JP2018151102A - Air-conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress excessive indoor cooling while bringing the interior of a room into a comfortable state, in an air-conditioning device for controlling an operation capacity of a compressor so that an evaporation temperature of a refrigerant reaches a target evaporation temperature at a cooling operation.SOLUTION: An air-conditioning device (1) includes: a refrigerant circuit (10) having a compressor (21), an outdoor heat exchanger (24), an expansion mechanism (25) and an indoor heat exchanger (42); and a control part (7) for controlling an operation of the refrigerant circuit (10). The control part (7) controls an operation capacity of the compressor (21) so that an evaporation temperature of a refrigerant reaches a target evaporation temperature at a cooling operation. Here, the control part (7) performs evaporation temperature limit control for limiting the target evaporation temperature so as to be raised according to a discomfort index.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner that controls the operating capacity of a compressor so that the evaporation temperature of a refrigerant becomes a target evaporation temperature during cooling operation.

  Conventionally, a refrigerant circuit having a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger, and a control unit that controls the operation of the refrigerant circuit are included, and the control unit converts the indoor heat exchanger into the refrigerant. There is an air conditioner that controls the operating capacity of the compressor so that the evaporation temperature of the refrigerant becomes the target evaporation temperature during the cooling operation in which the room is cooled by functioning as an evaporator. And as such an air conditioning apparatus, as shown in patent document 1 (Unexamined-Japanese-Patent No. 2011-257126), what sets a target evaporation temperature based on the temperature difference of indoor temperature and setting indoor temperature is set. is there.

  In the air conditioner of Patent Document 1, the target evaporation temperature is set low when the temperature difference between the room temperature and the set room temperature is large. For this reason, for example, when the temperature difference between the room temperature and the set room temperature becomes large due to the set room temperature being set too low with respect to the room temperature, the target evaporation temperature is too low accordingly. As a result, the room is excessively cooled. On the other hand, it is conceivable to set the target evaporation temperature high. However, simply setting the target evaporation temperature to a high value can suppress excessive cooling in the room, but the room cannot be cooled to a comfortable state. There is a fear.

  An object of the present invention is to suppress excessive cooling in a room while keeping the room in a comfortable state in an air conditioner that controls the operation capacity of the compressor so that the evaporation temperature of the refrigerant becomes the target evaporation temperature during cooling operation. It is in.

  An air conditioner according to a first aspect includes a refrigerant circuit having a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger, and a control unit that controls the operation of the refrigerant circuit. The control unit controls the operation capacity of the compressor so that the evaporation temperature of the refrigerant becomes the target evaporation temperature during the cooling operation in which the indoor heat exchanger functions as an evaporator of the refrigerant to cool the room. And here, a control part performs evaporation temperature restriction | limiting control which restrict | limits target evaporation temperature so that it may become high according to the discomfort index in a room | chamber interior.

  Here, as described above, by performing the evaporation temperature limit control, the target evaporation temperature can be increased when the room is sufficiently cooled as viewed from the discomfort index. Can be suppressed. On the contrary, when the room is not sufficiently cooled as viewed from the discomfort index, the room can be cooled to a comfortable state by promoting the room cooling without increasing the target evaporation temperature.

  As described above, by performing the evaporation temperature limit control, excessive cooling of the room can be suppressed while making the room comfortable.

  In addition, here, the target evaporation temperature can be increased by the evaporation temperature restriction control to reduce the operating capacity of the compressor, so that the power consumption of the compressor can be reduced and energy saving can be achieved. Further, by suppressing the operating capacity of the compressor to be small, it is possible to reduce the repetition of the start and stop of the compressor (that is, thermo-on and thermo-off), and thus it is possible to suppress fluctuations in the room temperature.

  In the air conditioner according to the second aspect, in the air conditioner according to the first aspect, the control unit obtains the target evaporation temperature based on the temperature difference between the room temperature and the set room temperature.

  As described above, when the target evaporation temperature is set based on the temperature difference between the room temperature and the set room temperature, for example, the set room temperature is excessively lower than the room temperature because the discomfort index is not considered. When the temperature difference between the room temperature and the set room temperature becomes large due to setting or the like, the target evaporation temperature is set low. For this reason, even if it is a case where the room is in a comfortable state that is sufficiently cooled as viewed from the discomfort index, the room is further cooled.

  However, here, by performing the evaporation temperature restriction control as described above, the target evaporation temperature may be made higher than the value obtained based on the temperature difference between the room temperature and the set room temperature according to the discomfort index. Therefore, excessive cooling of the room can be suppressed while making the room comfortable.

  The air conditioner according to the third aspect is the air conditioner according to the first or second aspect, wherein the control unit increases the target evaporation temperature lower limit, which is the lower limit value of the target evaporation temperature, to control the evaporation temperature limit. I do.

  Here, as described above, since the evaporation temperature limit control is performed by providing the target evaporation temperature lower limit that is the lower limit value of the target evaporation temperature, the set target evaporation temperature is lower than the target evaporation temperature lower limit. In this case, the target evaporation temperature can be increased to the target evaporation temperature lower limit. Conversely, if the set target evaporation temperature is equal to or higher than the target evaporation temperature lower limit, the target evaporation temperature can be maintained at the set value.

  Thereby, here, evaporating temperature restriction control can be performed while maintaining the setting of the target evaporating temperature as much as possible.

  In the air conditioner according to the fourth aspect, in the air conditioner according to the first aspect, the control unit obtains the discomfort index based on at least the room temperature and the room humidity.

  Here, as described above, the discomfort index is obtained based on the room temperature and the room humidity. For example, the discomfort index can be obtained by preparing the discomfort index in the form of a function of room temperature and humidity and inputting the room temperature and humidity in this function. In general, the discomfort index is expressed as a function of temperature and humidity only, but here, the discomfort index is obtained by taking into account "at least" the room temperature and the room humidity. The value obtained in consideration of factors other than humidity is also included in the discomfort index.

  Thereby, when performing evaporation temperature restriction | limiting control here, the discomfort index in a room | chamber interior can be considered correctly.

  As described above, according to the present invention, by performing the evaporation temperature limit control, it is possible to suppress excessive cooling of the room while making the room comfortable.

It is a schematic block diagram of the air conditioning apparatus concerning one Embodiment of this invention. It is a control block diagram of an air conditioning apparatus. It is a flowchart which shows evaporation temperature restriction | limiting control. It is a figure which shows the relationship between the discomfort index in a room | chamber, and the target evaporation temperature minimum.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an air conditioner according to the present invention will be described based on the drawings. In addition, the specific structure of embodiment of the air conditioning apparatus concerning this invention is not restricted to the following embodiment and its modification, It can change in the range which does not deviate from the summary of invention.

(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 is an apparatus that air-conditions a room such as a building by a vapor compression refrigeration cycle. The air conditioner 1 mainly includes an outdoor unit 2, an indoor unit 4, and a liquid refrigerant communication tube 5 and a gas refrigerant communication tube 6 that connect the outdoor unit 2 and the indoor unit 4. The vapor compression refrigerant circuit 10 of the air conditioner 1 is configured by connecting the outdoor unit 2 and the indoor unit 4 via a liquid refrigerant communication tube 5 and a gas refrigerant communication tube 6.

<Indoor unit>
The indoor unit 4 is installed in a room such as a building. As described above, the indoor unit 4 is connected to the outdoor unit 2 via the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6 and constitutes a part of the refrigerant circuit 10.

  Next, the configuration of the indoor unit 4 will be described.

  The indoor unit mainly has an indoor heat exchanger 42.

  The indoor heat exchanger 42 is a heat exchanger that functions as a low-pressure refrigerant evaporator in the refrigeration cycle during cooling operation to cool the room, and has a liquid side end connected to the liquid refrigerant communication pipe 5 and a gas side end. Is connected to the gas refrigerant communication pipe 6.

  Moreover, the indoor unit 4 has an indoor fan 43 for supplying indoor air as supply air after sucking indoor air into the indoor unit 4 and exchanging heat with the refrigerant in the indoor heat exchanger 42. . That is, the indoor unit 4 has an indoor fan 43 as a fan that sends indoor air as a heating source of the refrigerant flowing through the indoor heat exchanger 42 to the indoor heat exchanger 42. Here, as the indoor fan 43, a centrifugal fan or a multiblade fan driven by an indoor fan motor 44 is used.

  The indoor unit 4 is provided with various sensors. Specifically, the indoor unit 4 is provided with an indoor temperature sensor 45 and an indoor humidity sensor 46 that detect the temperature and humidity of the indoor air sucked into the indoor unit 4 (that is, the indoor temperature Tr and the indoor humidity Hr). It has been.

  Further, the indoor unit 4 includes an indoor side control unit 40 that controls the operation of each unit constituting the indoor unit 4. And the indoor side control part 40 has a microcomputer, memory, etc. provided in order to control the indoor unit 4, and exchanges a control signal etc. between remote controls (not shown). In addition, control signals and the like can be exchanged with the outdoor unit 2 via a communication line or the like.

<Outdoor unit>
The outdoor unit 2 is installed outside a building or the like. As described above, the outdoor unit 2 is connected to the indoor unit 4 via the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6 and constitutes a part of the refrigerant circuit 10.

  Next, the configuration of the outdoor unit 2 will be described.

  The outdoor unit 2 mainly includes a compressor 21, an outdoor heat exchanger 24, and an outdoor expansion valve 25.

  The compressor 21 is a device that compresses the low-pressure refrigerant in the refrigeration cycle until the pressure becomes high. Here, as the compressor 21, a compressor having a hermetic structure in which a rotary type or scroll type positive displacement compression element (not shown) is rotationally driven by a compressor motor 22 is used. Further, here, the compressor motor 22 can be controlled in rotation speed (frequency) by an inverter or the like, whereby the operation capacity of the compressor 21 can be controlled.

  The outdoor heat exchanger 24 is a heat exchanger that functions as a high-pressure refrigerant radiator in the refrigeration cycle during cooling operation, and has a gas side end connected to the discharge side of the compressor 21 and a liquid side end outdoor. It is connected to the expansion valve 25.

  The outdoor expansion valve 25 is an expansion mechanism that depressurizes the refrigerant to a low pressure in the refrigeration cycle during the cooling operation. Here, an electric expansion valve is used as the outdoor expansion valve 25. The outdoor expansion valve 25 is connected between the liquid side end of the outdoor heat exchanger 24 and the liquid refrigerant communication pipe 5.

  The outdoor unit 2 has an outdoor fan 26 for sucking outdoor air into the outdoor unit 2, exchanging heat with the refrigerant in the outdoor heat exchanger 24, and then discharging the outdoor air. That is, the outdoor unit 2 has an outdoor fan 26 as a fan that sends outdoor air as a cooling source of the refrigerant flowing through the outdoor heat exchanger 24 to the outdoor heat exchanger 24. Here, a propeller fan or the like driven by an outdoor fan motor 27 is used as the outdoor fan 26.

  The outdoor unit 2 is provided with various sensors. Specifically, the outdoor unit 2 is provided with a suction pressure sensor 28 that detects the suction pressure Ps of the compressor 21.

  Further, the outdoor unit 2 includes an outdoor side control unit 20 that controls the operation of each unit constituting the outdoor unit 2. The outdoor control unit 20 includes a microcomputer, a memory, and the like provided to control the outdoor unit 2, and communicates with the indoor control unit 40 of the indoor unit 4 via a communication line or the like. The control signals can be exchanged.

  As described above, the refrigerant circuit 10 of the air conditioner 1 is configured by connecting the outdoor unit 2 and the indoor unit 4 via the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6, and the compressor 21. The outdoor heat exchanger 24, the outdoor expansion valve 25 as an expansion mechanism, and the indoor heat exchanger 42 are provided. Moreover, the air conditioning apparatus 1 has the control part 7 comprised by connecting the indoor side control part 40 and the outdoor side control part 20 via a communication line etc. As shown in FIG. 2, the control unit 7 is connected to the various sensors 28, 45, and 46 so as to receive the detection signals of the various sensors 28, 45, and 46, and based on these detection signals and the like. Thus, the refrigerant circuit 10 (the compressor 21 and the outdoor expansion valve 25) and the fans 26 and 43 are connected to the various devices 21, 25, 26, and 43 so that the operations thereof can be controlled. And the control part 7 can perform the air_conditionaing | cooling operation etc. which cool an indoor by making the indoor heat exchanger 42 function as an evaporator of a refrigerant | coolant.

(2) Basic operation and basic control Next, the basic operation of the cooling operation of the air conditioner 1 will be described.

  The control unit 7 mainly supplies the refrigerant charged in the refrigerant circuit 10 to the compressor 21, the outdoor heat exchanger 24, the outdoor expansion valve 25, the liquid refrigerant communication pipe 5, the indoor heat exchanger 42, the gas refrigerant communication pipe 6, The cooling operation is performed by circulating the compressor 21 in order.

  Specifically, when the compressor 21, the outdoor fan 26, and the indoor fan 43 are operated, the refrigerant in the refrigerant circuit 10 is first sucked into the compressor 21 and compressed from low pressure to high pressure in the refrigeration cycle. After being discharged. The gaseous refrigerant discharged from the compressor 21 flows into the gas side end of the outdoor heat exchanger 24. The refrigerant flowing into the gas side end of the outdoor heat exchanger 24 exchanges heat with the outdoor air supplied by the outdoor fan 26 in the outdoor heat exchanger 24 to dissipate heat to become a liquid refrigerant, thereby exchanging the outdoor heat. It flows out from the liquid side end of the vessel 24. The refrigerant flowing out from the liquid side end of the outdoor heat exchanger 24 is depressurized to a low pressure in the refrigeration cycle by the outdoor expansion valve 25 adjusted to a predetermined opening, and is sent to the indoor unit 4 through the liquid refrigerant communication tube 5. The refrigerant sent to the indoor unit 4 flows into the liquid side end of the indoor heat exchanger 42. The refrigerant flowing into the liquid side end of the indoor heat exchanger 42 exchanges heat with the indoor air supplied by the indoor fan 43 in the indoor heat exchanger 42 to evaporate to become a refrigerant in a gas state, thereby exchanging indoor heat. It flows out from the gas side end of the vessel 42. In addition, the indoor air cooled by the heat exchange with the refrigerant in the indoor heat exchanger 42 is supplied into the room to cool the room. The refrigerant flowing out from the gas side end of the indoor heat exchanger 42 is sent to the outdoor unit 2 through the gas refrigerant communication pipe 6. The refrigerant sent to the outdoor unit 2 is sucked into the compressor 21 again.

  In the above cooling operation, the following basic control is performed.

  The control unit 7 mainly controls the room temperature to bring the room temperature Tr closer to the set room temperature Trs set by input from a remote controller (not shown) or the like, and the refrigerant evaporation temperature Te in the refrigerant circuit 10 is the target evaporation temperature Tes. Evaporation temperature control for controlling the operation capacity of the compressor 21 is performed.

  When the room temperature Tr is higher than the set room temperature Trs, the room temperature control performs the basic operation of the cooling operation (operation for operating the compressor 21 to circulate the refrigerant) (thermo on) When the temperature Tr reaches the set indoor temperature Trs, the compressor 21 is stopped to stop the refrigerant circulation and the cooling operation is stopped (thermo-off). Thereby, when the room temperature Tr is higher than the set room temperature Trs, the room temperature Tr can be lowered to approach the set room temperature Trs, and when the room temperature Tr reaches the set room temperature Trs, It is possible to prevent the indoor temperature Tr from moving away from the set indoor temperature Trs by suppressing the decrease in the indoor temperature Tr. In this way, the control unit 7 performs indoor temperature control that brings the room temperature Tr closer to the set room temperature Trs by performing the above-described thermo-on and thermo-off.

  In the evaporating temperature control, when the evaporating temperature Te of the refrigerant is higher than the target evaporating temperature Tes, the operating capacity of the compressor 21 is increased by increasing the rotational speed (frequency) of the compressor 21, and the evaporating temperature of the refrigerant. When Te is lower than the target evaporation temperature Tes, the operation capacity of the compressor 21 is reduced by reducing the rotational speed (frequency) of the compressor 21. As a result, when the refrigerant evaporation temperature Te is higher than the target evaporation temperature Tes, the refrigerant evaporation temperature Te can be lowered to approach the target evaporation temperature Tes, and the refrigerant evaporation temperature Te is higher than the target evaporation temperature Tes. If it is lower, the evaporation temperature Te of the refrigerant can be increased to approach the target evaporation temperature Tes. Here, the evaporating temperature Te of the refrigerant is obtained by converting the suction pressure Ps to the saturation temperature of the refrigerant. The refrigerant evaporation temperature Te represents a low-pressure refrigerant in a refrigeration cycle that flows from the outlet of the outdoor expansion valve 25 to the suction side of the compressor 21 through the indoor heat exchanger 42 during the cooling operation. Means the temperature obtained by converting the pressure (evaporation pressure Pe of the refrigerant in the refrigerant circuit 10) into the saturation temperature of the refrigerant, or the saturation temperature of the refrigerant in the indoor heat exchanger 42 functioning as the refrigerant evaporator Yes. For this reason, when providing a temperature sensor in the intermediate part of the indoor heat exchanger 42, the refrigerant temperature detected by this temperature sensor may be used as the refrigerant evaporation temperature Te. Here, the state quantity to be controlled is the evaporation temperature Te, but it may be the evaporation pressure Pe. In this case, the target evaporation pressure Pes corresponding to the target evaporation temperature Tes may be used as the control target value. That is, the evaporating pressure Pe and the evaporating temperature Te, and the target evaporating pressure Pe and the target evaporating temperature Te mean substantially the same state quantity although the wording itself is different. In this way, the control unit 7 performs the evaporation temperature control so that the refrigerant evaporation temperature Te becomes the target evaporation temperature Tes by performing the operation capacity control of the compressor 21 as described above.

(3) Evaporation Temperature Limit Control When the cooling operation with the basic control as described above is performed, the indoor temperature Tr in the indoor unit 4 is controlled to become the set indoor temperature Trs.

  Here, as in Patent Document 1, it is conceivable to set the target evaporation temperature Tes based on the temperature difference ΔTr (= Tr−Trs) between the room temperature Tr and the set room temperature Trs. That is, it is conceivable that the target evaporation temperature Tes is set lower as the temperature difference ΔTr is larger.

  Then, when the temperature difference ΔTr is large, the target evaporation temperature Tes is set low. For this reason, when the temperature difference ΔTr increases due to the set indoor temperature Trs being set too low with respect to the indoor temperature Tr, the target evaporation temperature Tes is also set too low accordingly. As a result, the room is excessively cooled. On the other hand, it is conceivable to set the target evaporation temperature Tes high. However, by simply setting the target evaporation temperature Tes high, excessive cooling of the room can be suppressed, but the room is cooled to a comfortable state. There is a risk that it will not be possible.

  For this reason, in the cooling operation in which the operation capacity of the compressor 21 is controlled so that the refrigerant evaporation temperature Te becomes the target evaporation temperature Tes, it is desirable to suppress excessive cooling in the room while keeping the room in a comfortable state.

  Therefore, here, when performing the evaporation temperature control, the control unit 7 performs the evaporation temperature limit control for limiting the target evaporation temperature Tes so as to increase according to the indoor discomfort index Di. Here, as the evaporation temperature restriction control, the control unit 7 performs the evaporation temperature restriction control by increasing the target evaporation temperature lower limit Tesm, which is the lower limit value of the target evaporation temperature Tes.

  Next, the evaporation temperature restriction control will be described with reference to FIGS. Here, FIG. 3 is a flowchart showing the evaporation temperature restriction control. FIG. 4 is a diagram showing the relationship between the indoor discomfort index Di and the target evaporation temperature lower limit Tesm.

  First, in step ST1, the control unit 7 obtains an indoor discomfort index Di based on the room temperature Tr and the room humidity Hr. Here, the indoor discomfort index Di is expressed as a function of the indoor temperature Tr and the indoor humidity Hr as in the following equation (k1 to k5 are coefficients).

Di = k1 * Tr + k2 * Hr * (k3 * Tr-k4) + k5
Then, the discomfort index Di is calculated by inputting the room temperature Tr and the room humidity Hr in the above equation. Here, the temperature and humidity detected by the room temperature sensor 45 and the room humidity sensor 46 are used as the room temperature Tr and the room humidity Hr.

  Next, in step ST2, the control unit 7 determines a target evaporation temperature lower limit Tesm according to the discomfort index Di obtained in step ST1. Here, as shown in FIG. 4, as the condition value of the discomfort index Di, the first index Di1, the second index Di2, the third index Di3, and the fourth index Di4 are set in order from the smallest, and the target evaporation As the set value of the temperature lower limit Tesm, the first lower limit Tesm1, the second lower limit Tesm2, the third lower limit Tesm3, the fourth lower limit Tesm4, and the fifth lower limit Tesm5 are set in order from the highest. When the discomfort index Di is less than the first index Di1, the target evaporation temperature lower limit Tesm is set to the first lower limit Tesm1. When the discomfort index Di is not less than the first index Di1 and less than the second index Di2, the target evaporation temperature lower limit Tesm is set to the second lower limit Tesm2. When the discomfort index Di is greater than or equal to the second index Di2 and less than the third index Di3, the target evaporation temperature lower limit Tesm is set to the third lower limit Tesm3. When the discomfort index Di is not less than the third index Di3 and less than the fourth index Di4, the target evaporation temperature lower limit Tesm is set to the fourth lower limit Tesm4. When the discomfort index Di is equal to or greater than the fifth index Di1, the target evaporation temperature lower limit Tesm is set to the fifth lower limit Tesm5. Thus, here, the lower the discomfort index Di in the room, the higher the target evaporation temperature lower limit Tesm. For example, the first index Di1 is set to a value of about 65 or less that the user in the room feels generally comfortable, and the fourth index Di4 is set to a value of about 80 or more that the user in the room generally feels uncomfortable. The second index Di2 and the third index Di3 are set in order so as to be a value between the first index Di1 and the fourth index Di4. The first lower limit Tesm1 is set to be about 6 ° C. to 10 ° C. higher than the fifth lower limit Tesm5, and the second lower limit Tesm2 to the fourth lower limit Tesm4 are the first lower limit Tesm1 and the fifth lower limit Tesm4. The values are set in order so as to be a value between Tesm5.

  Next, the control part 7 performs evaporation temperature restriction | limiting control which restrict | limits the target evaporation temperature Tes so that it may become high according to the indoor discomfort index Di in step ST3. That is, the untargeted evaporation temperature lower limit Tesm is set to a value (any one of the lower limits Tesm1 to Tesm5) determined in accordance with the indoor discomfort index Di in step ST2, and the target evaporation temperature Tes is the untargeted value that is the lower limit value It limits so that it may become more than evaporation temperature minimum Tesm.

  For example, the target evaporation temperature Tes obtained based on the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs is a value Tes4 between the fourth lower limit Tesm4 and the fifth lower limit Tesm5, and the indoor discomfort index Di Is less than the first index Di1. In this case, in step ST2, the target evaporation temperature lower limit Tesm becomes the first lower limit Tesm1 that is significantly higher than the value Tes4 obtained based on the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs. That is, in this case, since the room is sufficiently cooled as viewed from the discomfort index Di, in step ST3, the target evaporation temperature Tes becomes the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs. It is not limited to the value Tes4 obtained on the basis, but is limited to the first lower limit Tesm1 that is significantly higher than the value Tes4. Further, when the target evaporation temperature Tes obtained based on the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs is the value Tes4, and the indoor discomfort index Di is not less than the third index Di3 and less than the fourth index Di4. In step ST2, the target evaporation temperature lower limit Tesm is slightly higher than the value Tes4 obtained based on the temperature difference ΔTr between the indoor temperature Tr and the set indoor temperature Trs, and becomes the fourth lower limit Tesm4. That is, in this case as well, since the room is sufficiently cooled as viewed from the discomfort index Di, in step ST3, the target evaporation temperature Tes becomes the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs. It is not limited to the value Tes4 obtained on the basis, but is limited to the fourth lower limit Tesm4 that is slightly higher than the value Tes4. On the other hand, if the target evaporation temperature Tes obtained based on the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs is the value Tes4, and the indoor discomfort index Di is equal to or greater than the fourth index Di4, step ST2 The target evaporation temperature lower limit Tesm becomes the fifth lower limit Tesm5 that is slightly lower than the value Tes4 obtained based on the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs. That is, in this case, since the room is not sufficiently cooled as viewed from the discomfort index Di, the target evaporation temperature Tes is not limited by the fifth lower limit Tesm5 in step ST3, and the room temperature Tr and the set room temperature are set. The value Tes4 obtained based on the temperature difference ΔTr with respect to the temperature Trs is maintained.

  As described above, here, by performing the evaporation temperature limit control, the target evaporation temperature Tes can be increased when the room is sufficiently cooled as viewed from the discomfort index Di. Cooling can be suppressed. On the other hand, when the room is not sufficiently cooled as viewed from the discomfort index Di, the room can be cooled to a comfortable state by promoting the room cooling without increasing the target evaporation temperature Tes. it can.

  In particular, here, as described above, the target evaporation temperature Tes is set based on the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs, and therefore, the discomfort index Di is not considered as it is. For this reason, for example, when the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs becomes large due to the set room temperature Trs being set too low with respect to the room temperature Tr, the target evaporation temperature Tes is low. Will be set. For this reason, even if it is a case where it is a comfortable state where the room was fully cooled when viewed from the discomfort index Di, the room is further cooled. However, here, by performing the evaporation temperature restriction control as described above, the target evaporation temperature Tes is obtained from the value obtained based on the temperature difference ΔTr between the room temperature Tr and the set room temperature Trs according to the discomfort index Di. Can also be high.

  Thereby, here, by performing the evaporation temperature restriction control, it is possible to suppress excessive cooling of the room while making the room comfortable.

  In addition, here, the target evaporation temperature Tes can be increased by the evaporation temperature restriction control to reduce the operating capacity of the compressor 21, so that the power consumption of the compressor 21 can be reduced and energy saving can be achieved. Can do. Moreover, since the repetition of the start / stop of the compressor 21 (that is, thermo-on and thermo-off) can be reduced by suppressing the operating capacity of the compressor 21, fluctuations in the indoor temperature Tr can be suppressed.

  Here, as described above, since the evaporation temperature limit control is performed by providing the target evaporation temperature lower limit Tesm that is the lower limit value of the target evaporation temperature Tes, the set target evaporation temperature Tes is the target evaporation temperature. When the temperature is lower than the lower temperature limit Tesm, the target evaporation temperature Tes can be increased to the target evaporation temperature lower limit Tesm. Conversely, when the set target evaporation temperature Tes is equal to or higher than the target evaporation temperature lower limit Tesm, the target evaporation temperature Tes can be maintained at the set value.

  Thereby, here, evaporation temperature restriction | limiting control can be performed, maintaining the setting of target evaporation temperature Tes as much as possible.

  Here, as described above, since the discomfort index Di is obtained based on at least the room temperature Tr and the room humidity Hr, the discomfort index Di in the room is accurately considered when performing the evaporation temperature restriction control. can do.

(4) Modification <A>
In the evaporating temperature restriction control of the above embodiment, as shown in FIG. 3, the target evaporating temperature Tes is restricted so as to increase stepwise in accordance with the indoor discomfort index Di (that is, the smaller the discomfort index Di). However, it is not limited to this. For example, the target evaporation temperature Tes may be limited so as to be continuously increased according to the discomfort index Di in the room.

<B>
In the evaporation temperature restriction control of the above embodiment, the target evaporation temperature Tes is increased by increasing the target evaporation temperature lower limit Tesm in accordance with the indoor discomfort index Di (that is, the smaller the discomfort index Di). However, the present invention is not limited to this. For example, the target evaporation temperature Tes may be increased by adding a correction value corresponding to the indoor discomfort index Di to the target evaporation temperature Tes.

<C>
In the evaporating temperature restriction control of the above embodiment, the indoor discomfort index Di is obtained considering only the indoor temperature Tr and the indoor humidity Hr. However, the present invention is not limited to this. For example, in addition to the room temperature Tr and the room humidity Hr, factors other than temperature and humidity such as wind speed may be taken into consideration. That is, here, the discomfort index Di may be obtained in consideration of “at least” the room temperature Tr and the room humidity Hr.

<D>
In the above embodiment, the present invention is applied to the cooling-only air conditioner 1 that performs only the cooling operation. However, the present invention is not limited to this. For example, the present invention may be applied to an air conditioner that can be switched between a cooling operation and a heating operation. Moreover, in the said embodiment, although this invention is applied to the air conditioning apparatus 1 with which the one indoor unit 4 was connected to the outdoor unit 2, it is not limited to this. For example, the present invention may be applied to an air conditioner in which a plurality of indoor units are connected to an outdoor unit.

<E>
In the above embodiment, the electric expansion valve is used as the expansion mechanism, but the present invention is not limited to this. For example, the expansion mechanism may be a capillary tube or an expander. Moreover, in the said embodiment, although the outdoor expansion valve 25 is used as an expansion mechanism, it is not limited to this. For example, in a configuration in which the indoor unit 4 includes an indoor expansion valve, the indoor expansion valve may be used as an expansion mechanism.

  The present invention is widely applicable to an air conditioner that controls the operating capacity of a compressor so that the evaporation temperature of the refrigerant becomes a target evaporation temperature during the cooling operation.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 7 Control part 10 Refrigerant circuit 21 Compressor 24 Outdoor heat exchanger 25 Outdoor expansion valve (expansion mechanism)
42 Indoor heat exchanger

JP 2011-257126 A

Claims (4)

A refrigerant circuit (10) having a compressor (21), an outdoor heat exchanger (24), an expansion mechanism (25), and an indoor heat exchanger (42), and a controller (7) for controlling the operation of the refrigerant circuit; And the control unit compresses the refrigerant so that the refrigerant evaporating temperature becomes a target evaporating temperature during cooling operation in which the indoor heat exchanger functions as a refrigerant evaporator to cool the room. In the air conditioner that controls the operating capacity of the machine,
The control unit performs evaporation temperature restriction control for restricting the target evaporation temperature to be higher according to an uncomfortable index in the room.
Air conditioner (1). The control unit obtains the target evaporation temperature based on a temperature difference between a room temperature and a set room temperature.
The air conditioning apparatus according to claim 1. The control unit performs the evaporation temperature restriction control by increasing a target evaporation temperature lower limit that is a lower limit value of the target evaporation temperature.
The air conditioning apparatus according to claim 1 or 2. The control unit obtains the discomfort index based on at least indoor temperature and indoor humidity.
The air conditioning apparatus according to claim 1.

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