JPH0320571A - Air conditioner - Google Patents

Abstract

PURPOSE:To enlarge the operational range of an air conditioner by a method wherein, when the pressure condition exceeds the allowable operational range of the compressor, a solenoid valve provided in a third bypass is first opened and next a solenoid valve provided in a second bypass is opened. CONSTITUTION:When the pressure condition has exceeded the allowable operational range of a compressor 1 subsequently to a decline of the operational capacity of the compressor to the minimum, a solenoid valve 10 provided in a third bypass 13 is opened so that the refrigeration oil separated by an oil separator 2 does not flow into an accumulator 7 and hence adequate return of oil to the compressor can be ensured. When the pressure condition has exceeded the allowable operational range of the compressor subsequently to the opening of the solenoid valve of the third bypass, a solenoid valve 9 provided in a second bypass 12 is opened so that the operation of the compressor can be continued and thus the operational capacity range of the air conditioner can be enlarged.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention relates to a refrigeration cycle and a control device for an air conditioner, and in particular, to a control device for controlling the operating range of an air conditioner using a compressor capable of compressing a capacity of Mll. It's about expansion.

[Conventional technology]

As a conventional device of this type, there is one shown in FIG.

In the figure, (1) is a compressor, (2) is an oil separator, and (3) is a compressor.
) is a four-way valve, (4) is an outdoor heat exchanger, (5) is a pressure reducing device, (6) is an indoor heat exchanger, (7) is an accumulator, (
11) is a first bypass passage connected to the bottom of the oil separator and the suction pipe of the compressor (1) via a flow rate regulator (8) (hereinafter referred to as a capillary tube); (12) is a solenoid valve; This is a second bivanu passage connected from the bottom of the oil separator (2) to the inflow pipe of the accumulator (7) via A (9). In the figure, solid arrows indicate the direction of refrigerant flow during cooling operation, and dashed arrows indicate the direction of refrigerant flow during heating operation.

Next, the operation during cooling operation will be explained. Compressor (1
), the discharged high-temperature, high-pressure gas refrigerant and refrigerating machine oil flow into an oil separator (2) where the refrigerating machine oil is separated, and the high-temperature, high-pressure gas refrigerant is passed through a four-way valve (3). flows into the outdoor heat exchanger (4) and radiates heat to the outdoor air,
A pressure reducing device (5) that compresses the refrigerant Ia and becomes a high-pressure liquid refrigerant.
The refrigerant is depressurized at , becomes a low-pressure gas-liquid mixed refrigerant, and is supplied to the indoor heat exchanger (6). The indoor heat exchanger (6) extracts heat from the indoor air for cooling, while the refrigerant evaporates to become a low-pressure gas refrigerant, which flows into the accumulator (7) via the four-way valve. In the accumulator (7), the indoor heat exchanger (
The liquid refrigerant and gas refrigerant that were not completely evaporated in step 6) are separated and sucked into the compressor (1).

Next, the operation during heating operation will be explained. Compressor (1
), the discharged high-temperature, high-pressure gas refrigerant is supplied to the indoor heat exchanger (6) via the oil separator (2) and the four-way valve (3), where it radiates heat to the indoor air. While heating the room, the refrigerant condenses into a high-pressure liquid refrigerant. This liquid refrigerant is depressurized by the pressure reducing device (5), becomes a low-pressure gas-liquid mixed refrigerant, and is supplied to the outdoor heat exchanger (4), where it extracts heat from the outdoor air and becomes a low-pressure gas refrigerant. 3) is sucked into the compressor (1) via the cylinder and accumulator (7).

In addition, the refrigeration oil separated in the oil separator (2) is transferred to the capillary tube (
The oil is constantly returned to the suction pipe of the compressor (1) through the compressor (1) to ensure an appropriate amount of oil in the compressor (1). In addition, the solenoid valve A (9) provided in the second bypass path (12) opens when there is a rise in high pressure due to a change in indoor or outdoor air temperature, thereby suppressing the pressure rise. , which allows the compressor (1) to continue operating. Furthermore, the compression s(1)
When the compressor (1) starts up, or when switching to the cooling cycle during heating operation to melt frost on the outdoor heat exchanger (4), a large amount of refrigerating machine oil flows out from the compressor (1), so the solenoid valve 1 A(9} is opened and the accumulator V oneta(
7) is controlled to recover refrigerating machine oil.

[Problems to be Solved by the Invention] As described above, in the conventional air conditioner, the second bypass path (12) is connected to the inflow pipe of the accumulator (7) from the bottom of the oil separator (2). Therefore, when the solenoid valve A (9) opens due to an increase in high pressure, the refrigerating machine oil separated by the oil divider (2) flows into the accumulator (7), so that the inside of the accumulator (7) is There is a problem in that the oil is diluted with surplus refrigerant liquid, resulting in a delay in oil return to the compressor (1).

In addition, the compressor (1) used in the air conditioner is of variable capacity type, allowing indoor heat exchange! In the case of a multi-chamber air conditioner with a plurality of (6), the compressor (
1) It is highly necessary to continue the operation, and the more the capacity control range is expanded, the more the solenoid valve A (9) is opened and closed, resulting in a problem of reduced reliability.

This invention was made to solve these problems, and it is an air conditioner that is highly reliable and has a wide capacity control range, as well as ensuring a sufficient amount of oil return even when high pressure increases or capacity decreases. The purpose is to take advantage of the opportunity.

[Means to solve the problem]

This invention relates to an air conditioner having a refrigerant circuit to which a compressor, an oil separator, a four-way valve, an outdoor heat exchanger, a pressure reducing device, an indoor heat exchanger, and an accumulator are connected via piping. A first bypass line is connected to the suction pipe of the compressor via a flow rate adjustment device, and a second bypass line is connected to the inlet pipe of the accumulator or the accumulator from the bottom of the oil separator via a solenoid valve. A third pipe connected to the inlet pipe of the accumulator or the accumulator via the Dtlil valve is connected to the top of the oil M vessel or the middle of the pipe connecting the oil separator and the west valve.
a bypass path for the above, a pipe temperature detection means provided in the middle of the pipe connecting the pressure reducing device and the outdoor heat exchanger, a pressure detection means for detecting high pressure during heating operation and low pressure during cooling operation; Operating capacity control means for controlling the operating capacity of the compressor based on the detected pressure detected by the pressure detecting means or the air conditioning load, and switching the four-way valve based on the detected temperature detected by the piping temperature detecting means during heating operation. a defrost control means for melting the sheath adhering to the outdoor heat exchanger; and a first control for controlling the pressure detected by the pressure detection means after the operating capacity of the compressor reaches a minimum during heating operation. When the pressure value is greater than or equal to the pressure value, the magnetic valve provided in the third bypass path is opened, and the pressure detected by the pressure detection means in the third bypass path is set to the first control pressure value. When the pressure is higher than the second control pressure value, which is higher than the second control pressure value, the solenoid valve provided in the second bypass path is opened, and during cooling operation, the pressure detected by the pressure detection means is is equal to or less than the third control pressure value, the solenoid valve provided in the third bypass path is opened, and the third control pressure value is lower than the third control pressure value.
After opening the solenoid valve of the bypass passage, if the pressure detected by the pressure detection means is equal to or lower than the fourth control pressure value, which is as low as the third control pressure value, the solenoid valve of the second bypass passage is opened. , and during defrost operation, the solenoid valve provided in the second bypass passage is opened, and when the pressure detected by the pressure detection means is equal to or lower than the fifth control pressure value, the electromagnetic valve provided in the third bypass passage is opened. The iElia valve control means is provided to open the solenoid valve.

During the defrost operation, the TLA valves provided in the second bypass path and the third bypass path are always open.

[Effect]

In this invention, when the pressure exceeds the allowable operating range of the compressor after the compressor operating capacity reaches its minimum, the solenoid valve provided in the third bypass path is opened. The refrigerating machine oil separated by the separator does not flow into the accumulator, and sufficient oil return to the compressor can be ensured. Furthermore, if the pressure exceeds the allowable operating range of the compressor after the third bypass circuit solenoid valve is opened,
By opening the solenoid valve provided in the second bypass path, the operation can be continued and the operating capacity range can be expanded. Since the solenoid valve installed in the second bypass path is opened during defrost operation, the refrigerating machine oil that flows out from the compressor during defrost operation can be quickly returned to the compressor. . Further, after opening the solenoid valve provided in the second bypass path, if the detected pressure by the pressure detection means is equal to or lower than the fifth detection pressure, the solenoid valve provided in the third bypass path is opened and compressed. Increases the refrigerant circulation amount of the machine and improves the defrost ability.

During defrost operation, the amount of refrigerant circulated during defrost can be increased and the defrost capacity can be improved by constantly opening the magnetic valves installed in the 8th Ivanu path and the 3rd bypass path. can.

〔Example〕

FIG. 1 is a diagram showing the overall structure of an air conditioner according to an embodiment of the present invention. In the figure, (1) to (9) and (1)
1) (12) is the same as the conventional air conditioner shown in Fig. 5, and (13) is an oil separator (2) and a four-way valve (3).
) is connected to the inflow pipe of the accumulator <7> via the Km valve B (10) from the middle of the pipe connecting the pipe, (14) connects the four-way valve (3> and the indoor heat exchanger (6).
) pressure detection means for detecting the pressure of the refrigerant gas provided in the connecting pipe; (15) is the temperature of the refrigerant gas provided in the middle of the pipe connecting the outdoor heat exchanger (4) and the pressure reducing device (5); The distribution IW temperature detection means (16) detects the temperature of the compressor (1) based on the pressure detected by the pressure detection means (14).
), (17) is the t magnetic valve provided in the second and third bypass paths (12) (13); q A (9) h and W magnetic valve B (10 ), and (18) is a defrost control means that controls defrost operation based on the temperature detected by the pipe temperature detection means (15) during heating operation.In addition, the dormitory line arrow in the figure indicates the air conditioner. The direction of refrigerant flow during operation and defrost operation is shown, and the broken arrow indicates the direction of refrigerant flow during heating operation. Further, the compression capacity of the compressor (1) is variable by changing the operating frequency using an inverter (not shown).

The operation of the refrigerant side during cooling operation and heating operation is exactly the same as that of the conventional air conditioner shown in Fig. 4, so the explanation will be omitted.
! Description of the operation of i-valve A/B (9) (10) 0 FIG. 2 is a flowchart showing the control state of the operating capacity control means (16) and the solenoid valve control means (17) during heating operation. When the heating operation starts at step 7'' (2l), it is checked whether the pressure P detected by the pressure detection means (l4) is within a certain range with respect to the target pressure P.
(22) is determined, and if it is within the stable range, the operating frequency of the compressor (1) is maintained. Detected pressure P in step (22). is higher than the stable pressure upper limit (P0+1), the process proceeds to step (23), where it is determined whether the current operating frequency of the compressor (1) is the minimum, and if it is not the minimum station frequency, Proceed to step (32) to decrease the frequency. Further, if the frequency is the minimum value in step (23), the process advances to step (24) and the detected pressure P is determined. It is determined whether or not is higher than the first control pressure P1, and if it is lower, the process proceeds to steps (26) and (27) [
The iia valve B (10) is closed and the step (2
Proceed to 8). In step (28), the detected pressure P. is higher than a second control pressure P2 which is higher than the first control pressure. In addition, the control pressure set value P, , P2
The relationship between p. <p2, so step (28
), proceed to Nutetsude (30) and (31). In addition, when the detected pressure P0 is higher than the first control pressure P in the step (24), the process proceeds to the step (25) and the solenoid valve B (1
0) Open the circuit and solenoid valve B (10) After opening the circuit, step (2
6) Detected pressure P. It is determined whether or not the voltage has decreased, and if it has decreased, the solenoid valve B (1
0) is closed, and if it is not decreasing, step (2
Proceeding to step 8), it is determined whether the detected pressure PC is higher than the second control output P2, and if it is higher, the solenoid valve A (9) is opened in step (29), and the process proceeds to step (30). .

Among them, the detected pressure P is detected in step (22). is lower than the stable pressure lower limit (p0-1), step (33)
Proceed to solenoid valve A (9) & solenoid valve B (10)
is closed, and the process proceeds to step (34), where it is determined whether the operating frequency of the compressor (1) is the maximum station wave number. If it is not the maximum frequency, the process proceeds to step (35), where the operating frequency is increased. It is controlled as follows.

During cooling operation, the pressure P detected by the pressure detection means (14). becomes a low pressure, and the operating frequency is controlled by the operating capacity control means (16) so that the low pressure is constant.

Specifically, the control is performed as shown in the flowchart shown in FIG. The basic operation is the same as that during the heating operation shown in FIG. 2, so detailed explanation will be omitted. During cooling operation, the low pressure P0 is changed to the frequency control pressure P in step (52).
. (The value is different from that during heating operation) It is determined whether the pressure is within a certain range or not, and if the pressure is above a certain range, the operation proceeds to steps (63), (64), and (65). Increase frequency. Detected pressure P. is below the stable range, proceed to steps (53) and (62) to reduce the operating frequency, and when the operating frequency becomes the minimum, proceed to steps (54) to (6l) to reduce the solenoid valve. Opening control of B (10) and the receptacle valve A (9) is performed. tb, whether the solenoid valve control pressure during cooling operation is set to the third control pressure P3 and the fourth control pressure υtP3 and P
4 is (P3>P4), so the compressor (
After the operating frequency of 1) becomes the minimum, the detected pressure P. When the pressure becomes lower than the third control pressure P3, the IE magnetic valve B (10) opens in step (55). 'fII
After the Fili valve B (10) is opened, if the detected pressure P0 further decreases and becomes lower than the fourth control pressure P4, the solenoid valve A (9) is opened in step (59), and then the defrost control The control state by means (18) and tm valve control means (17) will be explained based on FIG. 4. The operation mode is determined in step (40), and if heating mode is selected, the process proceeds to step (4l) to determine whether defrost operation is in progress, and if defrost operation is not in progress, proceed to step (42). . Nuteg (42) determines whether or not the defrost prohibition time 11 has elapsed, and if the defrost prohibition time tl has elapsed, step (43) is performed.
), the detected temperature T by the pipe temperature detection means (15)
0 is lower than the defrost start temperature TI,
If To has decreased to f minutes, proceed to step (44) to start defrosting, switch the four-way valve (3) to the cooling cycle side, and cool the high-temperature gas refrigerant discharged from the compressor (1). is led to the outdoor heat exchanger (4), and the outdoor heat exchanger (4)
) to melt the frost that has adhered to the surface. When defrosting operation starts, the process proceeds from step (4l) to nuteg (45) and 'fI! ．． The magnetic valve A (9) is opened so that the refrigerating machine oil discharged from the compressor (1) due to the transient liquid backflow generated during defrosting can be quickly returned. Furthermore,
Proceeding to step (46), the detected pressure P of the pressure detection means (14) is detected. (The pressure is low during defrost operation) is determined as to whether it is as low as the fifth predetermined iiPs, and Po
If the is decreasing, proceed to step (47) and
l Solenoid valve B (10) is opened to maintain the low pressure at a high level,
The refrigerant flow rate of the compressor (1) can be increased. In (49), if the detected temperature Tc becomes the defrost end temperature T2 or higher, or if the defrost forced end time check t2 has elapsed, the steg (5g) is removed.
0), end the defrost, switch the four-way valve (2) to the heating cycle side, and turn on its valves A-B (
9) Close (10), reset timer t]・t2, and open heating operation again.

Note that during defrost operation, the blower (not shown) attached to the indoor heat exchanger (6) is stopped to prevent cold air from blowing into the room, so the evaporation capacity of the refrigerant decreases, causing extreme The low pressure becomes low.

Further, the refrigerant flow rate exerted by the pressure a machine (1) depends on the low pressure, and when the low pressure becomes less than a predetermined value, the refrigerant flow rate may be extremely reduced. The decrease in the low pressure as described above is influenced by the temperature conditions of the outdoor air 9C, the heat capacity of the indoor heat exchanger (6), the heat capacity of the refrigerant piping, etc. that constitute the refrigerant circuit, and the like. Therefore, when the defrost operation is performed in a state where the low pressure is low, the refrigerant flow rate of the compressor (1) becomes small and sufficient refrigerant does not reach the outdoor heat exchanger (4).
Sufficient defrost ability may not be obtained. However, in this invention, when the low pressure is detected during the defrost operation and the low pressure has decreased, the solenoid valve B (10) provided in the third bypass path (13) is opened to reduce the low pressure. The pressure is increased to increase the refrigerant flow rate of the compressor (1). A fifth valve that controls this solenoid valve B (10)
Control pressure P. is the point where the refrigerant flow rate is extremely reduced due to a decrease in low pressure, depending on the characteristics of the pressure A machine (1),
The increase in the refrigerant flow rate due to opening of the solenoid valve B (10) and raising the low pressure is set so that the amount of bypass of the solenoid valve B (10) is also increased.

In this embodiment, the pressure detection means (
14) Depending on the O detection pressure P0, tilia valve B (1
0) is open, but if both solenoid valves A-B (9) and (10) are always open during defrost operation, fine control of the defrost performance cannot be achieved. Defrost ability can be improved.

Further, a pressure detection means (14) is provided in the pipe connecting the four-way valve (3) and the indoor heat exchanger (6), and the operating capacity control means (16), the solenoid valve control means (17) and the defrost control means (18), but the pressure detection means is 2
It is also possible to provide two units to detect the high-pressure side pressure during heating and the low-pressure side pressure during cooling. In addition, the operating capacity control means (
16) is controlled based on the pressure detected by the pressure detection means (14), but it may also be controlled based on the refrigerant temperature of the indoor heat exchanger (6) or the suction air temperature.

〔Effect of the invention〕

Since this invention is constructed as described above, it produces the effects described below. If the pressure exceeds the allowable operating pressure range of the compressor after the compressor operating capacity reaches its minimum, the magnetic valve installed in the third bypass path is opened first, so the oil separator Separated refrigerating machine oil does not flow into the accumulator, so there is no delay in oil return to the compressor, and the compressor can continue to operate in good condition. In addition, when the solenoid valve in the third bypass path is open and the pressure exceeds the allowable operating range of the compressor, the solenoid valve installed in the second bypass path is opened, so the air conditioner It becomes possible to expand the operating range of the 1.During defrost operation, the solenoid valve provided in the second bypass path is opened, so that the leakage of refrigerating machine oil due to temporary liquid backing that occurs during defrost operation can be prevented.
Oil can be returned to the compressor efficiently.

Furthermore, when the low pressure during defrost operation is below the fifth control pressure value, the wLlia valve provided in the third bypass path is opened, so that the bypass flow rate via the am valve and the outdoor heat exchanger are It becomes possible to control the flow rate of inflowing refrigerant by low pressure, and the defrost ability that the compressor can exhibit can be efficiently extracted. In other words, if the bypass flow rate during defrost operation is set too high,
Although the flow rate of the compressor increases as the low pressure increases, the flow rate of refrigerant flowing into the outdoor heat exchanger decreases, and there are cases where the defrost ability decreases. Therefore, it is more efficient to increase the amount of bypass and increase the refrigerant flow rate of the compressor only when the refrigerant flow rate of the compressor is extremely reduced and the low pressure drops to a low pressure level. It is.

In addition, if the pressure exceeds the allowable operating range of the compressor after the compressor operating capacity reaches its minimum, two solenoid valves are used to control the pressure, so the pressure change width per solenoid valve is can be kept small ([because the flow rate passing through the magnetic valve can be made small)" f/t The number of times the valve opens and closes can be reduced,
Reliability can be improved.

Further, by opening the solenoid valves provided in the second and third bypass paths during the defrost operation, the low pressure during the defrost operation can be maintained high and the defrost capacity can be increased.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an air conditioner showing an embodiment of the present invention, and FIG. 2 and FIG. FIG. 4 is a flowchart showing the control state 0 during defrost operation, and FIG. 5 is a diagram showing the overall structure 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 pressure reducing device, and (6) is a four-way valve.
) is an indoor heat exchanger, (7) is a p-accumulator, (8) is a flow rate regulator, (9) is a solenoid valve, and (11) is a solenoid valve.
) is the first bypass path, (12) is the second bypass path,
(13) is the third bypass path, (l4) is the pressure detection means, (l5) is the pipe temperature detection means, (16) is the operating capacity control means, (17) is the solenoid valve control means, and (18) is the defrost It is a control means. The same reference numerals in each figure indicate corresponding parts of the same case. Masuo Daiiwa Figure 1-367- δ Funeral 5's Sliding 1') fan

Claims (2)

[Claims] (1) Refrigerant circuit with adjustable compressor capacity, oil separator, four-way valve, outdoor heat exchanger, pressure reduction device, indoor heat exchanger, and accumulator connected via piping, flow rate adjustment from the bottom of the oil separator. a first bypass path connected to the suction pipe of the compressor through a device; a second bypass path connected to the inlet pipe of the accumulator or the accumulator from the bottom of the oil separator through a solenoid valve; A third bypass path connected to the inflow pipe of the acumulator or the acumulator via a solenoid valve from the top of the oil separator or the middle of the pipe connecting the oil separator and the four-way valve, and the pressure reducing device and the outdoor air. A pipe temperature detection means provided in the middle of the pipe connecting the heat exchanger, a pressure detection means for detecting high pressure during heating operation and low pressure during cooling operation, detected pressure detected by the above pressure detection means, or Operating capacity control means for controlling the operating capacity of the compressor based on the air conditioning load; during heating operation, the four-way valve is switched based on the temperature detected by the piping temperature detection means to remove frost attached to the outdoor heat exchanger; a defrost control means for melting, and a third bypass path when the pressure detected by the pressure detection means is equal to or higher than a first control pressure value after the operating capacity of the compressor is minimized by the operating capacity control means during heating operation. When the solenoid valve provided in the third bypass path is opened and the pressure detected by the pressure detection means is equal to or higher than a second control pressure value higher than the first control pressure value, When the solenoid valve provided in the second bypass path is opened and the operating capacity of the compressor reaches the minimum during cooling operation, the third control pressure value is set when the pressure detected by the pressure detection means is below the third control pressure value. After opening the electromagnetic valve provided in the bypass path and opening the electromagnetic valve of the third bypass path, a fourth control pressure value whose detected pressure by the pressure detection means is lower than the third control pressure value is determined. In the following cases, the solenoid valve of the second bypass path is opened, and during defrost operation, the solenoid valve provided in the second bypass path is opened, and the pressure detected by the pressure detection means is An air conditioner comprising solenoid valve control means for opening a solenoid valve provided in the third bypass path when the pressure is equal to or less than a control pressure value. (2) The air conditioner according to claim 1, wherein the solenoid valves provided in the second bypass path and the third bypass path are always open during the defrost operation.