JPH10281576A - Multizone heat pump type air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent low gas state of an outdoor unit during operating by providing a switching valve closed during the suspension of operation between a receiver and an outdoor heat exchanger. SOLUTION: A receiver 12 is interleaved in a liquid refrigerant line 30 connected to an outdoor heat exchanger 4 of each outdoor unit, and a switching valve 31 for closing at the time of pausing an outdoor unit is interposed between the receiver 12 and the exchanger 4. When the outdoor unit is paused due to reduction of an air conditioning load, the valve 31 is closed. Hence, liquid refrigerant from the outdoor unit during operating is reserved in the receiver 12 via a connecting liquid tube 8, liquid operating valve 13 and liquid refrigerant line 30, but not reserved in the exchanger 4, accumulator 18 and compressors 1, 3 of a rear stream side of the valve 31. Accordingly, low gas state of the outdoor unit during operation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type heat pump type air conditioner having a plurality of outdoor units.

[0002]

2. Description of the Related Art An example of a conventional multi-type heat pump type air conditioner is shown in FIG. A plurality of (two in the figure) compressors 1, 2, a four-way switching valve 3, a plurality of (two in the figure) outdoor units A and B are respectively provided.
The outdoor heat exchanger 4, the accumulator 18 and the like are mounted. An indoor heat exchanger 5 and the like are mounted on a plurality of indoor units P and Q (only two are shown in the figure).

The plurality of outdoor units A,
B and the plurality of indoor units P and Q are connected in parallel via a connecting gas pipe 7 and a connecting liquid pipe 8, respectively.

[0004] During the cooling operation of the air conditioner,
The high-temperature and high-pressure gas refrigerant discharged from the compressors 1 and 2 of each of the outdoor units A and B passes through the check valves 9 and 10 and the four-way switching valve 3 to the outdoor heat exchanger 4 as shown by solid arrows. It enters and condenses and liquefies by exchanging heat with the outside air.

The liquid refrigerant enters the connecting liquid pipe 8 via the check valve 11 and the liquid-side operation valve 13 and joins there, and then flows into the indoor units P and Q via the liquid-side operation valve 14. After adiabatic expansion in the process of flowing through the cooling expansion valve 15, the air enters the indoor heat exchanger 5, where the indoor air is cooled to evaporate.

The gas refrigerant enters the connecting gas pipe 7 via the gas-side operation valve 16 and merges there, then flows into each of the outdoor units A and B via the gas-side operation valve 17, and the four-way switching valve 3, the accumulator 18 After that, it is branched and drawn into the compressors 1 and 2.

During the heating operation of the air conditioner, the four-way switching valve 3 is switched in the opposite direction, so that the refrigerant discharged from the compressors 1 and 2 receives the check valve 9,
10, the four-way switching valve 3, the gas-side operation valve 17, the connecting gas pipe 7, and the gas-side operation valve 16, enter the indoor heat exchanger 5 of each indoor unit P, Q, and condense by releasing heat to indoor air here. Liquefy.

The liquid refrigerant enters the outdoor units A and B via the check valve 6, the liquid-side operation valve 14, the connecting liquid pipe 8, and the liquid-side operation valve 13, and flows through the heating expansion valve 19. After adiabatic expansion, the heat enters the outdoor heat exchanger 4 and absorbs heat from outside air to evaporate. Next, the gas refrigerant is sucked into the compressors 1 and 2 via the four-way switching valve 3 and the accumulator 18.

[0009]

In the conventional air conditioner described above, when a part of the plurality of outdoor units A and B, for example, B is stopped due to a decrease in the air conditioning load, the liquid refrigerant is connected to the connection liquid. The liquid flows into the inactive outdoor unit B from the pipe 8 via the liquid control valve 13 and accumulates in the liquid refrigerant line 30, the outdoor heat exchanger 4, the accumulator 18, the compressors 1 and 2, etc. There is a problem that a so-called gas-low state such as a decrease in the pressure of the high-pressure refrigerant and the low-pressure refrigerant and an increase in the degree of superheat is caused by an insufficient amount of the refrigerant returning to the outdoor unit A.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the gist of the first invention is to provide at least a compressor, a four-way switching valve, and an outdoor heat exchanger. In a multi-type heat pump type air conditioner in which a plurality of outdoor units equipped with an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe,
A multi-function device, comprising a receiver installed in a liquid refrigerant line connected to the outdoor heat exchanger of each of the outdoor units, and an on-off valve that closes when operation is stopped between the receiver and the outdoor heat exchanger. In the heat pump type air conditioner.

The gist of the second invention is that a plurality of outdoor units each including at least a compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe. In the multi-type heat pump type air conditioner, the discharge pipe and the suction pipe of the compressor of each of the outdoor units are connected by a bypass circuit having a bypass valve, and the gas flow of the outdoor unit during the cooling operation is operated. When the condition is detected, the outdoor heat exchanger is opened by opening the bypass valve of the inactive outdoor unit,
The multi-type heat pump type air conditioner is characterized in that the refrigerant accumulated inside the accumulator or the like is recovered to the outdoor unit during operation through the suction pipe, the bypass circuit, the discharge pipe, the four-way switching valve, and the connecting gas pipe. is there.

The gist of the third invention is that a plurality of outdoor units each having at least a compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe. In the multi-type heat pump type air conditioner connected to the above, when the suction pipes of the respective outdoor units are connected by a refrigerant recovery circuit having a recovery valve, and a gas low state of the operating outdoor unit is detected during the heating operation. Opening the recovery valve and recovering the refrigerant accumulated inside the outdoor heat exchanger, accumulator, and the like of the outdoor unit that is inactive, via the suction pipe and the refrigerant recovery circuit, to the outdoor unit that is operating. Multi-type heat pump type air conditioner.

Another feature is that the discharge pipe and the suction pipe of the compressor of the outdoor unit are connected by a bypass circuit having a bypass valve, and the bypass valve is opened at the same time as the recovery valve to open. The refrigerant collected in the discharge gas line of the outdoor unit is recovered to the operating outdoor unit via the bypass circuit, the suction pipe, and the refrigerant recovery circuit.

The gist of the fourth invention is that a plurality of outdoor units each including at least a compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe. In the multi-type heat pump type air conditioner connected to the above, an inter-unit oil equalizing pipe having an oil equalizing valve communicating the oil sump of the compressor of each outdoor unit with each other, and a discharge pipe of the compressor of each outdoor unit. And a refrigerant recovery circuit having a recovery valve connected between the suction pipe of the compressor of each of the outdoor units and the oil equalizing pipe between the units. When the gas-low state of the outdoor unit during operation is detected during the heating operation, the oil equalizing valve, the recovery valve and the bypass valve are opened and the outdoor heat exchanger of the outdoor unit that is inactive and A multi-type heat pump type air conditioner characterized in that refrigerant accumulated in an accumulator and a discharge gas line is recovered to an operating outdoor unit through the bypass circuit, a suction pipe, a refrigerant recovery circuit and an oil equalizing pipe between units. It is in.

Another feature is that a bypass circuit having a bypass valve connected between a discharge pipe and a suction pipe of the compressor is also used as a capacity control hot gas bypass circuit.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIG. In the first embodiment, a liquid refrigerant line 30 connected to the outdoor heat exchanger 4 of each outdoor unit is provided.
The receiver 12 is interposed therein, and an on-off valve 31 that is closed between the receiver 12 and the outdoor heat exchanger 4 when the operation of the outdoor unit is stopped is interposed.

The capacity of the receiver 12 is such that the reference refrigerant amount required for the outdoor unit can be stored. Other configurations are the same as the conventional one shown in FIG.
Corresponding members have the same reference characters allotted, and description thereof will not be repeated.

When the outdoor unit is stopped due to a decrease in the air-conditioning load or the like, the on-off valve 31 is closed.
The liquid refrigerant from the outdoor unit during operation accumulates in the receiver 12 through the connection liquid pipe 8, the liquid operation valve 13, and the liquid refrigerant line 30, but the outdoor heat exchanger 4 on the downstream side of the on-off valve 31 and the accumulator 18 Does not accumulate inside the compressors 1, 2 and the like.

Thus, the reference amount of the liquid refrigerant can be stored in the suspended indoor unit. However, since an excessive amount of the liquid refrigerant can be prevented from being stored, the gas low operation and the overcharge operation of the operating outdoor unit can be prevented. (Operation in a state where the refrigerant amount is excessive) can be prevented.

A second embodiment of the present invention is shown in FIG. In the second embodiment, a bypass circuit 27 is connected between a discharge pipe 32 and a suction pipe 33 of the compressors 1 and 2 of each outdoor unit. The bypass circuit 27 includes a bypass valve 28 and a fixed throttle 29. Is interposed.

The discharge pipe temperature sensor 34 for detecting the temperature of the gas refrigerant discharged from the compressors 1 and 2 detects the gas low state. In addition, the compressor 1
Alternatively, the gas low state can be detected by detecting the temperature or pressure of the gas refrigerant sucked into 2. The other configuration is the same as that of the conventional one shown in FIG. 5, and the corresponding members are denoted by the same reference numerals and description thereof will be omitted.

However, during the cooling operation of the air conditioner, when some of the outdoor units are stopped due to a decrease in the cooling load, etc., the liquid refrigerant line 30, the outdoor heat exchanger 4, the accumulator 18, and the compressor 1 of the outdoor unit are operated. The liquid refrigerant accumulates inside the second and the like.

As a result, when a gas low state occurs in the outdoor unit during operation, a discharge pipe temperature sensor detecting the gas low state is detected.
The bypass valve 28 of the paused outdoor unit is opened by a signal from 34.

Then, the liquid refrigerant accumulated inside the outdoor heat exchanger 4, the accumulator 18, etc. of the suspended outdoor unit gradually evaporates, enters the suction pipe 33, and enters the bypass circuit 33.
The fluid enters a discharge pipe 32 through a fixed throttle 29 and a bypass valve 28 interposed therebetween.

Then, the compressors 1, 2 of the outdoor unit being operated via the four-way switching valve 3, the gas control valve 17, and the connecting gas pipe 7.
Therefore, the refrigerant is recovered in the outdoor unit during operation, and the gas-low state can be eliminated.

When the bypass valve 28 is opened during the operation of the compressors 1 and 2, a part of the gas refrigerant discharged from the compressors 1 and 2 is partially discharged to the bypass circuit 27 and the bypass valve interposed in the bypass circuit 27.
Since it flows into the suction pipe 33 via the fixed throttle 29, the capacity of the compressors 1 and 2 can be reduced.

A third embodiment of the present invention is shown in FIG. In the third embodiment, the outdoor unit A
A refrigerant recovery circuit 36 is provided to connect the suction pipe 33 of the outdoor unit B to the suction pipe 33 of the outdoor unit B. The refrigerant recovery circuit 36 is provided with a recovery valve 37. The other configuration is the same as that of the second embodiment shown in FIG. 2, and the corresponding members are denoted by the same reference numerals and description thereof will be omitted.

When a part of the outdoor unit, for example, B is stopped during the heating operation of the air conditioner due to a decrease in the heating load or the like, the liquid refrigerant accumulates inside the outdoor heat exchanger 4, the accumulator 18, and the like. At the same time, the gas refrigerant in the discharge gas line from the check valves 9 and 10 through the discharge pipe 32 and the four-way switching valve 3 to the gas-side operation valve 17 is liquefied and stored as liquid refrigerant.

As a result, when the outdoor unit A in operation is in the gas low state, a signal from the discharge temperature sensor 34 which detects the gas-low state detects a recovery valve 37 provided in the refrigerant recovery circuit 36.
Is opened and the bypass valve 28 of the suspended outdoor unit B is opened, so that the liquid refrigerant accumulated in the discharge gas line passes through the bypass circuit 27 and the bypass valve interposed in the bypass circuit 27.
28, enters the suction pipe 33 via the fixed throttle 29.

The liquid refrigerant accumulated in the outdoor heat exchanger 4, the accumulator 18 and the like of the suspended outdoor unit B also enters the suction pipe 33, and the refrigerant recovery circuit 37 and the recovery valve interposed in the refrigerant recovery circuit 37 37, the refrigerant enters the suction pipe 33 of the operating outdoor unit A, and is sucked into the operating compressors 1 and 2 through the accumulator 18, so that the refrigerant is recovered in the operating outdoor unit and its gas low state. Can be eliminated.

A fourth embodiment of the present invention is shown in FIG. In the fourth embodiment, oil equalizing pipes 20 communicating with oil reservoirs formed at the bottoms of the housings of the compressors 1 and 2 are provided, and the oil equalizing pipes 20 of the outdoor units A and B are provided.
Are connected to each other via an inter-unit oil level pipe 21.
An oil leveling valve 22 and an oil operation valve 23 are interposed in the inter-unit oil leveling pipe 21.

The inter-unit oil equalizing pipe 21 is connected to a suction pipe 33 via a refrigerant recovery circuit 38, and a recovery valve 39 is interposed in the refrigerant recovery circuit 38. The other configuration is the same as that of the second embodiment shown in FIG. 2, and the corresponding members are denoted by the same reference numerals and description thereof will be omitted.

When a part of the outdoor unit, for example, B is stopped during the heating operation of the air conditioner due to a decrease in the heating load or the like, the liquid refrigerant accumulates inside the outdoor heat exchanger 4, the accumulator 18, and the like. At the same time, the gas refrigerant in the discharge gas line extending from the check valves 9 and 10 through the discharge pipe 32 and the four-way switching valve 3 to the gas-side operation valve 17 is liquefied and stored as a liquid refrigerant.

As a result, when the outdoor unit A in operation is in a gas low state, the discharge pipe temperature sensor 34 which detects this state is detected.
The oil equalizing valve 22 and the recovery valve 39 and the bypass valve 28 of the inactive outdoor unit B are opened by the signal from the controller, so that the liquid refrigerant accumulated in the discharge gas line is interposed in the bypass circuit 27 and the bypass circuit 27. The gas enters the suction pipe 33 via the bypass valve 28 and the fixed throttle 29.

Further, since the oil leveling valve 22 and the recovery valve 39 are opened, the liquid refrigerant accumulated inside the outdoor heat exchanger 4, the accumulator 18, etc. of the outdoor unit B at rest also sucks the suction pipe.
33, flows into the compressors 1 and 2 of the outdoor unit A in operation through the refrigerant recovery circuit 38 and the inter-unit oil equalizing pipe 21,
Since the refrigerant is recovered in the outdoor unit A during the operation, the gas low state can be eliminated.

[0036]

According to the first aspect of the present invention,
When a part of the plurality of outdoor units is stopped, the liquid refrigerant flows into the stopped outdoor unit, but since the on-off valve is closed, the liquid refrigerant may accumulate in the outdoor heat exchanger or the accumulator. Therefore, the gas-low state of the outdoor unit during operation can be prevented.

Since the on-off valve is provided between the receiver and the outdoor heat exchanger, the liquid refrigerant flowing into the suspended outdoor unit can be stored in the receiver. If the size of the refrigerant can be stored, the outdoor unit during operation can be prevented from being overcharged.

According to the second aspect of the present invention, when a part of the plurality of outdoor units is stopped during the cooling operation, the operation is performed by accumulating the liquid refrigerant in the outdoor heat exchanger or the accumulator. When the outdoor unit is in a gas low state, the bypass valve of the suspended outdoor unit opens, so that the liquid refrigerant accumulated in the outdoor heat exchanger or the accumulator gradually enters the discharge pipe through the suction pipe and the bypass circuit, The gas is recovered by the outdoor unit during operation via the four-way switching valve and the connecting gas pipe, so that the gas low state of the outdoor unit can be eliminated.

In the third aspect of the present invention, when a part of the plurality of outdoor units is stopped during the heating operation, the liquid refrigerant is accumulated in the outdoor heat exchanger or the accumulator of the stopped outdoor unit. When the outdoor unit in operation becomes gas-low due to this, the recovery valve opens, so that the liquid refrigerant accumulated in the outdoor heat exchanger and accumulator of the outdoor unit that is inactive is gradually sucked into the suction pipe and refrigerant recovery. By being sucked into the suction pipe of the operating outdoor unit via the circuit, it is recovered by this outdoor unit and, therefore, its gas low state can be eliminated.

If the discharge pipe and the suction pipe of the compressor of the outdoor unit are connected by a bypass circuit having a bypass valve, and the bypass valve is opened at the same time as the recovery valve, the accumulation in the discharge gas line of the suspended outdoor unit is achieved. The introduced refrigerant can be recovered to the outdoor unit during operation via the bypass circuit, the suction pipe, and the refrigerant recovery circuit.

According to the fourth aspect of the present invention, when a part of the plurality of outdoor units is suspended during the heating operation, the outdoor heat exchanger, the accumulator, and the discharge gas line of the suspended outdoor unit are installed. When the outdoor unit during operation becomes gas low due to accumulation of liquid refrigerant,
Since the oil equalizing valve, the recovery valve, and the bypass valve are opened, the liquid refrigerant that has accumulated in the discharge gas line of the suspended outdoor unit enters the suction pipe via the bypass circuit and the bypass valve, and the outdoor heat exchanger and The liquid refrigerant accumulated in the accumulator gradually enters the suction pipe, and then enters the compressor of the operating outdoor unit through the refrigerant recovery circuit and the oil equalizing pipe between the units. Can be eliminated.

If the bypass circuit having the bypass valve connected between the discharge pipe and the suction pipe of the compressor is also used as the hot gas bypass circuit for controlling the capacity, the bypass valve is opened during the operation of the compressor. Since a part of the gas refrigerant discharged from the compressor can flow into the suction pipe via the bypass circuit and the bypass valve, the capacity of the compressor can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of an outdoor unit according to a first embodiment of the present invention.

FIG. 2 is a system diagram of an outdoor unit according to a second embodiment of the present invention.

FIG. 3 is a system diagram of an outdoor unit according to a third embodiment of the present invention.

FIG. 4 is a system diagram of an outdoor unit according to a fourth embodiment of the present invention.

FIG. 5 is a system diagram of a conventional multi-type heat pump air conditioner.

[Explanation of symbols]

 A, B Outdoor unit 1, 2 Compressor 3 Four-way switching valve 4 Outdoor heat exchanger 18 Accumulator 7 Connecting gas pipe 8 Connecting liquid pipe 30 Liquid refrigerant line 31 On-off valve 12 Receiver

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Toyotaka Hirao 1 Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya-shi Nagoya Research Laboratory, Mitsubishi Heavy Industries, Ltd.

Claims (6)

[Claims] 1. A multi-type heat pump system in which a plurality of outdoor units each including at least a compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe. In the air conditioner, a receiver is installed in a liquid refrigerant line connected to the outdoor heat exchanger of each of the outdoor units, and an on-off valve that closes when operation is stopped is provided between the receiver and the outdoor heat exchanger. Multi-type heat pump type air conditioner characterized by the following. 2. A multi-type heat pump system in which a plurality of outdoor units including at least a compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe. In the air conditioner, the discharge pipe and the suction pipe of the compressor of each of the outdoor units are connected by a bypass circuit having a bypass valve, and when a gas low state of the operating outdoor unit is detected during the cooling operation, the air conditioner is stopped. Open the bypass valve of the outdoor unit of the outdoor heat exchanger, the refrigerant accumulated inside the accumulator, etc. the suction pipe, bypass circuit, discharge pipe,
A multi-type heat pump type air conditioner characterized in that the air is recovered to an operating outdoor unit via a four-way switching valve and a connecting gas pipe. 3. A multi-type heat pump system in which a plurality of outdoor units including at least a compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe. In the air conditioner, the suction pipes of each of the outdoor units are connected by a refrigerant recovery circuit having a recovery valve, and when the gas low state of the outdoor unit being operated is detected during the heating operation, the recovery valve is opened and stopped. A multi-type heat pump type air conditioner characterized in that the refrigerant accumulated inside an outdoor heat exchanger, an accumulator and the like of the outdoor unit is recovered to the outdoor unit during operation via the suction pipe and the refrigerant recovery circuit. 4. A discharge gas line of the outdoor unit which is inactive by connecting a discharge pipe and a suction pipe of the compressor of the outdoor unit by a bypass circuit having a bypass valve and opening the bypass valve simultaneously with the recovery valve. 4. The multi-type heat pump type air conditioner according to claim 3, wherein the refrigerant accumulated in the air conditioner is recovered through the bypass circuit, the suction pipe, and the refrigerant recovery circuit to the outdoor unit in operation. 5. A multi-type heat pump system in which a plurality of outdoor units each including at least a compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are connected in parallel via a connecting gas pipe and a connecting liquid pipe. In the air conditioner, an inter-unit oil leveling pipe having an oil leveling valve communicating the oil sump of the compressor of each outdoor unit with each other, and a discharge pipe and a suction pipe of the compressor of each outdoor unit are connected. A bypass circuit having a bypass valve, and a refrigerant recovery circuit having a recovery valve connected between the suction pipe of the compressor of each outdoor unit and the oil equalizing pipe between the units. When the gas low state of the unit is detected, the oil equalizing valve, the recovery valve and the bypass valve are opened to open the outdoor heat exchanger, the accumulator, and the discharge gas of the outdoor unit at rest. The bypass circuit refrigerant elaborate reservoir within in-intake pipes, multi-type heat-pump air conditioner and recovering the outdoor unit in operation through the refrigerant recovery circuit and unit HazamaHitoshi Aburakan. 6. A hot gas bypass circuit for controlling a capacity, wherein a bypass circuit having a bypass valve connected between a discharge pipe and a suction pipe of the compressor is also used. The multi-type heat pump air conditioner as described in the above.