JP3092212B2 - 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 The prior art of the present invention will be described below. FIG. 4 is an overall configuration diagram mainly showing a refrigerant system of the air conditioner of the prior art of the present invention. FIGS. 5 to 7 show the operation states of the air-conditioning apparatus shown in FIG. 4 during the cooling and heating operation. FIG. 5 is an operation state diagram of only the cooling or heating operation, and FIGS. FIG. 6 is an operation state diagram showing the main operation of heating (when the heating operation capacity is larger than the cooling operation capacity), and FIG. 7 is an operation operation state showing the main operation of cooling (when the cooling operation capacity is larger than the heating operation capacity). . In this prior art, the indoor unit 3 is connected to one heat source unit.
The case where two or more indoor units are connected will be described, but the same applies to the case where two or more indoor units are connected.

In FIG. 4, 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 is a first branch unit 10, a second flow control unit 13, a second branch unit 11, a gas-liquid separator 12, a heat exchange unit 16a, 16b, 16c, 16d, 19,
This is a repeater incorporating a third flow control device 15 and a 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.

[0004] Also, 7b, 7c, 7d are indoor units B,
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.

[0005] 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 a 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 provided downstream of the third flow control device 15 provided in the middle of the bypass pipe 14, respectively, and the second connection pipes 7b, 7c,
This is a third heat exchanging section for exchanging heat with 7d. Reference numeral 19 denotes a pipe provided between the bypass pipe 14 downstream of the third flow control device 15 and downstream of the second heat exchange unit 16a, and 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 is provided between the heat source unit side heat exchanger 3 and the second check valve. 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 heat source unit A four-way switching valve 2 and the second connection pipe 7, and a refrigerant is supplied only from the four-way switching valve 2 to the second connection pipe 7. Allow distribution. 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 are switching valves.
Make up 40.

[0007] 25 the first pressure detecting means provided between the first branch portion 10 and the second flow quantity <br/> controller 13,
26 is a second pressure detecting means provided between the second flow control device 13 and the fourth flow control device 17, and 27 is a third pressure provided in the first connection pipe 6 part. It is a detecting means. Reference numeral 41 denotes a low-pressure saturation temperature detecting means provided in a pipe connecting the four-way switching valve 2 and the accumulator 4, and 42 denotes the four-way switching valve 2 and the compressor 1.
Discharge temperature detecting means provided in the middle of the pipe connecting
Reference numeral 18 denotes fourth pressure detecting means provided in the middle of a pipe connecting the compressor 1 and the four-way switching valve 2.

Next, the operation will be described. First, a case of only the cooling operation will be described with reference to FIG. As shown by the solid line arrow in the figure, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 whose capacity is controlled so that the detected temperature of the low-pressure saturation temperature detecting means 41 becomes a predetermined value passes through the four-way switching valve 2 and the heat source device 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 superheat amount at the outlet of each of the indoor heat exchangers 5, and the indoor heat exchanger 5 The heat exchanges with the indoor air to evaporate and gasify and 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, At 16d, the second connection pipes 7b, 7c on the indoor unit side of the second branch portion 11 are provided.
7d and a second heat exchange section 16a and a second branch section 11d.
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 refrigerant evaporated after replacement is
The gas enters the first connection pipe 6 and the fourth check valve 33, and is sucked into the compressor 1 through 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 units 19 and 16
The refrigerant in the second branch portion 11, which is cooled by exchanging heat in a, 16b, 16c, and 16d and 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.
To reduce the pressure to a low-pressure gas-liquid two-phase state. 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. , 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 to perform a heating operation. At this time, the three-way switching valve 8
Indicates that the second port 8b is closed and the first port 8a and the third port 8c are open. Also, at this time, the first connection pipe 6 has a low pressure and the second connection pipe 7 has a high pressure.
It flows to the sixth check valve 35.

Next, a description will be given of a case where heating and cooling are performed mainly in the 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. 5th check valve 34, 2nd
Is sent to the repeater E through the connection pipe 7 of
12, the first branch 10, the three-way switching valve 8, and the first connection pipes 6 b and 6 c on the indoor unit side, flow into the indoor units B and C to be heated, and perform indoor heat exchange. The heat is exchanged with the room air in the vessel 5 to condense and liquefy, and the room is heated. The condensed and liquefied refrigerant is controlled by the subcooling amount at the outlet of each indoor heat exchanger 5, passes through the first flow control device 9 which is almost fully open, and is slightly depressurized and flows into the second branch portion 11. .

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 superheat amount at the outlet of the indoor heat exchanger 5. After entering the first flow control device 9 and being decompressed, it enters the indoor heat exchanger 5 to exchange heat and evaporate into a gaseous state to cool the room, and the three-way switching valve via the first connection pipe 6d. 8
Flows into the first connection pipe 6 through the. On the other hand, the other refrigerant passes through a fourth flow control device 17 which is controlled so that the pressure difference between the detected pressure of the first pressure detecting means 25 and the detected pressure of the second pressure detecting means 26 is within a predetermined range. The first connecting pipe 6 which is combined with the refrigerant having passed through the indoor unit D to be cooled and is thick.
, Flows into the sixth check valve 35 of the heat source device A and the heat source device side heat exchanger 3, and exchanges heat with air to evaporate to a gas 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, 1st port 8a of indoor unit D is closed, 2nd port
8b and the third port 8c are open. Also, at this time, the refrigerant
Since the first connection pipe 6 has a low pressure and the second connection pipe 7 has a high pressure, it necessarily flows to the fifth check valve 34 and the sixth check valve 35.

In this cycle, a part of the liquid refrigerant is supplied to the second connection pipes 7b, 7c, 7 on the indoor unit side of the second branch portion 11.
d enters the bypass pipe 14 from the junction, and is reduced to a low pressure by the third flow control device 15,
b, 16c, and 16d between the second connection pipes 7b, 7c, and 7d on the indoor unit side of the second branch section 11 and the second branch section 11 at the second heat exchange section 16a. 2nd indoor unit side
Connection pipe 7b, 7c, with the association of 7d, the refrigerant emitted vapor, the first connecting pipe 6, through the check valve 35 of the sixth, enters the heat source unit side heat exchanger 3, air After the heat exchange with the evaporator, the refrigerant 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 exchangers 19, 16a, 16b, 16c, and 16d exchange heat, and are cooled, and the refrigerant in the second branch portion 11, which is sufficiently subcooled, tries to cool. To the indoor unit D that is located.

Next, a description will be given of a case in which cooling is mainly performed in simultaneous operation of cooling and heating with reference to FIG. As shown by the solid line arrow in the figure, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 whose capacity is controlled so that the detected temperature of the low-pressure saturation temperature detecting means 41 becomes a predetermined value passes through the four-way switching valve 2 and becomes 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, the pressure is controlled by the subcool amount at the outlet of the indoor heat exchanger 5, passes through the first flow control device 9 which is almost fully opened, 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 detected pressure of the first pressure detecting means 25 and the detected pressure of 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 second branch 11 flows 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 supplied to the indoor unit side heat exchanger 5.
After the pressure is reduced to a low pressure by the first flow control device 9 controlled to the superheat amount at the outlet of the outlet, it flows into the indoor heat exchanger 5 and exchanges heat with the indoor air to evaporate and gasify,
Cool the room. Further, the refrigerant in this gas state is
The first connection pipes 6b and 6c on the indoor unit side, the three-way switching valve 8, the first
, The first connection pipe 6 and the fourth check valve 3
3. A circulation cycle in which the refrigerant is sucked into the compressor 1 through the four-way switching valve 2 and the accumulator 4 of the heat source unit A, and the main cooling 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. Closed, first mouth 8a
And the third port 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.

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 in the third heat exchange sections 16b, 16c, 16c.
d, a second connection pipe 7b on each indoor unit side of the second branch portion 11,
7c and 7d, and between the second heat exchanger 16a and the junction of the second connection pipes 7b, 7c and 7d on the indoor unit side of the second branch 11 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 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 cooled by the heat exchange at a, 16b, 16c, and 16d and sufficiently subcooled, flows into the indoor units B and C to be cooled.

[0020]

Since the conventional multi-chamber heat pump type air conditioner is constructed as described above, if the compressor discharge temperature rises excessively during operation, the lubricity of the refrigerating machine oil decreases. There was a problem that the compressor was damaged. As an approximation technique, there is JP-A-1-134172.

The present invention has been made in order to solve the above-mentioned problems. A plurality of indoor units are connected to one heat source unit, and cooling and heating are selectively performed for each indoor unit. In an air conditioner that can simultaneously perform cooling in one indoor unit and heating in the other indoor unit, if the compressor discharge temperature rises excessively, the lubricity of the refrigerating machine oil decreases and the compressor is damaged. The purpose is to prevent.

[0022]

An air conditioner according to the present invention includes a heat source unit including a compressor, a switching valve for switching a refrigerant flow, a heat source side heat exchanger, and the like; an indoor heat exchanger;
A plurality of indoor units including 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 The first branching section that 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 is connected to the first flow control device. A second branch portion connected to the second connection pipe via
The second connection pipe connected to the heat source unit is connected to the first connection pipe.
The branch pipe and the pipe for branching connection to the second branch section
A second flow control device provided on the side of the second branch portion;
A fourth pipe provided in a pipe connecting the branch portion of the first pipe and the first connection pipe.
And a bypass pipe having one end connected to the second branch portion and the other end connected to the first connection pipe via a third flow control device. During the operation in which the side heat exchanger becomes a condenser, the refrigerant flows only from the refrigerant outlet side of the condenser to the second connection pipe side and to the switching valve side for switching the refrigerant flow from the first connection pipe. During the operation in which only the refrigerant is circulated and the heat source device side heat exchanger becomes the evaporator, the refrigerant is circulated only from the first connection pipe to the refrigerant inflow side of the evaporator, and the refrigerant flow is switched. A flow path switching device that allows the refrigerant to flow only from the switching valve to the second connection pipe side is provided, and a discharge temperature detected by discharge temperature detecting means provided between the compressor and the switching valve for switching the refrigerant flow. Is a predetermined temperature If higher than, it is provided with a predetermined amount greater control unit at least one of the valve opening of the third and fourth flow rate control device.

[0023]

According to the present invention, when the discharge temperature of the compressor rises, the discharge temperature detected by the discharge temperature detecting means provided between the compressor and the switching valve for switching the refrigerant flow is set to a predetermined value. When the temperature is higher than the temperature, the control means for increasing the valve opening degree of at least one of the third and fourth flow control devices by a predetermined amount is provided. It is possible to prevent the compressor from lowering and damaging the compressor.

[0024]

【Example】

Embodiment 1 FIG. 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. 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 is a first branch unit 10, a second flow control unit 13, a second branch unit 11, a gas-liquid separator 12, a heat exchange unit 16a, 16b,
This is a repeater incorporating 16c, 16d, 19, a third flow control device 15, and a fourth flow control device 17. 1 is a compressor,
2 is a four-way switching valve for switching the refrigerant flow direction of the heat source unit, 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. These constitute the heat source device A. 5 is an indoor heat exchanger provided in three indoor units B, C and D, and 6 is a heat source unit A
A thick first connection pipe 6b, 6c, 6d for connecting the four-way switching valve 2 and the repeater E via a fourth check valve 33, which will be described later, is used for indoor heat exchange of the indoor units B, C, D, respectively. The first connection pipe 7 on the indoor unit side corresponding to the first connection pipe 6 connects the heat exchanger 5 and the relay E to the heat source unit side heat exchanger 3 of the heat source unit A and the relay E. The first check valve connected via the third check valve 32
The second connection pipe is thinner than the connection pipe.

7b, 7c and 7d are the 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 on the outlet side of the indoor heat exchanger 5 during cooling and by the subcool amount during heating. Side second connection pipes 7b, 7c, 7d. Reference numeral 10 denotes a first branch portion including a three-way switching valve 8 that switches the first connection pipes 6b, 6c, and 6d on the indoor unit side to the first 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, and its gas phase is connected to the first port 8 a of the three-way switching valve 8, and its liquid phase is connected to the second branch 11. It is connected. 13 is a gas-liquid separator 12 and a second
A second flow control device (here, an electric expansion valve) that can be opened and closed and connected between the first and second branch portions 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 a 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 provided downstream of the third flow control device 15 provided in the middle of the bypass pipe 14, respectively, and the second connection pipes 7b, 7c,
This is a third heat exchanging section for exchanging heat with 7d. Reference numeral 19 denotes a pipe provided between the bypass pipe 14 downstream of the third flow control device 15 and downstream of the second heat exchange unit 16a, and 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 is provided between the heat source unit-side heat exchanger 3 and the second check valve. 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 flow path switching device 40.

Reference numeral 25 denotes first pressure detecting means provided between the first branch portion 10 and the second flow control device 13, and reference numeral 26 denotes the second flow control device 13 and the fourth flow control device. A second pressure detecting means 27 provided between the apparatus and the apparatus 17 is a third pressure detecting means provided on the first connection pipe 6. Also,
41 is a low-pressure saturation temperature detecting means provided in the pipe connecting the four-way switching valve 2 and the accumulator 4, and 42 is a discharge provided in the pipe connecting the four-way switching valve 2 and the compressor 1. A temperature detecting means 18 is provided at a fourth position provided in a pipe connecting the compressor 1 and the four-way switching valve 2.
Pressure detection means.

Next, the operation will be described. Only the cooling operation, only the heating operation, the main heating operation and the main cooling operation are exactly the same as those of the conventional air conditioner shown in FIGS. Therefore, the description is omitted here, and the flow control of the third and fourth flow controllers 15 and 17 when the compressor discharge temperature is increased will be described. During the operation of the compressor, when the discharge temperature detected by the discharge temperature detecting means 42 exceeds a predetermined temperature,
By increasing the valve opening of the third or fourth flow control device 15 or 17 by a predetermined amount preferentially, the valve opening of the third flow control device 15 reduces the pressure loss and facilitates the flow of the refrigerant. For this reason, the amount of the refrigerant returning to the heat source device A increases, the specific volume of the refrigerant sucked into the compressor decreases, and an increase in the discharge temperature can be suppressed.

Next, according to the flowchart of FIG. 2, the third and fourth flow control devices 15, 17 when the compressor discharge temperature rises.
Will be described. In step 50, it is determined whether or not the discharge temperature detected by the discharge temperature detecting means 42 is higher or lower than a predetermined temperature.If higher, the process proceeds to step 51. Proceed to. In step 52, the process proceeds to step 53 without changing the valve opening of the third flow control device 15. In step 53, the process returns to step 50 without changing the valve opening of the fourth flow control device 17. In step 51, it is determined whether the valve opening of the third flow control device 15 is the predetermined maximum opening or not the predetermined maximum opening. In this case, the process proceeds to step 55. In step 55, the third
The valve opening of the flow control device 15 is increased, and the process returns to step 50. In step 54, the valve opening of the fourth flow control device 17 is increased, and the process returns to step 50. In this way, the flow control of the third and fourth flow control devices 15 and 17 when the compressor discharge temperature rises is performed.

Embodiment 2 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 by providing two on-off valves such as two electromagnetic valves 30 and 31 as shown in FIG .

[0032]

As described above, the air conditioner according to the present invention includes one heat source unit including a compressor, a switching valve for switching a refrigerant flow, a heat source side heat exchanger, and the like, and an indoor side heat exchanger. , A plurality of indoor units including a first flow control device and the like connected via first and second connection pipes, and one of the indoor heat exchangers of the plurality of indoor units is connected to one of the indoor units. A first branch portion switchably connected to the first connection pipe or the second connection pipe and the other of the indoor heat exchangers of the plurality of indoor units, the first flow control device And a second branch connected to the second connection pipe via the second connection pipe connected to the heat source unit.
Of a pipe for branch connection to the first branch and the second branch
A second flow control device provided on the second branch portion side; a fourth flow control device provided on a pipe connecting the second branch portion and the first connection pipe; And a bypass pipe connected at the other end to the first connection pipe via a third flow control device, and the heat source unit side heat exchanger is a condenser. And flowing the refrigerant only from the refrigerant outlet side of the condenser to the second connection pipe side and flowing the refrigerant only from the first connection pipe to the switching valve side for switching the refrigerant flow, and During the operation in which the side heat exchanger becomes an evaporator, the first heat exchanger is used.
A flow path switching device that allows the refrigerant to flow only from the connection pipe of the evaporator to the refrigerant inflow side of the evaporator and allows the refrigerant to flow only from the switching valve for switching the refrigerant flow to the second connection pipe side; When the temperature rises, if the discharge temperature detected by the discharge temperature detecting means provided between the compressor and the switching valve for switching the refrigerant flow is higher than a predetermined temperature, the third And the control means for increasing the valve opening of at least one of the fourth flow control device by a predetermined amount is provided. Further, the compressor can be prevented from being damaged due to an excessive rise in the winding temperature of the compressor driving motor due to an increase in the discharge temperature.

[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 flowchart showing an operation of the control device of the air conditioner according to Embodiment 1 of the present invention.

FIG. 3 is an overall configuration diagram centering on a refrigerant system of an air conditioner according to Embodiment 2 of the present invention.

FIG. 4 is an overall configuration diagram mainly showing a refrigerant system of a conventional air conditioner.

FIG. 5 is a refrigerant circuit diagram for explaining an operation state of only cooling or heating of the conventional air conditioner.

FIG. 6 is a refrigerant circuit diagram for explaining an operating state mainly of heating of the conventional air conditioner.

FIG. 7 is a refrigerant circuit diagram for describing an operating state mainly of cooling of the conventional air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way switching valve 3 Heat source unit side heat exchanger 4 Accumulator 5 Indoor side heat exchanger 6, 6b, 6c, 6d First connection pipe 7, 7b, 7c, 7d Second connection pipe 9 First Flow control device 10 First branch portion 11 Second branch portion 13 Second flow control device 14 Bypass pipe 15 Third flow control device 16a, 16b, 16c, 16d, 19 Heat exchange section 17 Fourth flow control Apparatus 19 First heat exchange section 40 Flow path switching apparatus 42 Discharge temperature detecting means A Heat source unit B, C, D Indoor unit E Repeater

──────────────────────────────────────────────────続 き Continuing on 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 Shigeo Takada 6-5-6, Tehira, Wakayama City Mitsubishi Electric Wakayama Works, Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 29/00 361 F25B 13/00 104

Claims (1)

(57) [Claims] 1. One heat source unit comprising a compressor, a switching valve for switching a refrigerant flow, a heat source unit side heat exchanger, etc., and a plurality of indoor units comprising an indoor side heat exchanger, a first flow control device, etc. 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 switchable first branch unit and the other of the indoor heat exchangers of the plurality of indoor units are connected to the second connection pipe via the first flow control device. A second branch and a second connection pipe connected to the heat source unit, the second connection pipe being provided on the side of the second branch section of a pipe that branches and connects to the first branch section and the second branch section. Flow control device, and a fourth flow control device provided in a pipe connecting the second branch portion and the first connection pipe. And a bypass pipe having one end connected to the second branch portion and the other end connected to the first connection pipe via a third flow control device, wherein the heat source device side heat exchange is provided. During operation in which the condenser becomes a condenser, the refrigerant flows only from the refrigerant outlet side of the condenser to the second connection pipe side, and the refrigerant flows only from the first connection pipe to the switching valve side that switches the refrigerant flow. During the operation in which the heat is passed and the heat source unit side heat exchanger becomes an evaporator, the first
The refrigerant is circulated only from the connection pipe of the evaporator to the refrigerant inflow side of the evaporator, and the switching valve for switching the refrigerant flow is connected to the refrigerant valve.
A flow path switching device that allows the refrigerant to flow only on the side of the connection pipe 2 is provided, and a discharge temperature detected by discharge temperature detecting means provided between the compressor and the switching valve for switching the refrigerant flow is preset. Control means for increasing a valve opening of at least one of the third and fourth flow control devices by a predetermined amount when the temperature is higher than the predetermined temperature. apparatus.