JPH067028B2 - Heat pump type air conditioner - Google Patents

Description

The present invention relates to a heat pump type cooling and heating apparatus used as an air conditioner.

(B) Conventional technology In a heat pump type cooling and heating device, a heat exchanger for freezing is used to prevent the outdoor heat exchanger from freezing during heating operation, and the refrigerant is used in the outdoor heat exchanger as the outside air temperature decreases. However, the liquid refrigerant returns to the compressor because it cannot fully evaporate, and in order to prevent this, the one in which a heating capillary tube is connected to the liquid level displacement portion of the refrigerant container and the lower portion of the refrigerant container is Japanese Patent Publication No. 58- No. 21188 is disclosed.

(C) Problems to be solved by the invention The amount of refrigerant introduced to the heat exchanger for freeze prevention during heating should be such that the outdoor heat exchanger does not freeze in order to minimize the amount of heat loss in this heat exchanger. It is preferable that the liquid refrigerant is not returned to the compressor, but it is extremely difficult to cope with this by setting the resistance of the heating capillary tube.

Further, the heat exchanger for freeze prevention functions only as a condenser during cooling, and does not function as a supercooling coil like during heating, so that there is a problem that stable refrigerant pressure reduction control cannot be performed.

The present invention provides a heat pump type cooling and heating device that solves the above problems.

(D) Means for solving the problems A heat pump type in which a compressor, a four-way valve for switching the cooling / heating flow path, an indoor heat exchanger, a refrigerant container, a refrigerant pressure reducing element, and an outdoor heat exchanger are sequentially connected in an annular shape. In a cooling and heating device that constitutes a refrigeration cycle, an expansion and cooling valve for cooling and heating that operates by detecting the state of the suction refrigerant of the compressor as a refrigerant pressure reducing element, a cooling capillary tube, and a heating capillary tube are used, and outdoor heat exchange is also used. And a cooling cycle in which an auxiliary heat exchanger is arranged in a heat exchange relationship with the heat exchanger, and the liquid refrigerant drawn out from the lower portion of the refrigerant container flows in parallel to the expansion valve and the cooling capillary tube via the auxiliary heat exchanger. , A heating cycle in which the liquid refrigerant derived from the lower portion of the refrigerant container is guided to the expansion valve via the auxiliary heat exchanger and the refrigerant derived from the liquid level displacement portion of the refrigerant container is guided to the heating capillary tube. Is formed

(E) Action During heating operation, the indoor heat exchanger acts as a condenser and the outdoor heat exchanger acts as an evaporator, and the refrigerant flow rate during normal operation is mainly controlled by the heating capillary tube and the expansion valve. It is controlled to compensate for the shortage. When the outside air temperature is high and the heating capacity is sufficient, the outdoor heat exchanger can provide sufficient refrigerant superheat, so the expansion valve is opened to the maximum and a large amount of refrigerant flows to the auxiliary heat exchanger, suppressing an increase in high pressure. To be When the outside air temperature becomes lower, the opening degree of the expansion valve becomes smaller accordingly, the high-pressure liquid refrigerant flowing through the auxiliary heat exchanger decreases, and the amount of heat loss is minimized. Further, when the outside air temperature is lowered and the liquid level in the refrigerant container is lowered to stop the liquid refrigerant from flowing into the heating capillaries, only the refrigerant control by the expansion valve is performed and the refrigerant superheat degree of the outdoor heat exchanger is maintained constant.

Also, during cooling operation, the outdoor heat exchanger acts as a condenser, the indoor heat exchanger acts as an evaporator, and the auxiliary heat exchanger acts as a supercooling coil because only the liquid refrigerant drawn from the refrigerant container flows. When the supercooled refrigerant flows in parallel with the expansion valve and the cooling capillary tube, the decompression control is performed in a stable liquid state.

(F) Example An example of the present invention will be described with reference to the drawings. (1) is a compressor, (2) is a four-way valve for switching the heating / cooling flow path, (3) is an indoor heat exchanger, and (4) ) Is a refrigerant container, (5) is an outdoor heat exchanger, and (6) is an auxiliary heat exchanger disposed in a heat exchange relationship below the outdoor heat exchanger.

Then, as a refrigerant pressure reducing element, a temperature sensing element (7) and a pressure equalizing tube (8)
By installing on the refrigerant inlet side of the gas-liquid separator (9), the temperature type automatic expansion valve for cooling and heating that operates by detecting the state of the suction refrigerant of the compressor (1) and the expansion valve during the cooling cycle (Ten)
A cooling capillary tube (11) for decompressing the refrigerant flowing in parallel with the heating capillary tube (13) interposed between the liquid level displacement portion (12) of the refrigerant container (4) and the outdoor heat exchanger (5). ) Is used, the refrigerant is co-flowed to the expansion valve (10) and the cooling capillary tube (11) during the cooling cycle, and the refrigerant is added to the expansion valve (10) and the heating capillary tube (13) during the heating cycle. 4 check valves (1
4) (15) (16) (17) are provided.

Together, the auxiliary heat exchanger (6) acts as a supercooling coil for supercooling by exchanging heat between the high pressure liquid refrigerant drawn from the lower part of the refrigerant container (4) and the outside air in any operation of cooling and heating, In particular, during heating operation, it also acts as a freeze prevention coil that prevents the lower part of the outdoor heat exchanger (5) from freezing.

The heating operation is configured as described above, and the heating operation will be described first. During normal operation, the refrigerant filling amount is set so that a large amount of liquid refrigerant accumulates in the refrigerant container (4), and the refrigerant flow rate is mainly controlled by the heating capillary tube (13) and the expansion valve (10) Since the control is set to compensate for the shortage, the refrigerant discharged from the compressor (1) is a four-way valve in a solid line.
(2) -Indoor heat exchanger (3) -Check valve (14) -After passing through the refrigerant container (4), a large amount of high-pressure liquid refrigerant is discharged from the liquid level displacement point (12) of the refrigerant container (4). After being decompressed by the heating capillary tube (13) and a small amount of high-pressure liquid refrigerant discharged from the lower part of the refrigerant container (4) is supercooled by exchanging heat with the outside air in the auxiliary heat exchanger (6), The pressure is reduced by the expansion valve (10). The depressurized liquid refrigerant and the check valve (1) are decompressed by the heating capillary tube (13).
After exiting 5), they merge and then flow into the outdoor heat exchanger (5) to evaporate and vaporize, and then return to the compressor (1) via the four-way valve (2) -gas-liquid separator (9). To be done. By such a heating cycle, the room is heated by the indoor heat exchanger (3) acting as a condenser, and during this heating operation, the lower part of the outdoor heat exchanger (5) is separated from the auxiliary heat exchanger (6). It is heated by the sensible heat released.

Especially when the outside air temperature is high and the refrigerant is sufficiently vaporized in the outdoor heat exchanger (5) and the degree of refrigerant superheat is sufficient, the expansion valve
Since (10) opens to the maximum and a large amount of refrigerant flows to the auxiliary heat exchanger (6), the amount of sensible heat discharged to the outside increases and the heating amount in the indoor heat exchanger (3) increases. Because of the decrease, the number of times the compressor (1) is started and stopped by the thermocycle is reduced, and the high pressure is reduced, so that the power consumption can be suppressed to be small.

On the other hand, when the outside air temperature is low and the evaporation capacity in the outdoor heat exchanger (5) decreases and the refrigerant superheat degree decreases, the expansion valve (10) gradually closes and the high-pressure liquid flowing into the auxiliary heat exchanger (6). Refrigerant is reduced and the amount of heat loss is minimized.

When the outside air temperature further decreases and the liquid refrigerant accumulates in the gas-liquid separator (9), the liquid level (18) of the refrigerant in the refrigerant container (4) drops below the liquid level displacement point (12) and the heating capillary tube When the liquid refrigerant is no longer supplied to (13), it is switched to refrigerant pressure reduction control by only the expansion valve (10), and a stable operating state in which the refrigerant superheat degree is kept constant is maintained.

In this way, during heating operation, the expansion valve is changed from the refrigerant control by the heating capillary tube (13) and the expansion valve (10) as the outside air temperature decreases.
Switching to refrigerant control by (10) only, during this heating operation, the expansion valve (10) always keeps the liquid refrigerant in the auxiliary heat exchanger (6).
Flow through the heat exchanger, the lower part of the outdoor heat exchanger (5) is heated by the sensible heat released from this heat exchanger to prevent freezing, and the expansion valve (10) is connected to the auxiliary heat exchanger (6). Stable depressurization control is performed by introducing the supercooled liquid refrigerant.

Also, during cooling operation, by switching the four-way valve (2) to the broken line state, the refrigerant discharged from the compressor (1) is four-way valve (2) -outdoor heat exchanger (5) -check valve (16). -Refrigerant container (4) -After flowing through the auxiliary heat exchanger (6), a large amount of the distributed liquid refrigerant flows through the cooling capillaries (11), and a small amount of the liquid refrigerant flows through the expansion valve (10) and the check valve. (17) and then merge into the indoor heat exchanger (3) -four-way valve (2)
-Returned to the compressor (1) via the gas-liquid separator (9). By such a cooling cycle, the room is cooled by the indoor heat exchanger (3) acting as an evaporator, and during this operation, the auxiliary heat exchanger (6) supercools the high-pressure liquid refrigerant from the refrigerant container (4). As a result, the pressure of the liquid refrigerant flowing in the cooling capillary tube (11) and the expansion valve (10) in parallel is controlled under reduced pressure in a stable liquid state containing no flash gas.

In the above embodiment, the temperature type automatic expansion valve (10) having the temperature sensing element (7) and the pressure equalizing pipe (8) was used, but instead of this, the temperature of the suction refrigerant of the compressor (1) was detected. An electric expansion valve driven by a motor or a thermoelectric expansion valve generated by a heater may be used.

(G) Effect of the Invention According to the present invention, the heating capillaries during the heating operation and the cooling capillaries mainly during the cooling operation mainly control the refrigerant flow rate, so that the expansion valve compensates for the shortage. With a small capacity, the manufacturing cost can be reduced.

In addition, since the auxiliary heat exchanger acts as a supercooling coil during any heating / cooling operation, liquid refrigerant that does not contain flash gas always flows through the expansion valve to perform stable pressure reduction control, resulting in efficient cooling / heating. You can drive.

Moreover, during heating operation, when the outside air temperature is high, the expansion valve is opened to the maximum to suppress the rise in high pressure, and when the outside air temperature is decreased, the opening of the expansion valve becomes smaller and the amount of heat loss in the auxiliary heat exchanger is reduced. When the outside air temperature further decreases and the liquid level in the refrigerant container drops, the refrigerant is not decompressed in the heating capillary tube and only the refrigerant control by the expansion valve is automatically switched to the outside air temperature. It is possible to perform a wide range of operation control that prevents freezing of the outdoor heat exchanger and liquid return to the compressor while responding to changes in

[Brief description of drawings]

Drawing is a refrigerant circuit diagram of a heat pump type air conditioner which shows an example of the present invention. (1) ... Compressor, (2) ... Four-way valve, (3) ... Indoor heat exchanger, (4)
... Refrigerant container, (5) ... Outdoor heat exchanger, (6) ... Auxiliary heat exchanger, (10) ... Expansion valve, (11) ... Cooling capillary tube, (12) ... Liquid level displacement location, (13) … Heating capillaries.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-59-71961 (JP, A) JP-A-61-101762 (JP, A) JP-A-61-15051 (JP, A)

Claims (1)

[Claims] 1. A heat pump type refrigeration cycle in which a compressor, a four-way valve for switching cooling / heating channels, an indoor heat exchanger, a refrigerant container, a refrigerant pressure reducing element, and an outdoor heat exchanger are sequentially connected in an annular shape. In, using the expansion valve for cooling and heating that operates by detecting the state of the suction refrigerant of the compressor as the refrigerant decompression element, the cooling capillary tube, and the heating capillary tube, and assist in the heat exchange relationship with the outdoor heat exchanger. A cooling cycle in which a heat exchanger is provided and the liquid refrigerant led out from the lower portion of the refrigerant container flows in parallel to the expansion valve and the cooling capillary tube via the auxiliary heat exchanger, and from the lower portion of the refrigerant container The liquid refrigerant to be led out is guided to the expansion valve through the auxiliary heat exchanger, and the refrigerant to be led out from the liquid level displacement portion of the refrigerant container forms a heating cycle in which it is led to the heating capillary tube. Heat pump type Heating.