JP2536198B2 - Air conditioner - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air conditioner equipped with a reheat coil,
In particular, it relates to a measure for preventing frost formation on the evaporator without lowering the cooling capacity and the dehumidifying capacity.

(Prior Art) Generally, as an example of a refrigeration circuit in an air conditioner, there is one provided with a reheat coil as disclosed in Japanese Patent Laid-Open No. 59-125360. This type of refrigeration circuit is provided with a reheat coil in parallel with an evaporator disposed inside the indoor unit, and the refrigerant upstream side of this reheat coil is connected directly downstream of the discharge port of the compressor, while the refrigerant downstream side is connected. Is connected to the refrigerant upstream side of the evaporator, and the temperature of blown air is adjusted by the reheat coil. That is, in the dehumidifying operation of the air conditioner, when the compressor is operated at full load to improve the dehumidifying ability, water vapor contained in the primary side air in the evaporator is recovered as drain water. At the same time, since the indoor temperature will drop if left as it is, the temperature of the blown air is raised by the discharge gas flowing through the reheat coil.

(Problems to be Solved by the Invention) In general, during cooling operation of an air conditioner, when the difference between the indoor temperature and the target set temperature is large, that is, when the cooling load is large, compression is performed to improve the cooling capacity of the apparatus. The machine is running at full load. However, as shown in FIG. 3 (a) (in this FIG. 3, the horizontal axis indicates the indoor temperature during the air conditioning operation (when the air conditioning operation is performed for a predetermined time, it becomes a value approximately approximate to the target set temperature). The axes indicate the outside air temperature, and in normal air conditioning operation, the operation is performed within the frame shown by the solid line, that is, the frame shown by this solid line shows the air conditioning operation area performed in normal air conditioning.) If such a high load operation is attempted in an area where the indoor temperature is low (for example, the indoor temperature is 12 ° C. or less), the evaporation pressure of the refrigerant in the evaporator decreases. That is, when the cooling operation is performed in the area A shown in FIG. 3, the evaporation pressure of the refrigerant in the evaporator is reduced, and the evaporation temperature is also reduced accordingly, and frost is formed on the surface of the evaporator. May occur.

When such frost formation occurs, heat exchange between the refrigerant flowing in the evaporator and the primary side air and dehumidification of the primary side air are hindered, and the performance of the air conditioner deteriorates. Connect Therefore, conventionally, when the temperature in the air-conditioned room is lower than a predetermined value, the compressor is forced to be in an unloading operation state and the evaporation pressure is increased to prevent the frost formation.

However, as described above, if the compressor is forcibly unloaded, both the cooling capacity and the dehumidifying capacity of this air conditioner will be reduced, and the room temperature and humidity may not reach the set values. Therefore, it may not be possible to maintain good air conditioning in the room.

Therefore, the present invention utilizes the air conditioner equipped with the reheat coil as described above, so that when the air conditioner is operated in a low room temperature range, the evaporator capacity is reduced without lowering the cooling capacity and the dehumidifying capacity. The purpose is to prevent frosting.

(Means for Solving the Problem) In order to achieve the above object, the present invention does not use a reheat coil and uses the reheat coil as an evaporator when the cooling load is large. . And the concrete means is described below.

In the present invention, the compressor (4) having a variable capacity, the heat source side heat exchanger (5), the pressure reducing mechanism (6) and the use side heat exchanger (7) are connected in series by the refrigerant pipes (13) to {16). While the main refrigerant circuit (1a) is connected to the main refrigerant circuit (1a),
A bypass circuit (1b) branched from the discharge side of the compressor (4) of (a) and communicating between the pressure reducing mechanism (6) and the heat exchanger (7) on the use side is provided, and the bypass circuit (1b) is provided. ) Is
A reheat coil (9) is provided downstream of the utilization side heat exchanger (7) in the air flow, and a main refrigerant circuit (between the decompression mechanism (6) and the utilization side heat exchanger (7) ( 1a)
A decompression means (19) is provided between the connection portion to the reheat coil (9) and the reheat coil (9) to connect the reheat coil (9) of the bypass circuit (1b) and the discharge side of the compressor (4). It is premised on an air conditioner in which a first control valve (10) for controlling the flow of the refrigerant is provided. Then, from between the connection portion of the bypass circuit (1b) and the use side heat exchanger (7) between the pressure reducing mechanism (6) and the use side heat exchanger (7) in the main refrigerant circuit (1a). A branch pipe (21) which is branched and communicates with the reheat coil (9) of the bypass circuit (1b) and the pressure reducing means (19), and the branch pipe (21) provided in the branch pipe (21). ), The second control valve (11) for controlling the flow of the refrigerant, the reheat coil (9) of the bypass circuit (1b), and the first control valve (10) are branched off from the compressor (4). ), A recovery pipe (22) communicating with the suction side, and a third control valve (12) interposed in the recovery pipe (22) and controlling the flow of the refrigerant through the recovery pipe (22). Further, the temperature detecting means (23) for detecting the room temperature and outputting a temperature detecting signal, and the compressor (4) receiving the temperature detecting signal of the temperature detecting means (23).
In the maximum capacity operation and in the operating state in which all the refrigerant from the pressure reducing mechanism (6) is being supplied to the utilization side heat exchanger (7), the temperature detected by the temperature detecting means (23) is lower than the set temperature. When the pressure exceeds a predetermined range, the pressure reducing mechanism (6)
The switching control means (27) is provided to drive and control the second control valve (11) and the third control valve (12) so that a part of the refrigerant from (2) flows to the reheat coil (9).

(Operation) The operation of the present invention having the above configuration will be described below.

When the refrigerant flows through the main refrigerant circuit (1a), the heat is exchanged between the refrigerant and the air in the use side heat exchanger (7) to cool the air, while the temperature of the heat-exchanged air is changed. In the case of adjustment, the first control valve (10) is opened, a part of the discharge gas from the compressor (4) is caused to flow into the bypass circuit (1b), and the reheat coil (9) uses the heat on the utilization side. The heat-exchanged air is heated in the exchanger (7). Then, the temperature detecting means (23) detects the temperature inside the room, and supplies all the refrigerant from the pressure reducing mechanism (6) to the utilization side heat exchanger (7) during the maximum capacity operation of the compressor (4). When the detected temperature of the temperature detecting means (23) becomes higher than a predetermined range with respect to the set temperature in the operating state under control, the switching control means (2
7) opens the second control valve (11) and the third control valve (12) to flow a part of the refrigerant from the pressure reducing mechanism (6) to the reheat coil (9). As a result, the reheat coil (9) functions as an evaporator, and even when the reheat coil (9) is operated in a region where the indoor temperature is low, the evaporation pressure in the use side heat exchanger (7) can be kept high, and the use side heat exchange can be performed. Frost formation on the surface of the container (7) is prevented.

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

As shown in FIG. 1, an air conditioner (1) according to this example.
Is composed of an indoor unit (2) and an outdoor unit (3). The indoor unit (2) includes a compressor (4), an expansion valve (6) as a pressure reducing mechanism, and an evaporator (as a use side heat exchanger). 7), accumulator (8), reheat coil (9). On the other hand, the outdoor unit (3) is provided with a condenser (5) as a heat source side heat exchanger. And
The compressor (4) is provided with an unloader mechanism (not shown) and is configured to be controlled to be switched between unloading and full loading. The compressor (4) and the condenser (5) are high pressure gas. The condenser (5) and the expansion valve (6) are connected by a pipe (13), the high pressure liquid pipe (14) is connected, and the expansion valve (6) and the evaporator (7) are connected by a low pressure liquid pipe (15). And the evaporator (7), the accumulator (8), and the compressor (4) are sequentially connected by the low-pressure gas pipe (16) to form the main refrigerant circuit (1a). Also,
The reheat coil (9) is provided in a bypass circuit (1b) that bypasses the condenser (5), and its capacity is set to about 50% of the capacity of the evaporator (7). And, one end of the reheat coil (9) is connected to the high pressure gas pipe (1
Bypass pipe (1) of the bypass circuit (1b) branched from 3)
A first control valve (10), which is connected to the bypass gas pipe (17) and is composed of an electrically operated valve whose opening can be adjusted, is provided in the bypass gas pipe (17). On the other hand, the other end of the reheat coil (9) has a bypass circuit (1
The bypass liquid pipe (18) of b) is connected to the low pressure liquid pipe (15) between the expansion valve (6) and the evaporator (7), and the bypass liquid pipe (18) is provided with a capillary as a pressure reducing means. From the tube (19) and the low pressure liquid pipe (15) to the bypass liquid pipe (1
A check valve (20) is provided to prevent the inflow of refrigerant into 8). Also, the low pressure liquid pipe (15) of the main refrigerant circuit (1a)
To the utilization side heat exchanger (7) by branching from the connection part of the bypass circuit (1b) to the bypass circuit (1b).
A branch pipe (21) communicating between the reheat coil (9) and the capillary tube (19) of b) is provided, and the flow of the refrigerant to the branch pipe (21) is provided in the branch pipe (21). The 2nd control valve (11) which consists of a solenoid valve to control is installed. Furthermore,
A recovery pipe (22) is provided which branches from between the reheat coil (9) of the bypass circuit (1b) and the first control valve (10) and communicates with the upstream side of the accumulator (8). The pipe (22) is provided with a third control valve (12) which is an electromagnetic valve for controlling the flow of the refrigerant to the recovery pipe (22). In addition, this air conditioner is provided with a humidifier (28) on the downstream side of the reheat coil (9) in the air flow, and is adapted to supply the spray to the room during the humidifying operation.

Further, the air conditioner (1) is provided with a temperature sensor (23) as a temperature detecting means for detecting an indoor temperature and a humidity sensor (24) for detecting an indoor humidity. Furthermore,
The air conditioning equipment value (1) is provided with a controller (25) that controls the operation thereof. The controller (25) controls the operation capacity of the compressor (4) to cool and dehumidify the air. And the operation control means (2) for adjusting the opening temperature of the first control valve (10) to adjust the blown air temperature.
6) is provided, and a cutting base control means (27) for receiving and driving detection signals from the temperature sensor (23) and the humidity sensor (24) is provided.

Then, specifically, the operation control means (26) is
As shown in the table, the temperature sensor (23) and the humidity sensor (2
Based on the detection signal of 4), the operation is controlled to the state ~ in the cooling operation mode and the state ~ in the dehumidifying operation mode.
When the cooling request is small in the cooling operation mode or the dehumidification request is small in the dehumidification operation mode, or the compressor (4) is controlled to be unloaded at the initial start of the cooling and dehumidification operation ( The state of the cooling operation mode, the state of the dehumidification operation mode, and, if these cooling demand and dehumidification demand continue to be large, the control state is mapped (shift from right to left in Table 1). Then, the compressor (4) is controlled to be fully loaded (conditions of the cooling operation mode, the dehumidification operation mode-). Further, the operation control means (26) is configured to control the opening degree of the first control valve (10) so that the blown air temperature becomes a set value.
In the state of the cooling operation mode, the first control valve (10) is opened, hot gas (gas discharged from the compressor (4)) is caused to flow through the reheat coil (9), and air cooled by the evaporator (7) is discharged. It is heated to the set temperature. That is, in a state in which the cooling load is relatively small in the cooling operation mode, or in substantially the entire area in the dehumidifying operation mode (excluding the case where the cooling load is extremely large), hot gas is passed through the reheat coil (9) to evaporate. The air cooled in the vessel (7) is heated to the set temperature.

On the other hand, the switching control means (27) is driven when the room temperature is still higher than the target set temperature by a predetermined temperature (for example, 3 ° C.) or more (when the cooling load is large) during the operation in the control mode of the cooling mode. The control state,
While closing the first control valve (10), the second control valve (11)
And the third control valve (12) is opened so that the reheat coil (9) functions as an evaporator.

Further, in Table 1, the states and states in the cooling operation mode, the states and states in the dehumidification operation mode, and the states and states in the dehumidification operation mode are the operating state of the compressor (4) and the control valves (10, 11), respectively. , 12) are in the same switching state. The reason is that, as will be described later in the control operation, each state is switched every predetermined time (for example, 3 minutes) according to the state of the air conditioning load, so that the actual operating state of the compressor (4) and This is because the switching time intervals of the switching states of the control valves (10, 11, 12) are not set at the predetermined time intervals but are set at arbitrary time intervals. That is, in the cooling operation mode, for example, when each state is switched every 3 minutes during cooling operation, in the operation of sequentially switching from state to state, each state from state to state continues for 3 minutes. It will be. That is, after the state and are continuously performed for 3 minutes, respectively, the state is shifted to the state. At this time, since the states of the compressor (4) and the control valves (10, 11, 12) are the same, the compressor (4) is unloaded and the first control valve ( 10) open, second
And the state (state) in which the third control valve (11, 12) is closed is 6
After continuing for a minute, the compressor (4) is fully loaded and the first to third control valves (10, 11, 12) are both closed (the state continues for 3 minutes, and then the compressor (4) is full. The load and the first control valve (10) are closed, and the second and third control valves (11, 12) are opened (states). Even if the time is constant, the actual operating condition is the desired desired time interval (for example, 6
To make it possible to set a constant control operation (state) for 3 minutes, then another constant control operation (state) for 3 minutes, and then to another control operation (state). The state (and the state) adjacent to is the same state. Setting the adjacent states to the same state in this way is arbitrarily set according to the request of the designer. This also applies to the dehumidification operation mode.

Furthermore, in the cooling operation mode and the dehumidification operation mode,
The operating state of the compressor (4) and the switching state of each control valve (10, 11, 12) are the same (the state of the cooling operation mode and the state of the dehumidifying operation mode, the state of the cooling operation mode and the state of the dehumidifying operation mode). The reason why there is a state) will be described below.

Since it is considered that the cooling operation mode is an operation state in which there is no dehumidification request and the cooling request is small, the temperature of the blown air is lowered by heating the air with the reheat coil (9). We are trying to meet the air conditioning demand so that it will not become too much. Humidifiers actually (28)
Is operated to supplement the humidity of the air dehumidified by the dehumidifying action of the evaporator (7). On the other hand, the dehumidifying operation mode may be an operating state in which there is a dehumidifying request and a small cooling request. Therefore, by heating the air with the reheat coil (9), the temperature of the blown air is reduced. The air is dehumidified by the dehumidifying action of the evaporator (7) while preventing the temperature from becoming too low. Then, at this time, the humidifier (28) is not operated.

The state of the cooling operation mode is an operating state in which there is no dehumidification request and the cooling request is relatively large.
The reheat coil (9) is stopped and the air is cooled by the cooling action of only the evaporator (7). And in this case,
The humidifier (28) is operated to supplement the humidity of the air dehumidified by the dehumidifying action of the evaporator (7). On the other hand, the state of the dehumidifying operation mode is an operating state where there is a demand for dehumidification and a large demand for cooling, and the air is cooled and dehumidified by the evaporator (7) so as to increase both cooling and dehumidifying capabilities. Will be cooled and dehumidified. At this time, the humidifier (28) is not operated.

Thus, even if the operating state of the compressor (4) and the switching state of each control valve (10, 11, 12) are the same between the respective operating modes, the operating state of each humidifier (28). However, the conditioned air blown out from the air conditioner is adjusted to the appropriate air with the temperature and humidity according to the requirements (size of cooling requirement and presence / absence of dehumidification requirement). There is.

Next, the cooling operation and the like in each circuit will be described.

First, in the main refrigerant circuit (1a), the gas refrigerant that has become high-temperature and high-pressure discharge gas by the compressor (4) is sent to the condenser (5) of the outdoor unit (3) through the high-pressure gas pipe (13). The heat is exchanged with the outside air in the condenser (5) and cooled to become a liquid refrigerant. Then, the liquid refrigerant passes through the expansion valve (6) from the high pressure liquid pipe (14), expands at the expansion valve (6), and then flows into the evaporator (7) through the liquid pressure liquid pipe (15). . Then, the liquid refrigerant evaporates in the evaporator (7) to cool and dehumidify the primary air from the blower fan (not shown) provided in the indoor unit (2). And
The cooled and dehumidified air passes through the reheating coil (9) and then becomes conditioned air as secondary air and is blown out into the room. On the other hand, the gas refrigerant evaporated in the evaporator (7) passes through the accumulator (8), returns to the compressor (4) again, and circulates in the main refrigerant circuit (1a).

Further, the first control valve (10) of the bypass circuit (1b) is controlled by the operation control means (26), and when this first control valve (10) opens, a part of the gas refrigerant discharged from the compressor (4). Flows through the bypass gas pipe (17) toward the reheat coil (9), and in this reheat coil (9), the high-temperature and high-pressure gas refrigerant heats with the air flowing out from the evaporator (7). By exchanging, the temperature of this air is raised to become a liquid refrigerant. Then, this liquid refrigerant flows through the bypass liquid pipe (18), is decompressed by the capillary tube (19), then flows into the low pressure liquid pipe (15), and returns to the main refrigerant circuit (1a).

Next, the operation control operation of the air conditioner (1) in this example will be described with reference to the flowchart in FIG.

First, after starting, in step S1, the temperature control operation control of the air conditioner (1) is started, and then step S2
In, it is determined whether the humidity in the air-conditioned room detected by the humidity sensor (24) is within a predetermined range (for example, relative humidity 40 to 60%). Then, if the humidity is within the predetermined range, the process proceeds to step S3, and the operation mode of the air conditioning equipment value (1) is set to the cooling mode. Then, the process proceeds to step S4, and the control state in this cooling mode is determined according to the difference between the temperature inside the air-conditioned room detected by the temperature sensor (23) and the preset target temperature. That is, when the indoor temperature is higher than the target set temperature by a predetermined temperature or more (for example, when the target set temperature is 18 ° C and the indoor temperature is 25 ° C), it is determined that the cooling request is large and the up determination ( It is determined that there is a request for increasing the cooling capacity), and the process proceeds to step S5 to raise the control state shown in Table 1 (shift to the left side of Table 1).
That is, in the case of the current control state, the control state is increased by one and moved to the state. Then, the process returns to step S1 and the above-described operation is repeated until the cooling demand becomes small (for example, until the difference between the target set temperature and the room temperature becomes within the range of 3 ° C.), and the control state is sequentially set at predetermined time intervals. By increasing it, the cooling capacity will be increased.
That is, until the indoor temperature reaches the predetermined range, the operations of steps S1 to S5 are repeated at predetermined time intervals (for example, every 3 minutes) to sequentially increase the control state from to gradually increase the cooling capacity. Let

After that, when the indoor temperature reaches the above range when the operating state is one of the control states, the hold determination (determination that it is not necessary to increase the cooling capacity) is performed in step S4, and the above step is performed. Return to S1 and maintain the current control state.

In step S4, when the indoor temperature is substantially equal to the target temperature, the down determination is made in step S4 (the indoor temperature is required to be kept in the current state, and it is necessary to reduce the cooling capacity). Then, the operation proceeds to step S6, for example, when operating in the control state, the control state is lowered (shifted to the right side of Table 1), and the cooling capacity is lowered so as to maintain the indoor temperature at the target temperature. . Then, while the indoor temperature is substantially equal to the target temperature, the operations of steps S1 to S4 and S6 are repeated to bring down the control state to sequentially reduce the cooling capacity.

On the other hand, when the humidity in the air-conditioned room detected by the humidity sensor (24) is higher than the predetermined range in step S2, the process proceeds to step S7 and the dehumidification mode is set. Then step
In S8, the control state in the dehumidifying mode is determined according to the difference between the temperature inside the air-conditioned room detected by the temperature sensor (23) and the target set temperature. That is, when the indoor temperature is higher than the target set temperature by a predetermined temperature or more (for example, when the target set temperature is 18 ° C and the indoor temperature is 25 ° C), it is determined that the cooling request is large and the up determination is made. Then, the process goes to step S9 to raise the control state shown in Table 1. That is,
If the current control status is a status, set the control status to 1
Only up one and move to the state. At the time of this transition, the dehumidifying capacity is increased as the operating capacity of the compressor (4) is increased. That is, since the first control valve (10) is still open, control is performed to increase the dehumidifying capacity without increasing the cooling capacity so much as to ensure indoor comfort.
Then, the process returns to step S1 and the above-described operation is repeated until the dehumidification request becomes small, and the control state is sequentially increased. That is, until the indoor humidity reaches the predetermined range (until the hold determination (determination to maintain the indoor humidity in the current state) in step S2) is performed at predetermined time intervals (eg, every 3 minutes), the step S1, By repeating the operations of S2 and S7 to S9, the dehumidifying ability is increased by gradually increasing the control state from to. In the dehumidifying operation mode, when the cooling request is large (when the dehumidifying request is not canceled, the control condition is increased to the first control valve (10) to close the air. Without reheating, the cooling capacity is increased while maintaining the high dehumidification capacity.

After that, when the operating state is any one of the control states 1 to 4, when the indoor temperature reaches the predetermined range, the hold determination is made in step S8 and the process returns to step S1 to maintain the current control state.

Further, in step S8, if the indoor temperature is substantially equal to the target temperature, a down determination is made in step S8 and the process proceeds to step S10. For example, when operating in a control state, the control state is set and cooling is performed. The capacity is lowered, and when the engine is operating in the controlled state, the dehumidifying ability is lowered by setting the controlled state.

Further, when the humidity in the air-conditioned room detected by the humidity sensor (24) is lower than the predetermined range in step S2, the process proceeds to step S11 to drive the humidifier (28) to perform the humidifying operation.

The characteristic operation of this example is when the control state is changed so as to increase the cooling capacity in the cooling mode operation. That is, in the control state in the cooling mode, the compressor (4) is operated at full load, and the first to third control valves (10) to (12) are both controlled to be in the closed state. , All the refrigerant flows from the condenser (5) to the evaporator (7) and the reheat coil is not used. And at this time,
If the indoor temperature is still higher than the target set temperature by the predetermined value or more in step S4, the switching control means (27) is driven to shift to the control state. In this control state, the compressor (4) is maintained in full load operation, the first control valve (10) is kept closed, and the second and third control valves (11) and (12) are opened. . As a result, the hot gas discharged from the compressor (4) does not flow to the bypass circuit (1b), and the entire amount of the hot gas is stored in the condenser (5) and the expansion valve (6).
Flows to In addition, from this expansion valve (6) to the low pressure liquid pipe (1
Part of the liquid refrigerant flowing out to 5) goes through the branch pipe (21),
Flow through the reheat coil (9). Then, the refrigerant flowing through the reheat coil (9) exchanges heat with the air flowing out from the evaporator (7) to evaporate, and becomes a gas refrigerant, and the recovery pipe (22) passes through the compressor (4). ). That is, in this control state, the reheat coil (9) is connected to the evaporator (7).
Functioning as Therefore, unlike the case where the entire amount of the refrigerant in the circuit flows to the evaporator (7), the evaporation pressure in the evaporator (7) can be maintained high even when operated in a region where the room temperature is low. Since the evaporation temperature can also be maintained high, it is possible to prevent the formation of frost on the surface of the evaporator (7) as in the conventional case. That is, FIG. 3 (as described above,
The horizontal axis indicates the room temperature during air conditioning operation, the vertical axis indicates the outside air temperature, and the solid line frame indicates the air conditioning operation area where normal air conditioning is performed.) In the device, when the compressor (4) is operated at full load in the region A of Fig. 3 (a), frosting may occur, so the indoor temperature is a constant value (for example, 12 ° C).
In the following, the compressor is forcibly operated for unloading. However, in the present invention, the frosted region decreases with respect to the indoor temperature and becomes the region B shown in FIG. 3 (b). Frost does not occur even if the compressor (4) is operated at full load up to a temperature of about 10 ° C.

As described above, in the present invention, the reheat coil (9) functions as an evaporator to prevent frost formation while maintaining the full load operation of the compressor (4) even when the compressor is operated in a region where the indoor temperature is low. Therefore, the cooling capacity and dehumidifying capacity of the air conditioner (1) are improved.

Although the air conditioner of this example has one reheat coil, the present invention is not limited to this, and two or more reheat coils may be provided.

(Effects of the Invention) As described above, in the present invention, the temperature detected by the temperature detecting means is detected during the maximum capacity operation of the compressor and in the operating state in which all the refrigerant from the pressure reducing mechanism is supplied to the utilization side heat exchanger. Becomes higher than a predetermined range with respect to the set temperature, the reheat coil functions as an evaporator. This makes it possible to maintain a high evaporation pressure in the usage-side heat exchanger even when operating in a region where the indoor temperature is low, and prevent frost formation on the usage-side heat exchanger surface. As a result, the cooling capacity and dehumidifying capacity of the air conditioner are improved, and the reliability of operation in the air conditioner equipped with the reheat coil is improved.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a refrigerant circuit diagram of an air conditioner, FIG. 2 is a flow chart showing operation control contents of the air conditioner, and FIG. 3 is frost. It is a figure for comparing an attachment area with a conventional thing. (1) ...... Air conditioner (1a) ...... Main refrigerant circuit (1b) ...... Bypass circuit (1c) ...... Circuit switching means (4) ...... Compressor (5) ...... Condenser (heat source side heat exchange) (6) …… Expansion valve (pressure reducing mechanism) (7) …… Evaporator (use side heat exchanger) (9) …… Reheat coil (10) …… First control valve (11) …… First 2 control valve (12) …… third control valve (13) …… high pressure gas pipe (14) …… high pressure liquid pipe (15) …… low pressure liquid pipe (16) …… low pressure gas pipe (19) …… capillary Tube (pressure reducing means) (21) …… Branching pipe (22) …… Recovery pipe (23) …… Temperature sensor (temperature detecting means) (27) …… Switching control means

Claims (1)

(57) [Claims] 1. A variable capacity compressor (4), a heat source side heat exchanger (5), a pressure reducing mechanism (6) and a use side heat exchanger (7) are connected in series by refrigerant pipes (13) to (16). While being connected to the main refrigerant circuit (1a), the main refrigerant circuit (1a)
A bypass circuit (1b) branched from the discharge side of the compressor (4) and communicating between the pressure reducing mechanism (6) and the use side heat exchanger (7), and the bypass circuit (1b) is A main refrigerant circuit between the decompression mechanism (6) and the use side heat exchanger (7), the reheat coil (9) being installed on the air circulation downstream side of the use side heat exchanger (7) (1a)
A decompression means (19) is provided between the connection portion to the reheat coil (9) and the reheat coil (9) to connect the reheat coil (9) of the bypass circuit (1b) and the discharge side of the compressor (4). An air conditioner provided with a first control valve (10) for controlling the flow of a refrigerant between the decompression mechanism (6) and the use side heat exchanger (7) in the main refrigerant circuit (1a). It branches from between the connection part of a bypass circuit (1b) and the said use side heat exchanger (7), and connects between the reheat coil (9) and decompression means (19) of the said bypass circuit (1b). A branch pipe (21), a second control valve (11) provided in the branch pipe (21) for controlling the flow of the refrigerant in the branch pipe (21), and a reheat coil () of the bypass circuit (1b). A recovery pipe (22) that branches from between 9) and the first control valve (10) and communicates with the suction side of the compressor (4);
A third control valve (12) provided in the recovery pipe (22) for controlling the flow of the refrigerant in the recovery pipe (22), and a temperature detection means (23) for detecting the room temperature and outputting a temperature detection signal. And receiving the temperature detection signal of the temperature detecting means (23), and supplying all the refrigerant from the pressure reducing mechanism (6) to the utilization side heat exchanger (7) during the maximum capacity operation of the compressor (4). When the detected temperature of the temperature detecting means (23) becomes higher than a predetermined range with respect to the set temperature in the operating state under operation, a part of the refrigerant from the pressure reducing mechanism (6) is transferred to the reheat coil (9). An air conditioner comprising: a switching control means (27) for drivingly controlling the second control valve (11) and the third control valve (12) so as to flow.