Air conditioning system

Abstract

To provide an air conditioning system that reduces the on / off cycles of indoor units and stabilizes room temperature. [Solution] The air conditioning system comprises an outdoor unit and an indoor unit connected by refrigerant piping, wherein the refrigerant piping includes a liquid pipe through which liquid refrigerant passes and a gas pipe through which gaseous refrigerant passes, and the refrigerant piping is equipped with a shut-off valve kit having an expansion valve that adjusts the flow rate of refrigerant in the gas pipe and shuts off the gas pipe in the event of refrigerant leakage by opening and closing operations, and is equipped with a control unit that controls the opening and closing operation of the expansion valve.

Description

Technical Field

[0006] , , , , ,

[0001] This disclosure relates to an air conditioner.

Background Art

[0002] Patent Document 1 discloses an air conditioner including an outdoor unit and a plurality of indoor units. In this air conditioner, the indoor units and a plurality of outdoor units are connected via refrigerant pipes, and the refrigerant flow rate of each indoor unit is individually controlled by an expansion valve provided corresponding to each indoor unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] This disclosure provides an air conditioner capable of reducing the start / stop of indoor units and stabilizing the room temperature.

Means for Solving the Problems

[0005] In the air conditioner according to this disclosure, in an air conditioner in which an outdoor unit and an indoor unit are connected by a refrigerant pipe, the refrigerant pipe has a liquid pipe through which liquid refrigerant passes and a gas pipe through which gaseous refrigerant passes, and the refrigerant pipe is provided with a shut-off valve kit having an expansion valve that adjusts the flow rate of the refrigerant in the gas pipe and shuts off the gas pipe in case of refrigerant leakage by an opening / closing operation, and a control unit that controls the opening / closing operation of the expansion valve.

Effects of the Invention

[0006] The air conditioning system in this disclosure can control the opening degree of the gas pipe expansion valve according to predetermined conditions, thereby increasing the refrigerant temperature by introducing a pressure loss to the refrigerant. Therefore, the refrigerant can be controlled according to the conditions of the indoor unit, and repeated starting and stopping of operation can be suppressed, thereby stabilizing the room temperature. [Brief explanation of the drawing]

[0007] [Figure 1] Circuit diagram of the air conditioning system in Embodiment 1 [Figure 2] Block diagram of the air conditioning system in Embodiment 1 [Figure 3] Flowchart showing the control process of the gas pipe expansion valve in Embodiment 1 [Figure 4] Circuit diagram of the air conditioning system in Embodiment 2 [Figure 5] Circuit diagram of the air conditioning system in Embodiment 3 [Modes for carrying out the invention]

[0008] (Knowledge and other information that formed the basis of this disclosure) At the time the inventors conceived of this disclosure, there was a technology in which multiple indoor units were connected to an outdoor unit via refrigerant piping, and the flow rate of refrigerant to each indoor unit was individually controlled by an expansion valve provided for each indoor unit. However, in the conventional technology, the temperature of the refrigerant flowing to each indoor unit was the same, so in rooms with a small load on the indoor units, the unit would over-operate or repeatedly start and stop due to a drop in the temperature of the sensor installed in the indoor unit, resulting in an unstable room temperature. The inventors discovered this problem and, in order to solve it, came to constitute the subject of this disclosure. Therefore, this disclosure provides an air conditioning system that can reduce the starting and stopping of the indoor unit and stabilize the room temperature by adjusting the refrigerant temperature according to the load on the indoor unit.

[0009] The embodiments will be described in detail below with reference to the drawings. However, some unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. The attached drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0010] (Embodiment 1) [1-1. Structure] [1-1-1. Configuration of the air conditioning system] Figure 1 is a circuit diagram of the air conditioning system 1. The arrows in Figure 1 indicate the direction of refrigerant flow. The air conditioning system 1 comprises an outdoor unit 10 installed outside, three indoor units 20 installed in rooms R of the building, and three shut-off valve kits 30 provided for each indoor unit 20. One indoor unit 20 is provided for each room R. The outdoor unit 10, indoor units 20, and shut-off valve kits 30 are connected by refrigerant piping 5.

[0011] The refrigerant piping 5 consists of a liquid pipe 6 through which liquid refrigerant passes and a gas pipe 7 through which gaseous refrigerant passes. The liquid pipe 6 and the gas pipe 7 connect each shut-off valve kit 30 and indoor unit 20 in parallel to the outdoor unit 10, forming a refrigerant flow path. In this embodiment, the liquid pipe 6 is the piping through which refrigerant flows from the outdoor heat exchanger 11 installed in the outdoor unit 10 to the indoor heat exchanger 21 installed in the indoor unit 20, and the gas pipe 7 is the piping through which refrigerant flows from the indoor heat exchanger 21 to the outdoor heat exchanger 11. For example, a flammable refrigerant such as R32 is used.

[0012] The outdoor unit 10 includes a compressor 12 that inhales and compresses refrigerant, an outdoor heat exchanger 11 that performs heat exchange between the refrigerant and outdoor air, an outdoor fan (not shown) that supplies outdoor air to the outdoor heat exchanger 11, and an outdoor expansion valve 13 that adjusts the amount of refrigerant flowing out of the outdoor heat exchanger 11. The compressor 12, blower, and outdoor expansion valve 13 are controlled by an outdoor unit control unit (not shown).

[0013] Next, the configuration of the shut-off valve kit 30 will be described. In the present embodiment, since all the shut-off valve kits 30 have the same configuration, only one shut-off valve kit 30 will be described, and the description of the other shut-off valve kits 30 will be omitted. The shut-off valve kit 30 includes a liquid-side solenoid valve 31 and a gas pipe expansion valve (expansion valve) 32 to which a liquid pipe 6 and a gas pipe 7 extending from the outdoor unit 10 are connected.

[0014] Next, the configuration of the indoor unit 20 will be described. In the present embodiment, since all the indoor units 20 have the same configuration, only one indoor unit 20 will be described, and the description of the other indoor units 20 will be omitted. The liquid pipe 6 and the gas pipe 7 connected from the outdoor unit 10 to the shut-off valve kit 30 are subsequently connected to the indoor unit 20. The indoor unit 20 includes an indoor expansion valve 22 connected to the liquid pipe side, an indoor heat exchanger 21 that exchanges heat between the refrigerant and the indoor air, an indoor blower 29 that supplies indoor air to the indoor heat exchanger 21, and a sensor that measures information such as temperature. In the present embodiment, the sensors are a refrigerant temperature sensor, a blow-out temperature sensor 25, and a refrigerant leakage sensor 34.

[0015] The refrigerant temperature sensor is provided in the refrigerant flow path before and after the indoor heat exchanger 21. In the present embodiment, the refrigerant temperature sensor is an inlet-side temperature sensor 23 provided at the refrigerant inlet of the indoor heat exchanger 21 and an outlet-side temperature sensor 24 provided at the refrigerant outlet of the indoor heat exchanger 21. The inlet-side temperature sensor (liquid pipe temperature sensor) 23 and the outlet-side temperature sensor (gas pipe temperature sensor) 24 can measure the inlet refrigerant temperature and the outlet refrigerant temperature, which are the temperatures of the refrigerant flowing into and out of the indoor heat exchanger 21.

[0016] The blow-out temperature sensor 25 is provided at a blow-out port (not shown) through which the air heat-exchanged by the indoor heat exchanger 21 blows out from the indoor unit 20. Thereby, the blow-out temperature, which is the temperature of the air blown out from the indoor unit 20, is measured.

[0017] The refrigerant leakage sensor 34 is a sensor for detecting leakage of refrigerant from the refrigerant pipe 5.

[0018] A remote controller 40 for operating the indoor unit 20 is connected to the indoor unit 20. The remote controller 40 includes, for example, an operation unit 41 for the user to perform operations such as temperature setting for setting the indoor temperature, air volume setting, and switching between cooling and heating.

[0019] [1-1-2. Control configuration] FIG. 2 is a block diagram showing the control configuration of the air conditioner 1. The indoor unit 20 includes an indoor unit control unit 26 and an indoor unit communication unit 27.

[0020] The indoor unit control unit 26 includes, for example, a processor 26a that executes programs such as a CPU or MPU, and a memory 26b such as a ROM and a RAM. The processor 26a reads out a control program stored in the memory 26b and executes various processes through the cooperation of hardware and software.

[0021] In the present embodiment, the indoor unit communication unit 27 receives information from the remote controller 40 via wireless communication or wired communication. The indoor unit control unit 26 receives information from this indoor unit communication unit 27 and information from the inlet side temperature sensor 23, outlet side temperature sensor 24, and blowing temperature sensor 25 mounted on the indoor unit 20, and controls the indoor expansion valve 22, indoor blower 29, and shut-off valve kit 30.

[0022] More specifically, the processor 26a receives information such as temperature setting, air volume setting, and switching between cooling and heating for the user to set the indoor temperature from the remote controller 40 based on the control program, and controls the indoor unit 20. Further, when the conditions measured by the inlet side temperature sensor 23, outlet side temperature sensor 24, blowing temperature sensor 25, and refrigerant leakage sensor 34 satisfy predetermined conditions based on the control program, the opening degree of the indoor expansion valve 22, the driving of the indoor blower 29, and the opening degrees of the liquid side solenoid valve 31 and gas pipe expansion valve 32 of the shut-off valve kit 30 are controlled. The indoor unit communication unit 27 also communicates with the outdoor unit communication unit. As a result, the outdoor unit 10 starts operating in conjunction with the start of operation of the indoor unit 20.

[0023] [1-2. Operation] As described above, in this embodiment, the air conditioning system 1 starts operating in response to an operation from a remote control 40 provided for each indoor unit 20. Subsequently, the indoor unit control unit 26 receives information from various sensors 23, 24, 25, and 34 and controls the indoor blower 29, indoor expansion valve 22, liquid-side solenoid valve 31, and gas pipe expansion valve 32.

[0024] When the indoor units 20 in each room R are operating, the operating load of the indoor unit 20 will be high if the room temperature is higher than the set temperature, and low if the room temperature is lower than the set temperature, depending on the difference in room temperature between the rooms R. The refrigerant flow rate is adjusted by controlling the indoor expansion valve 22 on the liquid pipe side according to the operating load (operating state) of the indoor unit 20. However, if the refrigerant flow rate is controlled only by the indoor expansion valve 22 on the liquid pipe side, the indoor expansion valve 22 on the liquid pipe side alone may not be able to control the load, or the refrigerant temperature sensor installed in the indoor unit 20 may drop to the freezing point. In such cases, there is a concern that the room temperature will fluctuate and become unstable as the indoor unit 20 repeatedly starts and stops operating.

[0025] In this embodiment, if the information from the various sensors 23, 24, and 25 satisfies predetermined conditions, the opening degree of the gas pipe expansion valve 32 is also controlled to be reduced.

[0026] Figure 3 is a flowchart showing the control of the gas pipe expansion valve 32. In this embodiment, the predetermined conditions are set based on the outlet set temperature, which is the set temperature of the air blown out from the indoor unit 20 when cooling room R, and the temperature of the refrigerant inlet or outlet of the indoor heat exchanger 21.

[0027] First, in step 1, the processor 26a determines whether the outlet temperature of the air blown out from the indoor unit 20 (the temperature measured by the outlet temperature sensor 25) remains below a predetermined temperature for a predetermined period of time (first condition, S1). The predetermined temperature and time can be set arbitrarily. In this embodiment, the outlet set temperature of the indoor unit 20 is set to 12°C, and the condition is met if the temperature remains 4°C lower than the outlet set temperature for a continuous period of 5 minutes.

[0028] If the judgment determines that the conditions of Step 1 are met (S1: YES), proceed to Step 2. If the conditions of Step 1 are not met (S1: NO), continue checking whether the conditions of Step 1 are met.

[0029] Next, in step 2, the processor 26a determines whether the lower of the two measured temperatures—the refrigerant temperature at the refrigerant inlet of the indoor heat exchanger 21 (measured by the inlet-side temperature sensor 23) or the refrigerant temperature at the refrigerant outlet of the indoor heat exchanger 21 (measured by the outlet-side temperature sensor 24)—is below a predetermined temperature condition (second condition, S2). The predetermined temperature can be set arbitrarily, and in this embodiment, the condition is that the lower of the two temperatures at the refrigerant inlet or outlet of the indoor heat exchanger 21 is 2°C or less.

[0030] If the result of the determination satisfies the conditions of Step 2 (S2: YES), the process proceeds to Step 3. If the conditions of Step 2 are not met (S2: NO), processor 26a returns to Step 1 and determines again whether the conditions are met.

[0031] In step 3, if the conditions of steps 1 and 2 described above are met, the processor 26a controls the opening of the gas pipe expansion valve 32 (S3).

[0032] In other words, in this embodiment, if the air blown out from the indoor unit 20 remains below 8°C for a continuous 5 minutes, and the lower of the refrigerant temperatures at the inlet or outlet of the indoor heat exchanger 21 is 2°C or less, the processor 26a controls the opening of the gas pipe expansion valve 32 to be reduced. Note that, under the conditions of this embodiment, it is sufficient to satisfy steps 1 and 2, so the order of determination of steps 1 and 2 does not matter.

[0033] As described above, after the gas pipe expansion valve 32 is throttled in step 3, if predetermined release conditions are met, the opening degree of the gas pipe expansion valve 32 is increased and returned to the state before the throttling. In this embodiment, the release conditions are set based on the outlet setting temperature, which sets the temperature of the air blown out from the indoor unit 20 when cooling room R, and the temperature of the refrigerant inlet or outlet of the indoor heat exchanger 21.

[0034] First, in step 4, the processor 26a determines whether the outlet temperature of the indoor unit 20 remains above a predetermined temperature for a predetermined period of time (third condition, S4). The predetermined temperature and time can be set arbitrarily, and in this embodiment, the condition is met if the outlet set temperature of the indoor unit 20 remains above 17°C for 5 consecutive minutes.

[0035] If the judgment confirms that the conditions of Step 4 are met (S4:YES), proceed to Step 6. If the conditions of Step 4 are not met (S4:NO), proceed to Step 5.

[0036] In step 5, the processor 26a determines whether the lower of the temperatures measured by either the inlet temperature sensor 23 or the outlet temperature sensor 24 is above a predetermined temperature condition and this condition continues for a predetermined time (fourth condition, S5). The predetermined temperature and time can be set arbitrarily, and in this embodiment, the condition is met if the lower of the temperatures at the refrigerant inlet or outlet of the indoor heat exchanger 21 remains above 10°C for 5 minutes.

[0037] If the result of the assessment meets the conditions of Step 5 (S5: YES), proceed to Step 6. If the conditions of Step 5 are not met (S5: NO), return to Step 4 and assess whether the conditions are met again.

[0038] In step 6, processor 26a increases the opening of the gas pipe expansion valve 32, which was restricted in step 3, and returns the opening of the gas pipe expansion valve 32 to the state it was in before it was restricted in step 3 (S5).

[0039] In other words, if the set outlet temperature of the indoor unit 20 remains at 17°C or higher for 5 consecutive minutes, or if the lower temperature of the refrigerant inlet or outlet of the indoor heat exchanger 21 remains at 10°C or higher for 5 consecutive minutes, the indoor unit control unit 26 causes the gas pipe expansion valve 32 to open and return to its original opening degree. In this embodiment, it is sufficient to satisfy either step 4 or 5, so the order of determination of steps 4 and 5 does not matter.

[0040] In this way, by controlling the opening degree of the gas pipe expansion valve 32 according to predetermined conditions, it is possible to introduce pressure loss to the refrigerant and raise the refrigerant temperature according to the load conditions of the indoor unit 20. Therefore, compared to controlling the refrigerant only with the indoor expansion valve 22 on the liquid pipe side, it is possible to control the refrigerant in accordance with the load with greater precision, and repeated starting and stopping of operation can be suppressed, thereby stabilizing the room temperature. In addition, it is possible to prevent the refrigerant temperature sensor from dropping to the freezing point due to inability to fully control the refrigerant.

[0041] As described above, during normal operation of the air conditioner 1, the indoor unit control unit 26 controls the opening degree of the gas pipe expansion valve 32 of the shut-off valve kit 30. In addition, when the refrigerant leak sensor 34 detects a refrigerant leak, the indoor unit control unit 26 closes the liquid-side solenoid valve 31 and the gas pipe expansion valve 32, thereby shutting off the refrigerant flow path. In other words, the liquid-side solenoid valve 31 and the gas pipe expansion valve 32 also function as shut-off valves in the event of a refrigerant leak.

[0042] [1-3. Effects, etc.] The air conditioning system 1 comprises an outdoor unit 10 and an indoor unit 20 connected by refrigerant piping 5. The refrigerant piping 5 includes a liquid pipe 6 through which liquid refrigerant passes and a gas pipe 7 through which gaseous refrigerant passes. The refrigerant piping 5 is equipped with a shut-off valve kit 30 having a gas pipe expansion valve 32 that adjusts the flow rate of refrigerant in the gas pipe 7 and shuts off the gas pipe 7 in the event of refrigerant leakage through opening and closing operations. The indoor unit control unit 26 controls the opening and closing operation of the gas pipe expansion valve 32. According to this, the opening degree of the gas pipe expansion valve 32 can be controlled according to predetermined conditions, and the refrigerant temperature can be increased by introducing a pressure loss to the refrigerant. Therefore, the refrigerant can be controlled according to the condition of the indoor unit 20, and repeated starting and stopping of the indoor unit 20 can be suppressed, thereby stabilizing the room temperature.

[0043] The indoor unit 20 has an outlet temperature sensor 25 for measuring the outlet temperature of the air blown out from the indoor unit 20, an inlet temperature sensor 23 for measuring the temperature of the refrigerant in the liquid pipe 6, and an outlet temperature sensor 24 for measuring the temperature of the refrigerant in the gas pipe 7. The indoor unit control unit 26 causes the gas pipe expansion valve 32 to close when the following conditions are met: Step 1 (S1, first condition) is that the temperature difference between the outlet temperature and the set outlet temperature at which the air is blown out from the indoor unit 20 remains below a predetermined threshold for a predetermined period of time or longer; and Step 2 (S2, second condition) is that the temperature measured by either the liquid pipe temperature sensor or the gas pipe temperature sensor remains below a predetermined threshold for a predetermined period of time or longer. According to this, it is possible to prevent the refrigerant from being uncontrollable and the refrigerant temperature sensors (inlet temperature sensor 23, outlet temperature sensor 24) from dropping to the freezing point. Therefore, by introducing a pressure loss to the refrigerant, the refrigerant temperature can be increased, which can suppress repeated starting and stopping of the indoor unit 20, thereby stabilizing the room temperature.

[0044] After the indoor unit control unit 26 has closed the gas pipe expansion valve 32, if either step 4 (S4, third condition) is met, and the temperature difference between the discharge temperature and the set discharge temperature remains greater than a predetermined threshold for a predetermined time or longer, or step 5 (S5, fourth condition) is met, and either the temperature measured by the inlet temperature sensor 23 or the temperature measured by the outlet temperature sensor 24 remains greater than a predetermined threshold for a predetermined time or longer, the indoor unit control unit 26 will open the gas pipe expansion valve 32. According to this, compared to controlling the refrigerant using only the liquid pipe 6, the refrigerant can be controlled more precisely according to the operating conditions of the indoor unit 20. Therefore, by introducing a pressure loss to the refrigerant, the refrigerant temperature can be increased, which suppresses repeated starting and stopping of the indoor unit 20, thus stabilizing the room temperature.

[0045] (Embodiment 2) [2-1. Structure] Embodiment 2, to which the present invention is applied, will now be described. In this Embodiment 2, parts configured in the same way as in Embodiment 1 are denoted by the same reference numerals and their description is omitted.

[0046] Figure 4 is a circuit diagram of the air conditioning system 51 in Embodiment 2. In Embodiment 1, one shut-off valve kit 30 and one indoor unit 20 were provided for each room R. In Embodiment 2, each room R has two indoor units 20.

[0047] [2-2. Operation] In such cases, the indoor unit control unit 26 determines whether to control the opening degree of the gas pipe expansion valve 32 according to the operating status of each indoor unit 20. In this embodiment, if the operating conditions of each indoor unit 20 connected to the shut-off valve kit 30 are not substantially the same, the gas pipe expansion valve 32 is not controlled. If the operating conditions of each indoor unit 20 connected to the shut-off valve kit 30 are substantially the same, the average value of the same sensor among the sensors provided on the indoor unit 20 is used to make a decision regarding the control of the gas pipe expansion valve 32. That is, the average value of the temperature measured by the outlet temperature sensor 25 provided on each indoor unit 20 is used as the outlet temperature, the average value of the temperature measured by the inlet side temperature sensor 23 is used as the inlet refrigerant temperature, and the average value of the temperature measured by the outlet side temperature sensor 24 is used as the outlet refrigerant temperature, and a decision is made on whether to control the gas pipe expansion valve (expansion valve) 32.

[0048] [2-3. Effects, etc.] Multiple indoor units 20 are connected to the shut-off valve kit 30 via refrigerant piping 5. When the operating load of the indoor units 20 is approximately the same, the indoor unit control unit 26 uses the average of the measured temperatures of the outlet temperature sensors 25 located for each indoor unit 20 as the outlet temperature, the average of the measured temperatures of the inlet temperature sensors 23 as the measured temperature of the inlet temperature sensor 23, and the average of the measured temperatures of the outlet temperature sensors 24 as the measured temperature of the outlet temperature sensor 24, and causes the gas pipe expansion valve 32 to open and close. When the operating load of the indoor units 20 is not approximately the same, the control unit 26 does not control the gas pipe expansion valve 32. According to this, even when multiple indoor units 20 are connected to the shut-off valve kit 30, the refrigerant temperature can be increased by controlling the refrigerant and introducing pressure loss to the refrigerant. Therefore, the refrigerant can be controlled according to the status of the indoor units 20, and repeated starting and stopping of the indoor units 20 can be suppressed, thereby stabilizing the room temperature.

[0049] (Embodiment 3) [3-1. Structure] Embodiment 3, to which the present invention is applied, will now be described. In this Embodiment 3, parts configured in the same way as in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted.

[0050] Figure 5 is a circuit diagram of the air conditioning system 101 in Embodiment 3. In Embodiments 1 and 2, the outdoor unit 10, indoor unit 20, and shut-off valve kit 30 were connected by refrigerant piping 5 consisting of a liquid pipe 6 and a gas pipe 7. However, in Embodiment 3, the refrigerant piping 105 includes a liquid pipe 206 through which high-pressure liquefied air conditioning refrigerant flows, a gas pipe 207 through which high-temperature, high-pressure gasified air conditioning refrigerant flows, and an intake pipe 208 through which low-pressure air conditioning refrigerant flows. The indoor unit 20, outdoor unit 110, and shut-off valve kit 130 are connected by these pipes.

[0051] The outdoor unit 110 includes a compressor 112, an outdoor heat exchanger 111, an outdoor fan (not shown), an outdoor expansion valve (not shown), and a four-way valve 114. The four-way valve 114 is controlled by an outdoor unit control unit (not shown).

[0052] The shut-off valve kit 130 includes a gas pipe shut-off valve 137 that controls whether or not refrigerant flows through the gas pipe 207, and a suction pipe shut-off valve 138 that controls whether or not refrigerant for air conditioning flows through the suction pipe 208.

[0053] [3-2. Operation] The communication units of the outdoor unit 110 and the indoor unit 20 communicate with each other, and the gas pipe shut-off valve 137, the suction pipe shut-off valve 138 of the shut-off valve kit 130, and the four-way valve 114 of the outdoor unit are controlled. In other words, when operating in cooling mode, the suction pipe shut-off valve 138 of the shut-off valve kit 130 is opened and the gas pipe shut-off valve 137 is closed. When operating in heating mode, the suction pipe shut-off valve 138 of the shut-off valve kit 130 is closed and the gas pipe shut-off valve 137 is opened.

[0054] Therefore, the refrigerant flow can be switched for each room, and the heating and cooling operations can be individually set while controlling the gas pipe expansion valve (expansion valve) 132 and the liquid-side solenoid valve 131 of the shut-off valve kit 130.

[0055] [3-3. Effects, etc.] Multiple indoor units 20 are connected to the shut-off valve kit 130 via refrigerant piping 105. When the operating load of the indoor units 20 is approximately the same, the indoor unit control unit 26 uses the temperature measured by one of the outlet temperature sensors 25 located for each indoor unit 20 as the outlet temperature, the temperature measured by one of the inlet temperature sensors 23 as the temperature measured by the inlet temperature sensor 23, and the temperature measured by one of the outlet temperature sensors 24 as the temperature measured by the outlet temperature sensor 24, and causes the gas pipe expansion valve 132 to open and close. When the operating load of the indoor units 20 is not approximately the same, the control unit 26 does not control the gas pipe expansion valve 32. According to this, even when multiple indoor units 20 are connected to the shut-off valve kit 130, the refrigerant temperature can be increased by controlling the refrigerant and introducing pressure loss to the refrigerant. Therefore, the refrigerant can be controlled according to the status of the indoor units 20, and repeated starting and stopping of the indoor units 20 can be suppressed, thereby stabilizing the room temperature.

[0056] (Other embodiments) As described above, Embodiments 1 and 2 have been explained as examples disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted. Furthermore, it is possible to create new embodiments by combining the components described in Embodiments 1 and 2. Therefore, other embodiments are illustrated below.

[0057] Embodiments 1 and 3 describe an example in which three indoor units 20 and three shut-off valve kits 30 are connected to one outdoor unit 10. Embodiment 2 describes an example in which three indoor units 20 and two shut-off valve kits 30 are connected to one outdoor unit 10. However, the number of outdoor units, indoor units, and shut-off valve kits is not particularly limited. That is, it is sufficient to have one or more outdoor units, two or more indoor units, and one or more shut-off valve kits.

[0058] Furthermore, in Embodiment 2, an example was described in which two indoor units 20 are provided in a room and connected to one shut-off valve kit 30. However, a configuration with three or more indoor units is also possible with one shut-off valve kit. In addition, indoor units located in different rooms may be connected to one shut-off valve kit.

[0059] When three or more indoor units 20 are connected, the determination regarding the control of the gas pipe expansion valve 32 does not require taking the average value of all measurements from the inlet temperature sensor 23, outlet temperature sensor 24, and outlet temperature sensor 25. In other words, the average value of the temperatures measured by some of the inlet temperature sensors 23 installed in the indoor unit 20 may be used as the inlet refrigerant temperature, the average value of the temperatures measured by some of the outlet temperature sensors 24 may be used as the outlet refrigerant temperature, and the average value of the temperatures measured by some of the outlet temperature sensors 25 may be used as the outlet temperature to determine whether to control the gas pipe expansion valve 32.

[0060] Furthermore, when three or more indoor units are provided for a single shut-off valve kit, the decision to control the gas pipe expansion valve may be made using a representative value of the measured temperature rather than the average value of the measured temperatures from the various sensors. In other words, the inlet temperature sensor, outlet temperature sensor, and discharge temperature sensor of a particular indoor unit may be used as representative values ​​to determine whether to control the gas pipe expansion valve 32.

[0061] In Embodiment 1, the indoor unit 20 was connected to the outdoor unit 10 via a shut-off valve kit 30. However, it is also possible to provide an indoor unit that is connected to the outdoor unit without using a shut-off valve kit. That is, a configuration may be used in which an indoor unit connected via a shut-off valve kit and an indoor unit connected without using a shut-off valve kit are connected in parallel to a single outdoor unit.

[0062] Embodiment 1 describes an example in which the corresponding indoor unit 20 is operated using the remote control 40. However, the remote control may be connected to multiple indoor units and capable of controlling multiple indoor units.

[0063] In the above-described embodiment 3, the shut-off valve kit 130 is provided with a gas pipe shut-off valve 137, an intake pipe shut-off valve 138, a gas pipe expansion valve 132, and a liquid-side solenoid valve 131, but these may be provided separately. For example, a configuration may be installed that includes a switching valve kit equipped with a gas pipe shut-off valve 137 and an intake pipe shut-off valve 138, and a shut-off valve kit equipped with a gas pipe expansion valve 132 and a liquid-side solenoid valve 131.

[0064] Alternatively, instead of controlling the gas pipe expansion valve 132, the opening degrees of the gas pipe shut-off valve 137 and the suction pipe shut-off valve 138 may be controlled. This allows the gas pipe shut-off valve 137 and the suction pipe shut-off valve 138 to function as expansion valves, and, similar to the embodiment described above, pressure loss can be introduced into the refrigerant and the refrigerant temperature can be increased according to the load conditions of the indoor units installed in each room. Therefore, the refrigerant can be controlled more precisely in response to the load, and the repeated starting and stopping of the indoor unit 20 can be suppressed, thereby stabilizing the room temperature.

[0065] In Embodiments 1 and 2, the shut-off valve kit 30 was equipped with a refrigerant leak sensor 34. However, the shut-off valve kit 30 only needs to be able to control the gas pipe expansion valve 32 according to predetermined conditions, and does not need to be equipped with a refrigerant leak sensor or the like.

[0066] In the embodiments described above, steps 1, 2, 4, and 5 describe an example in which the opening degree of the gas pipe expansion valve 32 is controlled by setting a predetermined temperature and time, or only a predetermined temperature. However, these conditions can be arbitrarily changed. For example, the conditions may be set to only a predetermined temperature or only a predetermined time.

[0067] In the embodiment described above, the indoor unit control unit 26 controlled the opening and closing operations of the liquid-side solenoid valves 31 and 131 and the gas pipe expansion valves 32 and 132. However, the control unit that controls the opening and closing operations of the liquid-side solenoid valves 31 and 131 and the gas pipe expansion valves 32 and 132 is not limited to the indoor unit control unit. In other words, any part of the air conditioning system may be equipped with a control unit that controls the opening and closing operations of the liquid-side solenoid valves and the gas pipe expansion valves.

[0068] Since the embodiments described above are for illustrative purposes only, various modifications, substitutions, additions, omissions, etc., can be made within the claims or their equivalents.

[0069] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0070] (Technology 1) An air conditioning system in which an outdoor unit and an indoor unit are connected by refrigerant piping, wherein the refrigerant piping has a liquid pipe through which liquid refrigerant passes and a gas pipe through which gaseous refrigerant passes, and the refrigerant piping is equipped with a shut-off valve kit having an expansion valve that adjusts the flow rate of refrigerant in the gas pipe and shuts off the gas pipe in the event of refrigerant leakage by opening and closing operation, and the air conditioning system is equipped with a control unit that controls the opening and closing operation of the expansion valve. According to this, the opening degree of the expansion valve can be controlled according to predetermined conditions, and the refrigerant temperature can be increased by introducing pressure loss to the refrigerant. Therefore, the refrigerant can be controlled according to the condition of the indoor unit, and repeated starting and stopping of the indoor unit can be suppressed, thereby stabilizing the room temperature.

[0071] (Technology 2) The air conditioning system according to Technology 1, wherein the indoor unit has an outlet temperature sensor for measuring the outlet temperature of the air blown out from the indoor unit, a liquid pipe temperature sensor for measuring the temperature of the refrigerant in the liquid pipe, and a gas pipe temperature sensor for measuring the temperature of the refrigerant in the gas pipe, and the control unit causes the expansion valve to close when the following conditions are met: a first condition that the temperature difference between the outlet temperature and the set outlet temperature set to blow out from the indoor unit at a predetermined temperature is less than a predetermined threshold for a predetermined time or longer, and a second condition that the temperature of either the temperature measured by the liquid pipe temperature sensor or the temperature measured by the gas pipe temperature sensor is less than a predetermined threshold for a predetermined time or longer. This prevents the refrigerant from being uncontrollable, which could cause the liquid and gas pipe temperature sensors to drop to their freezing points. Therefore, by introducing pressure loss to the refrigerant, the refrigerant temperature can be increased, which can prevent the indoor unit from repeatedly starting and stopping, thus stabilizing the room temperature.

[0072] (Technical 3) After the control unit has performed a closing operation on the expansion valve, if either a third condition is met, where the temperature difference between the discharge temperature and the set discharge temperature remains greater than a predetermined threshold for a predetermined time or longer, or a fourth condition is met, where either the temperature measured by the liquid pipe temperature sensor or the temperature measured by the gas pipe temperature sensor remains greater than a predetermined threshold for a predetermined time or longer, the control unit performs an opening operation on the expansion valve, as described in Technical 2. According to this method, the refrigerant can be controlled more precisely according to the operating conditions of the indoor unit compared to controlling the refrigerant using only the liquid pipe. Therefore, by introducing pressure loss to the refrigerant, the refrigerant temperature can be increased, which suppresses repeated starting and stopping of the indoor unit, thus stabilizing the room temperature.

[0073] (Technical 4) The air conditioning system according to Technical 3, wherein a plurality of indoor units are connected to the shut-off valve kit via the refrigerant piping, and the control unit, when the operating conditions of the indoor units are substantially the same, uses the average of the measured temperatures of the outlet temperature sensors located for each indoor unit as the outlet temperature, the average of the measured temperatures of the liquid pipe temperature sensors as the measured temperature of the liquid pipe temperature sensor, and the average of the measured temperatures of the gas pipe temperature sensors as the measured temperature of the gas pipe temperature sensor, and causes the expansion valve to open and close, and does not control the expansion valve when the operating conditions of the indoor units are not substantially the same. According to this, even when multiple indoor units are connected to the shut-off valve kit, the refrigerant temperature can be increased by controlling the refrigerant and creating a pressure loss in the refrigerant. Therefore, the refrigerant can be controlled according to the status of the indoor units, and repeated starting and stopping of the indoor units can be suppressed, thereby stabilizing the room temperature.

[0074] (Technical 5) The air conditioning system according to Technical 3, wherein a plurality of indoor units are connected to the shut-off valve kit via the refrigerant piping, and the control unit, when the operating states of the indoor units are substantially the same, uses the measured temperature of one of the outlet temperature sensors located for each indoor unit as the outlet temperature, the measured temperature of one of the liquid pipe temperature sensors as the measured temperature of the liquid pipe temperature sensor, and the measured temperature of one of the gas pipe temperature sensors as the measured temperature of the gas pipe temperature sensor, and causes the control unit to perform an opening and closing operation on the expansion valve, and does not control the expansion valve when the operating states of the indoor units are not substantially the same. According to this, even when multiple indoor units are connected to the shut-off valve kit, the refrigerant temperature can be increased by controlling the refrigerant and creating a pressure loss in the refrigerant. Therefore, the refrigerant can be controlled according to the status of the indoor units, and repeated starting and stopping of the indoor units can be suppressed, thereby stabilizing the room temperature. [Industrial applicability]

[0075] As described above, the air conditioning system according to the present invention can be used for stabilizing room temperature. [Explanation of Symbols]

[0076] 1. Air conditioning system 5 Refrigerant piping 6 Liquid pipes 7 Gas pipes 10 Outdoor unit 11 Outdoor heat exchanger 12 Compressor 13 Outdoor expansion valve 20 Indoor unit 21 Indoor heat exchanger 22 Indoor expansion valve 23. Inlet-side temperature sensor (liquid tube temperature sensor) 24. Outlet side temperature sensor (gas pipe temperature sensor) 25. Outlet temperature sensor 26. Indoor Unit Control Unit (Control Unit) 26a Processor 26b memory 27 Indoor unit communication section 29 Indoor fan 30 Shut-off valve kit 31 Liquid-side solenoid valve 32. Gas pipe expansion valve (expansion valve) 34 Refrigerant leak sensor 40 Remote Controls 41 Operation section 51 Air conditioning system 101 Air conditioning system 110 Outdoor unit 111 Outdoor heat exchanger 112 Compressor 114 Four-way valve 130 Shut-off valve kit 131 Liquid-side solenoid valve 132 Gas pipe expansion valve (expansion valve) 137 Gas pipe shut-off valve 138 Intake pipe shut-off valve 206 Liquid pipe 207 Gas pipe 208 Suction pipe

Claims

1. In an air conditioning system in which an outdoor unit and an indoor unit are connected by refrigerant piping, The refrigerant piping comprises a liquid pipe through which liquid refrigerant passes and a gas pipe through which gaseous refrigerant passes. The refrigerant piping is equipped with a shut-off valve kit having an expansion valve that, by opening and closing, adjusts the flow rate of the refrigerant in the gas pipe and shuts off the gas pipe in the event of a refrigerant leak. The system includes a control unit that controls the opening and closing operation of the expansion valve. Air conditioning system.

2. The indoor unit has an outlet temperature sensor for measuring the outlet temperature of the air blown out from the indoor unit, a liquid pipe temperature sensor for measuring the temperature of the refrigerant in the liquid pipe, and a gas pipe temperature sensor for measuring the temperature of the refrigerant in the gas pipe. The control unit causes the expansion valve to close when the following conditions are met: first, the temperature difference between the discharge temperature and the set discharge temperature (set to be discharged from the indoor unit at a predetermined temperature) remains below a predetermined threshold for a predetermined period of time or longer; and second, the temperature measured by either the liquid pipe temperature sensor or the gas pipe temperature sensor remains below a predetermined threshold for a predetermined period of time or longer. The air conditioning device according to claim 1.

3. If, after the control unit has closed the expansion valve, the control unit opens the expansion valve when either of the following conditions is met: a third condition that the temperature difference between the discharge temperature and the set discharge temperature remains greater than a predetermined threshold for a predetermined time or longer, or a fourth condition that either the temperature measured by the liquid pipe temperature sensor or the temperature measured by the gas pipe temperature sensor remains greater than a predetermined threshold for a predetermined time or longer, the control unit opens the expansion valve. The air conditioning device according to claim 2.

4. Multiple indoor units are connected to the shut-off valve kit via the refrigerant piping. The control unit, when the operating state of the indoor units is substantially the same, uses the average of the measured temperatures of the outlet temperature sensors located for each indoor unit as the outlet temperature, the average of the measured temperatures of the liquid pipe temperature sensors as the measured temperature of the liquid pipe temperature sensor, and the average of the measured temperatures of the gas pipe temperature sensors as the measured temperature of the gas pipe temperature sensor, and causes the expansion valve to open and close accordingly. When the operating state of the indoor units is not substantially the same, the control unit does not control the expansion valve. The air conditioning device according to claim 3.

5. Multiple indoor units are connected to the shut-off valve kit via the refrigerant piping. The control unit, when the operating state of the indoor units is substantially the same, uses the measured temperature of one of the outlet temperature sensors located for each indoor unit as the outlet temperature, the measured temperature of one of the liquid pipe temperature sensors as the measured temperature of the liquid pipe temperature sensor, and the measured temperature of one of the gas pipe temperature sensors as the measured temperature of the gas pipe temperature sensor, and causes the expansion valve to open and close accordingly. When the operating state of the indoor units is not substantially the same, the control unit does not control the expansion valve. The air conditioning device according to claim 3.

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