessary to continue the operation after the operating capacity of the compressor is minimized,
An air conditioner characterized by comprising electromagnetic valve control means for opening an electromagnetic valve provided in the second bypass passage when it is necessary to continue the operation. 2. The air conditioner according to claim 1, wherein the solenoid valve control means opens the solenoid valve provided in the second bypass passage for a predetermined time after the compressor is started. 3. A discharge temperature detecting means for detecting the discharge gas temperature of the compressor is provided, and when the discharge gas temperature is equal to or higher than a predetermined temperature, a solenoid valve control means is provided on the basis of a temperature detection signal from the discharge temperature detecting means. The air conditioner according to claim 1 or 2, wherein the solenoid valves provided in the second and third bypass passages are controlled to be opened and closed.