JP2993180B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a positive cycle defrost circuit, and more particularly to a measure for improving a heating capacity during a defrosting operation.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 64-3348
As disclosed in Japanese Patent Publication No. 0, in an air conditioner provided with a refrigerant circuit in which a compressor, an indoor heat exchanger, a pressure reducing mechanism, and an outdoor heat exchanger are sequentially connected, a liquid pipe from the discharge pipe to the outdoor heat exchanger is provided. A hot gas bypass path for bypassing hot gas is provided via an on-off valve, and the decompression resistance value of the pressure reducing mechanism is variably configured in conjunction with the opening and closing of the on-off valve of the hot gas bypass path, so that the heating operation is performed during the heating operation. At the time of defrost command,
By opening the on-off valve and branching and circulating the discharged refrigerant to the indoor heat exchanger side and the hot gas bypass path side, it is intended to melt the frost of the outdoor heat exchanger while heating the room. This is a known technique.

[0003] Further, as disclosed in, for example, JP-A-1-208678, an air conditioner provided with a refrigerant circuit in which a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger are sequentially connected. A hot gas bypass path for bypassing hot gas from the discharge pipe to the liquid pipe of the outdoor heat exchanger is provided via an on-off valve, and a heating bypass for connecting the liquid pipe between the indoor heat exchanger and the expansion valve to the suction pipe. When the outdoor heat exchanger is frosted, the on-off valve of the hot gas bypass passage is opened to perform defrosting operation, while the on-off valve of the heating bypass passage is opened to close the expansion valve. A technique in which a refrigerant is circulated through a heat exchanger to heat a room is also a known technique.

[0004]

However, the former one of the above-mentioned conventional ones has a structure in which the refrigerant must always flow to the indoor heat exchanger when the defrosting operation of the outdoor heat exchanger is performed. Since the ratio between the defrosting capacity and the heating capacity is determined to be constant by the decompression mechanism, the time required for the defrosting may take a long time, but the heating demand on the indoor side may not be sufficiently satisfied.

On the other hand, in the latter of the above-mentioned conventional ones, only the defrosting operation can be performed, but when the defrosting operation and the heating operation are performed at the same time, the ratio of the defrosting capacity to the heating capacity is defrosted. There is a problem that the configuration is determined by the ratio of the pipe resistances of the heating bypass path and the heating bypass path, and cannot be adjusted according to the actual required capacity.

[0006] The present invention generally requires a small amount of refrigerant immediately after the start of the defrosting operation because there is preheating on the indoor side, and once the temperature on the outdoor heat exchanger side rises to some extent and is melted once. After that, in view of the fact that the required capacity changes between the outdoor heat exchanger and the indoor heat exchanger according to the progress of the defrost, so that the defrosting capacity is not so required, the ratio between the defrosting capacity and the heating capacity is changed. An object of the present invention is to improve the comfort of air conditioning without making the defrosting operation time excessive by adopting a structure that can be adjusted.

[0007]

To achieve the above object, according to an aspect of, means taken in the invention of claim 1, as shown in FIG. 1
, The compressor (1), an outdoor heat exchanger (3), the electric expansion valve (4), the indoor fan (5a) indoor heat exchangers attached to (5) and formed by sequentially connecting a main refrigerant It is assumed that the air conditioner includes the circuit (7).

Then, one part (P) of the discharge pipe (6a) of the main refrigerant circuit (7) and one part (Q) of the liquid pipe between the outdoor heat exchanger (3) and the expansion valve (4) are connected. A first bypass path (10) for bypass connection and an on-off valve (11) for opening and closing a pipe of the first bypass path (10) are provided.

Furthermore, a liquid pipe between the connection part (Q) of the first bypass passage (10) of the main refrigerant circuit (7) and the electric expansion valve (4) and a suction pipe (6b) of the compressor (1). A second bypass passage (20) for bypass-connecting the refrigerant, and switching means (2) for switching the refrigerant flow downstream of the electric expansion valve (4) between the outdoor heat exchanger (3) and the second bypass passage (20). 21) is provided
Have been.

On the other hand, the temperature of the air blown out of the indoor heat exchanger (5)
Blowout temperature detecting means (Thu) for detecting the temperature
You.

During the heating operation, the first bypass passage (10)
A heating operation control means (31) for closing the on-off valve (11) of the air conditioner and controlling the refrigerant from the indoor heat exchanger (5) to flow to the outdoor heat exchanger (3) by the switching means (21); When a defrosting operation command is issued during operation, the first bypass path (1
Start control means (32) for opening the on-off valve (11) of (0), closing the electric expansion valve (4), and controlling the air flow of the indoor fan (5a) to a low air flow is provided.

In addition, after receiving the output of the blow-out temperature detecting means (Thu) and starting the defrosting operation by the start control means (32), the temperature of the blow-off air of the indoor heat exchanger (5) is increased to the first temperature.
When the temperature falls below the set temperature, the refrigerant discharged from the compressor (1)
While being introduced into the outdoor heat exchanger (3), the compressor (1)
There is provided a first heating capacity increasing means (33) for opening the electric expansion valve (4) at a constant opening so that a part of the discharged refrigerant flows into the indoor heat exchanger (5) .

In addition, the first heating capacity increasing means (33)
After the heating capacity is increased by the above, the outlet temperature detecting means (Th
When the temperature of the air blown out of the indoor heat exchanger (5) detected in u) becomes equal to or lower than the second set temperature lower than the first set temperature, the switching means (21) causes the electric expansion valve (4) downstream. A second heating capacity increasing means (34) for switching the refrigerant flow to the second bypass passage (20) side and adjusting the opening of the electric expansion valve (4) according to the load is provided.

[0014]

According to the above construction, in the first aspect of the invention, when the outdoor heat exchanger (3) is frosted during the heating operation, the on-off valve (11) is opened to discharge refrigerant to the outdoor heat exchanger (3). And a defrosting operation by a so-called normal cycle for melting the frost of the outdoor heat exchanger (3) is possible.
By switching the refrigerant on the downstream side of the electric expansion valve (4) to the second bypass passage (20) side by switching of the switching means (21), the refrigerant discharged from the compressor (1) is discharged to the first point (P) at the point (P). The cycle is divided into two independent cycles: a cycle passing through the bypass path (10) -the outdoor heat exchanger (3) and a cycle passing through the indoor heat exchanger (5) -the second bypass path (20). Frost and heating can be performed simultaneously.

At this time, since the second bypass passage (20) is branched from the downstream side of the electric expansion valve (4), the opening degree of the electric expansion valve (4) is adjusted so that the defrosting capacity and the heating capacity are not changed. The ratio can be adjusted, and appropriate capacity distribution can be performed in accordance with the state of preheating in the room during the heating operation and the progress of melting of frost in the outdoor heat exchanger (3).

That is , during the heating operation by the heating control means (31), when the defrost operation is started in response to the defrost command,
Since the electric expansion valve (4) is closed and the on-off valve (11) is opened by the start control means (32), all the refrigerant discharged from the compressor (1) is introduced into the outdoor heat exchanger (3) and the outdoor heat exchanger (3) is heated. The frost on the exchanger (3) is quickly melted. At this time,
Since the indoor fan (5a) is operated at a low air volume, the indoor heating is continued by the preheating of the indoor heat exchanger (5), and the comfort of air conditioning is maintained.

When the temperature of the blown air of the indoor heat exchanger (5) detected by the blowout temperature detecting means (Thu) falls below the first set temperature, the first heating capacity increasing means (33) causes the electric expansion valve to increase. Since (4) is opened to a certain opening, the discharged refrigerant flows toward the indoor heat exchanger (5) to heat the room, thereby suppressing a decrease in the temperature of the blown air and maintaining the comfort of air conditioning. You.

When the temperature of the blown air falls below the second set temperature lower than the first set temperature, the switching means (21) is switched by the second heating capacity increasing means (34) to the second bypass passage (20). Side, the degree of opening of the electric expansion valve (4) is adjusted according to the load, the flow rate of the refrigerant to the indoor heat exchanger (5) is increased, and the indoor heating is ensured. That is, two independent cycles of a cycle in which the discharged refrigerant passes through the first bypass path (10) -the outdoor heat exchanger (3) and a cycle in which the discharged refrigerant passes through the indoor heat exchanger (5) -the second bypass path (20). The defrosting of the outdoor heat exchanger (3) proceeds without stopping, and at the same time, the heating capacity of the indoor heat exchanger (5) increases, and the air conditioning is performed without excessive defrosting operation time. The comfort will be improved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 2 shows a refrigerant piping system of an air conditioner according to an embodiment of the present invention. The air conditioner has a compressor (1) whose operating frequency is variably adjusted by an inverter (not shown). ) And a four-way switching valve (2) that switches during heating operation as indicated by the solid line in the figure and during cooling operation as indicated by the broken line in the figure,
An outdoor fan (3a) is provided, and an outdoor heat exchanger (3) functioning as an evaporator during a heating operation and as a condenser during a cooling operation, an electric expansion valve (4), and an indoor fan (5a) are provided. A main refrigerant circuit (7) is provided in which a refrigerant pipe (6) is connected to an indoor heat exchanger (5) functioning as an evaporator during cooling operation as a condenser during cooling operation.

Then, one part (P) of the discharge pipe (6a) of the main refrigerant circuit (7) and one part (Q) of the liquid pipe between the outdoor heat exchanger (3) and the electric expansion valve (4). A first bypass passage (10) for directly introducing the discharged refrigerant to the outdoor heat exchanger (3) is provided through a normally-closed on-off valve (11). In the case of frost formation in 3), the on-off valve (1)
By opening 1) and directly introducing the discharged refrigerant into the outdoor heat exchanger (3), frost formation on the outdoor heat exchanger (3) can be melted .

Further, a junction (Q) between the first bypass passage (10) and the main refrigerant circuit (7) -the electric expansion valve (4).
A second bypass path (20) for bypass-connecting the liquid pipe and the suction pipe (6b) between the second bypass path (20) and the main refrigerant circuit (7) is provided at a connection portion between the second bypass path (20) and the main refrigerant circuit (7). A three-way valve (21) is provided as switching means for switching the flow of the refrigerant downstream of the electric expansion valve (4) between the outdoor heat exchanger (3) and the second bypass path (20).

That is, during the normal heating operation, the three-way valve (21) is switched to the outdoor heat exchanger (3) to allow the refrigerant downstream of the electric expansion valve (4) to flow through the outdoor heat exchanger (3). By switching the connection of the three-way valve (21) to the side of the second bypass passage (20) as necessary, the indoor heat exchanger (5) is connected to the electric expansion valve (4) -the second bypass passage (20).
To return to the compressor (1).

(Thu) is an outlet temperature sensor as an outlet temperature detecting means for detecting the temperature Tu of the outlet air of the indoor heat exchanger (5). It is connected to a controller (30) for controlling the operation of the harmony device. And the control
The operation frequency of the compressor (1), the air flow of the indoor fan (5a), and the on-off valve (1) of the first bypass passage (10) according to a signal from the blow-out temperature sensor (Thu) and the like.
Opening / closing of 1), opening of electric expansion valve (4), three-way valve (21)
And the like are controlled.

During the heating operation, the four-way switching valve (2) is switched to the solid line side in the figure, and the on-off valve (1) of the first bypass passage (10) is turned on.
1) is closed and the three-way valve (21) is the outdoor heat exchanger (3)
The refrigerant discharged from the compressor (1) is condensed and liquefied in the indoor heat exchanger (5), expanded by the electric expansion valve (4), and then expanded to the outdoor heat exchanger (3). And circulates back to the compressor (1). During the cooling operation, the four-way switching valve (2) switches to the broken line side in the drawing, and the flow is reverse to the above.

Here, the control contents of the controller (30) during the heating operation will be described with reference to the time chart of FIG.
Explanation will be given based on the

Here, FIG. 3A shows the operating frequency of the compressor (1), FIG. 3B shows the opening of the electric expansion valve (4), and FIG. 3C shows the opening and closing of the on-off valve (11). (D) Switching of the three-way valve (21), FIG. (E) shows the airflow of the indoor fan (5a), and FIG. (F) shows the temperature Tu of the air blown from the indoor heat exchanger (5). Shows the time change .

As described above, the on-off valve (11) of the first bypass passage (10) is closed, and the three-way valve (21) is switched to the outdoor heat exchanger (3) to perform the heating operation. This control constitutes a heating operation control means (31) according to the first aspect of the present invention. When the outdoor heat exchanger (3) functioning as an evaporator is frosted during the heating operation, a defrost command is output, the opening and closing valve (11) of the first bypass passage (10) is opened, and the electric expansion valve is opened. (4) is closed and the indoor fan (5a) is closed.
Is controlled to be low (see time t1 in the figure). This control start control means in the invention of claim 1 (3
2) is configured.

Next, when the temperature of the air blown out of the indoor heat exchanger (5) becomes equal to or lower than the first set temperature T1 after the start of the defrosting operation by the start control means (32), the operation of the other devices remains unchanged. in to open the motor-operated expansion valve opening degree of (4) to a predetermined opening degree
Controls (see time t2 in the drawing). With this control,
The first heating / heating capacity increasing means (3 ) according to the invention of claim 1
3) is configured.

The first heating capacity increasing means (33)
After the heating capacity is increased by the above, the outlet temperature sensor (Thu)
Of the air blown out of the indoor heat exchanger (5) detected at
When the temperature becomes lower than the second set temperature T2, which is lower than the first set temperature T1, the operation of the other devices is kept as it is, and the three-way valve (21) connects the refrigerant flow passage downstream of the indoor heat exchanger (5). is switched to the first bypass passage (20) side is controlled so as to adjust according to the load of the opening degree of the electronic expansion valve (4) (see figure time t3). This control second heating capacity increased means in the invention of claim 1 (34) is configured.

Thereafter, when the defrosting of the outdoor heat exchanger (3) is completed, a command to end the defrosting operation is output, and all the states of the devices are returned to the state of the normal heating operation, and the operation returns to the heating operation. (See time t4 in the figure).

Therefore, in the above embodiment, the first bypass passage (10) for directly introducing hot gas from the discharge pipe (6a) to the outdoor heat exchanger (3) is provided to the air conditioner via the on-off valve (11). And a main refrigerant circuit (7).
A second bypass passage (20) for bypassing the outdoor heat exchanger (3) and allowing the refrigerant to flow through the suction pipe (6b) is provided downstream of the electric expansion valve (4). When the heat exchanger (3) is frosted, the open / close valve (11) is opened to introduce the discharged refrigerant into the outdoor heat exchanger (3) to melt the frost on the outdoor heat exchanger (3), a so-called normal cycle. Defrosting operation is possible and the three-way valve (21)
By switching the refrigerant, the refrigerant on the downstream side of the electric expansion valve (4) is bypassed to the second bypass passage (20), so that the refrigerant can be circulated through the indoor heat exchanger (5) to perform the indoor heating operation. Becomes

That is, as shown in the Mollier diagram of FIG. 4, a cycle in which the refrigerant discharged from the compressor (1) passes through the first bypass path (10) and the outdoor heat exchanger (3) at the point (P). (A) and the indoor heat exchanger (5) -second bypass path (2)
It is separated into two independent cycles from the cycle (B) passing through 0), and it is possible to simultaneously perform defrosting and heating. At this time, the second from the downstream side of the electric expansion valve (4)
Since the bypass path (20) is branched, the flow rate of the refrigerant flowing through the first bypass path (10) -the outdoor heat exchanger (3) and the indoor temperature are adjusted by adjusting the opening of the electric expansion valve (4). The ratio between the flow rate of the refrigerant flowing through the heat exchanger (5) and the second bypass path (20), that is, the ratio between the defrosting capacity and the heating capacity can be adjusted, and the state of preheating of the room during the heating operation is performed. In accordance with the progress of the melting of the frost of the outdoor heat exchanger (3) or the outdoor heat exchanger (3), appropriate capacity distribution can be performed. Therefore, the comfort of air conditioning can be improved without making the defrosting operation time excessive.

Further, when specific control is performed by the controller (30) according to the progress of defrosting as in the above embodiment, the effect becomes remarkable. That is, during the heating operation by the heating operation control means (31), when the defrost operation is started in response to the defrost command, the start control means (32) closes the electric expansion valve (4) and closes the on-off valve (11). By opening, all the refrigerant discharged from the compressor (1) is introduced into the outdoor heat exchanger (3), and frost formation on the outdoor heat exchanger (3) is quickly melted. At this time, since the indoor fan (5a) is operated at a low air volume, the indoor heating is continued by the preheating of the indoor heat exchanger (5), and the comfort of the air conditioning is maintained.

When the blown air temperature Tu of the indoor heat exchanger (5) detected by the blowout temperature sensor (Thu) falls below the first set temperature T1, the first heating capacity increasing means (33).
As a result, the electric expansion valve (4) is opened to a certain opening degree, so that the discharged refrigerant flows toward the indoor heat exchanger (5) to heat the room, thereby suppressing a decrease in the blown air temperature Tu.

After that, the blown air temperature Tu becomes the first
When the temperature becomes equal to or lower than the second set temperature T2 lower than the set temperature T1, the three-way valve (2) is increased by the second heating capacity increasing means (34).
1) is switched to the second bypass path (20) side, and the opening degree of the electric expansion valve (4) is adjusted according to the load;
The flow rate of the refrigerant to the indoor heat exchanger (5) increases, and indoor heating is ensured. That is, as shown in the Mollier diagram in FIG. 4, the refrigerant discharged from the compressor (1) is at the point (P) at the first point (P).
Two independent cycles, a cycle (A) via a bypass (10) -outdoor heat exchanger (3) and a cycle (B) via an indoor heat exchanger (5) -second bypass (20) The heating capacity of the indoor heat exchanger (5) can be increased by appropriately adjusting the capacity distribution ratio of the electric expansion valve (4) by adjusting the opening degree of the electric expansion valve (4) as well as separating the cycle.

That is, as described above, by switching the three-way valve (21) in accordance with the progress of defrosting and adjusting the defrosting capacity and the heating capacity, the air conditioning can be performed without excessively increasing the defrosting operation time. The comfort of the car can be improved.

In the above embodiment, the air conditioner is provided with the four-way switching valve (2) so that the cooling and heating cycle can be switched. However, the present invention is not limited to such an embodiment. The present invention can also be applied to an air conditioner dedicated to heating.

[0039]

As described above, according to the first aspect of the invention, the compressor, the outdoor heat exchanger, the electric expansion valve, and the outdoor heat exchanger are sequentially connected to form a main refrigerant circuit of the air conditioner. A first bypass path for bypassing the hot gas from the discharge pipe to the inlet-side liquid pipe of the outdoor heat exchanger is provided via an on-off valve, and a first bypass path for bypassing the outdoor heat exchanger from immediately downstream of the electric expansion valve to the suction pipe. (2) Since the flow of the refrigerant is switched between the outdoor heat exchanger side and the bypass path side by providing the two bypass paths, during the defrosting operation during the heating operation, the refrigerant flows through the first bypass path-the outdoor heat exchanger. Of the cycle that circulates and the cycle that passes through the indoor heat exchanger-second bypass path
It can be separated into two independent cycles, and can perform indoor heating operation while performing defrosting operation in the main cycle, and by adjusting the opening of the electric expansion valve, the ratio of defrosting capacity to heating capacity can be adjusted. Adjustments can be made.

During the heating operation, when the defrosting operation is started in response to the defrosting command, the electric expansion valve is closed and the on-off valve is opened to operate the indoor fan at a low air flow. When the air temperature becomes equal to or lower than the first set temperature, the electric expansion valve is opened to a certain opening, and thereafter, when the blown air temperature becomes equal to or lower than the second set temperature lower than the first set temperature, immediately downstream of the electric expansion valve. The refrigerant flow is switched to the second bypass path side, and the opening of the electric expansion valve is adjusted according to the load. Therefore, the refrigerant flow is switched and the opening of the electric expansion valve is adjusted according to the progress of defrosting. Thus, the defrosting capacity and the heating capacity can be appropriately adjusted, and the comfort of air conditioning can be improved without making the defrosting operation time excessive.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant piping system diagram of the air conditioner according to the embodiment of the present invention.

FIG. 3 is a time chart showing an operation change of each device during a defrosting operation.

FIG. 4 is a Mollier diagram showing a state of a refrigeration cycle during simultaneous operation of defrosting and heating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 3 Outdoor heat exchanger 4 Electric expansion valve 5 Indoor heat exchanger 5a Indoor fan 6a Discharge pipe 6b Suction pipe 7 Main refrigerant circuit 10 1st bypass path 20 2nd bypass path 21 Three-way valve (switching means) 31 Heating operation Control means 32 Start control means 33 First heating capacity increasing means 34 Second heating capacity increasing means Thu Blow temperature sensor (Blow temperature detecting means)

Claims (1)

(57) [Claims] A compressor (1) and an outdoor heat exchanger (3)
And an air conditioner provided with a main refrigerant circuit (7) in which an electric expansion valve (4) and an indoor heat exchanger (5) provided with an indoor fan (5a) are sequentially connected. One part (P) of the discharge pipe (6a) of (7)
A first bypass passage (10) for bypass-connecting a part (Q) of the liquid pipe between the outdoor heat exchanger (3) and the expansion valve (4);
And an on-off valve (1) for opening and closing the pipeline of the first bypass passage (10).
1) , the liquid pipe between the connection part (Q) of the first bypass passage (10) of the main refrigerant circuit (7) and the electric expansion valve (4) and the suction pipe (6b) of the compressor (1). A second bypass passage (20) for bypass connection, and a switching means (21) for switching the flow of refrigerant downstream of the electric expansion valve (4) between the outdoor heat exchanger (3) and the second bypass passage (20). ) And a blow for detecting the temperature of the air blown out of the indoor heat exchanger (5).
An outlet temperature detecting means (Thu) and an on-off valve (1) for the first bypass passage (10) during the heating operation.
1) is closed and the indoor heat exchanger is switched by the switching means (21).
Let the refrigerant from (5) flow through the outdoor heat exchanger (3)
Operation control means (31) for controlling the first bypass passage (1 ) when the defrosting operation command is issued during the heating operation.
Open the open / close valve (11) of 0) and close the electric expansion valve (4)
To start controlling the air volume of the indoor fan (5a) to a low air volume
Receiving the output of the control means (32) and the outlet temperature detecting means (Thu),
After starting the defrosting operation by the control means (32), indoor heat exchange
The temperature of the air blown out of the vessel (5) falls below the first set temperature
And an outdoor heat exchanger (3) for discharging refrigerant discharged from the compressor (1).
And a part of the refrigerant discharged from the compressor (1)
Install the electric expansion valve (4) so that it flows to the indoor heat exchanger (5).
A first heating capacity increasing means to open a certain degree (33), the increase in heating capacity by first heating capacity increasing means (33)
After the indoor heat which is detected by the air temperature detecting means (Thu)
The temperature of the air blown from the exchanger (5) is higher than the first set temperature.
Is lower than the second set temperature, the switching means (2
According to 1), the flow of the refrigerant on the downstream side of the electric expansion valve (4) is
By switching to the bypass path (20), the electric expansion valve (4)
Second heating capacity increasing means (3) for adjusting the opening degree according to the load.
4) An air conditioner comprising: