air conditioning equipment

Abstract

To improve energy saving performance in an air conditioner.SOLUTION: An air conditioner includes a refrigerant circuit (50) having a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54), performs a refrigeration cycle by circulating a refrigerant in the refrigerant circuit (50), and cools air in the evaporator (54). The air conditioner includes a first detecting unit (65, 66) for detecting at least one of the temperature and the humidity of the air passing through the evaporator (54), and a controller (70) for controlling the opening of the expansion valve (53) on the basis of the detection result of the first detecting unit (65, 66).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an air conditioning apparatus. [Background technology]

[0002] BACKGROUND ART Air conditioners equipped with refrigerant circuits have been known for some time. In the refrigerant circuits of air conditioners, a refrigeration cycle is performed by circulating a refrigerant.

[0003] In air conditioners, the opening degree of an expansion valve provided upstream of an evaporator in a refrigerant circuit may be controlled based on the degree of superheat of the refrigerant at the outlet of the evaporator (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-035880 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, if the temperature setting range for air conditioning is wide, from -20°C to 50°C, the evaporator (direct expansion coil) is set to a size that can cool air to -20°C. In this case, if the set temperature is set to 50°C, the evaporator size (heat transfer area) will be too large, resulting in an excessive amount of heat exchange compared to the required cooling amount, resulting in excessive cooling. This is because the superheat control described above controls the opening of the expansion valve with the aim of completely gasifying the refrigerant at the evaporator outlet, rather than controlling the opening of the expansion valve with the aim of bringing the temperature of the air cooled by the evaporator closer to the set temperature. If the temperature of the air cooled by the evaporator is too low, the cooled air must be heated using a heater or other device to bring it closer to the set temperature. This reduces energy efficiency.

[0006] An object of the present disclosure is to improve energy efficiency in air conditioners. [Means for solving the problem]

[0007] A first aspect of the present disclosure is directed to an air conditioner. The air conditioner includes a refrigerant circuit (50) having a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54). A refrigerant is circulated through the refrigerant circuit (50) to perform a refrigeration cycle, and air is cooled in the evaporator (54). The air conditioner includes first detectors (65, 66) that detect at least one of the temperature and humidity of air that has passed through the evaporator (54), and a controller (70) that controls the opening degree of the expansion valve (53) based on the detection result of the first detectors (65, 66).

[0008] According to the first aspect, the opening of the expansion valve (53) can be controlled so that at least one of the temperature and humidity of the air that has passed through the evaporator (54) approaches a target value (desired value), thereby improving energy saving.

[0009] In a second aspect of the present disclosure, in the first aspect, the first detection unit (65) detects the temperature of the air that has passed through the evaporator (54), and the controller (70) determines the aperture of the expansion valve (53) based on the air temperature detected by the first detection unit (65) and controls the aperture of the expansion valve (53) to the determined aperture.

[0010] According to the second aspect, the opening of the expansion valve (53) can be controlled so that the temperature of the air that has passed through the evaporator (54) approaches a target temperature, thereby improving energy saving.

[0011] In a third aspect of the present disclosure, in the first aspect, the first detection unit (66) detects the humidity of the air that has passed through the evaporator (54), and the controller (70) determines the aperture of the expansion valve (53) based on the humidity of the air detected by the first detection unit (66) and controls the aperture of the expansion valve (53) to the determined aperture.

[0012] According to the third aspect, the opening of the expansion valve (53) can be controlled so that the humidity of the air that has passed through the evaporator (54) approaches the target humidity, thereby improving energy saving.

[0013] In a fourth aspect of the present disclosure, in the first aspect, the first detection units (65, 66) detect the temperature of the air that has passed through the evaporator (54) and the humidity of the air that has passed through the evaporator (54), and the controller (70) determines a first degree of aperture of the expansion valve (53) based on the temperature of the air detected by the first detection units (65, 66), determines a second degree of aperture of the expansion valve (53) based on the humidity of the air detected by the first detection units (65, 66), and controls the degree of aperture of the expansion valve (53) to be the larger of the first degree of aperture and the second degree of aperture.

[0014] According to the fourth aspect, the opening of the expansion valve (53) can be controlled so that the temperature or humidity of the air that has passed through the evaporator (54) approaches a target value (desired value), thereby improving energy saving.

[0015] In a fifth aspect of the present disclosure, in the first aspect, the air conditioning apparatus includes a second detection unit (63) that detects the temperature of the refrigerant flowing from the evaporator (54) to the compressor (51) and a third detection unit (62) that detects the pressure of the refrigerant flowing from the evaporator (54) to the compressor (51), and the controller (70) controls the opening degree of the expansion valve (53) based further on the detection results of the second detection unit (63) and the third detection unit (62).

[0016] According to the fifth aspect, it is possible to prevent the degree of superheat of the refrigerant at the outlet of the evaporator from decreasing, thereby protecting the compressor.

[0017] In a sixth aspect of the present disclosure, in the fifth aspect, the first detection unit (65) detects the temperature of the air having passed through the evaporator (54), and the controller (70) determines a third degree of aperture of the expansion valve (53) based on the temperature of the air detected by the first detection unit (65), determines a fourth degree of aperture of the expansion valve (53) based on the temperature of the refrigerant detected by the second detection unit (63) and the pressure of the refrigerant detected by the third detection unit (62), and controls the aperture of the expansion valve (53) to be the smaller of the third degree of aperture and the fourth degree of aperture.

[0018] According to the sixth aspect, it is possible to improve energy saving while suppressing a decrease in the degree of superheat of the refrigerant at the outlet of the evaporator.

[0019] In a seventh aspect of the present disclosure, in the fifth aspect, the first detection unit (66) detects the humidity of the air that has passed through the evaporator (54), and the controller (70) determines a fifth degree of aperture of the expansion valve (53) based on the humidity of the air detected by the first detection unit (66), determines a sixth degree of aperture of the expansion valve (53) based on the temperature of the refrigerant detected by the second detection unit (63) and the pressure of the refrigerant detected by the third detection unit (62), and controls the aperture of the expansion valve (53) to be the smaller of the fifth degree of aperture and the sixth degree of aperture.

[0020] According to the seventh aspect, it is possible to improve energy saving while suppressing a decrease in the degree of superheat of the refrigerant at the outlet of the evaporator.

[0021] An eighth aspect of the present disclosure is the fifth aspect, wherein the first detection unit (65, 66) detects the temperature of the air having passed through the evaporator (54) and the humidity of the air having passed through the evaporator (54), and the controller (70) determines a seventh degree of aperture of the expansion valve (53) based on the temperature of the air detected by the first detection unit (65, 66), determines an eighth degree of aperture of the expansion valve (53) based on the humidity of the air detected by the first detection unit (65, 66), determines a ninth degree of aperture which is the larger of the seventh degree of aperture and the eighth degree of aperture, determines a tenth degree of aperture of the expansion valve (53) based on the temperature of the refrigerant detected by the second detection unit (63) and the pressure of the refrigerant detected by the third detection unit (62), and controls the aperture of the expansion valve (53) to be the smaller of the ninth degree of aperture and the tenth degree of aperture.

[0022] According to the eighth aspect, it is possible to improve energy saving while suppressing a decrease in the degree of superheat of the refrigerant at the outlet of the evaporator. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of a user-side unit of an air conditioner. [Figure 2] FIG. 2 is a piping diagram showing the refrigerant circuit of the air conditioner of the first embodiment. [Figure 3] FIG. 3 is a piping diagram showing a refrigerant circuit of an air conditioner according to a second embodiment. [Figure 4] FIG. 4 is a piping diagram showing a refrigerant circuit of an air conditioner according to a third embodiment. [Figure 5] FIG. 5 is a piping diagram showing a refrigerant circuit of an air conditioner according to a fourth embodiment. [Figure 6] FIG. 6 is a piping diagram showing a refrigerant circuit of an air conditioner according to a fifth embodiment. [Figure 7] FIG. 7 is a piping diagram showing a refrigerant circuit of an air conditioner according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since each drawing is intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding. In each embodiment, modified example, and drawing, the same or equivalent parts are designated by the same reference symbols, and detailed descriptions and descriptions of the accompanying effects will not be repeated.

[0025] -First embodiment- An embodiment will now be described. An air conditioner (10) of this embodiment provides air conditioning for a test room (100) used for automobile driving tests and the like.

[0026] The air conditioner (10) includes a utilization side unit (20) and a heat source side unit (40), and also includes a refrigerant circuit (50).

[0027] -User unit- As shown in Fig. 1, the user-side unit (20) is a so-called air handling unit. The user-side unit (20) includes a casing (25). An inlet (27) is formed in one end surface of the casing (25), and an outlet (28) is formed in the other end surface of the casing (25). An air flow path (26) is formed inside the casing (25) from the inlet (27) to the outlet (28).

[0028] The utilization side unit (20) is connected to the test chamber (100) via a suction duct (16) and a discharge duct (17). The suction duct (16) is connected to an inlet (27) of the casing (25) and connects the air flow path (26) to the interior space of the test chamber (100). The discharge duct (17) is connected to an outlet (28) of the casing (25) and connects the air flow path (26) to the interior space of the test chamber (100).

[0029] The air flow path (26) in the casing (25) is provided with a filter (31), an evaporator (54), an electric heater (32), and a user-side fan (33) in this order from the suction port (27) side toward the discharge port (28) side. The filter (31) collects dust and other particles contained in the air flowing in through the suction port (27). The evaporator (54) is connected to the refrigerant circuit (50) and cools the air. The electric heater (32) heats the air that has passed through the evaporator (54). The user-side fan (33) draws in the air that has passed through the electric heater (32) and blows it out toward the discharge port (28).

[0030] <Driving operation> The operation of the user unit (20) will now be described.

[0031] When the user-side fan (33) is activated, air in the interior space of the test chamber (100) flows through the intake duct (16) into the air flow path (26) in the casing (25). The air flowing through the air flow path (26) passes through the filter (31), the evaporator (54), and the electric heater (32) in this order.

[0032] The air is cooled while passing through the evaporator (54) and heated while passing through the electric heater (32). Note that the electric heater (32) may temporarily stop heating the air. The air that has passed through the electric heater (32) is blown out from the user-side fan (33) and flows into the blow-out duct (17), and then blown into the interior space of the test chamber (100).

[0033] -Air temperature sensor, heater controller- The air conditioner (10) includes an air temperature sensor (36) and a heater controller (37).

[0034] The air temperature sensor (36) is provided in the discharge duct (17) and measures the temperature of the air flowing through the discharge duct (17). The measured value of the air temperature sensor (36) indicates the temperature of the air supplied by the utilization side unit (20) to the internal space of the test room (100).

[0035] The heater controller (37) receives the measurement value of the air temperature sensor (36). The heater controller (37) controls the amount of heat generated by the electric heater (32) based on the measurement value of the air temperature sensor (36). Specifically, the heater controller (37) adjusts the amount of heat generated by the electric heater (32) so that the measurement value of the air temperature sensor (36) becomes the set air temperature. When the measurement value of the air temperature sensor (36) is lower than the set air temperature, the heater controller (37) increases the amount of heat generated by the electric heater (32). When the measurement value of the air temperature sensor (36) is higher than the set air temperature, the heater controller (37) decreases the amount of heat generated by the electric heater (32).

[0036] -Refrigerant circuit- The refrigerant circuit (50) is a closed circuit filled with a refrigerant, and performs a refrigeration cycle by circulating the refrigerant.

[0037] 2, the refrigerant circuit (50) includes a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54). In the refrigerant circuit (50), the condenser (52), the expansion valve (53), and the evaporator (54) are arranged in this order from the discharge port to the suction port of the compressor (51). In the refrigerant circuit (50), a receiver (57) is provided between the condenser (52) and the expansion valve (53) to store surplus refrigerant due to fluctuations in heat load.

[0038] The compressor (51) compresses and discharges the drawn refrigerant. Although not shown, the compressor (51) includes a compression mechanism and an electric motor for driving the compression mechanism. The condenser (52) is a cross-fin type air heat exchanger that exchanges heat between the refrigerant and outdoor air. The expansion valve (53) is an electric expansion valve with a variable opening. The evaporator (54) is a cross-fin type air heat exchanger that exchanges heat between the refrigerant and air in the air flow path (26).

[0039] <Refrigeration cycle> The refrigeration cycle performed by the refrigerant circuit (50) will be described.

[0040] When the compressor (51) is operated, refrigerant circulates in the refrigerant circuit (50). The refrigerant discharged from the compressor (51) flows into the condenser (52) and condenses by dissipating heat to the outdoor air passing through the condenser (52). The refrigerant flowing out of the condenser (52) is reduced in pressure while passing through the expansion valve (53) and then flows into the evaporator (54).

[0041] The refrigerant flowing into the evaporator (54) absorbs heat from the air passing through the evaporator (54) and evaporates. The refrigerant flowing out of the evaporator (54) is drawn into the compressor (51) and compressed. The compressor (51) compresses the drawn refrigerant and discharges it.

[0042] -Heat source unit- The heat source side unit (40) is provided with a compressor (51) and a condenser (52) of a refrigerant circuit (50). The heat source side unit (40) also includes a heat source side fan (41) and an inverter (42). The heat source side fan (41) supplies outdoor air to the condenser (52). Although not shown, the inverter (42) is connected to an external power source such as a commercial power source. The inverter (42) converts the frequency of the supplied AC current to a set frequency and supplies the AC current of the set frequency to the motor of the compressor (51). Changing the output frequency of the inverter (42) changes the rotation speed of the compressor (51).

[0043] The heat source side unit (40) includes a suction pressure sensor (46). The suction pressure sensor (46) is connected to the refrigerant circuit (50). The suction pressure sensor (46) is attached to a pipe connected to the suction port of the compressor (51) and measures (detects) the pressure of the refrigerant sucked into the compressor (51).

[0044] <Compressor Controller> The heat source side unit (40) includes a compressor controller (47). The compressor controller (47) receives a measurement value of the suction pressure sensor (46). The compressor controller (47) is configured to control the rotation speed of the compressor (51) based on the measurement value of the suction pressure sensor (46).

[0045] Specifically, the compressor controller (47) adjusts the rotation speed of the compressor (51) so that the measurement value of the suction pressure sensor (46) becomes equal to the set suction pressure. When the measurement value of the suction pressure sensor (46) is lower than the set suction pressure, the compressor controller (47) reduces the output frequency of the inverter (42) to reduce the rotation speed of the compressor (51). When the measurement value of the suction pressure sensor (46) is higher than the set suction pressure, the compressor controller (47) increases the output frequency of the inverter (42) to increase the rotation speed of the compressor (51).

[0046] -Sensor- The air conditioner (10) includes a frequency sensor (64) and a temperature sensor (65).

[0047] The frequency sensor (64) is provided on a power supply electrical wiring that connects the inverter (42) to the motor of the compressor (51). The frequency sensor (64) measures the output frequency of the inverter (42). The measured value of the frequency sensor (64) is the frequency of the AC current supplied from the inverter (42) to the compressor (51), in other words, the drive frequency of the compressor (51).

[0048] The temperature sensor (65) detects the temperature of the air that has passed through the evaporator (54). The temperature sensor (65) is provided downstream of the evaporator (54) in an air flow path that passes through the evaporator (54), and detects the temperature of the air downstream of the evaporator (54). The temperature sensor (65) is provided around the evaporator (54) and detects the temperature of the air around the evaporator (54). In the first embodiment, the temperature sensor (65) is provided, for example, between the evaporator (54) and the electric heater (32) in the casing (25), and detects the temperature of the air between the evaporator (54) and the electric heater (32). The measurement value of the temperature sensor (65) indicates the temperature of the air that has passed through the evaporator (54). The air is cooled by heat exchange with the refrigerant while passing through the evaporator (54). The temperature sensor (65) is a first example of a first detection unit.

[0049] -Controller- The air conditioner (10) includes a first expansion valve controller (75). The compressor controller (47) and the first expansion valve controller (75) form a controller (70) that controls the expansion valve (53).

[0050] <First expansion valve controller> The first expansion valve controller (75) receives the measurement value of the temperature sensor (65) as an input. The first expansion valve controller (75) is configured to calculate a first command value for the opening degree of the expansion valve (53) based on the measurement value of the temperature sensor (65).

[0051] Specifically, the first expansion valve controller (75) calculates the degree of opening of the expansion valve (53) such that the measurement value of the temperature sensor (65) becomes a predetermined target temperature, and determines the calculated degree of opening as a first command value for the degree of opening of the expansion valve (53). The first expansion valve controller (75) transmits the determined first command value to the expansion valve (53). As a result, the degree of opening of the expansion valve (53) becomes the degree of opening corresponding to the first command value. This can prevent the amount of heat exchanged in the evaporator (54) from becoming excessively larger than the required cooling amount, and can bring the temperature of the air cooled by the evaporator (54) closer to the predetermined target temperature. As a result, it is possible to prevent the temperature of the air cooled by the evaporator (54) from deviating from the predetermined target temperature, and it is not necessary to perform a heating process on the air cooled by the evaporator (54) to bring it closer to the predetermined target temperature, thereby improving energy efficiency.

[0052] When the measurement value of the temperature sensor (65) is higher than a predetermined target temperature, the first expansion valve controller (75) transmits to the expansion valve (53) a first command value indicating an opening degree that is larger than the current opening degree of the expansion valve (53). The opening degree of the expansion valve (53) is increased to an opening degree corresponding to the first command value. When the opening degree of the expansion valve (53) is increased, the amount of refrigerant flowing into the evaporator (54) increases. As a result, the cooling of the air by the evaporator (54) is promoted.

[0053] When the measurement value of the temperature sensor (65) is lower than a predetermined target temperature, the first expansion valve controller (75) transmits a smaller opening degree than the current opening degree of the expansion valve (53) as a first command value to the expansion valve (53). The opening degree of the expansion valve (53) is reduced to the opening degree corresponding to the first command value. When the opening degree of the expansion valve (53) is reduced, the amount of refrigerant flowing into the evaporator (54) is reduced. As a result, the cooling of the air by the evaporator (54) is suppressed.

[0054] -Second embodiment- A second embodiment of the air conditioner (10) will be described below, focusing mainly on the differences from the first embodiment.

[0055] As shown in FIG. 3, the air conditioner (10) of the second embodiment differs from the first embodiment in that it further includes a humidity sensor (66) and a second expansion valve controller (76) and does not include a temperature sensor (65) and a first expansion valve controller (75).

[0056] In the second embodiment, the second expansion valve controller (76) constitutes the controller (70) that controls the expansion valve (53).

[0057] The humidity sensor (66) detects the humidity of the air that has passed through the evaporator (54). The humidity sensor (66) is provided downstream of the evaporator (54) in an air flow path that passes through the evaporator (54), and detects the humidity of the air downstream of the evaporator (54). The humidity sensor (66) is provided around the evaporator (54) and detects the humidity of the air around the evaporator (54). In the second embodiment, the humidity sensor (66) is provided, for example, between the evaporator (54) and the electric heater (32) in the casing (25), and detects the humidity of the air between the evaporator (54) and the electric heater (32). The measurement value of the humidity sensor (66) indicates the humidity of the air that has passed through the evaporator (54). The humidity sensor (66) is a second example of a first detection unit.

[0058] <Second expansion valve controller> The second expansion valve controller (76) receives the measurement value of the humidity sensor (66) as an input. The second expansion valve controller (76) is configured to calculate a second command value for the opening degree of the expansion valve (53) based on the measurement value of the humidity sensor (66).

[0059] Specifically, the second expansion valve controller (76) calculates the degree of opening of the expansion valve (53) such that the measurement value of the humidity sensor (66) becomes a predetermined target humidity, and determines the calculated degree of opening as a second command value for the degree of opening of the expansion valve (53). The second expansion valve controller (76) transmits the determined second command value to the expansion valve (53). As a result, the degree of opening of the expansion valve (53) becomes the degree of opening corresponding to the second command value. This makes it possible to bring the humidity of the air dehumidified by the evaporator (54) closer to the predetermined target humidity. As a result, it is possible to prevent the humidity of the air dehumidified by the evaporator (54) from deviating from the predetermined target humidity, and it is not necessary to perform a humidification process on the air dehumidified by the evaporator (54) to bring it closer to the predetermined target humidity, thereby improving energy efficiency.

[0060] When the measurement value of the humidity sensor (66) is higher than a predetermined target humidity, the second expansion valve controller (76) transmits to the expansion valve (53) a second command value indicating an opening degree that is larger than the current opening degree of the expansion valve (53). The opening degree of the expansion valve (53) is increased to an opening degree corresponding to the second command value. When the opening degree of the expansion valve (53) is increased, the amount of refrigerant flowing into the evaporator (54) increases. As a result, the dehumidification of the air by the evaporator (54) is promoted.

[0061] When the measurement value of the humidity sensor (66) is lower than a predetermined target temperature, the second expansion valve controller (76) transmits a second command value to the expansion valve (53) that is smaller than the current opening of the expansion valve (53). The opening of the expansion valve (53) is reduced to the opening corresponding to the second command value. When the opening of the expansion valve (53) is reduced, the amount of refrigerant flowing into the evaporator (54) is reduced. As a result, the dehumidification of the air by the evaporator (54) is suppressed.

[0062] -Third embodiment- The third embodiment of the air conditioner (10) will be described below, focusing mainly on the differences from the first embodiment.

[0063] As shown in FIG. 4, the air conditioner (10) of the third embodiment differs from the first embodiment in that it further includes a humidity sensor (66), a second expansion valve controller (76), and a first selector (77).

[0064] In the third embodiment, the first expansion valve controller (75), the second expansion valve controller (76), and the first selector (77) constitute a controller (70) that controls the expansion valve (53).

[0065] <First Selector> The first selector (77) receives the first command value output by the first expansion valve controller (75) and the second command value output by the second expansion valve controller (76). The first selector (77) is configured to compare the first command value with the second command value and transmit the larger of the first command value and the second command value to the expansion valve (53).

[0066] The expansion valve (53) sets its opening to the opening corresponding to the received first command value or the second command value. As described above, the opening of the expansion valve (53) corresponding to the first command value is the first opening, and the opening of the expansion valve (53) corresponding to the second command value is the second opening. Therefore, the opening of the expansion valve (53) is set to the larger of the first opening and the second opening.

[0067] If the first command value is greater than the second command value, the first selector (77) transmits the first command value to the expansion valve (53). As a result, the degree of opening of the expansion valve (53) is set to the first degree of opening, and therefore, when the air is cooled and dehumidified by the expansion valve (53), the temperature of the air can be made to approach a predetermined target temperature. Therefore, air at a temperature close to the predetermined target temperature can be sent to the test chamber (100).

[0068] In this case, the first opening corresponding to the first command value is larger than the second opening corresponding to the second command value. Therefore, when the opening of the expansion valve (53) is set to the first opening, the humidity of the air cooled and dehumidified by the expansion valve (53) becomes lower than the predetermined target humidity. Therefore, it is possible to prevent air having a humidity higher than the predetermined target humidity from being sent to the test chamber (100).

[0069] If the second command value is greater than the first command value, the first selector (77) transmits the second command value to the expansion valve (53). As a result, the opening of the expansion valve (53) is set to the second opening, and therefore, when the air is cooled and dehumidified by the expansion valve (53), the humidity of the air can be brought closer to a predetermined target humidity. Therefore, air with a humidity close to the predetermined target humidity can be sent to the test chamber (100).

[0070] In this case, the second opening corresponding to the second command value is larger than the first opening corresponding to the first command value. Therefore, when the opening of the expansion valve (53) is set to the second opening, the temperature of the air cooled and dehumidified by the expansion valve (53) becomes lower than the predetermined target temperature. Therefore, it is possible to prevent air having a temperature higher than the predetermined target temperature from being sent to the test chamber (100).

[0071] -Fourth embodiment- A fourth embodiment of the air conditioner (10) will be described below, focusing mainly on the differences from the first embodiment.

[0072] As shown in FIG. 5, the air conditioner (10) of the fourth embodiment differs from the first embodiment in that it further includes an outlet pressure sensor (62), an outlet temperature sensor (63), a third expansion valve controller (78), and a second selector (79).

[0073] In the fourth embodiment, the first expansion valve controller (75), the third expansion valve controller (78), and the second selector (79) constitute a controller (70) that controls the expansion valve (53).

[0074] The outlet pressure sensor (62) and the outlet temperature sensor (63) are attached to a pipe connected to the outlet of the evaporator (54). The outlet pressure sensor (62) detects the pressure of the refrigerant flowing out of the evaporator (54) and detects the pressure of the refrigerant flowing from the evaporator (54) toward the compressor (51). The outlet pressure sensor (62) is an example of a third detector. The outlet temperature sensor (63) detects the temperature of the refrigerant flowing out of the evaporator (54) and detects the temperature of the refrigerant flowing from the evaporator (54) toward the compressor (51). The outlet temperature sensor (63) is an example of a second detector.

[0075] <Third expansion valve controller> The third expansion valve controller (78) receives the measurement value of the outlet pressure sensor (62) and the measurement value of the outlet temperature sensor (63). The third expansion valve controller (78) is configured to calculate a third command value for the opening of the expansion valve (53) based on the measurement values ​​of the outlet pressure sensor (62) and the outlet temperature sensor (63).

[0076] First, the third expansion valve controller (78) calculates the degree of superheat of the refrigerant at the outlet of the evaporator (54). The third expansion valve controller (78) calculates the degree of superheat SH (=T-Ts) of the refrigerant at the outlet of the expansion valve (53) by subtracting the saturation temperature Ts of the refrigerant corresponding to the measurement value of the outlet pressure sensor (62) from the measurement value T of the outlet temperature sensor (63).

[0077] Next, the third expansion valve controller (78) calculates the opening of the expansion valve (53) such that the degree of superheat of the refrigerant at the outlet of the evaporator (54) becomes the set degree of superheat. The opening calculated by the third expansion valve controller (78) is the third opening. The third expansion valve controller (78) determines the calculated third opening as a third command value for the opening of the expansion valve (53). The third expansion valve controller (78) transmits the determined third command value to the expansion valve (53). As a result, the opening of the expansion valve (53) becomes the third opening corresponding to the third command value.

[0078] If the refrigerant at the outlet of the evaporator (54) becomes wet, the liquid refrigerant may be drawn into the compressor (51), which may result in damage to the compressor (51). Therefore, in order to prevent damage to the compressor (51), it is necessary to keep the refrigerant at the outlet of the evaporator (54) in a single-phase gas state.

[0079] On the other hand, when the aperture of the expansion valve (53) is changed, the amount of refrigerant flowing into the evaporator (54) changes, and as a result, the state of the refrigerant at the outlet of the evaporator (54) changes. Therefore, the third expansion valve controller (78) calculates the aperture of the expansion valve (53) so that the degree of superheat of the refrigerant at the outlet of the evaporator (54) becomes a set degree of superheat (for example, a value in the range of 5 K or more and 10 K or less), thereby completely gasifying the refrigerant at the outlet of the evaporator (54).

[0080] When the opening degree of the expansion valve (53) is reduced, the amount of refrigerant flowing into the evaporator (54) decreases, and as a result, the degree of superheat of the refrigerant at the outlet of the evaporator (54) increases. Therefore, when the degree of superheat of the refrigerant at the outlet of the evaporator (54) is lower than the set degree of superheat, the third expansion valve controller (78) determines, as the third command value, an opening degree smaller than the current opening degree of the expansion valve (53).

[0081] On the other hand, when the opening degree of the expansion valve (53) increases, the amount of refrigerant flowing into the evaporator (54) increases, resulting in a decrease in the degree of superheat of the refrigerant at the outlet of the evaporator (54). Therefore, when the degree of superheat of the refrigerant at the outlet of the evaporator (54) is higher than the set degree of superheat, the third expansion valve controller (78) determines, as the third command value, a degree of opening larger than the current degree of opening of the expansion valve (53).

[0082] <Second Selector> The second selector (79) receives the first command value output by the first expansion valve controller (75) and the third command value output by the third expansion valve controller (78). The second selector (79) is configured to compare the first command value with the third command value and transmit the smaller of the first command value and the third command value to the expansion valve (53).

[0083] The expansion valve (53) sets its opening to the opening corresponding to the received one of the first command value and the third command value. As described above, the opening of the expansion valve (53) corresponding to the first command value is the first opening, and the opening of the expansion valve (53) corresponding to the third command value is the third opening. Therefore, the opening of the expansion valve (53) is set to the smaller of the first opening and the third opening.

[0084] When the first command value is smaller than the third command value, the second selector (79) transmits the first command value to the expansion valve (53), so that the opening of the expansion valve (53) is set to the first opening.

[0085] In this case, the first opening corresponding to the first command value is smaller than the third opening corresponding to the third command value. Therefore, when the opening of the expansion valve (53) is set to the first opening, the degree of superheat of the refrigerant at the outlet of the evaporator (54) becomes higher than the set degree of superheat. Therefore, the refrigerant drawn into the compressor (51) is kept in a single-phase gas state, and damage to the compressor (51) due to drawing in liquid refrigerant is avoided.

[0086] If the third command value is smaller than the first command value, the second selector (79) transmits the third command value to the expansion valve (53). As a result, the opening of the expansion valve (53) is set to the third opening, and the degree of superheat of the refrigerant at the outlet of the evaporator (54) becomes the set superheat. Therefore, the refrigerant drawn into the compressor (51) is kept in a single-phase gas state, and damage to the compressor (51) caused by drawing liquid refrigerant is avoided.

[0087] In this case, the third degree of opening corresponding to the third command value is smaller than the first degree of opening corresponding to the first command value. Therefore, when the degree of opening of the expansion valve (53) is set to the third degree of opening, it is possible to prevent air having a temperature higher than a predetermined target temperature from being sent to the test chamber (100).

[0088] -Fifth embodiment- A fifth embodiment of the air conditioner (10) will be described below, focusing mainly on the differences from the second embodiment.

[0089] As shown in FIG. 6, the air conditioner (10) of the fifth embodiment differs from the second embodiment in that it further includes an outlet pressure sensor (62), an outlet temperature sensor (63), a third expansion valve controller (78), and a third selector (80).

[0090] In the fifth embodiment, the second expansion valve controller (76), the third expansion valve controller (78), and the third selector (80) constitute a controller (70) that controls the expansion valve (53).

[0091] <Third Selector> The third selector (80) receives the second command value output by the second expansion valve controller (76) and the third command value output by the third expansion valve controller (78). The third selector (80) is configured to compare the second command value with the third command value and transmit the smaller of the second command value and the third command value to the expansion valve (53).

[0092] The expansion valve (53) sets its opening to the opening corresponding to the received second command value or the received third command value. As described above, the opening of the expansion valve (53) corresponding to the second command value is the second opening, and the opening of the expansion valve (53) corresponding to the third command value is the third opening. Therefore, the opening of the expansion valve (53) is set to the smaller of the second opening and the third opening.

[0093] If the second command value is smaller than the third command value, the third selector (80) transmits the second command value to the expansion valve (53), so that the opening of the expansion valve (53) is set to the second opening.

[0094] In this case, the second opening corresponding to the second command value is smaller than the third opening corresponding to the third command value, and therefore the degree of superheat of the refrigerant at the outlet of the evaporator (54) becomes higher than the set degree of superheat, so that the refrigerant drawn into the compressor (51) is kept in a single-phase gas state, and damage to the compressor (51) caused by drawing in liquid refrigerant is avoided.

[0095] If the third command value is smaller than the second command value, the third selector (80) transmits the third command value to the expansion valve (53), so that the opening of the expansion valve (53) is set to the third opening.

[0096] In this case, the third degree of opening corresponding to the third command value is smaller than the second degree of opening corresponding to the second command value. Therefore, when the degree of opening of the expansion valve (53) is set to the third degree of opening, it is possible to prevent air having a humidity higher than a predetermined target humidity from being sent to the test chamber (100).

[0097] -Sixth embodiment- A sixth embodiment of the air conditioner (10) will be described below, focusing mainly on the differences from the third embodiment.

[0098] As shown in FIG. 7, the air conditioner (10) of the sixth embodiment differs from the third embodiment in that it further includes an outlet pressure sensor (62), an outlet temperature sensor (63), a third expansion valve controller (78), and a fourth selector (81).

[0099] The air conditioner (10) of the sixth embodiment is also different from the third embodiment in that the command value output by the first selector (77) is sent to the fourth selector (81) instead of the expansion valve (53).

[0100] As described above, the first selector (77) outputs the larger of the first command value and the second command value. Hereinafter, the command value (the larger of the first command value and the second command value) output by the first selector (77) may be referred to as a fourth command value. The opening of the expansion valve (53) corresponding to the fourth command value may be referred to as a fourth opening.

[0101] In the sixth embodiment, the first expansion valve controller (75), the second expansion valve controller (76), the first selector (77), the third expansion valve controller (78), and the fourth selector (81) constitute a controller (70) that controls the expansion valve (53).

[0102] <4th Selector> The fourth selector (81) receives the third command value output by the third expansion valve controller (78) and the fourth command value output by the first selector (77). The fourth selector (81) is configured to compare the third command value with the fourth command value and transmit the smaller of the third command value and the fourth command value to the expansion valve (53).

[0103] The expansion valve (53) sets its opening to the opening corresponding to the received third command value or the fourth command value. As described above, the opening of the expansion valve (53) corresponding to the third command value is the third opening, and the opening of the expansion valve (53) corresponding to the fourth command value is the fourth opening. Therefore, the opening of the expansion valve (53) is set to the smaller of the third opening and the fourth opening.

[0104] If the third command value is smaller than the fourth command value, the fourth selector (81) transmits the third command value to the expansion valve (53), so that the opening of the expansion valve (53) is set to the third opening.

[0105] If the fourth command value is smaller than the third command value, the fourth selector (81) transmits the fourth command value to the expansion valve (53), so that the opening of the expansion valve (53) is set to the fourth opening.

[0106] Other Embodiments The following modifications may be applied to the air conditioner (10) of the above embodiment. The following modifications may be combined or substituted as appropriate, as long as the functionality of the air conditioner (10) is not impaired.

[0107] The object for air conditioning by the air conditioners (10) of the first to sixth embodiments is not limited to the test room (100). The air conditioners (10) of the first to sixth embodiments may be used for air conditioning a large space such as a hall, for example.

[0108] In the air conditioner (10) of the first to sixth embodiments, each of the first expansion valve controller (75), the second expansion valve controller (76), the first selector (77), the third expansion valve controller (78), the second selector (79), the third selector (80), and the fourth selector (81) may include a microcomputer. The controller (70) may be configured as a single microcomputer. The microcomputer constituting the controller (70) may also be configured to perform the control operation performed by at least one of the compressor controller (47) and the heater controller (37).

[0109] Furthermore, the air conditioner (10) of the first to sixth embodiments may be provided with a hot gas flow rate control configuration in which a gas supply pipe is provided in the refrigerant circuit (50) for sending the gas refrigerant (hot gas) discharged from the compressor (51) to the evaporator (54) bypassing the condenser (52), and a control valve is provided in the gas supply pipe, and the opening of the control valve is adjusted based on the pressure of the refrigerant flowing out of the evaporator (54), thereby controlling the amount of hot gas supplied to the evaporator (54).

[0110] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and detail are possible without departing from the spirit and scope of the claims. Furthermore, elements of the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate. Furthermore, the terms "first," "second," "third," etc. in the specification and claims are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0111] As described above, the present disclosure is useful for air conditioning apparatuses. [Explanation of symbols]

[0112] 10 Air conditioning equipment 50 Refrigerant circuit 51 Compressor 52 Condenser 53 Expansion valve 54 Evaporator 62 Outlet temperature sensor (third detection unit) 63 Outlet pressure sensor (second detection unit) 65 Air conditioning device (first detection unit) 66 Air conditioning device (first detection unit) 70 Controller

Claims

1. An air conditioner comprising a refrigerant circuit (50) having a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54), wherein a refrigerant is circulated in the refrigerant circuit (50) to perform a refrigeration cycle, and air is cooled in the evaporator (54), a first detector (65, 66) for detecting the temperature and humidity of air that has passed through the evaporator (54); a controller (70) that controls the opening of the expansion valve (53) based on the detection result of the first detection section (65, 66); Equipped with The first detection section (65, 66) the temperature of the air having passed through the evaporator (54); and and detecting the humidity of the air that has passed through the evaporator (54); The controller (70) determining a first opening degree of the expansion valve (53) based on the temperature of the air detected by the first detection section (65); determining a second opening degree of the expansion valve (53) based on the humidity of the air detected by the first detection part (66); The air conditioner controls the opening degree of the expansion valve (53) so that the opening degree becomes the larger of the first opening degree and the second opening degree.

2. An air conditioner comprising a refrigerant circuit (50) having a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54), wherein a refrigerant is circulated in the refrigerant circuit (50) to perform a refrigeration cycle, and air is cooled in the evaporator (54), a first detector (65) for detecting the temperature of air that has passed through the evaporator (54); a second detector (63) for detecting the temperature of the refrigerant flowing from the evaporator (54) toward the compressor (51); a third detector (62) for detecting the pressure of the refrigerant flowing from the evaporator (54) toward the compressor (51); a controller (70) that controls the opening degree of the expansion valve (53) based on the detection results of the first detection section (65), the second detection section (63), and the third detection section (62); Equipped with The controller (70) determining a third degree of opening of the expansion valve (53) based on the temperature of the air detected by the first detection section (65); determining a fourth degree of opening of the expansion valve (53) based on the temperature of the refrigerant detected by the second detection part (63) and the pressure of the refrigerant detected by the third detection part (62); The air conditioner controls the opening degree of the expansion valve (53) so that the opening degree becomes the smaller of the third opening degree and the fourth opening degree.

3. An air conditioner comprising a refrigerant circuit (50) having a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54), wherein a refrigerant is circulated in the refrigerant circuit (50) to perform a refrigeration cycle, and air is cooled in the evaporator (54), a first detector (66) for detecting the humidity of air that has passed through the evaporator (54); a second detector (63) for detecting the temperature of the refrigerant flowing from the evaporator (54) toward the compressor (51); a third detector (62) for detecting the pressure of the refrigerant flowing from the evaporator (54) toward the compressor (51); a controller (70) that controls the opening degree of the expansion valve (53) based on the detection results of the first detection section (66), the second detection section (63), and the third detection section (62); Equipped with The controller (70) determining a fifth degree of opening of the expansion valve (53) based on the humidity of the air detected by the first detection section (66); determining a sixth degree of opening of the expansion valve (53) based on the temperature of the refrigerant detected by the second detection part (63) and the pressure of the refrigerant detected by the third detection part (62); The air conditioner controls the opening degree of the expansion valve (53) so that the opening degree becomes the smaller of the fifth opening degree and the sixth opening degree.

4. An air conditioner comprising a refrigerant circuit (50) having a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54), wherein a refrigerant is circulated in the refrigerant circuit (50) to perform a refrigeration cycle, and air is cooled in the evaporator (54), a first detector (65, 66) for detecting the temperature and humidity of air that has passed through the evaporator (54); a second detector (63) for detecting the temperature of the refrigerant flowing from the evaporator (54) toward the compressor (51); a third detector (62) for detecting the pressure of the refrigerant flowing from the evaporator (54) toward the compressor (51); a controller (70) that controls the opening of the expansion valve (53) based on the detection results of the first detectors (65, 66), the second detector (63), and the third detector (62); Equipped with The first detection section (65, 66) the temperature of the air having passed through the evaporator (54); and and detecting the humidity of the air that has passed through the evaporator (54); The controller (70) determining a seventh degree of opening of the expansion valve (53) based on the temperature of the air detected by the first detection section (65); determining an eighth degree of opening of the expansion valve (53) based on the humidity of the air detected by the first detection section (66); determining a ninth opening degree that is the larger of the seventh opening degree and the eighth opening degree; determining a tenth degree of opening of the expansion valve (53) based on the temperature of the refrigerant detected by the second detection part (63) and the pressure of the refrigerant detected by the third detection part (62); The air conditioner controls the opening degree of the expansion valve (53) so that the opening degree becomes the smaller of the ninth opening degree and the tenth opening degree.

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