air conditioning unit

Abstract

To provide an air conditioning system that can be operated in the appropriate operating mode. [Solution] After stopping operation in heating mode, the control unit 13 issues an instruction to switch the four-way valve 40 to the cooling mode state at predetermined intervals. Even if the air conditioning system 10 remains inactive for a long period of time from the end of the winter season to the start of the summer season after stopping operation in heating mode, the likelihood of the four-way valve 40 switching to cooling mode is increased. This increases the likelihood of reliable operation in cooling mode at the start of the summer season, thereby improving product performance.

Description

Technical Field

[0001] This invention relates to an air conditioner for adjusting the temperature indoors.

Background Art

[0002] Conventionally, in this type of air conditioner, when switching between a heating mode for warming a room and a cooling mode for cooling the room, there is a four-way valve for switching the refrigerant flow path. A self-holding solenoid valve that is energized only when switching the operation mode and is not energized during normal times is used for this four-way valve.

[0003] Since the self-holding solenoid valve only needs to be energized when switching the mode, it is preferable in that the power consumption can be suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in this conventional air conditioner, after being continuously used as heating during the winter period, it is continuously used as cooling during the summer period. And some air conditioners are not used for a long time between winter and summer. For this reason, once the self-holding four-way valve is held in the position of one operation mode, it may be continuously held in that position for a long time. Such a four-way valve may cause some parts to become fixed due to being held in one position for a long time. If fixing of parts or the like occurs, when trying to displace it to another position in order to switch the operation mode, it will not displace properly. If the four-way valve cannot be switched, the operation mode will not switch either, and the air conditioner will not operate normally, so there was room for improvement.

Means for Solving the Problems

[0006] To solve the above problems, claim 1 of the present invention provides a self-holding four-way valve installed in the middle of a refrigerant flow path through which the refrigerant circulates, which switches the refrigerant flow path between cooling mode and heating mode, The control unit for controlling the four-way valve, and the following are provided: The control unit is characterized by issuing an instruction to switch the four-way valve to the cooling mode state at predetermined intervals after operation in heating mode has stopped.

[0007] Furthermore, claim 2 further includes an ambient temperature sensor for detecting ambient temperature, The control unit is characterized by shortening the predetermined interval as the detected value from the ambient temperature sensor, which is checked when the operation is stopped, decreases.

[0008] Furthermore, claim 3 further comprises a heating heater installed in a case housing the refrigerant flow path and the four-way valve, and whose drive is controlled by the control unit. The control unit is characterized by checking the value detected by the ambient temperature sensor at predetermined intervals, and driving the heating heater if the detected value is less than or equal to a predetermined value. [Effects of the Invention]

[0009] According to this invention, the control unit issues an instruction to switch the four-way valve to the cooling mode state at predetermined intervals after operation in heating mode has stopped, thereby enabling the air conditioning system to operate more reliably and normally. [Brief explanation of the drawing]

[0010] [Figure 1] This figure schematically shows an air conditioning system according to Embodiment 1 of the present invention. [Figure 2] This diagram illustrates the internal structure of the outdoor unit in Example 1. [Figure 3] Figure 3A illustrates the operation of the air conditioning system in cooling mode, and Figure 3B illustrates the operation of the air conditioning system in heating mode. [Figure 4] This is a schematic diagram of the four-way valve shown in Figure 1. [Figure 5] This diagram explains the operation of the four-way valve when it switches from the state shown in Figure 4 to the heating mode. [Figure 6] This is a control block diagram of Example 1. [Figure 7] This flowchart shows the control after the heating mode is stopped in Example 1. [Figure 8] This flowchart shows the control after the heating mode is stopped in Example 2. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the attached figures. The embodiments shown in the attached figures are examples of the present invention, and the present invention is not limited to these embodiments.

[0012] <Example 1> Refer to Figure 1. Figure 1 shows an air conditioning system 10 according to the present invention. The air conditioning system 10 includes a cooling function for cooling the indoor space (In) and a heating function for heating the indoor space (In). It may also have a dehumidifying function for dehumidifying the indoor space (In).

[0013] These functions can be switched, for example, by the user operating the remote control R located indoors (In). The user can select a specific operating mode, or they can select an auto mode, which allows the operating mode to be automatically switched based on indoor and outdoor temperature and humidity.

[0014] The air conditioning system 10 comprises an outdoor unit 20 installed outdoors Ou and an indoor unit 30 installed indoors In. The outdoor unit 20 and the indoor unit 30 are connected to each other by a refrigerant flow path so that the refrigerant can be circulated. Unless otherwise specified, the direction of refrigerant circulation is based on the cooling operation.

[0015] The outdoor unit 20 is composed of an outdoor unit case 21 which is a box-shaped housing, and includes a compressor 22 that compresses refrigerant, a four-way valve 40 that switches the direction of refrigerant circulation during cooling operation and heating operation through which the refrigerant passing through the compressor 22 flows, an outdoor heat exchanger 23 through which the refrigerant compressed and turned into high temperature and high pressure in the compressor 22 flows, an outdoor fan 24 that blows air toward the outdoor heat exchanger 23 and cools the refrigerant passing through the outdoor heat exchanger 23, an expansion valve 25 that decompresses the refrigerant passing through the outdoor heat exchanger 23, and an outdoor air temperature sensor 26 that detects the outside air temperature. The compressor 22, the four-way valve 40, the outdoor heat exchanger 23, and the indoor heat exchanger 34 are annularly connected by a refrigerant flow path R, and the refrigerant flows in the refrigerant flow path R.

[0016] Refer to FIG. 2. A linear heater 28 is installed in a predetermined range on a sheet metal base 27 that constitutes the lower part of the outdoor unit case 21. When the operation in the heating mode is carried out, low-temperature refrigerant flows in the outdoor heat exchanger 23 as an evaporator, and drain water drips from the surface of the outdoor heat exchanger 23 onto the base 27. When the outside air temperature is below freezing, the drain water dripping onto the base 27 freezes. When the frozen drain water grows, it collides with internal components such as the outdoor heat exchanger 23, which may cause a failure. When the control unit 13 determines that the detected value of the outdoor air temperature sensor 26 has become equal to or lower than a predetermined value at which the drain water may freeze, the control unit 13 drives the heater 28 for a predetermined time. The frozen drain water on the base 27 can be surely thawed, and the problems caused by the freezing of the drain water can be prevented in advance.

[0017] The indoor unit 30 is used by hanging on a wall Wa indoors In. The indoor unit case 31 which is the case of the indoor unit 30 is fixed to the wall Wa via a support plate. The indoor unit case 31 extending in the left-right direction houses an indoor fan 33 that takes in the air in the indoor In into the indoor unit case 31 and blows air into the indoor In, and an indoor heat exchanger 34 that exchanges heat with the air taken in by the indoor fan 33.

[0018] In addition to these, the air conditioning unit 10 has a control unit 13 that supplies power to and controls the four-way valve 40, etc. The control unit 13 can also receive electrical signals from a remote control R operated by the user, and can receive indoor temperature information and humidity information, etc. The control unit 13 is installed, for example, inside the indoor unit case 31.

[0019] The control unit 13 includes, for example, a CPU, a ROM in which programs and various data executed by the CPU are stored, a RAM used as the CPU's working memory, and an EEPROM which is a non-volatile memory.

[0020] The refrigerant flow paths R1 to R6, which are the refrigerant flow paths R through which the refrigerant flows, include the first flow path R1 from the compressor 22 to the four-way valve 40, the second flow path R2 from the four-way valve 40 to the outdoor heat exchanger 23, the third flow path R3 from the outdoor heat exchanger 23 to the expansion valve 25, the fourth flow path R4 from the expansion valve 25 to the indoor heat exchanger 34, the fifth flow path R5 from the indoor heat exchanger 34 to the four-way valve 40, and the sixth flow path R6 from the four-way valve 40 to the compressor 22.

[0021] Refer to Figure 3A as well. During operation in cooling mode, the refrigerant, which has been heated to high temperature and pressure by the compressor 22, exchanges heat with the outside air in the outdoor heat exchanger 23 and releases heat. At this time, the outdoor fan 24 operates to forcibly circulate the outside air around the outer circumference of the outdoor heat exchanger 23, promoting heat exchange. The refrigerant that has passed through the outdoor heat exchanger 23 and released heat is depressurized in the expansion valve 25, and its temperature drops. The refrigerant with reduced temperature is sent to the indoor unit 30.

[0022] Air is introduced into the indoor unit case 31 of the indoor unit 30 by the operation of the indoor fan 33. The introduced air passes around the outer perimeter of the indoor heat exchanger 34 and is blown into the indoor inlet. The indoor heat exchanger 34 is supplied with refrigerant that has been cooled in the outdoor unit 20. The air passing around the outer perimeter of the indoor heat exchanger 34 exchanges heat with the refrigerant and is cooled. The cooled air is then blown into the indoor inlet.

[0023] Refer to Figures 1 and 3B. For example, when the user operates the remote control R to select the heating mode, an electrical signal is sent to the control unit 13. The control unit 13 operates the four-way valve 40 to switch the flow paths R1 to R6 through which the refrigerant passes. More specifically, in cooling mode, the first flow path R1 and the second flow path R2 are connected (see Figure 3A), but in heating mode, the first flow path R1 and the fifth flow path R5 are connected. Accordingly, in cooling mode, the fifth flow path R5 and the sixth flow path R6 are connected, but in heating mode, the second flow path R2 and the sixth flow path R6 are connected.

[0024] In heating mode, the refrigerant, which has been heated to high temperature and pressure by the compressor 22, flows to the indoor heat exchanger 34. Air sent from the indoor fan 33 toward the indoor heat exchanger 34 is sent to the indoor In area, heated, and warm air is sent to the indoor In area. The refrigerant that has passed through the indoor heat exchanger 34 is reduced to low pressure in the expansion valve 25 and passes through the outdoor heat exchanger 23. The refrigerant that has passed through the outdoor heat exchanger 23 passes through the four-way valve 40 and returns to the expansion valve 25.

[0025] Next, we will explain the four-way valve 40 in detail.

[0026] Refer to Figure 4. A conventionally known self-holding four-way valve can be used for the four-way valve 40. The four-way valve 40 has a pilot valve 50 that is operated by energizing from the control unit 13, and a main valve 60 that switches the flow paths R1 to R6 through which the refrigerant flows when the pilot valve 50 is operated.

[0027] The pilot valve 50 includes a coil 51 connected to the control unit 13 and energized, a magnet 52 made of a permanent magnet and provided adjacent to one axial end of the coil 51, an attractive element 53 in close contact with the magnet 52, a spring 54 made of a compression coil spring and having one end in contact with the attractive element 53, a plunger 55 that is in contact with the other end of the spring 54 and is displaced in the axial direction when the coil 51 is energized, and a pilot valve body 56 provided at the tip of the plunger 55.

[0028] The coil 51, magnet 52, suction element 53, spring 54, and part of the plunger 55 are housed in the first case 57. The remainder of the plunger 55 and the pilot valve body 56 are housed in the second case 58. The first case 57 and the second case 58 are sealed to prevent refrigerant leakage from the second case 58 to the first case 57.

[0029] The main valve 60 includes a main case 61 to which the first passage R1, second passage R2, fifth passage R5, and sixth passage R6 are connected; partition walls 64 provided displaceably inside the main case 61 and dividing the first chamber 62 and second chamber 63 formed at both ends of the main case 61; and a main valve body 65 which is displaceable together with the partition walls 64 and connects the sixth passage R6 to the fifth passage R5 or the sixth passage R6 to the second passage R2.

[0030] The first flow path R1 and the second case 58 are connected by the first connecting path R11. The second case 58 and the first chamber 62 are connected by the second connecting path R12. The second case 58 and the second chamber 63 are connected by the third connecting path R13. The second case 58 and the sixth flow path R6 are connected by the fourth connecting path R14. Refrigerant flows through the first to fourth connecting paths R11 to R14.

[0031] In cooling mode, most of the refrigerant flowing through the first channel R1 flows to the second channel R2 via the inside of the main case 61. On the other hand, a portion of the refrigerant flowing through the first channel R1 can flow to the second case 58 via the first connection passage R11. The refrigerant that flows to the second case 58 flows to the first chamber 62 via the second connection passage R12. The refrigerant in the second chamber 63 flows to the fourth connection passage R14 via the inside of the pilot valve body 56 from the third connection passage R13. The refrigerant flowing through the fourth connection passage R14 flows to the sixth channel R6.

[0032] Refer to Figure 5 as well. By switching from cooling mode to heating mode, the four-way valve 40 changes from the state shown in Figure 4 to the state shown in Figure 5.

[0033] More specifically, the control unit 13 energizes the coil 51 to switch to heating mode. This generates a magnetic field along the axis of the coil 51, causing the plunger 55 to displace against the force of the spring 54 until it attaches to the suction element 53. The pilot valve body 56 also displaces axially along with the plunger 55. As a result, in cooling mode, the third connection passage R13 and the fourth connection passage R14 are connected by the pilot valve body 56, while in heating mode, the second connection passage R12 and the fourth connection passage R14 are connected by the pilot valve body 56. After the plunger 55 attaches to the suction element 53, the control unit 13 terminates the energization of the coil 51.

[0034] As a result, the refrigerant that has passed through the first connection passage R11 and flowed into the second case 58 flows through the third connection passage R13 into the second chamber 63. As the refrigerant flows in, the compartment wall 64 and the main valve body 65 move towards the first chamber 62. The refrigerant in the first chamber 62 flows from the second connection passage R12 through the pilot valve body 56 to the fourth connection passage R14. The refrigerant that has flowed through the fourth connection passage R14 flows into the sixth flow path R6. In cooling mode, the main valve body 65 connects the fifth flow path R5 and the sixth flow path R6, but in heating mode, it connects the second flow path R2 and the sixth flow path R6. This completes the switch to heating mode. In heating mode, the refrigerant that has flowed through the first flow path R1 and into the main case 61 flows into the fifth flow path R5.

[0035] When switching from heating mode to cooling mode, the control unit 13 energizes the plunger 55 until it separates from the suction element 53. The plunger 55, having separated from the suction element 53, is then moved by the spring 54 The biasing force causes the coil 51 to be displaced along its axis, connecting the third connection path R13 and the fourth connection path R14. After the plunger 55 separates from the attractor 53, the control unit 13 terminates the energization of the coil 51.

[0036] As a result, the partition wall 64 and the main valve body 65 move to the second chamber 63 side. In heating mode, the main valve body 65 connects the second flow path R2 and the sixth flow path R6, but in cooling mode, it connects the fifth flow path R5 and the sixth flow path R6. This completes the switch to cooling mode. In cooling mode, the refrigerant that has flowed through the first flow path R1 and into the main case 61 flows into the second flow path R2.

[0037] Next, we will explain the problems associated with using the self-holding four-way valve 40.

[0038] From the time the system is shut down until it is restarted, the pilot valve 50 of the four-way valve 40 is held in the state of the operating mode that was immediately used. If the air conditioning system 10 is not used for a long period of time, from the end of the winter season to the start of the summer season, and the pilot valve 50 is held in the state of the heating mode that was immediately used, there is a risk that the refrigerant oil inside the pilot valve 50 will deteriorate and solidify. In this case, even if an instruction to start operation in cooling mode is given at the start of the summer season and an attempt is made to switch the four-way valve 40 to cooling mode, the pilot valve 50 will not operate properly, and there will be a problem in that the system will not operate in cooling mode.

[0039] To address this problem, one possible method is to energize the four-way valve 40 for a predetermined time when the heating mode is stopped, switch the pilot valve 50 to the cooling mode state shown in Figure 4, and then turn off the power. However, if the pilot valve 50 of the four-way valve 40 is activated only once when the operation is stopped, there is a possibility that the system will not switch to cooling mode.

[0040] The present invention provides an air conditioning system 10 that can increase the likelihood of it operating in cooling mode the next time it is operated, even if the air conditioning system 10 is not used for a long period of time from the end of the winter season to the start of the summer season. The specific control is described below.

[0041] Next, the control after operation stops in heating mode in Example 1 will be explained based on the flowchart in Figure 7.

[0042] During operation in heating mode, the control unit 13 determines whether a stop operation command has been issued from the remote control R (step S101). If it determines that a stop operation command has been issued, it energizes the four-way valve 40, activates the pilot valve 50 so that the four-way valve 40 is in cooling mode, and starts counting the elapsed time (step S102). If the control unit 13 determines that no stop operation command has been issued, it repeats the determination in step S101.

[0043] In step S102, the control unit 13 switches the four-way valve 40 to the cooling mode state. In step S103, it determines whether the counted elapsed time has elapsed to a predetermined interval. If it determines that the predetermined elapsed time has elapsed, it energizes the four-way valve 40 and issues an instruction to operate the pilot valve 50 so that the four-way valve 40 enters the cooling mode state. In step S104, the control unit 13 also resets the elapsed time count and starts a new elapsed time count.

[0044] The control unit 13 determines whether the elapsed time counted in step S103 has not elapsed for a predetermined time, or, after completing the process in step S104, whether the remote control R has been operated and an operation restart instruction has been issued (step S105). If it determines that an operation restart instruction has been issued, it restarts operation in the predetermined mode and terminates the control. If it determines that an operation restart instruction has not been issued, it repeats the determination in step S103.

[0045] As described above, after operation in heating mode is stopped and before operation is restarted, instructions are issued to switch the four-way valve 40 to the cooling mode at predetermined intervals, thus increasing the likelihood that the four-way valve 40 will be switched to the cooling mode by the time operation starts again. Therefore, even if the system is not operated for a long period from the end of the winter season to the start of the summer season, the likelihood that operation in cooling mode will be reliably implemented at the start of the summer season can be increased.

[0046] Next, the effects of Example 1 will be explained. Note that the effects of Example 1, as described below, are also exhibited in Example 2, which will be described below.

[0047] The control unit 13 issues an instruction to switch the four-way valve 40 to the cooling mode at predetermined intervals after operation in heating mode has stopped. Even if the air conditioning system 10 remains idle for a long period from the winter season to the summer season after operation in heating mode has stopped, the likelihood of the four-way valve 40 switching to cooling mode is increased. This increases the likelihood of reliable operation in cooling mode at the start of the summer season, thereby improving product performance.

[0048] <Example 2> Next, the control after operation stops in heating mode in Embodiment 2 of the present invention will be explained based on the flowchart in Figure 8. Note that the configuration of Embodiment 2 is the same as that of Embodiment 1, so the explanation will be omitted.

[0049] During operation in heating mode, the control unit 13 determines whether a stop operation command has been issued from the remote control R (step S201). If it determines that a stop operation command has been issued, it energizes the four-way valve 40, activates the pilot valve 50 so that the four-way valve 40 is in cooling mode, and checks the detected value of the outside temperature sensor 26 (step S202). If the control unit 13 determines that no stop operation command has been issued, it repeats the determination in step S201.

[0050] In step S202, the control unit 13 switches the four-way valve 40 to the cooling mode state and checks the outside temperature, then determines whether the value detected by the outside temperature sensor 26 is equal to or greater than a predetermined value A (step S203). If the control unit 13 determines in step S203 that the value detected by the outside temperature sensor 26 is equal to or greater than a predetermined value A, it sets a predetermined interval of energization interval 1 for issuing an instruction to energize the four-way valve 40 to enter the cooling mode state, and starts counting time (step S204).

[0051] If the control unit 13 determines in step S203 that the detected value of the outside temperature sensor 26 is less than a predetermined value A, it determines in step S205 whether the detected value of the outside temperature sensor 26 is less than a predetermined value A and greater than or equal to a predetermined value B. Note that A > B. If the control unit 13 determines in step S205 that the detected value of the outside temperature sensor 26 is less than a predetermined value A and greater than or equal to a predetermined value B, it sets the energization interval to 2, which is a predetermined interval for instructing the four-way valve 40 to enter the cooling mode state, and starts counting time (step S206). Note that energization interval 1 > energization interval 2.

[0052] If the control unit 13 determines in step S205 that the value detected by the outside temperature sensor 26 is less than a predetermined value B, it sets the energization interval to 3 and starts counting time to instruct the four-way valve 40 to be energized and enter cooling mode (step S207). Note that the relationship is energization interval 2 > energization interval 3.

[0053] If the control unit 13 sets the energization interval to one of 1 to 3 in step S204, step S206, or step S207 and starts counting time, it determines whether the counted elapsed time has reached the time of each set energization interval (step S208). If the counted elapsed time has reached the time of each set energization interval, it energizes the four-way valve 40 and issues an instruction to operate the pilot valve 50 so that the four-way valve 40 enters the cooling mode state, and at the same time resets the time count and checks the detected value of the outside temperature sensor 26 (step S209). If the control unit 13 determines in step S208 that the elapsed time has not reached the time of each set energization interval, it repeats the determination in step S208.

[0054] In step S209, the control unit 13 issues an instruction to energize the four-way valve 40 to enter cooling mode, and after confirming the value detected by the outside temperature sensor 26, it determines whether the value detected by the outside temperature sensor 26 is less than or equal to a predetermined value C (step S210). Note that B > C. If the control unit 13 determines in step S210 that the value detected by the outside temperature sensor 26 is less than or equal to the predetermined value C, it drives the heating heater 28 for a predetermined time set in advance (step S211).

[0055] The control unit 13 determines in step S210 whether the detected value of the ambient temperature sensor 26 is higher than a predetermined value C, or whether the remote control R was operated and an operation restart instruction was given after the heating heater 28 was driven in step S211 (step S212). If it determines that an operation restart instruction has been given, it restarts operation in the predetermined mode and terminates the control. If it determines that an operation restart instruction has not been given, it repeats the determination in step S203.

[0056] As described above, after operation stops in heating mode, until operation resumes, the four-way valve 40 is instructed to switch to cooling mode every 1 to 3 hours based on the detection value of the outside temperature sensor 26. Furthermore, the lower the detected outside temperature, the shorter the power supply interval is set to be, so the four-way valve 40 is instructed to switch to cooling mode more frequently compared to when the detected outside temperature is high. Therefore, even if the unit is not operated for a long period from the end of the winter season to the start of the summer season, the likelihood of operation in cooling mode being reliably implemented at the start of the summer season can be increased.

[0057] Next, we will explain the effects of Example 2.

[0058] The control unit 13 shortens the predetermined interval the lower the value detected by the ambient temperature sensor 26 when the unit is stopped. The lower the value detected by the ambient temperature sensor 26, the higher the possibility that the refrigerant oil inside the pilot valve 50 will deteriorate and solidify. As the value detected by the ambient temperature sensor 26 decreases, the interval at which the four-way valve 40 is energized is shortened, and the timing of issuing an instruction to switch to cooling mode becomes more frequent. This increases the likelihood that the four-way valve 40 will switch to cooling mode before the next start of operation, and increases the likelihood that operation in cooling mode will be reliably carried out even if an instruction to operate in cooling mode is issued after a long period of inactivity.

[0059] Furthermore, the control unit 13 checks the value detected by the outside temperature sensor 26 at predetermined intervals, and drives the heating heater 28 if the detected value is less than or equal to a predetermined value C. The lower the value detected by the outside temperature sensor 26, the higher the possibility that the refrigerant oil inside the pilot valve 50 will deteriorate and solidify. When the heating heater 28 is driven, the temperature inside the outdoor unit case 21 rises, and the four-way valve 40 is heated. By heating the four-way valve 40, solidification of the refrigerant oil inside the pilot valve 50 can be prevented. As the value detected by the outside temperature sensor 26 decreases, the interval at which power is supplied to the four-way valve 40 is shortened, and the timing of instructing to switch to cooling mode becomes more frequent. This increases the possibility that the four-way valve 40 will switch to the cooling mode state before the next start of operation, and even if an instruction to operate in cooling mode is given after a long period of inactivity, the possibility of reliable operation in cooling mode is increased.

[0060] Although the present invention has been described using Examples 1 and 2, the embodiments of the present invention are not limited to Examples 1 and 2 and can be applied to other embodiments.

[0061] For example, the control system may learn the operating status of the air conditioning unit 10 in heating mode and cooling mode, or, based on information set in advance by the user, identify periods of long-term shutdown between the end of the winter season and the start of the summer season, and then energize the four-way valve 40 at predetermined intervals only during those periods to issue an instruction to switch to cooling mode. By energizing the four-way valve 40 only at times when there is a high possibility of solidification of the refrigerant oil inside the pilot valve 50 due to long-term shutdown, more efficient control becomes possible. [Explanation of Symbols]

[0062] 10 Air conditioner 13 Control Unit 21 Outdoor unit case 26. Outdoor temperature sensor 28 Heating heater 40 Square valve

Claims

1. A self-holding four-way valve is installed in the middle of the refrigerant flow path through which the refrigerant circulates, and switches the refrigerant flow path between cooling mode and heating mode. The control unit for controlling the four-way valve, and the following are provided: The control unit is characterized by issuing an instruction to switch the four-way valve to the cooling mode state at predetermined intervals after operation in heating mode has stopped.

2. It further includes an ambient temperature sensor that detects the ambient temperature, The air conditioning device according to claim 1, characterized in that the control unit shortens the predetermined interval as the detected value from the outside temperature sensor, which was checked when the operation was stopped, decreases.

3. The case housing the refrigerant flow path and the four-way valve further includes a heating heater, the heating element of which is controlled by the control unit. The air conditioning device according to claim 2, characterized in that the control unit checks the value detected by the outside temperature sensor at predetermined intervals, and drives the heating heater if the detected value is less than or equal to a predetermined value.

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