JP2002181408A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an air conditioner, in which deterioration of the lubricity of a compressor is prevented or restricted, when differential temperature between high outside-temperature and low indoor-temperature is greater than a predetermined value, and the reliability is improved in a dehumidification operation. SOLUTION: The air conditioner comprises heat exchangers, dehumidification equipment, sensors and a controller. The refrigeration cycle is constituted of thermally halved heat exchangers on the use side, that is, a heat exchanger on the first use side and a heat exchanger on the second use side operated respectively as a condenser and an evaporator in the dehumidification operation. A dehumidification restrictor comprises a refrigerant flow path connecting the heat changers to each other at a low pressure loss for the refrigerant flow, a dehumidification restrictor, a valve element closing the refrigerant flow path in dehumidification operation, and a refrigerant restricting path, which is provided with a flow path formed to allow the heat exchangers to communicate with each other, when the low- pressure loss refrigerant path is closed by the valve element. Further sensors and a controller is provided. The sensors sense respectively outdoor and indoor temperatures. The controller opens intermittently the valve element of the dehumidification restrictor, when an outdoor temperature detected by the outdoor temperature sensor is higher than an indoor temperature detected by the indoor temperature sensor, and besides, a differential temperature between them is at least a predetermined value in a dehumidification operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner capable of cooling, heating and dehumidifying operations, and more particularly to a heat pump type air conditioner in which a temperature difference between a high outside temperature (outdoor temperature) and a low room temperature (indoor temperature) is more than a predetermined value. The present invention relates to an air conditioner in which the valve element of a dehumidifying expansion device that is closed during a dehumidifying operation is intermittently opened to prevent or suppress a decrease in lubrication characteristics of a compressor.

[0002]

2. Description of the Related Art Conventionally, as an example of this type of heat pump type air conditioner capable of dehumidifying operation, in order to realize a dehumidifying control operation cycle such as an isothermal dry cycle, during dehumidifying operation, a condenser and an evaporator are used. Two adjacent working
Some refrigerant passages between two indoor heat exchangers are provided with a dehumidifying expansion device such as a two-way valve having a throttling function as a dehumidifying expansion valve for restricting the refrigerant. The dehumidifying expansion device includes a valve body that opens and closes a low-loss refrigerant communication path that connects the condenser and the evaporator with low loss to a refrigerant flow, a V-groove formed in a joint surface of a valve seat, and the like. During the dehumidifying operation, the valve body is closed to close the low-loss refrigerant passage, and the refrigerant is throttled through the refrigerant throttle passage.

[0003]

However, in such a conventional dehumidifying expansion device, for example, the outside air temperature (outdoor temperature) is higher than room temperature (indoor temperature), and the temperature difference is large. Even when
During the dehumidification operation, the low pressure loss refrigerant passage is always closed by the valve element of the dehumidification expansion device, and the refrigerant flow is constantly restricted by the refrigerant expansion passage, so that there is a problem that the lubrication characteristics of the compressor deteriorate.

That is, in general, when the outside temperature is high,
Since the high-pressure side pressure of the refrigeration cycle increases, the flow rate of refrigerant discharged from the compressor in the outdoor unit installed outdoors decreases, and the flow rate of refrigerant circulating in the refrigeration cycle decreases. On the other hand, when the room temperature is low, the amount of refrigerant evaporated in the evaporator in the indoor unit installed indoors decreases, and the amount of liquid returning (liquid back) returning to the compressor in a liquid state increases. Moreover, the liquid refrigerant has a lower lubricating oil content (dilution degree) than the gaseous refrigerant,
When the amount of liquid back is large, a problem occurs in that the amount of lubricating oil returning into the compressor together with the refrigerant is insufficient, and the lubrication characteristics deteriorate.

FIG. 7 shows the relative relationship between the temperature difference between the outside air temperature (outdoor temperature) and room temperature (indoor temperature) and the thickness of the oil film at a required measurement point such as a sliding portion in the compressor. . As shown in FIG. 7, when the temperature difference between the high outside air temperature and the low room temperature is, for example, 10 ° C. or more, the thickness of the oil film of the measured portion becomes thin. This shows an area where the lubrication characteristics of the machine deteriorate.

When the lubrication characteristics of the compressor are deteriorated as described above, it is possible to improve the lubrication performance of the compressor by reducing the liquid return by reducing the flow rate of the refrigerant circulating in the refrigeration cycle. However, this method has a problem that a new problem such as a decrease in air conditioning capacity due to a decrease in the flow rate of the refrigerant occurs at the same time.

The present invention has been made in view of such circumstances, and has as its object to lubricate a compressor when a temperature difference between a high outside air temperature and a low room temperature is larger than a predetermined value during a dehumidifying operation. It is an object of the present invention to provide an air conditioner capable of preventing or suppressing deterioration of characteristics and improving reliability.

[0008]

According to the first aspect of the present invention, a use-side heat exchanger constituting a refrigeration cycle is thermally cooled by two times.
A first use-side heat exchanger and a second use-side heat exchanger which are divided and operated as a condenser and an evaporator during the dehumidifying operation, respectively, and the first and second use-side heat exchangers are connected to each other; A low pressure loss refrigerant passage connecting the low pressure loss refrigerant passage to the refrigerant flow, a valve body for closing the low pressure loss refrigerant passage during the dehumidifying operation, and the first and second valves when the low pressure loss refrigerant passage is closed by the valve body. A dehumidifying expansion device provided with a refrigerant throttle passage formed to communicate the two use-side heat exchangers and narrowing the refrigerant flow; an outdoor temperature sensor for detecting an outdoor temperature; and an indoor temperature sensor for detecting an indoor temperature. In the air conditioner provided with, the outdoor temperature detected by the outdoor temperature sensor is higher than the indoor temperature detected by the indoor temperature sensor during the dehumidifying operation, and the difference between these temperatures is equal to or less than a predetermined value. When is an air conditioner which is characterized in that a control device for intermittently opening the closing of the valve body of the dehumidifying stop apparatus.

According to the present invention, during the dehumidifying operation, when the control device detects that the temperature difference between the outdoor temperature (outside air temperature) and the indoor temperature (room temperature) is a predetermined value (for example, 11 ° C.) or more, The closing (closing) of the valve element of the dehumidifying expansion device is intermittently opened (opened) by the control device.

[0010] For this reason, the liquid refrigerant flowing into the dehumidifying expansion device from the first usage-side heat exchanger, when the valve body is closed,
Both the flow rate and the pressure are reduced through only the refrigerant throttle passage, and then flow into the second use side heat exchanger, where it is evaporated and then returned to the compressor again. Since the flow rate of the refrigerant returned into the compressor is restricted by the dehumidifying throttle valve, the refrigerant flow is reduced and, in addition, the refrigerant contains a liquid refrigerant having a low lubricating oil content. Is reduced back into the compressor.

However, since the valve element of the dehumidifying expansion device is closed for a predetermined time and then opened for a predetermined time to open the low-pressure-loss refrigerant passage, the first and second use-side heat exchanges are performed when the valve is opened. The units are connected via the low pressure loss refrigerant passage. For this reason, the refrigerant flow flowing into the dehumidifying throttle valve from the first usage-side heat exchanger flows through the low-pressure-loss refrigerant passage into the second usage-side heat exchanger with almost no reduction in flow rate and pressure. Then, it is evaporated and returned to the compressor again. Since the flow rate of the refrigerant returned into the compressor is hardly reduced by the dehumidifying expansion device, the amount of the returned refrigerant increases. For this reason, the amount of lubricating oil contained in the refrigerant that is returned into the compressor also increases. Therefore, it is possible to prevent shortage of the amount of lubricating oil returned into the compressor due to the repeated opening and closing of the valve body of the dehumidifying throttle valve, thereby preventing or reducing the deterioration of the lubrication characteristics of the compressor.

[0012] According to a second aspect of the present invention, the control device includes:
2. An opening / closing time control means for controlling a closing time and an opening time of a valve element of the dehumidifying expansion device according to a difference between the outdoor temperature and the indoor temperature, respectively. It is an air conditioner.

According to the present invention, the valve closing time of the valve body of the dehumidifying expansion device that is closed during the dehumidifying operation and the valve opening time that is intermittently opened are determined by the temperature difference between the outdoor temperature and the indoor temperature. Therefore, an appropriate amount of lubricating oil according to the temperature difference between the outdoor temperature and the indoor temperature can be returned into the compressor via the refrigerant. For this reason, the lubrication characteristics of the compressor can be improved.

According to a third aspect of the present invention, the control device includes:
The compressor according to claim 1 or 2, further comprising a compressor control means for increasing an operating frequency of the compressor by a predetermined value when a temperature difference between the outdoor temperature and the indoor temperature is equal to or less than a predetermined value. It is an air conditioner.

According to the present invention, the valve element of the dehumidifying throttle valve which is closed during the dehumidifying operation is intermittently opened as in the above-mentioned invention, or as in the above-mentioned invention. While controlling the valve opening time or valve closing time of the dehumidifying expansion device,
When the difference between the outdoor temperature and the indoor temperature is equal to or less than a predetermined value, the operating frequency of the compressor is increased by a predetermined value to increase the number of revolutions. Therefore, the flow rate of the refrigerant discharged from the compressor even at a high outdoor temperature must be increased. Can be. As a result, the flow rate of the refrigerant returning into the compressor increases, so that the amount of lubricating oil contained in the refrigerant flow rate can also be increased, and the lubrication characteristics of the compressor can be optimized.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A description will be given based on FIG. In these figures, the same or corresponding parts are denoted by the same reference characters.

FIG. 3 is a refrigeration cycle diagram of the air conditioner 1 according to one embodiment of the present invention.

As shown in FIG. 3, this air conditioner 1
Is a compressor 2 whose operation frequency is controlled by an inverter (not shown) to control the number of revolutions, a four-way valve 3 for switching a flow path, an outdoor heat exchanger 4, an expansion valve 5, which is an example of a pressure reducing device,
A first indoor heat exchanger 6 serving as a first use side, a dehumidifying expansion device 7 such as a solenoid valve having an opening / closing valve and a throttle function, and a second indoor heat exchanger 8 serving as a second use side are provided in this manner. A closed refrigeration cycle is constructed in which refrigerant is circulated by being sequentially connected by the refrigerant pipe 9 in order.

Further, the outdoor heat exchanger 4 is provided with an outdoor fan 10 such as a propeller fan for blowing outside air to promote heat exchange, and accommodates the outdoor fan 10 and the outdoor heat exchanger 4 and the like. An outside air temperature sensor 11 for detecting an outside air temperature (outdoor temperature) is provided in an outdoor unit case that is not used. On the other hand, an indoor unit case (not shown) installed indoors includes first and second indoor heat exchangers 6, 8 and the like, and the first and second indoor heat exchangers.
The room air is blown to the indoor heat exchangers 6 and 8 to promote heat exchange, and a common indoor fan 12 such as a cross-flow fan that blows the heat-exchanged conditioned air into the room and the room temperature (room temperature). A room temperature sensor 13 for detection is provided.

Further, in this refrigeration cycle, cooling or dehumidifying operation is performed by circulating the refrigerant in the direction of the solid line arrow by switching operation of the four-way valve 3, and heating operation is performed by circulating the refrigerant in the direction of the broken line arrow in the diagram. . This four-way valve 3
Is controlled by an unillustrated indoor controller.
Further, the compressor 2, the outside air temperature sensor 11, the dehumidifying expansion device 7,
The controller 14 is electrically connected to the room temperature sensor 13 by a signal line indicated by a dashed line in the figure. The control device 14 opens the valve element of the dehumidifying expansion device 7 during the cooling / heating operation as described later, and closes the valve element of the dehumidifying expansion device 7 during the dehumidifying operation, and the temperature difference between the outside air temperature and the room temperature is reduced. When the temperature is equal to or higher than a predetermined value (for example, 11 ° C.), the valve of the dehumidifying expansion device 7 is opened every predetermined time (intermittently).

FIG. 4 is a schematic longitudinal sectional view when the dehumidifying expansion device 7 is closed, and FIG. 5 is a schematic longitudinal sectional view when the valve is opened. As shown in these figures, the dehumidifying expansion device 7 allows the refrigerant to pass therethrough with little or no restriction by fully opening the valve body and passing the refrigerant through a low-pressure-loss refrigerant passage during cooling and heating operations. It consists of an electromagnetic two-way valve that acts as a throttle valve during the dehumidifying operation.

That is, as shown in FIGS. 4 and 5, the dehumidifying expansion device 7 includes first and second two valve chambers 16,
In the dehumidifying operation, the first valve chamber 16 is on the high pressure side of the refrigerant, and the second valve chamber 17 is on the low pressure side of the refrigerant.

The first valve chamber 16 is connected to a first refrigerant pipe 9a of the first indoor heat exchanger 6 shown in FIG. Indoor heat exchanger 8
The second refrigerant pipe 9b on the side is communicably connected. In the dehumidifying operation, the first refrigerant pipe 9a serves as a refrigerant inlet pipe and the first valve chamber 16 is on the high pressure side as shown by the white arrow in FIGS. And the second valve chamber 17 is on the low pressure side.

As shown in FIGS. 4 and 5, at the boundary between the first and second valve chambers 16 and 17, a cylindrical valve seat 18 protruding toward the first valve chamber 13 is provided. It is coupled with one. The valve seat 18 has a valve port 19 at the upper end in the figure.
And a valve seat 19 a is formed inside the valve port 19. Therefore, the first and second valve chambers 16 and 17 and the valve port 19 for communicating these are formed as a low-pressure-loss refrigerant passage through which the refrigerant flow is passed without being substantially reduced. On the other hand, as shown in FIG. 6, a plurality of cut grooves 19b, which are an example of a refrigerant throttle passage for communicating the first valve chamber 16 and the second valve chamber 17, are formed on the inner peripheral surface of the valve seat 19a. Are provided in such a manner as to be parallel to the flow direction and to be symmetrical with respect to the center of the valve port 19. As shown in FIG. 4, these cut grooves 19 b allow the first valve chamber 16 to communicate with the second valve chamber 17 when the valve body 21 is seated on the valve seat 19 a and the valve port 19 is closed. These are formed as simple refrigerant throttle passages.

On the other hand, a valve stem 20 is provided in the first valve chamber 16 so as to be movable in the vertical direction in FIGS. 4 and 5, and is provided at the tip (the lower end in FIGS. 4 and 5) of the valve stem 20. Is integrally connected to a cylindrical valve element 21 having a larger diameter than the valve rod 20.

As shown in FIGS. 4 and 5, the valve body 21 has a cylindrical shape having an outer diameter slightly larger than the valve port 19, and has a tapered tapered surface 21a formed at the leading end of the opening. The tapered surface 21a is liquid-tightly and air-tightly seated on the conical valve seat 19a to close the valve port 19.

The bottom of a cylindrical plunger 22 with a bottom is formed concentrically at the end (the upper end in FIGS. 4 and 5) of the valve stem 20 opposite to the valve body 21 in the axial direction. Forming
An excitation guide 23 is provided in the upper open end of the plunger 22.
Are arranged so as to be fitted concentrically, and when the plunger 22 moves in the axial direction (vertical direction in FIG. 4), the movement is controlled by the center projecting end 23a of the excitation guide 23. It is configured to guide and function as a stopper at the upper end.

The bottom of the plunger 22 and the valve box 15
Between the valve stem 20 and the stopper 24 fixed therein.
A coil-shaped spring 25 is externally fitted around the outer periphery of the excitation guide 23, and the spring force of the spring 25 constantly urges the plunger 22 and the valve body 21 to be pushed upward in FIGS. 4 and 5. Is provided with an excitation coil 26 for exciting the excitation guide 23. For this reason, when the excitation coil 26 is not excited, the plunger 22 is pushed up to the opposite side (upward in FIG. 4) of the valve seat 18 by the spring force of the spring 25, so that the valve port 19, that is, the low pressure loss refrigerant passage is formed. It is designed to be fully open at all times.

FIG. 1 is a flowchart of a control program at the time of the dehumidifying operation of the control device 14, in which S1 to S7 are shown.
Indicates each step of the flowchart. The control device 14 includes, for example, a microprocessor, and its function may be provided in an indoor controller (not shown).

First, as shown in FIG. 1, the control device 14
When the control program at the time of the dehumidifying operation is started and started, in S1, it is determined whether or not the dehumidifying operation mode is selected as the operation mode, for example, a remote controller (not shown) or an operation mode signal read from the remote controller (not shown). When it is determined that the dehumidifying operation mode has been selected by repeatedly reading from the indoor controller and determining that the dehumidifying operation mode has been selected, the exciting coil 2 of the dehumidifying expansion device 7 is determined in S2.
6 is energized and excited. Then, the large electromagnetic force generated between the excitation guide 23 and the plunger 22 pushes the valve body 21 downward in FIG. 4 against the spring force of the spring 25 to seat the valve seat 19a to close the valve port 19. .

As a result, the low pressure loss refrigerant passage communicating with the valve port 19 is closed, so that the first (upstream) utilization heat exchanger 6 radiates and condenses and liquefies, and the first of the dehumidifying expansion device 7 The liquid refrigerant flowing into the valve chamber 16 is prevented from passing through the low-pressure-loss refrigerant passage by the valve element 21.

However, when the valve body 21 is closed, a plurality of cut grooves 19b are formed between the outer peripheral surface of the valve body 21 and the inner peripheral surface of the valve seat 19 as throttle refrigerant passages. The first valve chamber 16 and the second valve chamber 17 are formed via the groove 19b.
Communicates with For this purpose, the liquid refrigerant condensed in the first indoor heat exchanger 6 on the upstream side and radiates heat to ambient air (indoor air) to be heated, while the liquefied liquid refrigerant flows into the first valve chamber 16 of the dehumidifying throttle valve 7. Flows into. Then, the liquid refrigerant is supplied to the valve port 1
9 is prevented from passing through the low-pressure-loss refrigerant passage by the valve body 21 while the valve body 9 is closed.
Only at that time, the flow rate and pressure are reduced and flow into the second indoor heat exchanger 8 via the second valve chamber 17, where it evaporates and cools the surrounding air while evaporating, The gas is returned to the suction port of the compressor 2 via the four-way valve 3 in a gas state.

Therefore, while the surrounding air is dehumidified by the cooling action of the second indoor heat exchanger 8, the air cooled by the cooling action is heated by the heat dissipation action of the first indoor heat exchanger 6. The humidity can be reduced without significantly lowering the temperature of the air blown into the room from the indoor unit.

In the next S3, it is repeatedly determined whether or not the valve closing state of the dehumidifying expansion device 7 has passed for a predetermined time, for example, three minutes. When three minutes have passed, it is determined that the refrigerant flow circulating in the refrigeration cycle has become stable. Then, the process proceeds to the next S4 as Yes.

In S4, the control device 14 controls the outside air temperature sensor 11
While reading the outside air temperature from the room temperature sensor 13, it is determined whether the following equation (1) is satisfied.

[0036]

[Outside 1]

When the equation (1) is satisfied, that is, when Y
In the case of es, it is determined that the oil film of the sliding portion of the compressor 2 and the like becomes thin and the lubrication characteristic of the compressor 2 is deteriorated as shown in FIG. 7, and the process proceeds to S5. In the case of No, the process proceeds to S6.

In S5, the intermittent opening / closing control of the valve element 21 of the dehumidifying expansion device 7 closed in S2 is executed. That is, the valve 21 of the dehumidifying expansion device 7 is repeatedly closed and opened for a predetermined time. That is, when the valve closing state of the dehumidifying expansion device 7 is continued, the amount of liquid back to the compressor 2 increases as described above,
Since the lubricating characteristic of the compressor 2 deteriorates due to the shortage of the lubricating oil returning to the compressor 2 together with the refrigerant, the valve element 21 is closed for a predetermined time and then opened for a predetermined time.

When the valve 21 is opened, the dehumidifying expansion device 7
Is opened, and the low pressure loss refrigerant passage communicating with the valve port 19 is opened, so that the liquid refrigerant from the first indoor heat exchanger 6 passes through the low pressure loss refrigerant passage and the pressure of the refrigerant is reduced. And the second indoor heat exchanger 8 is hardly throttled.
And then returns to the suction port of the compressor 2 via the four-way valve 3. Therefore, since the flow rate of the refrigerant returning to the compressor 2 increases intermittently, the amount of lubricating oil contained in the refrigerant can be increased. For this reason, it is possible to prevent or suppress deterioration of the lubrication characteristics of the compressor 2 due to insufficient lubricating oil. After S5, the process returns to S4 again, and the steps from S4 are repeated. That is, the closing of the valve body 21 is intermittently opened.

On the other hand, if No in S4, it is determined in S6 whether the following equation (2) holds.

[0041]

[Outside 2] Outdoor temperature-Indoor temperature ≤ 10 ° C (2)

When the equation (2) is satisfied, that is,
In the case of Yes, even if the valve body 21 of the dehumidifying expansion device 7 is kept closed, there is little risk that the amount of lubricating oil returning to the compressor 2 will be insufficient. The body 21 is kept closed. After S7, the process returns to S4 again, and S
Repeat steps 4 and below.

FIG. 2 is a graph for explaining the second embodiment of the present invention. In the drawing, a substantially U-shaped curve shows the locus of the temperature difference between the outside air temperature (T0) and the room temperature (Ta). , The horizontal axis indicates time. In the second embodiment, when the closing of the valve body 21 of the dehumidifying expansion device 7 is intermittently opened,
It is characterized in that the valve opening time and the valve closing time are controlled by the controller 14 in accordance with the temperature difference T0−Ta between the outside air temperature T0 and the room temperature Ta.

That is, as shown in FIG. 2, the zones for controlling the opening and closing of the valve element 21 of the dehumidifying expansion device 7 are divided into three zones A, 3 based on the temperature difference T0-Ta between the outside air temperature and the room temperature Ta.
It is divided into B and C. For example, when the temperature difference T0−Ta between the outside air temperature and the room temperature Ta is 10 ° C. or more, the valve body 21
A in which the valve 21 is not intermittently opened
When the temperature difference T0-Ta is 11 ° C. to 15 ° C., the valve closing time of the valve body 21 is set to 3 minutes, and the zone B and the valve opening time are set to 5 minutes. T0-T
When a is equal to or higher than 15 ° C., the C zone 3 in which the valve closing time of the valve element 21 is set to 5 minutes and the valve opening time is set to 5 minutes, respectively.
Divided into two zones.

Each of the zones A to C has a temperature difference T.
When 0-Ta is in a decreasing direction, the temperature difference setting range is set higher by a predetermined temperature, for example, 1 ° C., than when the temperature difference T0-Ta is in a increasing direction. It is set to become. For example, in the B zone, when the temperature difference T0-Ta is in the direction of increasing, the temperature difference setting range is set to 11 ° C. to 15 ° C., but in the direction in which the temperature difference T0-Ta decreases. In some cases, the temperature difference setting range is set to 10 ° C to 14 ° C. Similarly, when the temperature difference T0-Ta is also decreasing in the A and C zones, the set value of the temperature difference is 10
° C and 14 ° C or higher.

Therefore, according to this control method, each opening / closing time of the valve element 21 of the dehumidifying throttle valve 7 is set to the outside temperature T0 and the room temperature T0.
Since an appropriate amount of lubricating oil is returned into the compressor 2 in accordance with the temperature difference T0-Ta from the pressure a, the lubrication characteristics of the compressor 2 can be optimized.

Further, when the temperature difference T0−Ta between the outside air temperature T0 and the room temperature Ta is 10 ° C. or less, the valve 21 of the dehumidifying expansion device 7 is kept closed and the operating frequency of the compressor 2 is increased.
Control means for increasing the frequency by a predetermined value via an inverter (not shown) may be provided in the control device 14.

According to this, the flow rate of the refrigerant discharged from the compressor 2 itself increases, and the flow rate of the refrigerant circulating in the refrigeration cycle increases. Even if the refrigerant flow rate itself is reduced by
Since the flow rate of the refrigerant returned to the compressor 2 through the cut grooves 19b increases, the amount of lubricating oil contained in the refrigerant also increases. For this reason, the lubrication characteristics of the compressor 2 are further improved.

[0049]

As described above, according to the present invention, the valve element of the dehumidifying expansion device which is closed during the dehumidifying operation is intermittently opened, so that the flow rate of the refrigerant returning to the compressor when the valve is opened is increased. Can be done. Therefore, the amount of lubricating oil contained in the refrigerant returning to the compressor can be increased, so that the lubrication characteristics of the compressor can be improved.

[Brief description of the drawings]

FIG. 1 is a chart of a program for controlling a dehumidifying operation of an air conditioner according to a first embodiment of the present invention.

FIG. 2 is a graph showing a dehumidification operation control method for an air conditioner according to a second embodiment of the present invention.

FIG. 3 is a refrigeration cycle diagram of an air conditioner having a control device provided with the dehumidifying operation control program shown in FIG.

FIG. 4 is a vertical sectional view showing a main part of the dehumidifying expansion device shown in FIG. 1 in a valve closed state.

FIG. 5 is a vertical sectional view of a main part showing a valve opening state of the dehumidifying expansion device shown in FIG. 1;

FIG. 6 is a view taken in the direction of arrow VI in FIG. 5;

FIG. 7 is a graph showing a relative relationship between a temperature difference between an outdoor temperature (outside air temperature) and an indoor temperature (room temperature) in a conventional compressor and an oil film thickness of the compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Compressor 3 Four-way valve 4 Outdoor heat exchanger 5 Expansion valve 6 1st indoor heat exchanger 7 Dehumidification expansion device 8 2nd indoor heat exchanger 9, 9a, 9b Refrigerant piping 11 Outside air temperature sensor 13 Room temperature sensor 14 Control device 16 First valve chamber 17 Second valve chamber 18 Valve seat 19 Valve port 19a Valve seat 19b Cut groove (refrigerant throttle passage) 20 Valve rod 21 Valve element 23 Excitation guide 26 Excitation coil

Claims (3)

[Claims] 1. A first use-side heat exchanger and a second use-side heat exchanger which are respectively operated as a condenser and an evaporator during a dehumidifying operation, wherein a use-side heat exchanger constituting a refrigeration cycle is thermally divided into two parts. A use-side heat exchanger; a low-pressure-loss refrigerant passage connecting the first and second use-side heat exchangers with a low-pressure loss to the refrigerant flow; and closing the low-pressure-loss refrigerant passage during a dehumidifying operation. A dehumidifying expansion device provided with a valve element and a refrigerant restriction path formed to communicate the first and second use-side heat exchangers when the low pressure loss refrigerant path is closed by the valve element and for restricting the refrigerant flow; An air conditioner comprising: an outdoor temperature sensor that detects an outdoor temperature; and an indoor temperature sensor that detects an indoor temperature, wherein the outdoor temperature sensor is higher than the indoor temperature detected by the indoor temperature sensor during a dehumidifying operation. To And a controller that intermittently opens the valve of the valve body of the dehumidifying expansion device when the detected outdoor temperature is higher and the difference between the temperatures is equal to or greater than a predetermined value. Air conditioner. 2. The control device further comprises an opening / closing time control means for controlling a closing time and an opening time of a valve element of the dehumidifying expansion device in accordance with a difference between the outdoor temperature and the indoor temperature, respectively. The air conditioner according to claim 1, wherein: 3. The control device according to claim 1, further comprising: a compressor control unit configured to increase an operating frequency of the compressor by a predetermined value when a temperature difference between the outdoor temperature and the indoor temperature is equal to or less than a predetermined value. The air conditioner according to claim 1 or 2, wherein