JPH03158664A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent a compressor from oil lacking by forcibly switching to an oil recovery operation if the state that refrigerant flowing speed to a heat source side heat exchanger is slow is continued for predetermined time. CONSTITUTION:When refrigerant flows to a main refrigerant circuit 1a, the refrigerant is heat exchanged with the air in a user side heat exchanger 7. On the other hand, part of the refrigerant flowing in the circuit 1a is fed to a bypass circuit 1b via bypass control means 11, 12, and temperature of conditioned air is regulated in reheating coils 9, 10. When solenoid valves 11, 12 provided in the circuits 1b, 1b are opened together for predetermined time, oil recovery operating means 24 close both the valves 11, 12 to control a compressor 4 to a maximum capacity operation. Thus, the refrigerant is fed to the circuit 1a and a heat source side exchanger 5 at a high speed, and oil fed to the circuit 1a is recovered to the compressor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air conditioner equipped with a reheating coil, and more particularly to measures to prevent a compressor from running out of oil.

(Prior Art) Generally, as an example of a refrigeration circuit in an air conditioner, there is one equipped with a reheating coil as shown in Japanese Unexamined Patent Publication No. 125360/1983. This type of refrigeration circuit has a reheating coil installed in parallel with the evaporator installed inside the indoor unit.
The upstream side of the refrigerant of this reheating coil is connected directly downstream of the discharge port of the compressor, while the downstream side of the refrigerant is connected to the upstream side of the refrigerant of the evaporator, and the temperature of the blown air is adjusted by the reheating coil. I have to. In other words, in the above air conditioner, the compressor is operated at full load in order to improve the dehumidification ability, and the water vapor contained in the primary air is recovered as drain water by the evaporator, and at the same time, if Since the indoor temperature will drop, the temperature of the blown air is raised by the discharge gas flowing through the reheating coil.

(Problems to be Solved by the Invention) However, in such a device, if the capacity of the reheating coil is too small compared to the evaporator, the temperature of the air passing through the reheating coil cannot be sufficiently raised. In view of this point, it is conceivable to increase the capacity of the reheating coil, increase the amount of refrigerant flowing into the reheating coil, and promote heating of the conditioned air by the reheating coil. However, if the capacity of the reheat coil is increased in this way, the flow rate of refrigerant flowing into the condenser of the outdoor unit will be significantly reduced. The oil that leaked into the refrigeration circuit could not be smoothly recovered, and there was a risk that the compressor would run out. In addition, as a conventional technology for solving such an oil-out situation, there is an oil return control device as shown in Japanese Patent Application Laid-Open No. 58-208545, but this simply controls the operation of the compressor in a low-capacity operating state for a predetermined period of time. In this case, the compressor is placed in a high capacity operating state, and as mentioned above, there is a risk that the compressor may run out of oil depending on the operating state of the reheating coil.

Therefore, an object of the present invention is to prevent the compressor from running out of oil in a refrigeration circuit equipped with such a reheating coil.

(Means for Solving the Problems) In order to achieve the above object, the present invention causes the oil return operation to be performed when the reheating coil operates at a predetermined capacity or more and for a predetermined time or more. The specific means will be described below.

First, the invention of claim (1), as shown in FIG. ) and refrigerant piping (13)
~(16) are connected in series to the main refrigerant circuit (1a
), while a bypass is branched from the discharge side of the compressor (4) of the main refrigerant circuit (1a) and communicates between the pressure reduction mechanism (6) and the utilization side heat exchanger (7). circuit(
1b), and the bypass circuit (1b) is provided with reheating coils (9) and (10) disposed on the downstream side of the air flow of the user-side heat exchanger (7), and The target is an air conditioner equipped with bypass control means (11) and (12) that control the flow rate of refrigerant in the bypass circuit (1b) to control the operating capacity of the reheat coils (9) and (10). . and the reheating coil (9)
, (10) and detects the operating state of the reheating coil (9).
), (10) which outputs a status signal when the unit reaches a preset predetermined capacity operation status, and the reheating coil ( 9), (10) continue operating at a predetermined capacity for a predetermined period of time, an operating state determining means (23) outputs a continued operating signal;
3) outputs a continuous operation signal, the compressor (4) is controlled to maximum capacity operation, and the bypass circuit (1b)
bypass control means (11), (1
2) and an oil recovery operation means (24) for driving and controlling.

In addition, in the invention of claim (2), the indoor unit (2) includes a variable capacity compressor (4), a pressure reduction mechanism (6), a user side heat exchanger (7), a first reheating coil (9), and A second reheating coil (10) is provided, the outdoor unit (3) is provided with a heat source side heat exchanger (5), the compressor (4) and the heat source side heat exchanger (5) are provided.
), the pressure reducing mechanism (6), and the user-side heat exchanger (7) are connected in series by refrigerant pipes (13) to (16) to constitute the main refrigerant circuit (1a), while the compressor (4) )
First and second bypass circuits (
1b), (1b) are provided, and each bypass circuit (
1b), (1b) includes the reheat coil (9) arranged in parallel on the air flow downstream side of the utilization side heat exchanger (7).
), (10) are interposed, and each reheating coil (9), (1
Solenoid valves (11), (1) that control on/off operation of 0)
2) is intended for air conditioners equipped with the following.

and an operating state detection means (22) that detects the open/closed states of the solenoid valves (11) and (12) and issues a state signal when each of the solenoid valves (11) and (12) is fully open; Operating state determining means (23) receives the state signal issued by the state detecting means (22) and outputs a continued operation signal when both the solenoid valves (11) and (12) remain fully open for a predetermined period of time.
), and when the operating state determining means (23) outputs a continuous operating signal, the compressor (4) is controlled to operate at maximum capacity, and both the electromagnetic valves (11) and (12) are controlled to a fully closed state. The structure includes an oil recovery operation means (24).

(effect) The operation of the present invention with the above configuration will be described below.

First, in the invention of claim (1), when the refrigerant flows through the main refrigerant circuit (1a), heat is exchanged between the refrigerant and air in the user side heat exchanger (7), while the main refrigerant circuit ( 1a) bypass control means (11) for a part of the refrigerant flowing therethrough;
(12) to the bypass circuit (1b), and in the reheating coils (9) and (10), the air heat-exchanged in the user-side heat exchanger (7) is heated to adjust the temperature of the conditioned air. . And this reheating coil (9), (1
The operating state detection means (22) detects the operating state of 0), and outputs a state signal when the reheating coils (9) and (10) reach a predetermined capacity operating state. The driving state determining means (23) receives this state signal,
When the reheating coils (9) and (10) continue operating at a predetermined capacity and the above-mentioned status signal continues for a predetermined time, a continuation operation signal is output. Then, the oil recovery operation means (24) receives this continuous operation signal and controls the compressor (4) to the maximum capacity operation, and at the same time, the bypass control means (11), (1
2) to close the bypass circuit (1b) and reheat coil (9).

(10) Stop the capacity operation. Specifically, claim (2
In the invention according to, two bypass circuits (1b) (1b)
When both the solenoid valves (11) and (12) provided in the compressor (4 ) to maximum capacity operation. As a result, the refrigerant flows at high speed through the main refrigerant circuit (1a), and at the same time, the refrigerant flows through the heat source side heat exchanger (
5) flows at a high speed and is discharged into the main refrigerant circuit (1a) and is recovered by the compressor (4). Therefore, the compressor (
4) Oil running out is prevented.

(Example) Next, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 2, the air conditioner (1) according to this example consists of an indoor unit (2) and an outdoor unit (3), and the indoor unit (2) includes a compressor (4), a pressure reducing mechanism an expansion valve (6) as a heat exchanger, and an evaporator (7) as a heat exchanger on the user side.
), an accumulator (8), and first and second reheat coils (9).

(10), and the main parts are first and second solenoid valves (11) and (12) as bypass control means.

On the other hand, the outdoor unit (3) is provided with a condenser (5) as a heat source side heat exchanger.

The compressor (4) is equipped with an unloader mechanism (not shown) and is configured to be controlled to switch between unloading and full loading.
) are connected by a high pressure gas pipe (13), and the condenser (
5) and the expansion valve (6) are connected by a high pressure liquid pipe (14), and the expansion valve (6) and the evaporator (7) are connected by a low pressure liquid pipe (15).
), and a main refrigerant circuit (1a) is formed by connecting an evaporator (7), an accumulator (8), and a compressor (4) in order through a low-pressure gas pipe (16). In addition, each of the reheating coils (9) and (10)
is a bypass circuit (1b) that bypasses the condenser (5)
The evaporator (7) is provided with a capacity of about 50% of the capacity of the evaporator (7). The refrigerant upstream side of each reheating coil (9), (10) is connected to the high pressure gas bypass pipe (17a), (17b) of the bypass circuit (1b) branched from the high pressure gas pipe (13). ,
This high pressure gas bypass pipe (17a).

(17b) is provided with the electromagnetic valves (11) and (12). Meanwhile, each reheat coil (9).

The downstream side of the refrigerant in (10) is connected to the low pressure liquid pipe (15) between the evaporator 1 (7) and the expansion valve (6) by high pressure liquid bypass pipes (18a) and (18b) of the bypass circuit (1b). This high pressure liquid bypass pipe (18a), (18b
) have capillary tubes (19a) and (19b)
is interposed.

The air conditioner (1) is also provided with a controller (20) that controls its operation, and this controller (20) controls the compressor (4) and both of the solenoid valves (1).
1) and (12) to adjust the temperature of the blown air.
and an operating state determining means (23) and an oil recovery operating means (24).
) is provided. The operation control means (21) is
As shown in Table 1, the system is configured to control operation between states ■ to ■ in the cooling operation mode and dehumidification operation mode based on detection signals from a temperature sensor and a humidity sensor (not shown), and the load of cooling and dehumidification is small. In case compressor (4)
The state of cooling operation mode is controlled to unload.
Dehumidifying operation mode status (■～■), and when the load is large, the compressor (4) is controlled to full load (cooling operation mode status ■■, dehumidifying operation mode status ■～■) has been done. Furthermore, the operation control means (21) controls both the electromagnetic valves (11) so that the temperature of the blown air becomes the set value.
(12), and for example, in state (2) in the cooling operation mode, both electromagnetic valves (11
), (12) and both heating coils (9), (10
), and the air cooled by the evaporator (7) is heated to the set temperature.

Next, the cooling operation etc. in each circuit will be explained.

First, in the main refrigerant circuit (1a), the gas refrigerant, which has become high temperature and high pressure discharge gas, is passed through the high pressure gas pipe (13) by the compressor (4) to the condenser (5) of the outdoor unit (3).
The air is sent to the condenser (5), where it exchanges heat with the outside air and is cooled. This cooled refrigerant is then sent from the high pressure liquid pipe (14) to the expansion valve (6).
After being expanded in , it flows through a low pressure liquid pipe (15) into an evaporator (7). This refrigerant evaporates in the evaporator (7) to cool and dehumidify the primary air from a blower fan (not shown) provided in the indoor unit (2). This cooled and dehumidified air is then transferred to a reheating coil (9),
After passing through (10), it becomes conditioned air as secondary air and is blown into the room. On the other hand, the gas refrigerant evaporated in the evaporator (7) passes through the accumulator (8), is sent to the compressor (4) again, and circulates within this main refrigerant circuit (1a).

In addition, each solenoid valve (11) (12) of the bypass circuit (1b)
) is controlled by the operation control means (21), and both solenoid valves (11
), (12) is opened, a part of the gas refrigerant discharged from the compressor (4) is transferred to the high pressure gas bypass pipe (17a),
(17b) to reheat coils (9), (10)
The high-temperature, high-pressure gas refrigerant exchanges heat with the air flowing out from the evaporator (7) in the reheating coils (9) and (10), increasing the temperature of this air. It becomes a liquid refrigerant. Then, this liquid refrigerant flows through the high-pressure liquid bypass pipes (18a) and (18b), and is depressurized by the capillary tubes (19a) and (19b).
15) and returns to the main refrigerant circuit (1a).

Next, the operation control operation of the air conditioner (1) in this example will be explained along the flowchart of FIG. 3.

First, when temperature adjustment operation control of the air conditioner (1) is started, in step S1, a cooling operation mode or a dehumidification operation mode is determined, and for example, the operation mode is determined based on indoor temperature and indoor humidity. And step S2
Control status depending on indoor temperature and humidity conditions
~ ■, and specifically, the operation control means (21) operates the compressor (4) and both electromagnetic valves (11) as shown in Table 1 above.
).

(12) and compressor (4) in each operation mode.
While switching control is performed between unloading and full loading, both solenoid valves (11) and (12) are opened and closed to control the temperature of the blown air. Thereafter, the process moves to step S3, and the operating state detection means (22) determines whether the control state is state (2). That is, it is determined whether both electromagnetic valves (11) and (12) are in the closed state. Here, if it is determined that the control state is not the state ■, the process moves to step S4, and it is determined whether the control state corresponds to the cooling operation mode state ■ or the dehumidification operation mode state ■, ■, or ■. Determine. In other words, in each of these control states, the state of cooling operation mode ■
, ■, ■ or the state of the dehumidifying operation mode ■, ■, the process returns to step S1, and the step 8 described above is performed.
The operations from 1 to S4 are repeated to perform temperature control operation. In other words, in the cooling operation mode (2), etc., the refrigerant is flowing into the condenser (5) at a predetermined flow rate, so a predetermined amount of oil returns to the compressor (4), and temperature control operation continues. .

On the other hand, in step S4, if the control state described above is applicable, the process moves to step S5. Then, in step S5, 1 is added to the count of the driving state determining means (23), and the process moves to step S6. In this step S6, it is determined whether or not the count of the driving state determining means (23) has reached 1000. If it has not reached 1000, the process returns to step SI, and steps 81 to S6 are continued until the count reaches 1000. Repeat the action.

Then, the count of the driving state determining means (23) is 100.
0, that is, when the flow rate of the refrigerant flowing into the condenser (5) continues for a predetermined period of time (for example, count 10
00 is set to 3 hours), step S7
Then, the control state of the air conditioner (1) is forced into state (2) for a predetermined period of time (for example, 30 minutes) by operating the oil recovery operation means (24). That is, by setting the compressor (4) to full load and simultaneously closing the solenoid valves (11) and (12), the refrigerant circulates through the main refrigerant circuit (1a) at a high speed, and the compressor (4) The oil leaked into the main refrigerant circuit (1a) is recovered into the compressor (4). After that, in step S3, if the state is determined, the process moves to step S8, and the count of the driving state determining means (23) is set to 0.
, return to step Sl, and repeat the above-described operation.

In this way, in the present invention, when the refrigerant flow rate to the condenser (5) continues for a predetermined period of time, the compressor (4) is prevented from running out of oil by forcibly switching to oil recovery operation. Avoided.

Although the air conditioner of this example was equipped with two reheating coils, the present invention is not limited to this.
More than two reheat coils may be provided.

(Effects of the Invention) As described above, the present invention has the following effects.

In the inventions of claims (1) and (2), when the refrigerant flow rate to the heat source side heat exchanger continues for a predetermined period of time, the compressor is forced to switch to oil recovery operation, thereby causing the compressor to run out of water. is avoided, improving operational reliability in air conditioners equipped with reheat coils.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram corresponding to the invention of claim (1). 2 and 3 show an embodiment of the present invention,
FIG. 2 is a refrigerant circuit diagram of the air conditioner, and FIG. 3 is a flow chart showing operation control details of the air conditioner. (1)...Air conditioner (1a)...Main refrigerant circuit (1b)...Bypass circuit (2)...Indoor unit (3)...Outdoor unit (4)...Compressor (5)... Condenser (heat source side heat exchanger) (6)... Expansion valve (pressure reduction mechanism) (7)... Evaporator (user side heat exchanger) (9), (10
)...Reheating coil (11), (12)...Solenoid valve (bypass control means)
(13)...High pressure gas pipe (14)...High pressure liquid pipe (15)...Low pressure liquid pipe (16)...Low pressure gas pipe (22)...Operating state detection means (23)・・Operating state determination means (24) ・・Oil recovery operation means

Claims (2)

[Claims] (1) Variable capacity compressor (4) and heat source side heat exchanger (5)
The pressure reducing mechanism (6) and the user-side heat exchanger (7) are connected in series through refrigerant pipes (13) to (16) to form a main refrigerant circuit (1a). 1a
) is provided with a bypass circuit (1b) branched from the discharge side of the compressor (4) and communicating between the pressure reduction mechanism (6) and the utilization side heat exchanger (7), and the bypass circuit (1b) Reheating coils (9) and (10) arranged on the air circulation downstream side of the user-side heat exchanger (7) are interposed, and
In the air conditioner provided with bypass control means (11) and (12) for controlling the refrigerant flow rate of the bypass circuit (1b) and the operating capacity of the reheat coils (9) and (10), Operating state detection means (22) that detects the operating state of the reheating coils (9), (10) and issues a state signal when the reheating coils (9), (10) reach a predetermined capacity operating state. ), and an operating state determination unit that outputs a continued operating signal when the reheating coils (9) and (10) continue operating at a predetermined capacity for a predetermined time in response to a state signal issued by the operating state detecting means (22). When the means (23) and the operating state determining means (23) output a continuous operation signal, the compressor (
bypass control means (11) for controlling 4) to maximum capacity operation and closing the bypass circuit (1b);
An air conditioner comprising: (12) an oil recovery operation means (24) for driving and controlling the oil recovery operation means (24). (2) The indoor unit (2) includes a variable capacity compressor (4), a pressure reducing mechanism (6), a user side heat exchanger (7), a first reheating coil (9), and a second reheating coil (10). , the outdoor unit (3) includes a heat source side heat exchanger (5), the compressor (4), the heat source side heat exchanger (5), the pressure reduction mechanism (6), and the user side heat exchanger (7). are connected in series by refrigerant pipes (13) to (16) to form the main refrigerant circuit (1a), while the main refrigerant circuit (1a) is branched from immediately downstream of the compressor (4) and connected to the pressure reducing mechanism (6) and the user side. First and second bypass circuits (1b), (1b) communicating with the heat exchanger (7) are provided, and each bypass circuit (1b), (1b) is connected to the user-side heat exchanger ( The reheating coils (9) and (10) arranged in parallel on the downstream side of air circulation of 7) are interposed, and
The bypass circuit (1b) is opened and closed by controlling each reheating coil (
9) Solenoid valve (1) that controls on/off operation of (10)
1) and (12), the open/close states of the solenoid valves (11) and (12) are detected, and when each of the solenoid valves (11) and (12) is fully open, An operating state detecting means (22) that issues a state signal, and both electromagnetic valves (1) receiving the state signal that the operating state detecting means (22) issues.
1), (12) which outputs a continuous operation signal when the fully open state continues for a predetermined period of time; and when the operation condition discrimination means (23) outputs a continuous operation signal, the compressor (4) An air conditioner characterized in that it is equipped with an oil recovery operation means (24) for controlling the solenoid valves (11) and (12) to a fully closed state.