WO2007007576A1

WO2007007576A1 - Air conditioner

Info

Publication number: WO2007007576A1
Application number: PCT/JP2006/313216
Authority: WO
Inventors: Makoto Kojima; Shinichi Kasahara
Original assignee: Daikin Industries, Ltd.
Priority date: 2005-07-07
Filing date: 2006-07-03
Publication date: 2007-01-18
Also published as: JP3915819B2; JP2007017086A

Abstract

A model for simulating heat exchange performed, via piping and an indoor heat exchanger (53), between the air and refrigerant flowing from directly after an expansion valve (52) up to an entrance or exit of an indoor heat exchanger (53). The quantity G of leakage of the refrigerant from an expansion valve (52a) of an indoor unit (12a) that is stopped while other indoor units (12b, 12c) are engaged in cooling operation is quantitatively estimated using the model based on the temperature To of the refrigerant immediately after the expansion valve (52a), room temperature TH1, heat exchanger entrance temperature TH2, etc. When the leakage quantity G is equal to or greater than a predetermined level, the expansion valve (52a) is determined to be abnormal and the fact is informed to a user.

Description

Specification

Air conditioner

Technical field

[0001] The present invention relates to a so-called multi-type air conditioner in which a plurality of utilization units are connected to a refrigerant circuit.

Background art

Conventionally, as this type of multi-type air conditioner, as disclosed in Patent Documents 1 and 2, for example, one in which a plurality of indoor units are connected to a single outdoor unit is known. . In such a case, when each indoor unit is in cooling operation, the individual cooling load may be different. There is a risk of freezing. Therefore, at this time, an ice melting operation is performed to melt the ice. In this ice melting operation, the expansion valve is closed to stop the inflow of refrigerant from the refrigerant circuit, and the wind is sent to melt the ice.

More specifically, FIG. 2 of Patent Document 1 shows an air conditioner in which three indoor units are provided for one outdoor unit. Each indoor unit is provided with a liquid temperature sensor that measures the temperature of the liquid refrigerant in the heat exchanger, and when a predetermined time elapses after the measured value by the liquid temperature sensor exceeds the reference temperature during the ice melting operation. Finish the ice melting operation.

[0004] FIG. 1 of Patent Document 2 shows an air conditioner in which two indoor units are provided for one outdoor unit. In the heat exchange of each indoor unit, a temperature sensor is provided as a means for detecting refrigerant leakage of the expansion valve. When the refrigerant leakage is detected during the ice melting operation, the expansion valve is fully opened to eliminate the refrigerant leakage. Recovery that repeats the closing action Performs one action.

Patent Document 1: Japanese Patent Laid-Open No. 03-186135

Patent Document 2: Japanese Patent Laid-Open No. 10-26429

Disclosure of the invention

Problems to be solved by the invention [0005] By the way, in the multi-type air conditioner as described above, the cooling load is often different for each indoor unit. In an indoor unit with a small load, the cooling is performed when the target temperature set in advance is reached. The operation is temporarily stopped, the expansion valve is closed, and the refrigerant flow from the refrigerant circuit is shut off (so-called thermo-off).

[0006] When a plurality of indoor units are arranged in separate rooms, V, one of the indoor units is used !, but another! /, One of the indoor units May not be used.

[0007] Among the plurality of usage units connected to the refrigerant circuit in this way, when at least one of the usage units performs a cooling operation and at least one other usage unit has stopped operating, the operation is stopped. The high-pressure liquid refrigerant tries to flow into the used unit from the refrigerant circuit. Therefore, in this usage unit, it is desirable to close the expansion valve firmly so that the refrigerant does not flow in!

[0008] However, the expansion valve prevents the valve body and the valve seat from coming into close contact with each other due to aging or accumulation of foreign matter, and the refrigerant leaks downstream even when it is closed. End up. If the amount of leakage increases, the refrigerant piping and the heat exchanger are cooled by the leaked refrigerant, and there is a risk of causing problems such as dew condensation.

[0009] Further, if the amount of refrigerant leakage due to the expansion valve force increases as described above, malfunction may occur when the ice melting operation is executed as in the conventional examples (Patent Documents 1 and 2). . In other words, when the ice melting operation is terminated after the measured value by the liquid temperature sensor exceeds the reference temperature as in Patent Document 1, the amount of refrigerant leakage due to the expansion valve force increases, and the liquid temperature sensor If the measured value does not rise to the reference temperature, the ice melting operation will not end.

[0010] The refrigerant leakage due to such an expansion valve force can be detected by a heat exchange temperature sensor as shown in Patent Document 2, and the temperature measurement result by this sensor alone is only to the extent of refrigerant leakage. Because the amount of leakage is so large that the malfunctions such as dew and malfunction, that is, the time for maintenance and replacement of the expansion valve cannot be specified, the malfunction can be prevented in advance. I couldn't do it.

[0011] Therefore, the present invention prevents the above-described problems such as dew and malfunction. Therefore, in the so-called multi-type air conditioner, it is possible to quantitatively and accurately estimate the refrigerant leakage amount of the expansion valve of the stopped use unit.

Means for solving the problem

[0012] In order to achieve the above object, the present invention reduces the refrigerant leakage amount of the expansion valve (52) using a model of a heat conduction state in a predetermined range downstream of the expansion valve of the utilization unit that is stopped. Estimated.

[0013] Specifically, the first invention includes a refrigerant circuit (20) in which a heat source unit (11) and a plurality of use units (12) are connected, and at least an air conditioner that performs a cooling operation (10 ). Then, when at least one of the usage units (12) performs the cooling operation and at least one other usage unit (12) is stopped, the usage unit ( A refrigerant leakage amount estimation means (81) for estimating the refrigerant leakage amount of the expansion valve (52) using a model of a heat conduction state in a predetermined range downstream of the expansion valve (52) of 12) is provided.

[0014] In the first invention, at least one of the plurality of usage units (12) connected to the refrigerant circuit (20) performs the cooling operation, and at least one other usage unit. When the operation (12) is stopped, the refrigerant leakage amount is measured using a model of the heat conduction state in the predetermined range downstream of the expansion valve (52) of the utilization unit (12). The estimation means (81) quantitatively estimates the refrigerant leakage amount of the expansion valve (52).

[0015] That is, the expansion valve (52) of the stopped use unit (12) force When the refrigerant leaks, the refrigerant pipe or the like in a predetermined range downstream is cooled, and when the temperature becomes lower than room temperature, the pipe or the like The refrigerant absorbs ambient heat through The amount of heat absorbed at this time also changes depending on dynamic factors such as the temperature and flow rate of the refrigerant, as well as static factors such as the heat transfer area and heat transfer coefficient of the pipe.

[0016] Therefore, using a model that generally simulates the heat conduction state to the atmospheric power refrigerant, for example, the room temperature or the temperature of the refrigerant in the predetermined range is input, and the predetermined range is set per unit time. Calculate the endothermic amount of the circulating refrigerant. By doing so, it is possible to quantitatively determine the refrigerant flow rate in that range, that is, the refrigerant leakage amount of the expansion valve. This Therefore, it is possible to identify the time when the refrigerant leaks excessively and causes a malfunction such as dew, so that the malfunction can be prevented.

[0017] As a more specific configuration of the air conditioner, an inlet temperature measuring means (54) for measuring an inlet temperature of the heat exchanger (53) is preferably provided in the use unit (12), and an indoor temperature. And a room temperature measuring means (56) for measuring. In the above model, the refrigerant flowing in the piping from immediately after the expansion valve (52) to the heat exchanger (53) of the stopped use unit (12) is connected to the atmosphere through the piping. Simulate heat exchange. Then, the refrigerant leak amount estimation means (81) includes the measured value by the inlet temperature measuring means (54) of the stopped use unit (12), the measured value by the room temperature measuring means (56), and the expansion. Based on the refrigerant temperature immediately after the valve (52), the refrigerant leakage amount is estimated using the above model (second invention).

[0018] That is, the refrigerant temperature and heat exchange immediately after the expansion valve (52) of the utilization unit (12) are stopped.

If the inlet temperature of (53) is known, the average temperature state of the refrigerant flowing in the piping from immediately after the expansion valve (52) to the heat exchanger (53) is divided. Using the above model, the heat absorption amount of the refrigerant in the range can be calculated. As a result, the amount of refrigerant leakage can be obtained. Further, the inlet temperature measuring means (54) and the room temperature measuring means (56) can usually be constituted by a temperature sensor provided in the utilization unit (12), which is advantageous in terms of cost.

[0019] In that case, more preferably, the refrigerant leakage amount estimation means (81) stops the measurement value by the inlet temperature measurement means (54) of another utilization unit (12) during the cooling operation. It is assumed that the refrigerant temperature is immediately after the expansion valve (52) of the utilization unit (12) (third invention). In this way, it is possible to obtain the refrigerant temperature immediately after the expansion valve (52) without providing a dedicated temperature sensor or the like, which is advantageous in terms of cost.

[0020] However, as described above, the amount of heat transferred to the atmospheric refrigerant is not so much in the piping from immediately after the expansion valve (52) of the utilization unit (12) to the heat exchanger (53). Therefore, when there is a large amount of refrigerant leakage, the temperature immediately after the expansion valve (52) is not much different from the inlet temperature of the heat exchanger (53). As a result, if the accuracy of the temperature sensor is not very high, it becomes difficult to estimate the amount of refrigerant leakage as described above. [0021] Therefore, preferably, the utilization unit (12) measures the inlet temperature measuring means (54) for measuring the inlet temperature of the heat exchanger (53) and the outlet temperature of the heat exchanger (53). The outlet temperature measuring means (55) for performing the measurement and the room temperature measuring means (56) for measuring the temperature in the room are provided. In the above model, the refrigerant that stops and / or flows through the piping and heat exchanger (53) immediately after the expansion valve (52) of the utilization unit (12) and reaches the outlet of the heat exchanger (53) However, it shall simulate heat exchange with the atmosphere through the piping and heat exchange (53). The refrigerant leakage amount estimation means (81) includes the measured value by the inlet temperature measuring means (54) of the stopped use unit (12) and the stopped use unit (12). Based on the measured value by the outlet temperature measuring means (55), the measured value by the room temperature measuring means (56), and the refrigerant temperature immediately after the expansion valve (52), the amount of refrigerant leakage is estimated using the above model. (6th invention).

[0022] In this configuration, particularly in heat exchange (53), the amount of heat transferred to the atmospheric refrigerant is sufficiently large, so even if the amount of refrigerant leakage is large, the temperature immediately after the expansion valve (52) The outlet temperature of the heat exchanger (53) becomes a value greatly different, and the amount of refrigerant leakage can be obtained quantitatively in the same manner as in the second invention.

[0023] In this case as well, more preferably, the refrigerant leak amount estimation means (81) uses the measured value by the inlet temperature measurement means (54) of another utilization unit (12) during the cooling operation, It is assumed that the refrigerant temperature is stopped immediately after the expansion valve (52) of the utilization unit (12) (seventh invention). By doing so, it is possible to obtain the refrigerant temperature immediately after the expansion valve (52) without providing a dedicated temperature sensor or the like, which is advantageous in terms of cost.

The estimation of the amount of refrigerant leakage performed as described above is performed, for example, when the usage unit (12) of any of the multi-type air conditioners (10) starts the cooling operation and stops. The measured value of the inlet temperature measuring means (54) or outlet temperature measuring means (55) of the bottom (12) is lowered, and is lower than the measured value by the room temperature measuring means (56) by a predetermined value or more. Sometimes it can be done (fourth and eighth inventions). In this way, in the stopped utilization unit (12), the liquid refrigerant from the refrigerant circuit (20) leaks downstream from the closed expansion valve (52) and enters the inlet of the heat exchanger (53). When the outlet temperature is lowered to a certain extent, the amount of leakage can be accurately estimated. [0025] In addition, the refrigerant leakage amount is estimated, for example, after one of the usage units (12) in the cooling operation stops the operation due to thermo-off, and then one of the other usage units (12) performs the cooling operation. In the state of continuous, the measured value due to the deviation of the inlet temperature measuring means (54) or the outlet temperature measuring means (55) of the stopped use unit (12) increases, and the room temperature measuring means (5 6 ) May be executed when the temperature is stabilized at a temperature lower than the measured value by a predetermined value or more (fifth and ninth inventions).

[0026] If the refrigerant leakage amount of the expansion valve (52) is estimated using the thermo-off of the utilization unit (12) as described above, the frequency of the estimation is increased, so the expansion valve (52) This will increase the possibility that it will be possible to detect the amount of refrigerant leak before it actually increases due to deterioration over time, etc., and it will be possible to more reliably prevent problems caused by excessive refrigerant leakage.

[0027] As in any one of the first to ninth inventions, the refrigerant leakage amount due to the aging of the expansion valve (52) is quantitatively determined by the refrigerant leakage amount estimation means (81). If it becomes possible to estimate, it is more preferable to further include notification means (82) for performing notification when the estimated refrigerant leakage amount is equal to or larger than a predetermined amount (tenth invention). In this way, maintenance and replacement of the deteriorated expansion valve (52) is urged to the user, and it is possible to more reliably prevent the use unit (12) from causing a malfunction such as dew condensation.

The invention's effect

[0028] According to the present invention, in a so-called multi-type air conditioner, at least one usage unit (12) performs cooling operation, and at least one other usage unit (12) stops operation. In this case, a model that comprehensively simulates the state of heat conduction to the refrigerant in a predetermined range downstream of the expansion valve (52) of the utilization unit (12) is used. By inputting the measured value of the refrigerant temperature in the above specified range, etc., the heat absorption capacity of the refrigerant per hour can be estimated quantitatively and accurately, so the amount of refrigerant leakage becomes excessive and exposure It is possible to identify the time when such troubles occur and prevent them from occurring.

[0029] In particular, according to the second and sixth inventions, the means (54, 55, 56) for measuring the temperature can usually be constituted by a temperature sensor provided in the use unit (12), and the third means. And the seventh invention uses the temperature sensor of another utilization unit (12) during the cooling operation, Since the refrigerant temperature immediately after (52) can be detected, it is advantageous in terms of cost.

[0030] According to the fourth, fifth, eighth, and ninth inventions, the estimation accuracy of the refrigerant leakage amount can be ensured by performing the estimation in a predetermined state, and in particular, In the fifth and ninth inventions, the frequency of estimation can be increased by using the thermo-off of the usage unit (12), so that the above-mentioned problems can be prevented more reliably.

[0031] Further, as in the tenth aspect of the invention, if the user is notified when the estimated amount of refrigerant leakage is large, the replacement of the expansion valve (52), etc. is urged, and the problem is further improved. It can be reliably prevented.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention.

[FIG. 2] FIG. 2 is an explanatory view showing a model of a heat conduction state in which the refrigerant leaking from the expansion valve force absorbs the aerodynamic heat of the surroundings in the refrigerant pipe and the indoor heat exchanger.

FIG. 3 is a graph showing the temperature change of the refrigerant that gradually rises from immediately after the expansion valve to the inlet or outlet of the indoor heat exchanger.

FIG. 4 is a flowchart showing a procedure for estimating a refrigerant leakage amount.

[FIG. 5] FIG. 5 is an explanatory diagram showing how the deviation between the actual temperature of the refrigerant flowing through the pipe and the like and the measured value by the sensor change according to the flow rate of the refrigerant.

Explanation of symbols

10 Air conditioner

11 Outdoor unit (heat source unit)

12 Indoor unit (Usage unit)

20 Refrigerant circuit

52 expansion valve

53 Indoor heat exchanger (heat exchanger)

54 1st temperature sensor (Inlet temperature measurement means)

55 Second temperature sensor (outlet temperature measurement means)

56 Indoor temperature sensor (room temperature measurement means)

80 controller 81 Refrigerant leakage amount estimation unit (Refrigerant leakage amount estimation means)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0035] As shown in FIG. 1, the air conditioner (10) of the present embodiment is configured in a multi-type that is installed in a building or the like and performs temperature adjustment in a plurality of indoor spaces.

[0036] The air conditioner (10) of the first embodiment includes one outdoor unit (11) as a heat source unit and three indoor units (12a, 12b, 12c) as use units. The number of indoor units (12) is merely an example, and may be two or four or more. The outdoor unit (11) is provided outdoors. On the other hand, the three indoor units (12a, 12b, 12c) are provided in separate rooms.

[0037] The outdoor unit (11) is provided with an outdoor circuit (40). Each indoor unit (12) is provided with an indoor circuit (50). In the air conditioner (10), the refrigerant circuit (20) is configured by connecting these circuits (40, 50a, 50b, 50c) with refrigerant piping. The outdoor circuit (40) constitutes a heat source side circuit. Each indoor circuit (50) constitutes a use side circuit.

[0038] Each of the indoor circuits (50) is connected in parallel to the outdoor circuit (40).

Specifically, each indoor circuit (50) is connected to the outdoor circuit (40) via the liquid side connecting pipe (21) and the gas side connecting pipe (22). One end of the liquid side connecting pipe (21) is connected to the liquid side closing valve (25) of the outdoor circuit (40). The other end of the liquid side connection pipe (21) branches into three and each is connected to the liquid side end of the indoor circuit (50). One end of the gas side communication pipe (22) is connected to the gas side shutoff valve (26) of the outdoor circuit (40). The other end of the gas side connecting pipe (22) is branched into three and each is connected to the gas side end of the indoor circuit (50).

[0039] <Outdoor unit>

As described above, the outdoor unit (11) includes the outdoor circuit (40). The outdoor circuit (40) is provided with a variable capacity compressor (41, a fixed capacity compressor (41b), an outdoor heat exchanger (43), and a four-way switching valve (51). The compressor (41a) and the fixed capacity compressor (41b) are all hermetic scroll compressors, and are configured as so-called high-pressure dome type. [0040] Electric power is supplied to the variable capacity compressor (41a) via an inverter. The capacity of the variable capacity compressor (41a) can be changed by changing the rotation speed of the compressor motor by changing the output frequency of the inverter. The variable capacity compressor (4 la) constitutes the main compressor.

[0041] On the other hand, in the fixed capacity compressor (41b), the compressor motor is always operated at a constant rotational speed, and the capacity cannot be changed.

[0042] A discharge pipe (64) is connected to the variable capacity compressor (41a) and the fixed capacity compressor (41b). One end of the discharge pipe (64) is connected to the first port of the four-way switching valve (51). The discharge pipe (64) is branched into a first discharge pipe (64a) and a second discharge pipe (64b) on the other end side. The first discharge pipe (64a) is connected to the discharge side of the variable capacity compressor (41a), and the second discharge pipe (64b) is connected to the discharge side of the fixed capacity compressor (41b).

[0043] A suction pipe (61) is connected to the suction side of the variable capacity compressor (41a) and the fixed capacity compressor (41b). One end of the suction pipe (61) is connected to the second port of the four-way selector valve (51). The suction pipe (61) is branched at the other end into a first suction pipe (61a) and a second suction pipe (61b). The first suction pipe (61a) is connected to the suction side of the variable capacity compressor (41a), and the second suction pipe (61b) is connected to the suction side of the fixed capacity compressor (41b)! .

[0044] The outdoor heat exchanger (43) is a cross-fin type fin-and-tube heat exchanger, and constitutes a heat source side heat exchanger. One end of the outdoor heat exchanger (43) is connected to the third port of the four-way selector valve (51). On the other hand, the other end of the outdoor heat exchanger (43) is connected to the liquid side shutoff valve (25). The outdoor unit (11) is provided with an outdoor fan (48). Outdoor air is sent to the outdoor heat exchanger (43) by the outdoor fan (48).

[0045] The four-way switching valve (51) has a first port to the discharge pipe (64), a second port to the suction pipe (61), and a third port to the outdoor heat exchange (43) In addition, a fourth port is connected to each gas side shut-off valve (26). The first four-way selector valve (51) is in a first state (shown by a solid line in FIG. 1) in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other. Status), the first port and the fourth port communicate with each other, and the second port and the third port It is possible to switch to the second state (the state indicated by the broken line in Fig. 1) communicating with the cage.

In the outdoor circuit (40), the suction pipe (61) is provided with a suction pressure sensor (93), and the discharge pipe (64) is provided with a discharge pressure sensor (97). . The suction pressure sensor (93) measures the pressure of the low-pressure side refrigerant flowing through the suction pipe (61). The discharge pressure sensor (97) measures the pressure of the high-pressure side refrigerant flowing through the discharge pipe (64). Based on the difference between the measured value of the suction pressure sensor (93) and the measured value of the discharge pressure sensor (97), the difference between the high and low pressures of the refrigeration cycle performed in the refrigerant circuit (20) can be detected.

[0047] <Indoor unit>

As described above, each indoor unit (12) includes an indoor circuit (50). Each indoor circuit (50) is provided with an expansion valve (52) and an indoor heat exchanger (53) in order according to the liquid side end force toward the gas side end. The indoor heat exchanger (53) is a cross fin type fin 'and' tube heat exchanger, and constitutes a use side heat exchanger. The indoor expansion valve (52) is an electronic expansion valve. The indoor unit (12) is provided with an indoor fan (57). Indoor air exchange ^^ (53) is sent indoor air by this indoor fan (57).

[0048] In the indoor circuit (50), for the refrigerant pipe connecting the expansion valve (52) and the indoor heat exchanger (53), the temperature of the pipe near the inlet of the indoor heat exchanger (53) is measured. A first temperature sensor (54) is provided as described above. The first temperature sensor (54) constitutes the inlet temperature measuring means according to the present invention. In addition, the refrigerant pipe connecting the indoor heat exchanger (53) and the gas side end of the indoor circuit (50) is configured to measure the temperature of the pipe near the outlet of the indoor heat exchanger (53). Two temperature sensors (55) are provided. This second temperature sensor (55) constitutes the outlet temperature measuring means according to the present invention. The first and second temperature sensors (54, 55) may be provided at the inlet and the outlet of the indoor heat exchanger (53), respectively.

Furthermore, the indoor unit (12) is provided with an indoor temperature sensor (56) for measuring the temperature of the room where the indoor unit (12) is installed. This indoor temperature sensor (56) constitutes a room temperature measuring means according to the present invention. The measured value of the first temperature sensor (54), the measured value of the second temperature sensor (55), and the measured value of the indoor temperature sensor (56) are sent to a controller (80) described later. <Controller configuration>

The air conditioner (10) of this embodiment includes a controller (80) that controls the compressors (41a, 41b) and adjusts the opening degree of the expansion valve (52) according to the operating state. . This controller (80) controls the cooling operation, heating operation, ice melting operation, etc. of the air conditioner (10) as described below, and performs control related to estimation of the refrigerant leakage amount described later. An amount estimation unit (81) is provided, and the refrigerant leakage amount estimation unit (81) constitutes the refrigerant leakage amount estimation means according to the present invention. The controller (80) is connected to a display device (82) as a notification means for notifying the user of a refrigerant leak as will be described later. Details of the operation of the controller (80) will be described later.

[0050] Driving action

The air conditioner (10) performs a cooling operation and a heating operation. The air conditioner (10) performs an ice melting operation as necessary during the cooling operation.

[0051] <Cooling operation>

First, the cooling operation will be described. In the cooling operation, the four-way selector valve (23) is set to the first state indicated by the solid line in FIG. 1, and the variable capacity compressor (41a) and the fixed capacity compressor (41b) are operated. The opening of the expansion valve (52) of each indoor unit (12) is individually controlled according to the cooling load in each room, and the refrigerant flow rate is set. The air volume is also individually controlled by each indoor unit (12).

[0052] The refrigerant discharged from the variable capacity compressor (41a) and the fixed capacity compressor (41b) passes from the discharge pipe (64) through the four-way switching valve (51) to the outdoor heat exchanger (43). Into the air, where it dissipates heat to the outdoor air and condenses. The refrigerant condensed in the outdoor heat exchanger (43) flows through the liquid side connecting pipe (21) and is distributed to each indoor circuit (50).

[0053] The refrigerant distributed to the indoor circuit (50) is decompressed when passing through the expansion valve (52) and then flows into the indoor heat exchanger (53). In the indoor heat exchanger (53), the refrigerant absorbs heat from the indoor air and evaporates. At that time, the room air cooled by the indoor heat exchange (53) is supplied to the room. The refrigerant evaporated in the indoor heat exchange (53) flows into the outdoor circuit (40) through the gas side connecting pipe (22). The refrigerant flowing into the outdoor circuit (40) passes through the four-way selector valve (51), and then is sucked into the variable capacity compressor (41a) and the fixed capacity compressor (41b) through the suction pipe (61). The The refrigerant sucked into the variable capacity compressor (41a) and the fixed capacity compressor (41b) is compressed again and discharged to the discharge pipe (64).

[0054] <Heating operation>

Subsequently, the heating operation will be described. In the heating operation, the four-way selector valve (23) is set to the second state indicated by the broken line in FIG. 1, and the variable capacity compressor (41a) and the fixed capacity compressor (41b) are operated. The opening degree of the expansion valve (52) of each indoor unit (12) is individually controlled according to the heating load in each room, and the refrigerant flow rate is set. The air volume is also individually controlled by each indoor unit (12).

[0055] The refrigerant discharged from the variable capacity compressor (41a) and the fixed capacity compressor (41b) passes from the discharge pipe (64) through the four-way switching valve (51) and the gas side communication pipe (22). Distributed to each indoor circuit (50). The refrigerant flowing into the indoor circuit (50) is introduced into the indoor heat exchanger (53), where it dissipates heat to the indoor air and condenses. At that time, the indoor air heated by the indoor heat exchanger (53) is supplied into the room.

[0056] The refrigerant condensed in the indoor heat exchanger (53) flows into the outdoor heat exchanger (43) through the expansion valve (52) and the liquid side connecting pipe (21), and absorbs heat from the outdoor air there. Evaporate. The refrigerant evaporated in the outdoor heat exchanger (43) is sucked into the variable capacity compressor (41a) and the fixed capacity compressor (41b) from the four-way switching valve (51) through the suction pipe (61). The refrigerant sucked into the variable capacity compressor (41a) and the fixed capacity compressor (41b) is compressed again and discharged to the discharge pipe (64).

[0057] <Ice melting action>

In the multi-type air conditioner (10), as described above, when the cooling operation is performed in each indoor unit (12), the cooling load is often different for each indoor unit (12). Yes, the load is small! / In the indoor heat exchanger (53) of the indoor unit (12), the evaporation temperature is too low and the drain water adhering to the indoor heat exchanger (12) may freeze. In such a situation, an ice melting operation is performed to melt the ice.

[0058] The operation of the air conditioner (10) during the ice melting operation will be described. In this air conditioner (10), the ice thawing operation can be performed for each indoor unit (12). Therefore, even if the ice thawing operation is performed in one indoor unit (12a). The other indoor units (12b, 12c) can perform the cooling operation regardless of the ice melting operation. Of course, multiple In some cases, the indoor units (12a, 12b,.

[0059] For example, when the ice melting operation is started in a certain indoor unit (12a), the controller (80) adjusts the refrigerant flow rate to the indoor heat exchanger (53a) of the indoor unit (12a). Set (52a) to the closed state. In this state, the cooling operation force continues to drive the indoor fan (57a). As a result, the ice melting operation is performed, and the ice adhering to the indoor heat exchanger (53a) is melted by the indoor air sent by the indoor fan (57a).

[0060] When the controller (80) ends the ice melting operation, the expansion valve (52a) is opened while the indoor fan (57a) is driven. As a result, the refrigerant flows into the indoor heat exchanger (53a) and the cooling operation is performed again.

By the way, in the multi-type air conditioner as in this embodiment, as described above, there are many cases where the cooling load is different for each indoor unit (12), and the indoor unit (12) with a small load is set. When the target temperature is reached, the cooling operation is temporarily stopped, the expansion valve (52) is closed, and the refrigerant flowing in the refrigerant circuit (20) is shut off (so-called thermo-off). In addition, since the three indoor units (12a, 12b, 12c) are provided in different rooms, even if any one of the indoor units (12) is used, 1 2) is sometimes used.

[0062] Of the three indoor units (12a, 12b, 12c) connected to the same refrigerant circuit (20) as described above, at least one performs the cooling operation, and at least one other stops the operation. In this case, the indoor unit (12) is stopped and (20) high-pressure liquid refrigerant is supplied from the refrigerant circuit to the indoor unit (12). Therefore, even if the expansion valve (52) of the stopped indoor unit (12) is closed, the refrigerant may leak downstream, and if the amount of leakage increases, the refrigerant piping of the indoor circuit (50) In addition, the indoor heat exchanger (53) may be cooled to cause problems such as dew condensation.

[0063] Further, when the leakage amount of the refrigerant into the downstream piping increases as described above, even if the expansion valve (52) is closed to perform the above ice melting operation, the indoor heat The ice attached to the exchanger (53) cannot be melted easily, it takes time to melt the ice, and after the ice melts However, since the temperature of the indoor heat exchanger (53) does not rise easily, if the end of ice melting operation is judged based on this temperature rise, this judgment will be delayed and unnecessary ice melting will occur. If the operation continues, there is a risk of malfunction.

[0064] Therefore, in this embodiment, for the purpose of preventing problems such as the above-mentioned dew condensation and malfunction, at least one of the indoor units (12a, 12b, 12c) performs the cooling operation as described above. When at least one other operation is stopped, the refrigerant is leaked from the expansion valve (52) of the indoor unit (12) to the downstream indoor circuit (50) when the operation is stopped. The flow rate is calculated using a model of the heat conduction state in which the refrigerant absorbs atmospheric force through piping, etc., and based on this, the refrigerant leakage amount of the expansion valve (52) can be estimated quantitatively and accurately. I am doing so.

[0065]-Method for estimating refrigerant leakage

Hereinafter, estimation of the refrigerant leakage amount by the refrigerant leakage amount estimation unit (81) of the controller (80) will be specifically described.

[0066] This estimation is performed when each of the indoor units (12) is stopped as described above, and in the following, one of the three indoor units (12a, 12b, 12c) The estimation of the refrigerant leakage amount in the indoor unit (12a) of the base will be described. The description will be omitted. The refrigerant leakage amount estimation unit (81) similarly estimates the refrigerant leakage amount for the other indoor units (12b, 12c).

[0067] First, FIG. 2 shows the expansion valve (52a) force of the stopped indoor unit (12a), the leaked refrigerant force, and the ambient air (atmosphere) in the refrigerant pipe and the indoor heat exchanger (53a) downstream thereof. The model of the heat conduction state that absorbs heat from is shown. Immediately after leaking from the expansion valve (52a), the temperature of the refrigerant decreases to the evaporation temperature, and then absorbs atmospheric force through the peripheral wall of the refrigerant pipe while flowing to the inlet of the indoor heat exchanger (53a). Rise gradually. For this reason, when the amount of leakage is relatively small, the temperature of the refrigerant changes from the temperature To (° C) immediately after the expansion valve (52a) to the temperature near the inlet of the indoor heat exchanger (53a) as shown in Fig. 3. It gradually rises to TH2 (° C) and approaches room temperature TH1 (° C).

[0068] Therefore, Kl is the heat transfer coefficient in the refrigerant pipe from immediately after the expansion valve (52a) to the inlet of the indoor heat exchanger (53a), and Al (m ² ) is the heat transfer area. Large refrigerant and If the average temperature difference from the air is ΔΤ1, the endothermic quantity Ql (k J /) of the refrigerant per hour is

Q1 = K1 XA1 X ΔΤ1

It becomes. Here, the average temperature difference ΔΤ1 is the measured value TH1 of the indoor temperature sensor (56), the measured value TH2 of the first temperature sensor (54a) (that is, the inlet temperature of the indoor heat exchanger (53a)), the expansion valve Using the refrigerant temperature To immediately after (52a), for example, logarithmic average,

ΔΤ1 = (TH2-To) / ln {(TH1—To) / (TH1 -TH2)}

Or, as a simpler addition average,

ΔΤ1 = ΤΗ1-(To + TH2) / 2

It's a monkey.

[0069] If the endothermic amount Q1 is obtained in this way, the refrigerant flow rate in the pipe downstream of the expansion valve (52a), that is, the refrigerant leakage amount per hour from the expansion valve (52a) G (kg / h) Is the difference in enthalbi between the refrigerant expansion valve (52a) and the heat exchange ^^ (53a) inlet, (Hout—Hin) (kj / kg)

G = Ql / (Hout— Hin)

It becomes. However, Hin is the enthalpy of the liquid refrigerant immediately after the expansion valve (52a), and the force is calculated as the refrigerant temperature To and the evaporation pressure (for example, monitored by an outdoor unit) immediately after the expansion valve (52a). The Hout is the enthalpy of the refrigerant gas at the inlet of the indoor heat exchanger (53a), and is calculated from the measured value TH2 of the first temperature sensor (54a) and the evaporation pressure.

[0070] The measured values of the temperature sensors (54a, 56a) installed in the indoor unit (12a) for normal operation control may be used for the temperatures TH1, TH2, respectively. The refrigerant temperature To immediately after the expansion valve (52a) can be substituted with the measured value of the first temperature sensor (54b, 54c) of another indoor unit (12b, 12c) during the cooling operation. During cooling operation, the flow rate of the refrigerant flowing from the expansion valve (52b, 52c) to the inlet of the indoor heat exchanger (53b, 53c) is large, so the refrigerant temperature immediately after the expansion valve (52b, 52c) is This is because it is approximately equal to the inlet temperature of the indoor heat exchanger (53b, 53c).

[0071] Thus, using the above model, the refrigerant leakage amount G from the expansion valve (52a) of the stopped indoor unit (12a) is expressed as the refrigerant temperature To immediately after the expansion valve (52a), Room temperature TH1, It can be estimated quantitatively and accurately based on the inlet temperature TH2 of the indoor heat exchanger (53a).

[0072] By the way, the amount of heat absorbed by the refrigerant in the pipe from immediately after the expansion valve (52a) to the indoor heat exchanger (53a) is not very large, so when the amount of refrigerant leakage is large, the same as in the above cooling operation. If the temperature To immediately after the expansion valve (52a) is not much different from the inlet temperature TH2 of the indoor heat exchanger (53a) and the accuracy of the first temperature sensor (54a) is not very high, the amount of refrigerant leakage as described above It becomes difficult to estimate G.

Therefore, in this embodiment, the amount of refrigerant leakage is large, and the temperature To immediately after the expansion valve (52a) and the inlet temperature TH2 of the indoor heat exchanger (53a) do not change so much. The leakage amount G is estimated from the heat absorption amount Q (kj / h) of the refrigerant during the period from 52 a) to the outlet of the indoor heat exchanger (53a).

[0074] That is, basically the same concept as described above, if the indoor heat exchanger heat transfer coefficient (53a) K2, the same heat transfer area A2 and (m ^2), the expansion valve (52a) The average temperature difference ΔT (ΔT1, ΔT2) between the refrigerant that leaks and flows to the outlet of the indoor heat exchanger (53a) and the atmosphere is also shown in Figure 3 above. The amount of heat absorbed per unit Q is

Q = Q1 + Q2 = K1 X A1 X Δ Τ1 + Κ2 Χ Α2 Χ Δ Τ2

It becomes. Δ Τ1 and Δ Τ2 in this case are, for example, using the logarithmic average as described above,

Δ Τ1 = ΤΗ1 -ΤΗ2

Δ Τ2 = (ΤΗ3 -ΤΗ2) / ln {(TH1 -TH2) / (TH1 -TH3)}

And it is sufficient. Note that ΤΗ3 is the measured value of the second temperature sensor (55a) (that is, the outlet temperature of the indoor heat exchanger (53a)).

[0075] Then, the leakage amount G of refrigerant from the expansion valve (52a) per hour is similar to the above,

G = Q / (Hout-Hin)

It becomes. The above Hin is the enthalpy of liquid refrigerant immediately after the expansion valve (52a), and Hout is the enthalpy of refrigerant gas at the outlet of the indoor heat exchanger (53a).

[0076] Thus, using a model that simulates heat exchange between the refrigerant and the atmosphere over a wider range, including the indoor heat exchanger (53a) connected only by the refrigerant pipe downstream of the expansion valve (52a), In particular, the amount of heat absorbed by the refrigerant in the indoor heat exchanger (53a) is sufficiently large. Even when the amount is large, the outlet temperature TH3 of the indoor heat exchanger (53a) is significantly different from the refrigerant temperature To immediately after the expansion valve (52a), and the refrigerant leakage amount G is quantified as described above. And accurately.

[0077] Procedure of estimation calculation

Next, a specific estimation calculation procedure in which the refrigerant leakage amount is estimated by the refrigerant leakage amount estimation unit (81) of the controller (80) will be described with reference to the flowchart of FIG.

[0078] First, in step S1 after the start of the illustrated flow, a force signal such as a temperature sensor (54a, 55a, 56a, ···) is input, and data stored in the memory is read as necessary. . In step S2, the measured value TH2 of the first temperature sensor (54a) of the indoor unit (12a) that has been stopped for a predetermined time or longer is lower than the measured value TH1 of the indoor temperature sensor (56a) by a predetermined value a or more. It is determined whether the inlet temperature TH2 of the indoor heat exchanger (53a) of the stopped indoor unit (12a) has become lower than the room temperature TH1 by a predetermined value or more (TH2 <TH1-α). The predetermined value α may be determined in advance in consideration of the heat transfer state of the refrigerant pipe.

[0079] If the determination in step S2 is NO and TH2≥TH1-a, the process proceeds to step S3, determines that there is no abnormality, and returns, while the determination in step S2 is YES. For example, this is because one of the indoor units (12b, 12c) of the air conditioner (10) starts the cooling operation, and after a while, the indoor unit (12a) It is determined that the refrigerant is leaking to some extent downstream from 52a), and the process proceeds to step S4.

[0080] In step S4, the measured value TH2 of the first temperature sensor (54b, 54c) of the other indoor unit (12b, 12c) during the cooling operation is used for the expansion of the stopped indoor unit (12a). In step S5, the difference between the refrigerant temperature To immediately after the expansion valve (52a) and the inlet temperature TH2 of the indoor heat exchanger (53a) is preliminarily determined. Judge whether it is less than the set value j8. This set value j8 may be determined by the accuracy of the first temperature sensor (54a).

[0081] If this determination is YES and TH2—Το <β, the amount of refrigerant leakage is large, and the temperature To immediately after the expansion valve (52a) and the inlet temperature TH2 of the indoor heat exchanger ^^ (53a) Therefore, based on the heat absorption amount Q1 of the refrigerant to the indoor heat exchanger (53a) inlet, the refrigerant It is determined that it is difficult to estimate the leakage amount G, and the process proceeds to Step S12 described later. On the other hand, if the determination is NO, the amount of refrigerant leakage is small, so the process proceeds to the following steps S6 to S8, and immediately after the expansion valve (52a) to the inlet of the indoor heat exchanger (53a) as described above. Calculate the heat absorption amount Q1 of the refrigerant, and based on this, calculate the leakage amount G of the refrigerant.

[0082] That is, in step S6, the measured values TH1, TH2, and the refrigerant temperature To immediately after the expansion valve (52a) adopted in step S4 and the temperature sensors (54a, 55a, 56a, ...) are used. From TH3, etc., calculate the average temperature difference ΔΤ between the refrigerant and the atmosphere immediately after the expansion valve (52a) and the inlet of the indoor heat exchanger (53a), and the refrigerant enthalpy difference (Hout−Hin) during this period. . In step S7, the heat transfer coefficient K1 and heat transfer area A1 of the refrigerant pipe stored in the memory are read, and a coefficient KA representing the heat transfer state is calculated. In step S8, the refrigerant leakage amount G is calculated from the coefficient KA, the average temperature difference ΔΤ, and the enthalpy difference (Hout-Hin), and the refrigerant leakage amount G is converted into the air flow rate to calculate the leakage air flow rate. Calculate the value V ( _CC / min).

[0083] Then, in step S9 following step S8, it is determined whether or not the leakage air flow rate conversion value V calculated as described above is larger than a preset threshold value γ. If this determination is NO, the refrigerant leakage amount of the expansion valve (52a) force is still within the allowable range, so the routine proceeds to step S10, where it is determined that there is no abnormality and the process ends (END). On the other hand, if the determination in step S9 is YES and the amount of refrigerant leaking from the expansion valve (52a) is considerably large, this is likely to cause dew condensation or an ice melting operation malfunction. In this case, since maintenance and replacement of the expansion valve (52a) are necessary, the process proceeds to step SI 1 where it is determined that there is an abnormality, and the display device (82) indicates that there is an abnormality in the expansion valve (52a), and the process ends. (End).

[0084] In Step S12, which has been determined that the amount of refrigerant leakage is large in Step S5, first, the refrigerant temperature To immediately after the expansion valve (52a) and the outlet temperature of the indoor heat exchanger (53a) are detected. Determining whether the difference from degree TH3 is smaller than the set value β. If this judgment is YES (TH 3— To <), the amount of refrigerant leakage is very large, and the outlet temperature TH3 of the indoor heat exchanger (53a) is not much different from the refrigerant temperature To immediately after the expansion valve (52a). Since it is unchangeable, t, it is determined that the process proceeds to step S13 and immediately determines that there is an abnormality. The display device (82) indicates that there is an abnormality in the expansion valve (52a), and the process ends. . [0085] On the other hand, if the determination is NO, the following step S14, SI5 force and the process proceeds to step S8, and the outlet of the indoor heat exchanger (53a) immediately after the expansion valve (52a) as described above. The heat absorption amount Q of the refrigerant up to is calculated, and based on this, the leakage amount G of the refrigerant is obtained. That is, in step S14, similar to step S6 above, the average temperature difference ΔΤ (ΔΤ1, ΔΤ2) between the refrigerant and the atmosphere immediately after the expansion valve (52a) to the outlet of the indoor heat exchanger (53a), and the refrigerant between them In step S15, the heat transfer coefficient Kl, K2 and the heat transfer area Al, A2 of the refrigerant piping and heat exchange (53a) are read and the heat transfer state is calculated. The coefficient KA that represents is calculated.

[0086] Then, the process proceeds to step S8, where the refrigerant leakage amount G and its air flow rate conversion value V are calculated, respectively, and the size of the leakage air flow rate conversion value V and the threshold value γ is determined (step S). 9) In accordance with this determination result, it is determined whether or not there is an abnormality in the expansion valve (52a) (steps S10 and S11) .If there is an abnormality (S11), this is indicated on the display device (82) End (end).

[0087] Effect of one embodiment

Therefore, in the above-described embodiment, in the so-called multi-type air conditioner (10), at least one indoor unit (12b, 12c) performs a cooling operation, and at least one other indoor unit (12a) ) Has stopped operating, and the refrigerant atmosphere flowing from immediately after the expansion valve (52a) of the stopped indoor unit (12a) to the inlet or outlet of the indoor heat exchanger (53a) Using a model that comprehensively simulates the heat conduction state between, for example, the measured values TH1 to TH3 of the room temperature or the inlet or outlet temperature of the indoor heat exchanger (53a) are input, and the expansion valve ( The refrigerant leakage amount G from 52a) can be estimated quantitatively and accurately.

[0088] If the refrigerant leakage amount G estimated in this way increases beyond a predetermined level, the leakage amount increases further, and before the malfunction such as dew condensation or malfunction of the ice melting operation occurs, the user swells. Since the abnormality of the tension valve (52a) can be notified and the maintenance or replacement thereof can be promoted, the above-mentioned problems can be reliably prevented.

[0089] In particular, in the present embodiment, when the refrigerant leakage amount G is relatively small, based on the heat absorption amount Q1 of the refrigerant in the refrigerant pipe immediately after the expansion valve (52a) to the inlet of the indoor heat exchanger (53a). Therefore, the leakage amount G is estimated, and the refrigerant pipe is cooled relatively short. Since the change in the medium temperature can be regarded as approximately linear, a fairly accurate estimation can be performed using a simple model. On the other hand, when the refrigerant leakage amount G is large, the leakage amount G can be estimated by further considering the refrigerant heat absorption amount Q2 in the indoor heat exchanger (53a).

[0090] In this embodiment, the temperature force (54a, 55a, 56a) provided for the normal operation control in the indoor unit (12a) is measured with the measured values TH1 to TH3 and the like used for the above estimation. ), And the refrigerant temperature To immediately after the expansion valve (52) is substituted with the value measured by the temperature sensor (54b, 54c) of another indoor unit (12) during the cooling operation. Therefore, there is no need to provide a dedicated sensor for the estimation calculation, which is advantageous in terms of cost.

Note that this embodiment is essentially a preferred example, and is not intended to limit the scope of the present invention, its application, or its application. For example, in this embodiment, the measured values TH1 to TH3 measured by the temperature sensors (54a, 55a, 56a) are used as they are for the above calculation of the refrigerant leakage amount. The actual temperature of the cooling medium to be measured is slightly different from the measured value by the sensor, and the magnitude of this deviation varies depending on the flow rate of the refrigerant as shown in Fig. 5, for example. It is preferable to create a correction map by investigating through a pilot experiment, etc., and correcting the above temperature measurement values TH1 to TH3 by the state quantity related to the refrigerant flow (for example, the differential pressure of the expansion valve (52a)). .

[0092] Further, in the present embodiment, the refrigerant temperature To immediately after the expansion valve (52a) of the stopped indoor unit (12a) is used as the first temperature of another indoor unit (12b, 12c) during the cooling operation. The force using the measured values of the sensors (54b, 54c) is not limited to this. For example, the evaporation temperature monitored in the outdoor unit (11) can be substituted.

In this embodiment, as shown in step S9 of the flow in FIG. 4 and the like, when the air amount converted value V of the refrigerant leakage amount G is larger than the threshold value γ, the expansion valve (52a) Although the abnormality is determined and notified, the present invention is not limited to this, and the abnormality may be determined when the refrigerant leakage amount G itself is larger than a preset threshold value. In addition, the amount of dew condensation due to refrigerant leakage may be calculated and notified to the user when this is more than a predetermined amount. Yes.

[0094] In that case, the dew amount D (kg / h) in the refrigerant pipe and the indoor heat exchanger (53a) is obtained by integrating the refrigerant heat absorption amounts Ql and Q2 obtained in the above embodiment over time. Calculate the total endotherm Qal to date, and roughly calculate it as D = QalZ water vaporization heat (245 kJ / kg) with the total endotherm Qal, and make corrections based on room temperature, outside temperature, humidity, etc. as necessary. You can do so.

[0095] Furthermore, in the present embodiment, in the multi-type air conditioner (10), any indoor unit (12b, 12c) has stopped for a while after a certain time has elapsed since the start of the cooling operation. (12a) expansion valve (52a) force The amount of leakage is estimated in a state where the refrigerant leaks to some extent downstream! /, And by estimating in such a state, For example, when any indoor unit (12) stops due to thermo-off, the amount of refrigerant leakage from the expansion valve (52) is estimated. Anyway ヽ.

[0096] In this way, even when all indoor units (12a, 12b, 12c) are basically used, estimation can be performed using the thermo-off, so that the frequency is increased and expansion is performed. There is a high possibility that this can be detected before the amount of refrigerant leakage becomes excessive due to, for example, aging of the valve (52). Therefore, problems such as dew and malfunction can be prevented more reliably.

Industrial applicability

As described above, the present invention is useful for a so-called multi-type air conditioner in which a plurality of usage units are connected to a refrigerant circuit.

Claims

The scope of the claims

[1] An air conditioner that includes a refrigerant circuit (20) in which a heat source unit (11) and a plurality of use units (12) are connected, and performs at least a cooling operation,

When at least one of the use units (12) performs cooling operation, and at least one other use unit (12) stops operating, the use unit stops. The refrigerant leakage amount estimation means (81) for estimating the refrigerant leakage amount of the expansion valve (52) using a model of the heat conduction state in a predetermined range downstream of the expansion valve (52) of (12) is provided! / An air conditioner characterized by squeezing.

[2] In claim 1,

The utilization unit (12) is provided with an inlet temperature measuring means (54) for measuring the inlet temperature of the heat exchanger (53) and a room temperature measuring means (56) for measuring the temperature in the room,

In the above model, the refrigerant flowing in the pipe from the position immediately after the expansion valve (52) of the utilization unit (12) to the heat exchanger (53) is stopped and heated with the atmosphere through the pipe. It simulates exchange,

The refrigerant leakage amount estimating means (81) includes a measured value by the inlet temperature measuring means (54) of the stopped use unit (12), a measured value by the room temperature measuring means (56), and the expansion valve ( 52. An air conditioner that estimates the refrigerant leakage amount using the above model based on the refrigerant temperature immediately after 2).

[3] In claim 2,

The refrigerant leakage amount estimation means (81) uses the measured value of the inlet temperature measurement means (54) of another usage unit (12) during cooling operation to the expansion valve (52) of the usage unit (12) that has stopped. Regarded as the refrigerant temperature immediately after

An air conditioner characterized by that.

[4] In claim 2,

The refrigerant leak amount estimation means (81) is used for the room temperature measurement because the measured value of the inlet temperature measurement means (54) or the outlet temperature measurement means (55) of the stopped use unit (12) decreases. Estimate the refrigerant leakage amount of the expansion valve (52) when the measured value is lower than the measured value by the means (56) by a predetermined value. An air conditioner characterized by that.

[5] In claim 2,

The refrigerant leakage amount estimation means (81) is configured such that after the use unit (12) in the cooling operation stops operation due to thermo-off, the inlet temperature measurement means (54) or the outlet temperature measurement means ( 55) When the measured value due to the deviation rises and stabilizes at a temperature lower than the measured value by the room temperature measuring means (56) by a predetermined value or more, the refrigerant leakage amount of the expansion valve (52) is estimated. Do

An air conditioner characterized by that.

[6] In claim 1,

The utilization unit (12) includes an inlet temperature measuring means (54) for measuring the inlet temperature of the heat exchanger (53), an outlet temperature measuring means (55) for measuring the outlet temperature of the heat exchanger (53), and And room temperature measuring means (56) for measuring the indoor temperature,

The above model stops! /, Immediately after the expansion valve (52) of the utilization unit (12), flows through the piping and the heat exchanger (53) to reach the outlet of the heat exchanger (53). The refrigerant simulates heat exchange with the atmosphere through the pipe and heat exchange (53).

The refrigerant leakage amount estimation means (81) includes the measured value by the inlet temperature measurement means (54) of the stopped usage unit (12) and the outlet of the usage unit (12) that stops and / or is stopped. Estimate the amount of refrigerant leakage using the above model based on the measured value by the thermometer (55), the measured value by the room temperature measuring means (56), and the refrigerant temperature immediately after the expansion valve (52). An air conditioner characterized by.

[7] In claim 6,

An air conditioner characterized by that.

[8] In claim 6,

The refrigerant leak amount estimating means (81) is a measure of whether the measured value of the inlet temperature measuring means (54) or the outlet temperature measuring means (55) of the use unit (12) being stopped is reduced. Estimate the refrigerant leakage amount of the expansion valve (52) when the measured value is lower than the measured value by the measuring means (56).

An air conditioner characterized by that.

[9] In claim 6,

An air conditioner characterized by that.

[10] In claim 1,

Further provided is a notification means (82) for performing a notification when the refrigerant leakage amount estimated by the refrigerant leakage amount estimation means (81) is a predetermined amount or more.

An air conditioner characterized by that.