JPS586857B2 - Air conditioning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Conventionally, multi-room air conditioning systems use temperature-type (or constant-pressure type) automatic expansion valves to control the refrigerant flow rate, as shown in FIG. The outdoor unit had a dedicated structure.

That is, in FIG. 1, 1 indicates the outdoor units 2a, 2
b is an indoor unit, each having a pair of refrigerant gas pipes 3a and 3b.
, are mutually connected by refrigerant liquid pipes 4a and 4b.

The refrigerant discharged from the compressor 5 passes through a four-way valve 6 during heating operation through a refrigerant gas pipe 7, branches into multiple paths at a branch point 8, and is connected to a gas side reversible flow solenoid valve (or a solenoid valve with a built-in check valve). The refrigerant gas passes through 9a and 9b and is guided to the indoor units 2a and 2b from the refrigerant gas pipes 3a and 3b.

The refrigerant heat-radiated and condensed by the indoor heat exchangers 10a and 10b bypasses the indoor expansion valves 11a and 1lb used during cooling operation and passes through the check valves 12a and 12b installed in parallel. Coolant liquid pipes 4a, 4b
Then return to the outdoor unit 1 again and close the liquid side reversible flow solenoid valve (
or a solenoid valve with a built-in check valve) Branch point 14 from 13a and 13b
The refrigerant flows through the refrigerant liquid pipe 15 and receiver 16, expands under reduced pressure at the heating expansion valve 1T, absorbs heat at the outdoor heat exchanger 18, passes through the four-way valve 6, and returns to the compressor 5 from the accumulator 19. It gets sucked in.

20 and 21 are a high pressure control valve and a pipe line during heating overload operation.

The operation of the circuit during two-room heating operation has been explained above, but in one-room operation, for example, if the indoor unit 2b is not used, the gas side reversible flow solenoid valve 9b and the liquid side reversible flow solenoid valve 13b should be closed. This enables single-room operation.

In this case, the refrigerant that remains in the piping on the indoor unit 2b side that is stopped or that has entered the piping due to leakage from the closed gas side reversible flow solenoid valve 9b or liquid side reversible flow solenoid valve 13b is transferred to the low pressure side. A conduit 22b consisting of a check valve 23b and a capillary tube 24b for suction is installed between the refrigerant liquid pipe 4b and the side of the heating expansion valve 17 that is at low pressure during heating.

That is, the inside of the stop-side unit is maintained at a low pressure (suction-side pressure) to prevent liquid accumulation.

Note that 23a and 24a are check valves and capillary tubes for other indoor units 2a, and 25 is a check valve installed so as to bypass the heating expansion valve 17 during cooling operation.

However, the conventional multi-room air conditioning system having such a configuration has the following problems.

([) Since the expansion valve method is adopted, there is a problem with the stability of the operation of the expansion valve.

(Uneven settings during manufacturing, aging, and clogging.

) (11) It is easy to create an even balance in capacity between the two chambers by uniformly setting and operating the expansion valves.

(Surface) Even if a distributor is provided when a plurality of refrigerant flow paths are provided in a heat exchanger, imbalance in refrigerant distribution tends to occur, making it difficult to fully utilize the entire surface of the heat exchanger.

(1) Due to the structure, it is necessary to manufacture a dedicated outdoor unit, making it difficult to create a series of models.

(v) Since an expansion valve is used, the cost is high.

In particular, the reliability of expansion valves and the mutual imbalance in heat exchanger flow paths when a large number of them are used in parallel are major problems in multi-room air conditioning systems.

The present invention has been made to solve these problems.

As a configuration for this purpose, the present invention includes a capillary tube for controlling the refrigerant flow rate of the refrigeration cycle, and a high-pressure gas pipeline and an indoor unit during heating operation of an air-conditioning system in which capillary tubes are provided in each of the indoor unit and the outdoor unit. In addition to the pair of medium-pressure liquid pipes leading from the unit to the outdoor unit, a low-pressure suction line is provided that communicates with the pipe that becomes low-pressure during heating operation, and when the number of indoor units in operation during heating operation is reduced, the high-pressure gas a first bypass circuit branching from the pipeline and bypassing the low pressure suction line or the medium pressure liquid pipeline; and a second bypass circuit branching from the medium pressure liquid pipeline and bypassing the low pressure suction line. A receiver tank and a capillary tube for controlling outflow of refrigerant from the receiver tank are provided in the second bypass circuit.

The present invention will be explained below with reference to FIG. 2 showing one embodiment thereof.

30 is an outdoor unit, 31a, 3lb are indoor units, 32 is a piping branch unit, and the outdoor unit 30 includes a compressor 33, an outdoor heat exchanger 23, a four-way valve 35, an accumulator 36, a heating capillary tube 37, and an inverter. The stop valve 38 is configured as shown in the figure, and the outdoor heat exchanger 34 is provided with multiple refrigerant flow paths in order to reduce piping pressure loss and effectively utilize the heat exchanger. A plurality of capillary tubes 4 corresponding to each
6 in parallel, the effective use of the heat exchanger is achieved by uniformly distributing the refrigerant.

39 is the third conduit, that is, the check joint conduit;
It communicates with a pipe section that becomes a high-pressure section during cooling operation and a low-pressure section during heating operation, and is a so-called check joint pipe line that is normally used to check the operating pressure.

In the indoor units 31a and 3lb, indoor heat exchangers 40a and 40b, indoor capillary tubes 41a and 41b, gas pipes 42a and 42b, and liquid pipe 4 are installed, respectively.
3a and 43b form a normal refrigerant circuit.

The above is the same as the configuration of the outdoor unit and indoor unit of a normal heat pump air conditioning system.To further explain the configuration and operation of the outdoor unit 30, in the condensing unit of a package air conditioner, usually the gas side piping and the liquid side Each connection end of the piping with the indoor units 31a, 31b is equipped with a so-called service valve 44, which is equipped with a flare connection port and a pressure check port as a closing valve. 45
is provided.

When measuring pressure during heating operation, high pressure can be checked using the service port provided in the gas side service valve 44.

However, when attempting to check the pressure on the low pressure side, the liquid side service valve 45 indicates a high pressure, making it impossible to check the necessary low pressure.

Therefore, the check joint line 39, which communicates with the low pressure portion during heating operation, is provided to accurately check the low pressure and also add or adjust the amount of refrigerant as necessary.

The check joint pipe line 39 is connected to the outdoor heat exchanger 3.
4 and the four-way valve 35, it is possible to accurately check low pressure during heating operation without being affected by the pressure reduction effect of capillary tube 46 and heating capillary tube 37, and to check high pressure during cooling operation. Can be checked.

Note that it is preferable to provide a closing valve such as a service valve 70 as appropriate at the end 69 of the check joint conduit 39.

The internal configuration and operation of the piping branch unit 32 for connecting the outdoor unit 30 with such a configuration and the plurality of indoor units 31a, 3lb will be described in detail below, focusing on the flow of refrigerant during heating.

The gas pipe 47 branches into a plurality of routes from a branch point 48 to pilot type four-way valves 49a, 49b, and branch gas pipes 50a, 50b connect to indoor units 31a, 3lb with gas pipes 51a,
Connected to 5lb.

Furthermore, the four-way valves 49a and 49b are connected to open the branch gas pipes 50a and 50b when the electromagnetic coil is energized.

The indoor units 31a and 31b are connected to branch liquid pipes 53a and 53b through connecting liquid pipes 52a and 52b, and then connected to liquid side branch point 5 via liquid side reversible flow solenoid valves 54a and 54b.
5 to form a medium-pressure liquid pipe 56 up to the outdoor unit.

Reference numeral 57 indicates a check valve, and reference numeral 58 indicates a cooling capillary tube, which are connected in parallel as shown in the figure and arranged in the liquid pipe 56.

Reference numeral 59 denotes a bypass electromagnetic valve for operation in one cooling room, which is installed via a capillary tube 60 between the liquid pipe 56 that becomes medium pressure liquid during cooling and the gas pipe 47 that becomes low pressure gas during cooling.

In addition, the indoor capillary tubes 41a and 4lb, which are properly set during operation in two cooling rooms, become too constricted as a whole system during operation in one room due to their characteristics, and the compressor 33
This is a liquid bypass circuit to the suction line used to prevent the discharge temperature from rising.

61 is the hot gas bypass solenoid valve when operating one heating room.
The gas pipe 47 that becomes a high-pressure gas section during heating and the third pipe line 63 in the piping branch unit 32 that connects with the check joint pipe line 39 of the outdoor unit 30 are interconnected via the capillary tube 62, and the heating 1 Configures the first bypass circuit during room operation.

Similarly, 64 is a solenoid valve that opens the circuit of the receiver 65 during single-room heating operation.The liquid refrigerant is drawn from the liquid pipe 56, which becomes medium-pressure liquid during heating operation, and is guided to the receiver 65 and stored. The liquid refrigerant flows to the third pipe line 63 through capillary tubes 66 and 67 and a check valve 68, which are provided at the lower part of the receiver 65 and join together below the bottom of the receiver 65 to allow the liquid refrigerant to escape when the solenoid valve 64 is closed. They are provided so as to communicate with each other, and constitute a second bypass circuit during single-room heating operation.

To further explain the role of the two bypass circuits during single-room heating operation, the heat exchanger capacity and capillary tube orifice settings are properly set during two-room heating operation, but when operating one heating room, In this case, the capacity of the indoor heat exchangers 40a and 40b, which act as condensers, is relatively reduced, so that the high pressure during operation increases excessively, causing problems in operation.

Therefore, in order to control this pressure, the first bypass circuit performs high pressure control using a hot gas bypass, and the second bypass circuit performs pressure and temperature control using refrigerant storage and liquid bypass circuit, respectively. The refrigeration cycle is appropriately controlled during indoor operation.

In addition, when operating a single heating room, in order to prevent refrigerant from unnecessarily accumulating in the indoor unit on the stopping side and causing problems with the operation of the refrigeration cycle, the piping of the indoor unit on the stopping side is connected to the low-pressure gas line, and Unit 31a,
It is necessary to close the front and rear four-way valves 49a, 49b and the liquid side reversible flow solenoid valves 54a, 54b.

In the circuit of the above embodiment, four-way valves 49a and 49b are used as valves on the gas pipe 47 side, and when the indoor unit 31b is operated, the four-way valve 49b operates as shown by the solid line in the figure, and the liquid side reversible flow solenoid valve 54b also operates. Operates in open state.

When the indoor unit 31b is stopped, the liquid side reversible flow solenoid valve 54
b is closed, and the four-way valve 49b is operated as shown by the broken line in the figure, and the piping of the stop-side indoor unit 31b is isolated from the main refrigerant circulation circuit, and at the same time, it is connected to the compressor 33 via the third piping 63. The refrigerating cycle is connected to the low-pressure suction pipe side, and only low-pressure superheated refrigerant gas is present in the pipe, and the operation of the refrigeration cycle is not hindered by liquid accumulation.

In addition, as shown in the above embodiment, the connection of each refrigerant pipe to the four-way valve 49b is such that the branch pipe of the gas pipe 47, which becomes a high-pressure gas pipe during heating, is connected to the high-pressure side H of the normal four-way valve, and the check joint pipe is connected to the four-way valve 49b. A branch pipe of the third pipe line 63 communicating with the pipe 39 is connected to the four-way valve low pressure side L, and the indoor unit 31a, 3lb
The branch gas pipe 50b, which is a connection pipe to the four-way valve 49b, is connected to the high-pressure side on the E side of the four-way valve when the coil is energized during normal use, and the C side of the four-way valve 49b is closed.

That is, when the four-way valve 49b is not energized and excited during heating operation, it is in a closed state as shown by the broken line in the figure.

On the other hand, when the heat pump unit is in cooling operation, the gas pipe 47
, branch gas pipes 50a and 50b become low pressure gas lines,
It is desirable that the four-way valves 49a, 49b are always open regardless of whether the indoor units 31a, 3lb are in operation or stopped.

In the case of the above embodiment, during cooling operation, the check joint line 39 and the third pipe line 63 are on the high pressure side, and the gas pipe 47 is on the low pressure side, so the four-way valve 49a,
The operating pressure of the four-way valve 49b works in the opposite direction to that during heating, and a circuit as shown by the solid line in the figure is formed when the electromagnetic coils of the four-way valves 49a and 49b are not excited.

Therefore, during cooling operation, even if the four-way valves 49a and 49b are not electrically actuated, the circuit can be kept open in a desired state by the pressure from the check joint system at all times, and there is an advantage that no electrical control is required.

Further, FIG. 3 shows another embodiment of the present invention.
The main difference from the system shown in the figure is that the hot gas bypass circuit (first bypass circuit) during single room heating operation, which consists of a hot gas bypass solenoid valve 61' and a capillary tube 62', is connected to the gas pipe 47. The low pressure side L of the four-way valves 49a and 49b is configured to communicate with the pressure liquid pipe 56.
and the liquid side reversible flow path solenoid valve 54 of the branch liquid pipes 53a, 53b.
A, 54b communicates with the indoor units 31a, 31b side through communication pipes 71a, 7lb to form a four-way valve 49.
The operating pressure of a and 49b is ensured, and when switching from two-room heating operation to one-room heating operation, the stop-side indoor unit portion is made into a sealed circuit.

Further, a third pipe line 63 is provided to suck the refrigerant liquid accumulated in the sealed circuit, and a branch liquid pipe 5 is provided in a part of the sealed circuit.
The liquid side reversible flow solenoid valves 54a, 54b of 3a, 53b communicate with the indoor unit via check valves 72a, 72b and capillary tubes 73a, 73b.

Therefore, during operation of two heating rooms, the branch liquid pipe 53 is
Although the liquid refrigerant is bypassed from a and 53b to the low-pressure suction line, there is no problem with the heating capacity expressed by the condensing capacity of the refrigerant.

As shown in the above two embodiments, to further explain the bypass circuit during heating operation, which is the main focus of the present invention, in the case of a refrigerant control method using a capillary tube method, the number of heating operation rooms can be changed from multi-room operation to multi-room operation. For example, when switching to single-room operation, the condenser capacity decreases relatively, and because the degree of restriction of the capillary tube in the main circuit is constant, excess refrigerant accumulates in the indoor heat exchanger (condenser) during single-room operation. This causes the condensation pressure to rise abnormally, causing trouble in the operation of the refrigeration cycle.

An increase in the high pressure itself is preferable because it increases the temperature of the air blown indoors and improves the heating capacity of the driver's cabin, but it is not preferable for the high pressure side pressure to exceed 25 to 26 kg/cm'G.

Therefore, in order to reduce this high pressure to an appropriate level, a two-circuit bypass system has been adopted as described above.

That is, first, a receiver tank system is adopted, and by opening the solenoid valve 64, surplus refrigerant during single-room heating operation is stored as a liquid refrigerant in the receiver 65, thereby reducing the high pressure, thereby reducing the relative amount of liquid refrigerant. At the same time as the high pressure decreases, the low pressure also tends to decrease, and at the same time, the degree of superheating on the suction side of the compressor increases and the discharge temperature increases.

In order to prevent this discharge temperature rise and to improve the low pressure slightly, the capillary tube 6 is
6. 67 leads the liquid refrigerant to the low pressure suction line.

However, it has been experimentally found that achieving a sufficiently high pressure drop using only the receiver tank method is not desirable from a cycle standpoint.

In other words, if you try to lower the high pressure to a level close to the normal set pressure of 18 to 20 kg/cm'G, you will need a large-capacity receiver, and at the same time as the high pressure drops, the low pressure will also be affected and drop. However, the low pressure drops to such an extent that frost forms on the outdoor heat exchanger, which acts as an evaporator, and the capillary tubes 66 . The liquid bypass provided by 67 is not enough to deal with the problem.

Therefore, the pressure drop caused by the receiver and the liquid bypass is kept within an appropriate range, and as a bypass circuit, the gas discharged from the high pressure gas pipe 47 is transferred to the hot gas bypass solenoid valves 61, 61',
Capillary tube 62. 62' to a low pressure suction line (the embodiment shown in FIG. 2) or a medium pressure liquid line 5.
6 (embodiment shown in FIG. 3) to reduce the amount of refrigerant circulating to the condenser and lower the high pressure,
At the same time, it has been confirmed that the low pressure (evaporation) pressure is significantly increased to solve the frost formation problem, and the discharge temperature is also lowered.

Furthermore, in the case of the capillary tube system, if cycle control is attempted only by the hot gas bypass system, it is clear that the coefficient of performance will be extremely lowered and at the same time the stability of the cycle will be lacking during overload operation.

According to the present invention, by appropriately combining the receiver tank bypass method and the hot gas bypass method, a stable one-room (or a few rooms) heating operation cycle can be configured even in a capillary tube-type heat pump multi-room air conditioning system. becomes possible.

[Brief explanation of the drawing]

Figure 1 is a refrigerant circuit diagram of a conventional multi-room air conditioning system;
FIG. 3 is a refrigerant circuit diagram of a heating and cooling system showing an embodiment of the present invention. 30...Outdoor unit, 31a, 31b...
...Indoor unit, 47...Gas pipe (high pressure gas pipe), 56...Liquid pipe (medium pressure liquid pipe), 61,
61'... Hot gas bypass solenoid valve (first bypass circuit), 62, 62'... Capillary tube (first bypass circuit), 65... Third pipe line (low pressure suction line), 65... Receiver (second bypass circuit), 66, 67...
Capillary tube (second bypass circuit).

Claims (1)

[Claims] 1 The refrigerant flow rate control of the refrigeration cycle is configured using capillary tubes, and the high-pressure gas pipes and the connections from the indoor unit to the outdoor unit during heating operation of an air-conditioning system in which capillary tubes are installed in each of the indoor and outdoor units. In addition to the pair of medium-pressure liquid pipes, a low-pressure suction line is provided that communicates with the pipe that becomes low-pressure during heating operation.
a first bypass circuit that branches from the high-pressure gas pipe and bypasses the low-pressure suction line or the medium-pressure liquid pipe when the number of operating indoor units decreases during heating operation; and a first bypass circuit that branches from the medium-pressure liquid pipe and bypasses the low-pressure suction line. A heating and cooling device comprising: a second bypass circuit that bypasses a line; and a receiver tank and a capillary tube for controlling the outflow of refrigerant from the receiver tank in the second bypass circuit.