JP3138491B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-room heat pump air conditioner in which a plurality of indoor units are connected to one heat source unit, and in particular, air conditioning and heating are selectively performed for each indoor unit. The present invention relates to an air conditioner capable of simultaneously performing cooling in one indoor unit and heating in the other indoor unit.

[0002]

2. Description of the Related Art Conventionally, a heat pump type air conditioner in which a plurality of indoor units are connected to one heat source unit by two pipes of a gas pipe and a liquid pipe to perform a cooling and heating operation is generally used. The machines are all configured to heat or all cool.

[0003]

Since the conventional multi-chamber heat pump type air conditioner is constructed as described above, all the indoor units are operated only for cooling or heating. There has been a problem that heating is performed, or conversely, cooling is performed in a place that requires heating. In particular, when installed in a large-scale building, there is a particular problem because the load of air conditioning is significantly different between an interior unit and a perimeter unit, or a general office room and a computer room or other OAized room. As an approximation technique, there is JP-A-1-134172.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. A plurality of indoor units are connected to one heat source unit, and air conditioning is selectively performed for each indoor unit. In addition, one indoor unit can perform cooling and the other indoor unit can simultaneously perform heating, and when installed in a large-scale building, the OA such as the interior and perimeter, or the general office and the computer room, etc. It is an object of the present invention to provide a multi-room heat pump type air conditioner that can cope with a large difference in the load of air conditioning in a room.

Another object of the present invention is to return the lubricating oil stagnated in the repeater discharged from the compressor together with the refrigerant to the compressor (hereinafter referred to as oil recovery).

[0006]

An air conditioner according to the present invention includes a heat source unit including a compressor, a heat source unit side heat exchanger, and the like, an indoor side heat exchanger, a first flow control device, and the like. Are connected via first and second connection pipes, and one of the indoor heat exchangers of the plurality of indoor units is connected to the first connection pipe or the second connection pipe. A first branch portion switchably connected to the second connection pipe and the other of the indoor heat exchangers of the plurality of indoor units via the first flow control device; A second branch connected to the second connection pipe and the first branch via the flow control device of the first embodiment, and further comprising the second branch and the first connection pipe connected to the second branch. 3 via flow control,
A switching valve is provided between the first and second connection pipes of the heat source unit, and when the heat source side heat exchanger is operated as a condenser,
In either case during the operation to become an evaporator,
In the air conditioner capable of simultaneous operation of cooling and heating, in which the connection pipe of the heat source unit can be switched to the low pressure side and the second connection pipe of the second connection pipe can be switched to the high pressure side, the second flow rate is periodically changed during the continuous operation of the compressor. An opening determining means of the second flow control device for controlling the opening of the control device to be greatly opened is provided.

A single heat source unit including a compressor, a heat source unit side heat exchanger and the like, and a plurality of indoor units including an indoor side heat exchanger and a first flow rate control device are first and second units. A first connection pipe which is connected via a second connection pipe and one of the indoor heat exchangers of the plurality of indoor units is switchably connected to the first connection pipe or the second connection pipe; And the other of the indoor-side heat exchangers of the plurality of indoor units are connected via the first flow control device, and the second connection pipe is connected via the second flow control device. And a second branch portion connected to the first branch portion.
Is connected to the first connection pipe via a third flow control, a switching valve is provided between the first and second connection pipes of the heat source unit, and the heat source side heat exchanger is The first connection pipe can be switched to the low pressure side of the heat source unit and the second connection pipe can be switched to the high pressure side of the heat source unit in any case of the operation of the condenser or the operation of the evaporator. In the air conditioner capable of simultaneous cooling and heating operation, a predetermined minimum value is provided for the opening degree of the second flow control device during the compressor operation.

In addition, one heat source unit including a compressor, a heat source unit side heat exchanger, and the like, and a plurality of indoor units including an indoor side heat exchanger, a first flow control device, etc., are first and second units. A first connection pipe which is connected via a second connection pipe and one of the indoor heat exchangers of the plurality of indoor units is switchably connected to the first connection pipe or the second connection pipe; And the other of the indoor-side heat exchangers of the plurality of indoor units are connected via the first flow control device, and the second connection pipe is connected via the second flow control device. And a second branch portion connected to the first branch portion.
Is connected to the first connection pipe via a third flow control, a switching valve is provided between the first and second connection pipes of the heat source unit, and the heat source side heat exchanger is The first connection pipe can be switched to the low pressure side of the heat source unit and the second connection pipe can be switched to the high pressure side of the heat source unit in any case of the operation of the condenser or the operation of the evaporator. In the air conditioner capable of simultaneous cooling and heating operation,
Is provided with a capillary in parallel with the flow control device.

[0009]

According to the present invention, during operation of the compressor, the lubricating oil of the compressor which has flowed in from the second connection pipe side and stagnated in the second flow control device is used to reduce the opening degree of the second flow control device. The air is periodically passed through the compressor, and is returned from the third flow control device or the cooling indoor unit to the compressor via the first connection pipe.

In addition, during the operation of the compressor, a predetermined minimum value is provided for the opening of the second flow control device to secure a flow path for the lubricating oil of the compressor. Eliminating stagnation on the inlet side of the control device, lubricating oil of the compressor is returned from the third flow control device or the cooling indoor unit to the compressor via the first connection pipe.

In addition, by providing a capillary in parallel with the second flow control device, a lubricating oil flow path of the compressor can be secured during the operation of the compressor even when the second flow control device is in the fully closed state. Eliminating the stagnation of the lubricating oil of the compressor on the inlet side of the second flow control device, and supplying the lubricating oil of the compressor from the third flow control device or the cooling indoor unit via the first connection pipe. Return to compressor.

[0012]

[Embodiment 1] Hereinafter, embodiments of the present invention will be described. FIG. 1 is an overall configuration diagram mainly showing a refrigerant system of an air conditioner according to an embodiment of the present invention. FIGS. 2 to 4 show the operation states during the cooling / heating operation in the embodiment of FIG.
FIG. 2 is an operation state diagram of only cooling or heating, and FIGS. 3 and 4
Fig. 3 shows an operation of simultaneous cooling and heating operation, Fig. 3 shows an operation mainly for heating (when the heating operation capacity is larger than the cooling operation capacity), and Fig. 4 shows an operation mainly for cooling (when the cooling operation capacity is larger than the heating operation capacity). It is an operation | movement state diagram. In this embodiment, a case where three indoor units are connected to one heat source unit will be described, but the same applies to a case where two or more indoor units are connected.

In FIG. 1, A is a heat source unit, and B, C and D are indoor units connected in parallel to each other as described later, and have the same configuration. E denotes a first branch 10, a second flow controller 13, a second branch 11, a gas-liquid separator 12, a heat exchanger 16a, 16b, 16c, 16d, 19, a third branch 19, as will be described later. Is a repeater incorporating the fourth flow control device 17 and the fourth flow control device 17. Further, 1 is a compressor, 2 is a four-way switching valve for switching the refrigerant flow direction of the heat source machine, 3 is a heat source side heat exchanger, and 4 is an accumulator, which is connected to the compressor 1 via the four-way switching valve 2. I have. These constitute the heat source device A. Reference numeral 5 denotes an indoor heat exchanger provided in three indoor units B, C and D, and reference numeral 6 denotes a four-way switching valve 2 of the heat source unit A and a relay unit E via a fourth check valve 33 which will be described later. The first connecting pipes 6b, 6c, and 6d that are connected to each other are indoor units B,
C and D indoor-side heat exchangers 5 are connected to the repeater E, and a first connection pipe on the indoor unit side corresponding to the first connection pipe 6 is a heat source unit-side heat exchanger 3 of the heat source unit A. And a second connection pipe which is thinner than the first connection pipe and connects the relay E with a third check valve 32 to be described later.

7b, 7c and 7d are indoor units B and
A second connection pipe on the indoor unit side corresponding to the second connection pipe 7, wherein the indoor heat exchangers 5 of C and D and the repeater E are connected via the first flow control device 9. Reference numeral 8 denotes a three-way switching valve for switchably connecting the first connection pipes 6b, 6c, 6d on the indoor unit side to the first connection pipe 6 or the second connection pipe 7 side. Reference numeral 9 denotes a first flow control device which is connected in proximity to the indoor heat exchanger 5 and is controlled by the amount of superheat at the outlet side of the indoor heat exchanger 5 during cooling and by the subcool amount during heating. It is connected to the second connection pipes 7b, 7c, 7d on the machine side. 10 is the first connection pipe 6b, 6c, 6d on the indoor unit side,
And a first branch portion including a three-way switching valve 8 which is switchably connected to the connection pipe 6 or the second connection pipe 7. 11
Denotes a second branch portion including the second connection pipes 7b, 7c, and 7d on the indoor unit side and the second connection pipe 7. Reference numeral 12 denotes a gas-liquid separation device provided in the middle of the second connection pipe 7, the gas phase portion of which is connected to the first port 8a of the three-way switching valve 8, and the liquid phase portion thereof is connected to the second port 8a.
Are connected to the branch portion 11. Reference numeral 13 denotes an openable and closable second flow control device (here, an electric expansion valve) connected between the gas-liquid separation device 12 and the second branch portion 11.

Reference numeral 14 denotes a bypass pipe connecting the second branch portion 11 and the first connection pipe 6, and reference numeral 15 denotes a third flow control device (here, an electric expansion valve) provided in the middle of the bypass pipe 14. , 16a are provided downstream of the third flow control device 15 provided in the middle of the bypass pipe 14, and are associated with the second connection pipes 7b, 7c, 7d on the indoor unit side in the second branch section 11. And a second heat exchange section for performing heat exchange between the first heat exchanger and the second heat exchanger. 16
b, 16c, 16d are respectively provided downstream of the third flow control device 15 provided in the middle of the bypass pipe 14, and the second connection pipes 7b, 7c,
This is a third heat exchanging section for exchanging heat with 7d. 19 is provided downstream of the third flow control device 15 of the bypass pipe 14 and downstream of the second heat exchange section 16a, and is connected to a pipe connecting the gas-liquid separation device 12 and the second flow control device 13. 1st heat exchange section which exchanges heat between, 17 is the 2nd branch section
A fourth flow control device (here, an electric expansion valve) that can be opened and closed is connected between the first connection pipe 6 and the first connection pipe 6.

On the other hand, reference numeral 32 denotes a third check valve provided between the heat source unit side heat exchanger 3 and the second connection pipe 7, and a third check valve 32. 2 connection piping 7
Only the refrigerant flow is allowed. Reference numeral 33 denotes a fourth valve provided between the four-way switching valve 2 of the heat source unit A and the first connection pipe 6.
And allows the refrigerant to flow only from the first connection pipe 6 to the four-way switching valve 2. Reference numeral 34 denotes a fifth check valve provided between the four-way switching valve 2 of the heat source unit A and the second connection pipe 7.
Is allowed to flow only to the connection pipe 7. Reference numeral 35 denotes a sixth check valve provided between the heat source unit-side heat exchanger 3 and the first connection pipe 6, and a sixth check valve 35 from the first connection pipe 6 to the heat source unit-side heat exchanger 3. Only the refrigerant flow is allowed. The third, fourth, fifth, and sixth check valves 32, 33, 34, and 35 constitute a switching valve 40.

Reference numeral 25 denotes a first pressure detecting means provided between the first branch portion 10 and the second flow control device 13, and 26 denotes a second flow control device 13 and a fourth flow control device. This is second pressure detection means provided between the apparatus and the apparatus 17. 50 is a low-pressure saturation temperature detecting means provided in the pipe connecting the four-way switching valve 2 and the accumulator 4, and 18 is provided in the pipe connecting the compressor 1 and the four-way switching valve 2. And a fourth pressure detecting means.

Next, the operation will be described. First, the case of only the cooling operation will be described with reference to FIG. As shown by a solid line arrow in the figure, the high-temperature high-pressure refrigerant gas discharged from the compressor 1 whose capacity is controlled so that the temperature detected by the low-pressure saturation temperature detecting means 50 becomes a predetermined value passes through the four-way switching valve 2 and passes through the heat source unit. After being condensed by exchanging heat with air in the side heat exchanger 3, the third check valve 32, the second connection pipe 7, the gas-liquid separator 12, and the second flow controller 13 are further passed in this order. The second branch portion 11 passes through the second connection pipes 7b, 7c, and 7d on the indoor unit side, and each indoor unit B,
Flow into C and D. The refrigerant flowing into each of the indoor units B, C, and D is decompressed to a low pressure by the first flow control device 9 controlled by the amount of superheat at the outlet of each of the indoor heat exchangers 5, and It exchanges heat with indoor air and evaporates and gasifies to cool the room.

The refrigerant in the gaseous state is supplied to the first connection pipes 6b, 6c, 6d on the indoor unit side, the three-way switching valve 8, the first branch 10, the first connection pipe 6, and the fourth reverse pipe. A circulation cycle is drawn into the compressor 1 through the stop valve 33, the four-way switching valve 2 of the heat source unit A, and the accumulator 4, and performs a cooling operation. At this time, the first port 8a of the three-way switching valve 8 is closed, and the second port 8b and the third port 8b are closed.
8c is open. At this time, the refrigerant naturally flows to the third check valve 32 and the fourth check valve 33 because the first connection pipe 6 has a low pressure and the second connection pipe 7 has a high pressure. At the time of this cycle, a part of the refrigerant that has passed through the second flow control device 13 enters the bypass pipe 14 and is reduced to a low pressure by the third flow control device 15, so that the third heat exchange units 16b, 16c, 16d, the second connection pipes 7b, 7c on the indoor unit side of the second branch 11
7d and the second branch 11
Between the second connection pipes 7b, 7c, 7d on the side of each indoor unit and the refrigerant flowing into the second flow control device 13 in the first heat exchange section 19, The evaporated refrigerant that has been exchanged enters the first connection pipe 6 and the fourth check valve 33, and is sucked into the compressor 1 via the four-way switching valve 2 and the accumulator 4 of the heat source unit A.

On the other hand, the first, second and third heat exchange sections 19 and 16
The refrigerant in the second branch portion 11, which is cooled by exchanging heat in b, 16c, and 16d and is sufficiently subcooled, flows into the indoor units B, C, and D to be cooled.

Next, the case of only the heating operation will be described with reference to FIG. That is, as shown by a dotted arrow in FIG. 3, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 whose capacity is controlled so that the pressure detected by the fourth pressure detecting means 18 becomes a predetermined value is supplied to the four-way switching valve 2 Through the fifth check valve 34, the second
Through the connection pipe 7 and the gas-liquid separation device 12 to the first branch 1
0, three-way switching valve 8, first connection piping 6b, 6c, 6 on indoor unit side
The air flows into each of the indoor units B, C, and D in the order of d, exchanges heat with indoor air to be condensed and liquefied, and heats the indoor.

The refrigerant in the liquid state is controlled by the subcooling amount at the outlet of each indoor side heat exchanger 5, passes through the first flow control device 9 which is almost fully opened, and the second connection on the indoor unit side. The pipes flow into the second branch portion 11 from the pipes 7b, 7c, and 7d, join together, and further pass through the fourth flow control device 17. Here, the first flow control device 9 or the third and fourth flow control devices 15 and 17 are used.
The pressure is reduced to a low-pressure gas-liquid two-phase state in one of the two.
The refrigerant decompressed to a low pressure flows into the sixth check valve 35 of the heat source device A and the heat source device side heat exchanger 3 via the first connection pipe 6, and exchanges heat with air to evaporate to a gas state. , Heat source unit A, four-way switching valve 2 and accumulator 4
A circulation cycle is drawn into the hopper and a heating operation is performed.
At this time, the three-way switching valve 8 has the second port 8b closed, and the first port 8a and the third port 8c open. At this time, the refrigerant naturally flows to the fifth check valve 34 and the sixth check valve 35 because the first connection pipe 6 has a low pressure and the second connection pipe 7 has a high pressure. At this time, the second flow control device 13 is normally in a fully closed state.

Next, a description will be given of a case where heating and cooling are mainly performed in simultaneous cooling and heating operation with reference to FIG. The high-temperature and high-pressure refrigerant gas discharged from the compressor 1 whose capacity is controlled so that the pressure detected by the fourth pressure detecting means 18 becomes a predetermined value as indicated by a dotted arrow in FIG. 5 check valve 34,
It is sent to the relay E through the second connection pipe 7, passes through the gas-liquid separator 12, passes through the first branch section 10, the three-way switching valve 8, and the first connection pipes 6b and 6c on the indoor unit side in this order, It flows into each of the indoor units B and C to be heated, exchanges heat with the indoor air in the indoor heat exchanger 5, is condensed and liquefied, and heats the room. The condensed and liquefied refrigerant is controlled by the amount of subcooling at the outlet of each indoor side heat exchanger 5, and is substantially fully opened.
And flows into the second branch portion 11 after being slightly reduced in pressure.

A part of the refrigerant passes through the second connection pipe 7d on the indoor unit side, enters the indoor unit D to be cooled, and is controlled by the amount of superheat at the outlet of the indoor heat exchanger 5. After being decompressed, it enters the indoor heat exchanger 5 and exchanges heat to evaporate to a gaseous state to cool the room, and the three-way switching valve 8 via the first connection pipe 6d. Flows into the first connection pipe 6 through the. On the other hand, other refrigerants are detected by the first pressure detecting means 25 and the second pressure detecting means.
Through the fourth flow control device 17, which is controlled so that the pressure difference of the detected pressure of 26 is within a predetermined range, the refrigerant flows through the indoor unit D to be cooled and merges with the refrigerant to form the first thick connection pipe 6. Through the sixth check valve 35 of the heat source device A, the heat source device side heat exchanger 3
And exchanges heat with air to evaporate to a gaseous state.

This refrigerant forms a circulation cycle which is drawn into the compressor 1 through the four-way switching valve 2 and the accumulator 4 of the heat source unit A, and performs a heating-main operation. At this time, the difference between the evaporation pressure of the indoor side heat exchanger 5 of the indoor unit D to be cooled and the pressure of the heat source unit side heat exchanger 3 is reduced due to the switching to the thick first connection pipe 6. At this time, the second port 8b of the three-way switching valve 8 connected to the indoor units B and C is closed, and the first port 8a is connected to the third port 8a.
8c is open, the first port 8a of the indoor unit D is closed,
The mouth 8b and the third mouth 8c are open. At this time, the refrigerant naturally flows to the fifth check valve 34 and the sixth check valve 35 because the first connection pipe 6 has a low pressure and the second connection pipe 7 has a high pressure.

During this cycle, a part of the liquid refrigerant enters the bypass pipe 14 from the junction of the second connection pipes 7b, 7c, 7d on the indoor unit side of the second branch section 11, and the third flow control The pressure is reduced to a low pressure by the device 15, and the third heat exchange units 16b, 16c, 16d
The second connection pipes 7b and 7 on each indoor unit side of the second branch 11
c, 7d, and between the second heat exchange section 16a and the junction of the second connection pipes 7b, 7c, 7d on the indoor unit side of the second branch section 11, and The second flow control device in the heat exchange section 19
The heat exchange is performed between the refrigerant and the thirteenth refrigerant inlet side pipe, and the evaporated refrigerant enters the heat source unit side heat exchanger 3 via the first connection pipe 6 and the sixth check valve 35, and exchanges with air. After evaporating by heat exchange, the refrigerant is sucked into the compressor 1 via the four-way switching valve 2 and the accumulator 4 of the heat source device A. On the other hand, the first, second, and third heat exchangers 19, 16a, 16b, 16c, and 16d exchange heat, are cooled, and are sufficiently cooled and provided with a subcool.
Flows into the indoor unit D to be cooled. At this time, the second flow control device 13 is normally in a fully closed state.

Next, a description will be given of a case in which cooling is mainly performed in simultaneous cooling and heating operation with reference to FIG. As shown by the solid line arrow in FIG. 3, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 whose capacity is controlled so that the temperature detected by the low-pressure saturation temperature detecting means 50 becomes a predetermined value passes through a four-way switching valve 2 and a heat source. It flows into the machine side heat exchanger 3 and exchanges heat with air to be in a gas-liquid two-phase high-temperature and high-pressure state. Thereafter, the two-phase high-temperature and high-pressure refrigerant is sent to the gas-liquid separator 12 of the repeater E via the third check valve 32 and the second connection pipe 7. Here, the gaseous refrigerant and the liquid refrigerant are separated, and the separated gaseous refrigerant is supplied to the first branch portion.
10, the three-way switching valve 8, and the first connection pipe 6d on the indoor unit side, flow into the indoor unit D to be heated, exchange heat with the indoor air in the indoor heat exchanger 5, and condense and liquefy. Heat the room. Further, it is controlled by the subcooling amount at the outlet of the indoor heat exchanger 5, passes through the first flow control device 9 in a substantially fully opened state, and is slightly reduced in pressure, and flows into the second branch portion 11.

On the other hand, the remaining liquid refrigerant passes through the second flow control device 13 controlled by the pressure detected by the first pressure detecting means 25 and the pressure detected by the second pressure detecting means 26, and passes through the second branch. The refrigerant flows into the unit 11 and merges with the refrigerant that has passed through the indoor unit D to be heated. The combined refrigerant is supplied to the second branch 1
1. Flow into the indoor units B and C in the order of the second connection pipes 7b and 7c on the indoor unit side. The refrigerant flowing into each of the indoor units B and C is depressurized to a low pressure by the first flow control device 9 controlled by the amount of superheat at the outlet of the indoor unit-side heat exchanger 5, and then is transferred to the indoor-side heat exchanger 5. It flows in, exchanges heat with room air, evaporates and gasifies, and cools the room. Further, the refrigerant in the gas state is supplied to the first connection pipe 6 on the indoor unit side.
b, 6c, passing through the three-way switching valve 8, the first branch portion 10, the first connection pipe 6, the fourth check valve 33, the four-way switching valve 2 of the heat source unit A,
A circulation cycle is drawn into the compressor 1 via the accumulator 4, and the cooling-main operation is performed. At this time, the first port 8a of the three-way switching valve 8 connected to the indoor units B and C is closed, the second port 8b and the third port 8c are open, and the second port 8b of the indoor unit D is closed. The circuit is closed, and the first port 8a and the third port 8c are open. At this time, the refrigerant naturally flows to the third check valve and the fourth check valve 33 because the first connection pipe 6 has a low pressure and the second connection pipe 7 has a high pressure.

In this cycle, a part of the liquid refrigerant enters the bypass pipe 14 from the junction of the second connection pipes 7b, 7c, 7d on the indoor unit side of the second branch section 11, and the third flow rate Control device 15
The pressure is reduced to a low pressure by the third heat exchange units 16b, 16c, 16
d, a second connection pipe 7b on each indoor unit side of the second branch portion 11,
7c and 7d, and in the second heat exchanger section 16a between the second connection pipes 7b, 7c and 7d of the second branch section 11 on the side of each indoor unit, and The first heat exchange section 19 exchanges heat with the refrigerant flowing into the second flow control device 13, and the evaporated refrigerant enters the first connection pipe 6 and the fourth check valve 33, and the heat source device A is sucked into the compressor 1 through the four-way switching valve 2 of A and the accumulator 4. On the other hand, the first, second, and third heat exchange units 19, 16
The refrigerant in the second branch portion 11, which has been subjected to heat exchange in a, 16b, and 16c and cooled and sufficiently subcooled, flows into the indoor units B and C to be cooled.

Next, as described above, in the first embodiment, the second
The oil recovery in the case where only the heating in which the flow control device 13 of FIG. FIG. 5 is a block diagram of the oil recovery of the first embodiment, FIG. 6 is a flowchart of the oil recovery of the first embodiment, and FIG. 7 is a diagram showing a change in the opening degree of the second flow control device 13 by the oil recovery. In FIG. 5, reference numeral 61 denotes first timing means for measuring the time since the previous control was performed in order to periodically perform the opening control of the second flow control device 13 in the first cycle. It is cleared each time the operation of the machine 1 is started or the opening control of the second flow control device 13 is performed. 62 is a second time measuring operation time of the compressor 1
Is cleared at the start of the operation of the compressor 1 or at every second cycle longer than the first cycle. 63 closes the opening of the second flow control device by a predetermined opening width based on the output of the first timing device, and closes the opening of the second flow control device based on the output of the second timing device. This is an opening determining means for determining the opening of the second flow control device 13 that restores the opening to the initial opening.

Next, the flow of control of oil recovery will be described with reference to FIGS. In step 71, the second timing means 62
Is measured as the second period for a predetermined time 2 or more. If the time has been measured, the process proceeds to step 76, and if not, the process proceeds to step 72. Step 7
In FIG. 6, the second flow control device 13 shown in FIG.
Is opened by a predetermined opening width to restore the initial opening. In step 77, the time data of the second time measuring means 62 is cleared, and the process returns to step 71. In step 72, it is determined whether or not the first clocking means 61 has clocked a predetermined period of 1 or more as a first cycle shorter than the predetermined time 2. If it is timed, the process proceeds to step 73, and if not, the process returns to step 71. In step 73, it is determined whether the opening of the second flow control device 13 is fully closed. If it is fully closed, the process proceeds to step 75, and if it is not fully closed, the process proceeds to step 74. In step 74, the initial opening a
The opening degree of the second flow control device 13 is sequentially determined from step
The shutter is closed by a predetermined closing width smaller than the predetermined opening width of No. 6 and the process proceeds to step 75. In step 75, the clock data of the first clock means 61 is cleared, and the process returns to step 71.

Embodiment 2 FIG. In order to prevent the lubricant oil of the compressor from stagnating at the inlet side of the second flow control device 13, the second flow control device 13 is not fully closed in the case of heating only and in the case of mainly heating, and the minimum opening degree is set. There is also an effect that a method of always providing a slight opening is provided.

Embodiment 3 FIG. Also, by providing the capillary 51 in parallel with the second flow control device 13 as shown in FIG. 8, the same effect as in the case where the second flow control device 13 is provided with the minimum opening degree can be obtained.

Embodiment 4 FIG. In the first embodiment, the three-way switching valve 8 is provided to switchably connect the first connection pipes 6b, 6c, 6d on the indoor unit side to the first connection pipe 6 or the second connection pipe 7. However, the same operation and effect can be obtained even if the on-off valves of the two solenoid valves 30 and 31 are provided as shown in FIG.

[0035]

As described above, the air conditioner according to the present invention comprises a compressor, a heat source unit-side heat exchanger, and the like.
Heat source units and a plurality of indoor units including an indoor heat exchanger, a first flow control device and the like are connected via first and second connection pipes, and the plurality of indoor units are connected to each other. A first branching section that is connected to one of the indoor heat exchangers so as to be switchable to the first connection pipe or the second connection pipe; and the indoor heat exchanger of the plurality of indoor units. In the other, the first
And a second branch portion connected to the second connection pipe and the first branch portion via a second flow control device, and further comprising the second branch portion. Is connected to the first connection pipe via a third flow control, a switching valve is provided between the first and second connection pipes of the heat source unit, and the heat source side heat exchanger is condensed. The first connection pipe can be switched to the low-pressure side of the heat source unit and the second connection pipe can be switched to the high-pressure side in both cases of the operation of the heat source and the operation of the evaporator. In the operable air conditioner, the second cycle is periodically performed during the compressor operation.
The opening degree determining means of the second flow control apparatus for controlling the opening degree of the flow control apparatus to be increased is provided. The lubricating oil of the compressor stagnant at the inlet side of the second flow control device is returned to the compressor by periodically increasing the opening of the flow control device 2 to prevent seizure of the compressor. it can.

In the air conditioner, the second
By providing a minimum opening degree to the flow control device, the refrigerant always flows through the second flow control device, and although a steady decrease in the heating capacity appears slightly, the flow rate to the second flow control device inlet side is reduced. Stagnation of the lubricating oil can be eliminated, and seizure of the compressor can be prevented.

Further, in the air conditioner, the second
By providing a capillary in parallel with the flow control device, the refrigerant always flows through the parallel portion of the second flow control device even when the second flow control device is in the fully closed state, The same effect as in the case where the minimum opening is provided in the flow control device can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram centering on a refrigerant system of an air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a refrigerant circuit diagram for explaining an operation state of only cooling or heating of the air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a refrigerant circuit diagram for explaining an operation state mainly of heating of the air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 4 is a refrigerant circuit diagram for explaining an operation state mainly for cooling of the air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 5 is a block diagram of oil recovery of the air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 6 is a flowchart of oil recovery of the air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 7 is a change diagram of an opening degree of the second flow control device 13 by oil recovery in the air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 8 is an overall configuration diagram of an air conditioner according to Embodiment 3 of the present invention, centering on a refrigerant system corresponding to Embodiment 3.

FIG. 9 is an overall configuration diagram of an air conditioner according to Embodiment 4 of the present invention, centering on a refrigerant system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way switching valve 3 Heat exchanger side heat exchanger 4 Accumulator 5 Indoor heat exchanger 6 6b, 6c, 6d First connection pipe 7 7b, 7c, 7d Second connection pipe 8 Three-way switching valve 9 1 flow control device 10 first branch portion 11 second branch portion 13 second flow control device 15 third flow control device 40 switching valve 61 first timing means 62 second timing means 63 second Opening determining means of flow control device A Heat source unit B, C, D Indoor unit E Repeater

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tokuaki Hayashida 6-66, Tehira, Wakayama-shi Mitsubishi Electric Corporation Wakayama Works (72) Inventor Tomohiko Kasai 6-66, Tehira, Wakayama-shi Mitsubishi Electric Wakayama Works, Ltd. (72) Inventor Junichi Kameyama 6-66, Teira, Wakayama City Mitsubishi Electric Wakayama Works, Ltd. (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 29/00 361 F25B 13/00 104

Claims (3)

(57) [Claims] 1. A compressor comprising a heat exchanger on the heat source unit side, etc.
Heat source units and a plurality of indoor units including an indoor heat exchanger, a first flow control device and the like are connected via first and second connection pipes, and the plurality of indoor units are connected to each other. A first branching section that is connected to one of the indoor heat exchangers so as to be switchable to the first connection pipe or the second connection pipe; and the indoor heat exchanger of the plurality of indoor units. In the other, the first
Connected through the flow control device of the second , the second flow control device
To the second connection pipe and the first branch through
A second branch portion connected to the first and second connection portions. The second branch portion is connected to the first connection pipe via a third flow rate control. A switching valve is provided between the connection pipes, and the first connection pipe is placed on the low pressure side of the heat source device in any case of the operation in which the heat source side heat exchanger becomes a condenser or the operation in which the heat source side heat exchanger becomes an evaporator. In an air conditioner capable of simultaneous cooling and heating operation in which the second connection pipe can be switched to the high pressure side, control is performed so that the opening of the second flow rate control device is periodically greatly opened during continuous operation of the compressor. An air conditioner comprising an opening determining means of the second flow control device. 2. A compressor comprising a heat exchanger and a heat source side heat exchanger.
Heat source units and a plurality of indoor units including an indoor heat exchanger, a first flow control device and the like are connected via first and second connection pipes, and the plurality of indoor units are connected to each other. A first branching section that is connected to one of the indoor heat exchangers so as to be switchable to the first connection pipe or the second connection pipe; and the indoor heat exchanger of the plurality of indoor units. In the other, the first
Connected through the flow control device of the second , the second flow control device
To the second connection pipe and the first branch through
A second branch portion connected to the first and second connection portions. Further, the second branch portion and the first connection pipe are connected to each other via a third flow rate control, and the first and second connection portions of the heat source device are connected to each other. A switching valve is provided between the connecting pipes of the first and second embodiments, and the first connecting pipe is connected to the low-pressure side of the heat source unit in any case where the heat source side heat exchanger operates as a condenser or operates as an evaporator. In addition, the second connection pipe can be switched to the high pressure side of the heat source device,
An air conditioner capable of simultaneous operation of cooling and heating, wherein a predetermined minimum value is provided for an opening degree of the second flow control device during operation of the compressor. 3. A compressor comprising a compressor, a heat source unit side heat exchanger, and the like.
Heat source units and a plurality of indoor units including an indoor heat exchanger, a first flow control device and the like are connected via first and second connection pipes, and the plurality of indoor units are connected to each other. A first branching section that is connected to one of the indoor heat exchangers so as to be switchable to the first connection pipe or the second connection pipe; and the indoor heat exchanger of the plurality of indoor units. In the other, the first
Connected through the flow control device of the second , the second flow control device
To the second connection pipe and the first branch through
A second branch portion connected to the first and second connection portions. Further, the second branch portion and the first connection pipe are connected to each other via a third flow rate control, and the first and second connection portions of the heat source device are connected to each other. A switching valve is provided between the connecting pipes of the first and second embodiments, and the first connecting pipe is connected to the low-pressure side of the heat source unit in any case where the heat source side heat exchanger operates as a condenser or operates as an evaporator. In addition, the second connection pipe can be switched to the high pressure side of the heat source device,
An air conditioner capable of simultaneous cooling and heating operation, wherein a capillary is provided in parallel with the second flow control device.