JPH0792288B2 - Air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an air conditioner having a refrigeration cycle, and more particularly to a measure for favorably continuing cooling operation even under a low outside air temperature.

(Prior Art) Generally, in this type of air conditioner, the refrigerant cooling capacity of the condenser is increased and the high pressure of the refrigeration cycle is lowered during cooling operation under a low outside air temperature. For this reason, the amount of refrigerant circulation may decrease and the cooling capacity may become insufficient, or the refrigerant may evaporate in the liquid pipe and become flash gas, which may cause a malfunction of the decompression mechanism and render it inoperable.

Therefore, conventionally, for example, in the one disclosed in Japanese Utility Model Laid-Open No. 52-152158, a three-way valve is provided in the refrigerant circulation system, and its two ports are provided in the outlet side pipe (liquid pipe) of the condenser and the remaining one By arranging the port on the inlet side pipe (gas pipe) of the condenser, during cooling operation, the liquid pipe on the outlet side of the condenser is throttled under low outside air temperature,
High pressure of the refrigeration cycle by storing the liquid refrigerant in the condenser to reduce the refrigerant cooling capacity, and directly connecting the gas pipe and the liquid pipe with a predetermined passage area and flowing the gas refrigerant to the liquid pipe bypassing the condenser. Is prevented so that the cooling operation can be continued even at a low outside air temperature.

(Problems to be Solved by the Invention) However, when the above conventional technique is applied to a heat pump type air conditioner capable of cooling and heating operations,
The three-way valve is a dedicated product during cooling operation, and the value of the expensive three-way valve is halved.

The present invention has been made in view of the above problems, and an object thereof is to use an existing device in a heat pump type air conditioner, thereby making it unnecessary to install a conventional high-priced three-way valve. The reason is that the cooling operation can be continued even at a low price even at a low outside air temperature.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, an auxiliary condenser used during heating overload and a capacity control mechanism of a compressor are used as existing equipment in a heat pump type air conditioner. We paid attention to the fact that there are some that have a hot gas bypass mechanism. In other words, a small capacity is selected for the above-mentioned auxiliary condenser, and it operates to assist this when the indoor heat exchanger (condenser) is overloaded during heating operation, and the refrigerant is used during cooling operation. Does not flow and does not function as a heat exchanger at all, so the refrigerant circulation amount is appropriately distributed to the large-capacity main condenser (outdoor heat exchanger) and the above-mentioned auxiliary condenser during the cooling operation under low outdoor air temperature ( By bypassing the refrigerant to the auxiliary heat exchanger), the refrigerant cooling capacity of the main and auxiliary condensers as a whole is reduced, while suppressing a decrease in the high pressure of the refrigeration cycle, and cooling operation even at low outside air temperature. To continue to be good.

In addition, if the liquid communication pipe between the outdoor heat exchanger (condenser) and the indoor heat exchanger (evaporator) during cooling operation is long, the liquid will increase as the high pressure of the refrigeration cycle decreases under low outdoor air temperature. When the temperature of the refrigerant greatly drops and drops below the outside air temperature, dew condensation occurs on the liquid communication pipe, so it is necessary to provide a heat insulating member on the liquid communication pipe. Therefore, in the invention according to claim (1) of the present application, in a situation where the high pressure is reduced and the ambient temperature becomes lower than the ambient temperature by bypassing the refrigerant to the auxiliary condenser as described above, the hot gas bypass mechanism of the compressor is further added. By using the hot gas from the compressor directly through the liquid communication pipe,
The purpose is also to raise the temperature of the liquid communication pipe to prevent dew condensation and to eliminate the need for heat insulation.

That is, the specific configuration of the invention according to claim (1) of the present application is the compressor (1) having the hot gas bypass mechanism (20), the four-way switching valve (2), and the outdoor heat exchanger (3). , An electronic expansion mechanism (4), and an indoor heat exchanger (7) are sequentially connected in a closed circuit, and a refrigerant circulation system (10) capable of cooling and heating operations
And a discharge pipe (9a) of the compressor (1) and the indoor heat exchanger (condenser) (7) downstream side during heating operation, with an auxiliary condenser (16) and an on-off valve. It is premised on an air conditioner in which (17) are connected in series by a heating overload pipe (15). Then, the pressure state detection means (P1) for detecting the pressure state of the refrigerant in the refrigerant circulation system (10) and the output of the pressure state detection means (P1) are received, and the pressure of the refrigerant is set at the low outside air temperature during the cooling operation. An opening control means (27) for opening the opening / closing valve (17) and controlling the opening of the electronic expansion mechanism (4) to a decreasing side when the set value is equal to or less than a set value. In addition, the hot gas introduction pipe (2) is provided on the downstream side of the opening / closing valve (17) of the heating overload pipe (15).
5) In the compressor (1) hot gas bypass mechanism (2)
It is configured to be connected to 0) so that hot gas can be introduced.

In that case, since the capacity of the outdoor heat exchanger (condenser) can be reduced by always operating the auxiliary condenser (16) during the cooling operation, in the invention according to claim (2) of the present application, the auxiliary condenser The objective is to make the outdoor heat exchanger compact by always operating even during cooling operation.

That is, in the invention according to claim (2) of the present application, the opening control means (27) controls the opening / closing valve (17) to be always open during the cooling operation.

(Operation) With the configuration described above, in the invention according to claim (1) of the present application, basically, the refrigerant circulation system (10) is appropriately changed to the cooling cycle and the heating cycle by the switching operation of the four-way switching valve (2). At the same time as switching, when the indoor heat exchanger (7) acts as a condenser during the heating operation and becomes the overload state, the on-off valve (1
7) is controlled to open, the heating overload pipe (15) is opened, the gas refrigerant flows into the auxiliary condenser (16) and is condensed, and the refrigerant condensing function of the indoor heat exchanger (7) is changed to the auxiliary condenser (16). ). When the operating capacity of the compressor (1) is large with respect to the heat load of the indoor heat exchanger (7), the hot gas bypass mechanism (20) is activated and discharged from the compressor (1). A part of the refrigerant immediately returns to the suction side and the operating capacity is reduced.

Now, during the cooling operation, if the outside air temperature falls below the set value,
The state of the refrigerant in the refrigerant circulation system (10) (for example, the condensation pressure or the evaporation pressure) decreases and becomes less than the set value. Thus, in this case, the opening / closing valve (17) of the heating overload pipe (15) is controlled to be opened, and the gas refrigerant flows through the auxiliary condenser (17).
The opening degree of the electronic expansion mechanism (4) becomes a small value, the amount of refrigerant flowing through the outdoor heat exchanger (condenser) decreases, and the amount of refrigerant bypass to the auxiliary condenser (17) increases. As a result, in the auxiliary condenser (17), due to its small capacity, the refrigerant circulation speed is high, and the refrigerant is not sufficiently cooled. As a result, the high pressure rises and the decrease is effectively suppressed.

Further, when the high pressure drop is large due to the bypass of the refrigerant to the auxiliary condenser (16) as described above, the compressor (1)
A part of the hot gas discharged from the bypass mechanism (2
It is possible to take it out from the (0) and flow it to the downstream side (liquid communication pipe) of the opening / closing valve (17) of the heating overload pipe (15), so that the temperature of the refrigerant flowing through the liquid communication pipe can be increased, and the liquid communication pipe It is possible to effectively prevent dew condensation.

Particularly, in the invention according to claim (2), during the cooling operation,
The opening / closing valve (17) for heating overload is controlled to be opened as described above, and the gas refrigerant constantly flows through the auxiliary condenser (16) to operate as a condenser. Therefore, the outdoor heat exchanger (condenser) (3) is Therefore, a smaller capacity can be selected, and the outdoor heat exchanger (3) can be downsized.

(Effect of the invention) As described above, according to the air conditioner of the invention according to claim (1) of the present application, the existing auxiliary condenser for heating overload and the hot gas bypass mechanism of the compressor are used. do it,
During cooling operation at low outside air temperature, a part of the refrigerant flowing in the outdoor heat exchanger (condenser) is bypassed to the auxiliary heat exchanger to lower the refrigerant cooling function of the entire condenser and to reduce the high pressure of the refrigerant. In addition to suppressing the decrease, the hot gas was caused to flow through the liquid communication pipe to raise the temperature of the refrigerant, so that the cooling operation at a low outside air temperature can be favorably continued with a low-cost configuration using existing equipment. , It is possible to prevent dew condensation on the liquid communication pipe,
It is not necessary to attach the heat insulating member.

In particular, in the invention according to claim (2), since the auxiliary condenser for heating overload is used also during the cooling operation, the capacity of the outdoor heat exchanger (condenser) during the cooling operation can be set smaller by that amount. Therefore, the outdoor heat exchanger can be downsized.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall schematic configuration of a heat pump type air conditioner capable of cooling and heating operations. In the figure, (A) is an outdoor unit and (B) is an indoor unit. The outdoor unit (A) is a compressor (1), a four-way switching valve (2), and an outdoor heat exchanger (3).
An electric expansion valve (electronic expansion mechanism) (4) for pressure reduction and flow rate control during heating operation, a receiver (5), and an accumulator (6) are provided. On the other hand, the indoor unit (B) includes an indoor heat exchanger (7) and an automatic expansion valve (8) for pressure reduction and flow rate control during cooling operation inside.

The device of the indoor unit (B) is connected to the device of the outdoor unit (A) by a refrigerant pipe (9) in a closed circuit to form a refrigerant circulation system (10). The refrigerant circulation system (10)
Is a cooling cycle when switching the position of the four-way switching valve (2) in the solid line in the figure, and causes the refrigerant to circulate as shown by the solid line arrow in the figure to cause the outdoor heat exchanger (3) to act as a condenser and to perform indoor heat exchange. The chamber (7) acts as an evaporator to cool the room. Further, when the four-way switching valve (2) is switched to the broken line position, a heating cycle is started, and the refrigerant is circulated as indicated by the broken line arrow in the figure, and the indoor heat exchanger (7) is used as a condenser and the outdoor heat exchanger ( 3) is operated as an evaporator to heat the room.

Thus, in the outdoor unit (A), the discharge pipe (9a) between the compressor (1) and the four-way switching valve (2) is communicatively connected to one end of the heating overload pipe (15). The other end is connected between the receiver (5) and the electronic expansion valve (4) for heating operation, that is, downstream of the indoor heat exchanger (condenser) (7) during heating operation. In the middle of the heating overload pipe (15), an auxiliary condenser (16) and an electromagnetic on-off valve (on-off valve) (1
7) and are installed in series.

Further, the compressor (1) includes a hot gas bypass mechanism (20) as its capacity control mechanism. The hot gas bypass mechanism (20) includes a discharge pipe (9a) of the compressor (1),
A bypass pipe (22) communicating with the upstream side of the accumulator (6) of the suction pipe (9b), a decompression mechanism (23) and a bypass opening / closing valve (24) provided in the bypass pipe (22). The bypass opening / closing valve (24) is controlled to be opened when the operating capacity of the compressor (1) is larger than the load of the indoor heat exchanger (7).

Further, between the decompression mechanism (23) of the hot gas bypass mechanism (20) and the on-off valve (24), and between the electronic expansion valve (4) and the receiver (5) of the refrigerant circulation system (10) (that is, What is the electromagnetic on-off valve (17) downstream side of the heating overload pipe (15)?
They are connected to each other via a hot dust introduction pipe (25).

In addition, (26) is a controller having a CPU and the like inside, and the controller (26) controls the opening degree of the electronic expansion valve (4) and the bypass opening / closing valve (2).
4) and the solenoid on-off valve (17) are controlled to open and close.

Further, the refrigerant pipe (gas pipe) (9) between the indoor heat exchanger (7) and the four-way switching valve (2) is connected to the evaporation pressure of the indoor heat exchanger (evaporator) (7) during cooling operation. (Refrigerant circulation system (1
A pressure sensor (pressure state detection means) (P1) for detecting (0) the refrigerant pressure state) is arranged. In addition, in the outdoor unit (A), an outside air temperature sensor (P
2) is arranged, and the detection signals of the sensors (P1) and (P2) are input to the controller (26) and used to control the opening of the electronic expansion valve (4).

The controller (26) switches the four-way switching valve (2) to the solid line position during the cooling operation, and first detects the opening control of the electronic expansion valve (4) during the cooling operation by the pressure sensor (P1). The evaporation temperature equivalent saturation temperature Te is converted and calculated as shown in Fig. 2 (b) based on the calculated evaporation pressure, and this saturation temperature Te is detected by the outside air temperature sensor (P2).
This temperature value (Te + Tair) is added to (see (a) in the figure).
Set as a parameter Set value corresponding to low outside air temperature
Compared with To, the opening of the electronic expansion valve (4) is fully opened when Te + Tair> To, and the opening of the electronic expansion valve (4) is controlled to a 1/4 opening value when Te + Tair ≦ To (the same). Figure (c),
(See (d)).

Further, the controller (26) controls the opening / closing of the electromagnetic opening / closing valve (17) during the cooling operation as shown in FIG. Furthermore,
When the parameter temperature value (Te + Tair) becomes Te + Tair = 0, the bypass on-off valve (24) is forcibly opened.

Therefore, the controller (26) receives the output of the pressure sensor (P1), opens the electromagnetic opening / closing valve (17) of the heating overload pipe (15), and changes the evaporation pressure Te of the refrigerant in consideration of the outside air temperature Tair. The opening control means (27) is configured to control the opening of the electronic expansion valve (4) from the full opening to the 1/4 opening value when the set value To is equal to or lower than the set low outside air temperature. is doing. Further, when the bypass opening / closing valve (24) is opened, a part of the hot gas bypassed to the suction side of the compressor (1) is electromagnetically connected to the heating overload pipe (15) via the hot gas introduction pipe (25). The hot gas is introduced to the downstream side of the on-off valve (17).

Therefore, in the above embodiment, when the indoor heat exchanger (condenser) (7) is overloaded during the heating operation, the electromagnetic opening / closing valve (17) is controlled to open and the heating overload pipe (15) is opened. Since the gas refrigerant from the compressor (1) flows into the auxiliary condenser (16) for heating overload and is condensed, the refrigerant cooling action of the indoor heat exchanger (condenser) (7) is assisted, The overload state of the indoor heat exchanger (condenser) (7) is suppressed and eliminated.

Also, during cooling operation, the solenoid on-off valve (1
By controlling the opening of 7), the gas refrigerant from the compressor (1) flows through the auxiliary condenser (16), and the outdoor heat exchanger (condenser) (3)
At the same time, it exerts a refrigerant cooling action and is used for cooling the room. In this case, when the outside air temperature Tair is greatly reduced, the refrigerant cooling performance in the outdoor heat exchanger (condenser) (3) is increased and the high pressure and low pressure (evaporation pressure) of the refrigerant circulation system (10) are also reduced, It is difficult to continue the cooling operation. However, as shown in FIG. 2, when the parameter (Te + Tair) becomes equal to or lower than the set value To as the evaporating pressure equivalent saturation temperature Te decreases, the opening degree of the electronic expansion valve (4) becomes 1/4 opening degree. Since the amount is controlled to be reduced to the value, the amount of the refrigerant flowing through the outdoor heat exchanger (3) is decreased, and the gas refrigerant is distributed to the auxiliary condenser (16) accordingly. At that time, since the auxiliary condenser (16) has a small capacity (that is, a small passage area) and the refrigerant circulation speed is high, the amount of heat radiated to the outside air is reduced and the refrigerant cooling performance is deteriorated. , High pressure of refrigerant circulation system (10) (condensing pressure)
Also, the low pressure (evaporation pressure) rises, and these decreases are suppressed or prevented.

In that case, if the high pressure and the low pressure do not rise even if the opening control of the electronic expansion valve (4) is controlled and continue to decrease, the vapor pressure equivalent saturation temperature Te should be Te = 0 as shown in FIG. For example, dew condensation may occur on the liquid communication pipe (9), but in this case, the bypass on-off valve (24) of the hot gas bypass mechanism (20) is controlled to be open as shown in (f) of the figure. ,
Since a part of the hot gas flows through the gas introduction pipe (25) to the liquid communication pipe (9) on the upstream side of the receiver (5), the pressure and temperature of the refrigerant flowing there rises, and the vapor pressure equivalent saturation temperature Te. Also, the cooling operation can be favorably continued even under a low outside air temperature, and the temperature of the refrigerant flowing through the liquid communication pipe (9) becomes high due to the flow of hot gas. Is prevented, and the heat insulating member attached to the liquid communication pipe (9) is unnecessary.

As the cooling operation continues under low outside air temperature, the existing auxiliary condenser (16) and hot gas bypass mechanism (20) are installed here.
Since the above-mentioned method is used, a high-priced three-way valve unlike the conventional case is not required, and the cooling operation can be continued at a low price accordingly. Moreover, since the auxiliary condenser (16) for heating overload is also used during the cooling operation, the outdoor heat exchanger (condenser) during the cooling operation.
The capacity can be reduced by that amount, and the outdoor heat exchanger can be downsized.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is an overall schematic configuration diagram, and FIG. 2 is an operation explanatory diagram. (1) …… Compressor, (2) …… Four way switching valve, (3) ……
Outdoor heat exchanger, (4) ... electronic expansion valve (electronic expansion mechanism), (7) ... indoor heat exchanger, (9a) ... discharge pipe,
(10) …… Refrigerant circulation system, (P1) …… Pressure sensor (pressure state detection means), (15) …… Heating overload piping, (16)
…… Auxiliary condenser, (17) …… Electromagnetic on-off valve (on-off valve),
(20) …… Hot gas bypass mechanism, (25) …… Hot gas introduction pipe, (26) …… Controller, (27) …… Opening control means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-181044 (JP, A) JP-A-2-97853 (JP, A) Actually open 61-205365 (JP, U) Actually open 47- 35250 (JP, U)

Claims (2)

[Claims] 1. A compressor (1) having a hot gas bypass mechanism (20), a four-way switching valve (2), an outdoor heat exchanger (3),
The electronic expansion mechanism (4) and the indoor heat exchanger (7) have a refrigerant circulation system (10) that is sequentially connected in a closed circuit and capable of cooling and heating operations, and a discharge pipe (9) of the compressor (1).
The heat pump connected between a) and the downstream side of the indoor heat exchanger (7) during heating operation by a heating overload pipe (15) in which an auxiliary condenser (16) and an on-off valve (17) are arranged in series. Type air conditioner, wherein the refrigerant circulation system (10)
State detection means (P1) for detecting the pressure state of the refrigerant
And the output of the pressure state detection means (P1), and when the pressure of the refrigerant during the cooling operation is equal to or lower than the set value corresponding to the set low outside air temperature, the opening / closing valve (17) is opened and the electronic expansion mechanism (4 ) Opening control means (2
7) and the above heating overload pipe (15)
A downstream side of the on-off valve (17) is connected to the hot gas bypass mechanism (20) of the compressor (1) by a hot gas introduction pipe (25) so that hot gas can be introduced. Air conditioner. 2. The air conditioner according to claim 1, wherein the opening control means (27) controls the opening / closing valve (17) to be always open during the cooling operation. .