JPS6028935Y2 - Heat pump air conditioning system - Google Patents

Description

[Detailed description of the invention] This invention is a heat pump air conditioning system, specifically a compressor,
Four-way switching valve, indoor heat exchanger that becomes an evaporator during cooling and a condenser during heating, an outdoor heat exchanger that becomes a condenser during cooling and an evaporator during heating, liquid receiver, expansion valve for cooling, expansion valve for heating. The present invention relates to a heat pump type air-conditioning device equipped with.

In general, when a heating load becomes small during heating operation, the evaporation capacity of the outdoor heat exchanger becomes excessive compared to the condensation capacity of the indoor heat exchanger, resulting in an abnormally high condensation temperature and pressure. There was a problem that the vehicle could no longer be operated, resulting in a narrower operating range.

For this reason, in the past, a bypass passage with a control valve interposed between the discharge gas pipe and the suction gas pipe was provided, and the discharge gas was bypassed to the suction side by controlling the opening degree of the control valve.

Therefore, when the heating load becomes significantly smaller and the difference in the balance between the indoor and outdoor heat exchangers becomes large, the amount of bypass must also be increased. There was a problem in that the outer dimensions of the device became larger and the cost increased.

In particular, in air-conditioning equipment that connects multiple indoor units to one outdoor unit, during low-load operation where only one indoor unit is operated during heating, the evaporation capacity should not be particularly large compared to the condensation capacity. Therefore, it was necessary to use a control valve with a larger capacity.

Therefore, in order to solve the above problems, first, a hot gas bypass pipe was installed between the discharge gas pipe of the compressor and the high-pressure liquid pipe connecting the inlet side of the heating expansion valve and the liquid receiver. A proposal was made to install a high pressure control valve in this bypass pipe (Japanese Utility Model Publication No. 55-28437).

However, according to the air conditioning system, the above-mentioned conventional problems could be solved, but when the high pressure control valve operates and hot gas flows into the high pressure liquid pipe, the expansion valve may experience intermittent There was a problem in that the noise generated caused discomfort to the hearing.

Therefore, the present invention was devised to solve the above-mentioned conventional problems and also solve the problems of the air conditioning system proposed earlier. It is characterized in that a mixing tank is interposed in the high-pressure liquid pipe between the heating expansion valve and the inlet side.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the heat pump air-conditioning apparatus of the present invention will be described below with reference to the drawings.

What is shown in FIG. 1 is a heat pump air-conditioning system in which five indoor units B can be connected to one outdoor unit A via connecting pipes C.

Although FIG. 1 shows a state in which only one indoor unit B is connected, the following description will be made assuming that five indoor units B are connected.

The outdoor unit A includes a compressor 1, a four-way switching valve 2, an outdoor heat exchanger 3 that serves as a condenser during cooling and an evaporator during heating, a temperature-sensitive expansion valve 4 for heating. A check valve 5, a liquid receiver 6, and an accumulator 7 are connected in parallel with the expansion valve 4, and these devices are connected by a refrigerant pipe 8.

Five liquid-side branch pipes 9a are connected to the high-pressure liquid pipe 9 and the gas pipe 10 in the refrigerant pipe 8 via headers, respectively.
and the gas side branch pipe 10a... are connected.

The liquid side branch pipe 9a... has a solenoid valve S■1... that opens during cooling.
At the same time, connecting branch pipes 9b... are branched from the outlet side positions of the solenoid valves SV1... which open during cooling of the liquid side branch pipes 9a...
・A check %V□ is interposed in the connecting branch pipe 9b to the distributor 9d.
is connected to the communication pipe 9C via the
It is connected to the high pressure liquid pipe 9 at an intermediate position between the liquid receiver 6 and the header.

In addition, the gas side branch pipe 10a... has a check valve CV2.
A solenoid valve S2 connected in parallel and opened during heating is installed.

The indoor unit B is connected between the liquid side branch pipe 9a and the gas side branch pipe 10a via the communication pipe C...
are connected.

The indoor unit B has an indoor heat exchanger 11 that serves as an evaporator during cooling and a condenser during heating, and a circuit in which a heating expansion valve 12 and a check valve 13 are connected in parallel through a refrigerant pipe 14.

The compressor 1 is driven by a motor that can detect, for example, high pressure or low pressure depending on the size of the load and change the number of poles between 4 poles and 2 poles. In this embodiment,
The capacity can be controlled between full load capacity and 172 load capacity.

Therefore, in the heat pump type air-conditioning system configured as described above, what is shown in FIG. A hot gas bypass pipe 15 is provided in the high pressure liquid pipe 9 connecting the inlet side of the heating expansion valve 4 and the liquid receiver 6,
This bypass pipe 15 is equipped with a high pressure control valve 16 that opens when the high pressure becomes higher than a set value during heating operation, and the connection position of the bypass pipe 15 to the high pressure liquid pipe 9 and the heating A mixing tank 20 is interposed between the high pressure liquid pipe 9 and the inlet side of the expansion valve 4.

The connection position of the bypass pipe 15 to the high-pressure liquid pipe 9 is preferably close to the inlet side of the expansion valve 4.

This is to reduce the backflow of the hot gas bypassed from the bypass pipe 15 to the liquid receiver 6. When the hot gas flows back to the liquid receiver 6, its internal pressure increases, causing the indoor heat to rise. This is because it may become difficult for condensed refrigerant to come out from the exchanger 11.

Further, the mixing tank 20 interposed in the high pressure liquid pipe 9 between the connection position and the inlet side of the expansion valve 4 is a second
As shown in the figure, an inlet pipe 23 that protrudes toward the bottom 22 and opens opposite the bottom 22 is attached to the top of the body 21 in a sealed manner, and at the side of the body 21 and on the top side, The outlet pipe 24 is installed in a sealed manner in a direction perpendicular to the inlet pipe 23.

This mixing tank 20 may be used with the body 21 positioned with the bottom 22 on the lower side and the top on the upper side as shown in FIGS. 1 and 3, or as shown in FIG. The bottom portion 22 and the top portion may be arranged horizontally.

In any case, even if the liquid refrigerant and the gas refrigerant flow into the inlet pipe 23 in a separated state, the liquid refrigerant and the gas refrigerant are mixed and disturbed inside the body 21, and the bubbles of the gas refrigerant are separated. , it mixes with the liquid refrigerant.

Therefore, the liquid refrigerant and the gas refrigerant flow out from the outlet pipe 24 in an evenly mixed state and reach the expansion valve 4, and when passing through the expansion valve 4, there is no intermittent noise. It does not occur.

In addition, in FIG. 1, 31 is a capillary tube 31.
In the liquid injection circuit with a, the liquid receiver 6
A high-pressure liquid pipe 9 between the heating expansion valve 4 and the heating expansion valve 4 is connected to the accumulator 7, and a part of the high-pressure liquid refrigerant is depressurized during heating and cooling and is supplied from the accumulator 7 to the compressor 1. are doing.

32 is a liquid accumulation prevention circuit that prevents refrigerant from accumulating in liquid form in the indoor unit B when it is stopped during heating, and is a circuit in which a capillary tube 32a and a check valve 32b are connected in series. 32c is connected to the low pressure liquid pipe 17 between the outdoor heat exchanger 3 and the heating expansion valve 4 from the liquid side branch pipe 9 on the heating outlet side of each solenoid valve SV□... It is.

Further, 4a and 4b are the temperature sensing cylinder and external pressure equalizing pipe of the heating expansion valve 4, 33 is the suction pressure regulating valve, 34 is the dryer filter,
35 is a filter, 36 is a closing valve, 37 is an outdoor fan, 3
8 is a silencer, HPS is a high pressure switch, and LPS is a low pressure switch.

Therefore, in the above configuration, when performing heating operation, the four-way selector valve 2 is switched as shown by the solid line to operate the compressor 1. For example, at full load when all five indoor units B are operating, , compressor 1 is operated at full load capacity, and three indoor units B are operated at approximately 1/2
During loading, the compressor 1 is operated with a load capacity of 1n.

In these operating conditions, the condensing pressure is maintained normally, and the discharge gas pressure is maintained at a normal pressure lower than the set pressure P at which the high pressure control valve 16 starts to open, and the high pressure control Valve 16 is closed.

When the state changes from such an operating state to a state in which only one indoor unit B operates, the condensing pressure increases, and as a result, the discharge gas pressure increases from the set pressure P of the high pressure control valve 16. 16 opens, and an amount of hot gas corresponding to the increase in discharge gas pressure flows into the high-pressure liquid pipe 9 on the inlet side of the heating expansion valve 4.

However, the hot gas that has flowed into the heating expansion valve 4
, the gas refrigerant inhibits the function of the expansion valve 4, and the liquid refrigerant passing through the expansion valve 4 decreases;
As a result, the amount of refrigerant circulating will decrease, and the refrigerant flowing out from the expansion valve 4 will be in a highly dry state with a large amount of gas compared to the amount of liquid, and the refrigerant will flow out from the outdoor heat exchanger 3.
It flows into.

As the amount of refrigerant circulating through the outdoor heat exchanger 3 decreases and the dryness of the circulating refrigerant is high, the evaporation capacity of the outdoor heat exchanger 3 decreases and one indoor heat exchanger 11
The condensing capacity of the discharge gas is in a balanced state, and the discharge gas pressure is suppressed to a safe pressure state where the set pressure P is evacuated.

Moreover, when the hot gas is bypassed, the hot gas flows into the mixing tank 20 from the inlet pipe 23 at a predetermined speed together with the liquid refrigerant in the high-pressure liquid pipe 9, and this velocity energy causes the mixing tank 20 to flow into the mixing tank 20. The liquid refrigerant is uniformly mixed with the liquid refrigerant that is almost completely filled, and flows through the outlet pipe 24 in a gas-liquid mixed state and passes through the expansion valve 4. No abnormal noise is generated.

As described above, during low-load operation in which only one indoor unit B is operated, a small amount of refrigerant with a high degree of dryness circulates in the outdoor heat exchanger 3, so the pressure of the suction gas decreases and the degree of superheating increases. Even if this happens, the liquid refrigerant is supplied from the liquid injection circuit 31 to the accumulator 7 side, so that the suction gas pressure and thus the degree of superheat can be maintained at normal values.

Furthermore, in the above explanation, five indoor units B are connected to one outdoor unit A, and the capacity of the compressor 1 is controlled in two stages according to the number of operating indoor units B. As described above, the present invention can be applied to various heat pump air-conditioning devices in which the condensing pressure and temperature abnormally increase during low-load heating operation.

As described above, the present invention provides a hot gas bypass pipe between the discharge gas pipe that connects the discharge port of the compressor and the four-way switching valve, and the high-pressure liquid pipe that connects the inlet side of the heating expansion valve and the liquid receiver. This bypass pipe was equipped with a high-pressure control valve that opened when the high pressure exceeded a set value during heating operation. The expansion valve cannot perform its normal refrigerant amount adjustment function due to the hot gas bypassing the expansion valve. Just by the discharge gas flowing into the heating expansion valve, the amount of refrigerant flowing through the heating expansion valve is reduced, and due to this reduction, the evaporation pressure in the outdoor heat exchanger decreases, causing condensation in the indoor heat exchanger. The pressure can be lowered.

Therefore, it is possible to balance the evaporation capacity and the condensation capacity, and it has become possible to use a high-pressure control valve with a small capacity, small external size, and low cost.

Moreover, the hot gas bypassed through the bypass pipe is fed to a mixing tank interposed in the high-pressure liquid pipe between the connection position of the bypass pipe to the high-pressure liquid pipe and the inlet side of the heating expansion valve. Since it is mixed with the high-pressure liquid refrigerant and enters the expansion valve in a gas-liquid mixed state, intermittent abnormal noise does not occur in the expansion valve, and even if there is pulsation in the flow of the refrigerant, it can be absorbed.

[Brief explanation of drawings]

Fig. 1 is a refrigerant piping system diagram showing an embodiment of the present invention, Fig. 2 is a sectional view of a mixing tank, and Figs. 3 and 4 are:
It is an explanatory view showing an example of use of a mixing tank. 1... Compressor, 2... Four-way switching valve, 3
...Outdoor heat exchanger, 4...Heating expansion valve, 6...Liquid receiver, 8a...Discharge gas pipe, 9... ... High pressure liquid pipe, 11 ... Indoor heat exchanger, 12 ... Air conditioning expansion valve, 15 ...
...Hot gas bypass pipe, 16...High pressure control valve, 20...Mixing tank.

Claims (1)

[Scope of utility model registration request] Compressor 1, four-way switching valve 2, indoor heat exchanger that becomes an evaporator during cooling and a condenser during heating, outdoor heat exchanger 3 that becomes a condenser during cooling and an evaporator during heating, liquid receiver 6, for cooling. expansion valve 1
2. In a heat pump type air-conditioning device equipped with a heating expansion valve 4, a discharge gas pipe 8a connecting the discharge of the compressor 1 and the four-way switching valve 2, and a liquid receiver and the inlet side of the heating expansion valve 4. A hot gas bypass pipe 15 is connected between the high pressure liquid pipe connecting the
A high-pressure control valve 16 is provided in the bypass pipe 15, which opens when the high pressure exceeds a set value during heating operation, and the high-pressure liquid pipe 9 of the bypass pipe 15
A heat pump type air-conditioning and heating system characterized in that a mixing tank 20 is interposed in a high-pressure liquid pipe 9 between a connection position to a heating expansion valve 4 and an inlet side of the heating expansion valve 4.