JPS6334385B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pump type multi-room air-conditioning/heating system in which a plurality of indoor units are connected by refrigerant piping to one outdoor unit to perform air-conditioning and heating.

Generally, in this type of air-conditioning and heating apparatus, when a small number of units are operated during heating, refrigerant is required only for the operation of a small number of units, so there is a surplus of refrigerant and the high pressure rises too much, making operation impossible. Therefore, a method has been proposed to deal with this by storing the surplus refrigerant in a unit that is not in use.However, when storing this surplus refrigerant in a unit that is not in use, the air flow to the indoor coil is relatively low, as in a floor-standing package air conditioner. If it is a good refrigerant, it can be stored as a liquid refrigerant, but if the airflow is poor, such as in a ceiling-hanging type air conditioner, it is difficult to change from a gaseous refrigerant and it cannot be stored. Therefore, when operating a small number of units, a bypass circuit with a refrigerant adjustment tank must be installed to store excess refrigerant. When switching from operation to multi-unit operation, the required amount of refrigerant could not be secured, and a temporary gas shortage occurred until the refrigerant returned from the tank to the system, making it impossible to achieve its capacity. It is possible that the system may malfunction and start unnecessary defrost operation.

The present invention has been made with the aim of eliminating the gas shortage phenomenon when a system having such a refrigerant adjustment tank transitions from a small number of units operation to a multiple unit operation during heating, and an example thereof is attached below. This will be explained according to the drawings.

In the figure, 1 is an outdoor unit, 2a and 2b are indoor units, and 3 is a piping branch unit, which are connected in a ring to form a heat pump air-conditioning system. That is, a compressor 4, an outdoor coil 5, a four-way valve 6, an accumulator 7, a heating capillary tube 8, a check valve 9, and a receiver tank 10 are connected to the outdoor unit 1 as shown in the figure. Also 1
Reference numeral 1 indicates a large number of capillary tubes arranged in parallel to evenly distribute refrigerant to the outdoor coil 5, and reference numeral 12 indicates a check joint conduit connected to a pipe section that is at high pressure during cooling operation and at low pressure during heating operation, and is normally operated. It is used for pressure checking, but here it is used for draining liquid. Further 13, 14,
15 is a service valve connected to the piping branch unit 3. Next, the piping branch unit 3 and indoor units 2a and 2b will be explained. 16 is a gas pipe connected to the service valve 14, and branch point 1
7, the solenoid valves 18a and 19b and the check valve 19, respectively.
The gas side branch pipe 20 is connected to the gas side branch pipe 20 via the parallel circuit of a and 18b.
a, 20b, these branch pipes 20a, 20b
are connected to the indoor coils 21a, 21b of the indoor units 2a, 2b, respectively. Indoor unit 2
The coils 21a and 21b of coils a and 2b are connected to liquid side branch pipes 23a and 23b via indoor capillary tubes 22a and 22b, and are connected to liquid side reversible flow type on-off solenoid valves 24a and 24b in the branch unit 3. Ru. The electromagnetic valves 24a and 24b merge at a branch point 25 to form a liquid pipe 26, which is connected to the service valve 13. Reference numeral 27 denotes a bypass electromagnetic valve during single-room cooling operation, which is installed via a capillary tube 28 between the liquid pipe 26 that becomes high-pressure liquid during cooling and the gas pipe 16 that becomes low-pressure gas. In other words, in this bypass circuit, although the capillary tubes 22a and 22b are properly set during operation in two cooling rooms, when operating in one room, the entire system becomes over-throttled due to its characteristics, and the discharge temperature of the compressor 4 increases. This is a liquid bypass circuit that prevents 29 is a bypass solenoid valve that opens during heating operation, and is a pressure regulating valve 2.
9', a refrigerant adjustment tank 30, a gas side capillary tube 31 communicating with the gas layer part of this tank 30, and a liquid side capillary tube 3 communicating with the liquid layer part.
A liquid pipe 26 forms a series circuit with a parallel circuit of 2 and a check valve 33, and one end becomes a high-pressure liquid during heating operation.
A first bypass circuit is configured to connect the service valve 15 connected to the pipe line 12 on the low-pressure suction side. That is, by opening the valve 29, the pressure regulating valve 29' senses the pressure, and while adjusting its opening degree, liquid refrigerant is drawn out from the liquid pipe 26 and guided to the tank 30, where it is stored. The refrigerant is gradually returned to the low pressure side via the liquid side capillary tube 32, the check valve 33, and the valve 15 while adjusting the amount of gas inside the refrigerant. Furthermore, in parallel with the liquid side capillary tube 32, there is provided a refrigerant regulating circuit 36 consisting of a capillary tube 34 having a sufficiently lower resistance than the capillary tube 32, and a solenoid valve 35 which is opened during multi-room operation. That is, when operating a small number of indoor units, the liquid side capillary tube 32 is set to gradually return the refrigerant stored in the tank 30 into the system, but when switching to operation of a large number of indoor units, the liquid side capillary tube 32 is set to immediately return the required amount of refrigerant to the system. In case of gas shortage due to failure, the solenoid valve 35 is opened to quickly return the gas to the system via the capillary tube 34. The above bypass circuit includes a capillary tube 37 that drains liquid from the tank 30 during cooling operation because the pipe line 12 is at high pressure during cooling, and a gas pipe whose check valve 38 connects to the bottom of the tank 30 to provide low-pressure gas during cooling. 16. In addition, when operating a single heating room, one of the solenoid valves 18a, 19b, 24a, and 24b is closed, but since all valves are under high pressure, refrigerant leaks and the inside of the indoor unit on the idle side is closed. Refrigerant may accumulate unnecessarily in the refrigeration cycle, causing trouble in the operation of the refrigeration cycle. Therefore, a check valve 39a is installed between the liquid side branch pipes 23a, 23b of each unit 2a, 2b and the upper part of the refrigerant adjustment tank 30. ,39
b. A second bypass circuit consisting of capillary tubes 40a and 40b is provided. This second bypass circuit is further provided with a third bypass circuit 41 that applies pressure from the gas pipe 16, which becomes high-pressure gas during heating, between the check valves 39a, 39b and the capillary tubes 40a, 40b. ing. This third bypass circuit 41 is connected to the check valves 39a, 3
A capillary tube 42 is interposed between the capillary tube 9b and the capillary tubes 40a and 40b to reduce the pressure to such an extent that excessive pressure is not applied and completely prevents liquid drainage.

Next, the operation and effects of the above configuration will be explained.

(i) During cooling two-room operation...The four-way valve 6 is switched so that the indoor coil 5 becomes a condenser and the indoor coils 21a and 21b become an evaporator, and the solenoid valve 24
a, 24b, 18a, and 19b are opened respectively.

(ii) When operating a single air conditioner...For example, indoor unit 2
In operation a, the solenoid valves 24b and 19b are closed,
In addition, the bypass solenoid valve 27 is opened to perform operation while preventing an increase in discharge pressure. In addition, in the cooling operation of (i) and (ii) above, the pressure in the pipe line 12 becomes high, so the first
The second bypass circuit is inactive.

(iii) During two-room heating operation......The four-way valve 6 is switched so that the outdoor coil 5 becomes the evaporator and the indoor coils 21a and 21b become the condensers, and the solenoid valve 24
a, 24b, 18a, 19b and solenoid valve 29
open and close respectively. On the other hand, the pipe line 12 is on the low pressure suction side, and the liquid side branch pipes 23a and 23b are connected to the low pressure through the second bypass circuit and the first bypass circuit, but the flow is blocked by the gas pressure applied by the third bypass circuit 41. There is almost no reduction in performance. Furthermore, at this time, the refrigerant adjustment circuit 36
The solenoid valve 35 opens, and the liquid refrigerant in the tank 30 flows to the low pressure side not only through the liquid side capillary tube 32 but also through the capillary tube 34. This is to quickly return the stored refrigerant to the system and operate the system, as when switching from a closed state to two-chamber operation. This can eliminate the gas shortage phenomenon during two-chamber operation.

(iv) When heating a single room...For example, indoor unit 2
In operation a, the solenoid valves 24b and 19b are closed,
And the solenoid valve 29 of the first bypass circuit opens.
In other words, the indoor coil 21 acts as a condenser.
The capacity of a is relatively reduced (compared to two-chamber operation)
Pressure regulating valve 2
9' senses the inflow of refrigerant into the tank 30.
It is controlled by the refrigerant liquid reservoir. On the other hand, inside the indoor unit 2 on the stop side (coil 2
The liquid side branch pipe 23b is communicated with the tank 30 through a second bypass circuit so that the refrigerant does not accumulate unnecessarily in the inside of the pipe 20b, etc.) and interfere with the operation of the refrigeration cycle. Although a predetermined pressure is applied to this bypass circuit by the third bypass circuit 41, as the operation continues, the liquid in the unit 2b is gradually drained and accumulation of liquid refrigerant is prevented. Furthermore, this second
Since the bypass circuit does not communicate directly with the pipe line 12 but via the tank 30, it is unlikely that the refrigerant in the tank 30 cannot be returned due to a difference in pressure balance.

As is clear from the above explanation, according to the present invention, when a small number of heaters are operated, the amount of refrigerant returned from the refrigerant adjustment tank that stores surplus refrigerant is increased by the refrigerant adjustment circuit when a large number of heaters are operated. This eliminates gas shortages when multiple units are operated, allowing them to quickly and fully utilize their capabilities, and also eliminates system malfunctions due to gas shortages.

[Brief explanation of the drawing]

The drawing is a refrigeration cycle diagram of a heat pump type multi-room air conditioning system according to an embodiment of the present invention. 1...Outdoor unit, 2a, 2b...Indoor unit, 12...Low pressure suction pipe, 26...High pressure liquid pipe,
29... Valve, 30... Refrigerant adjustment tank, 31...
Gas side capillary tube, 32... Liquid side capillary tube, 29, 30, 31, 32, 33...
...bypass circuit, 36...refrigerant adjustment circuit.

Claims (1)

[Claims] 1. In systems that perform heating and cooling by connecting multiple indoor units to one outdoor unit with refrigerant piping, a valve that is opened during heating operation between the high-pressure liquid pipe and the low-pressure suction pipe during heating operation, A bypass circuit is provided in which parallel circuits of a refrigerant adjustment tank for storing excess refrigerant, a gas side capillary tube communicating with the gas layer of this tank, and a liquid side capillary tube communicating with the liquid layer of the tank are connected in series. , a heat pump comprising a refrigerant adjustment circuit that is arranged in parallel with the liquid side capillary tube and includes a valve that opens in conjunction with control to increase the number of operating indoor units, and a capillary tube that has a lower resistance than the liquid side capillary tube. Multi-room air conditioning system.