Air conditioner, air conditioning system, control method for air conditioner, and program

Abstract

An air conditioner (1) comprises: a fan (43) that sucks in air from a suction port (731) of an indoor unit chamber (73) and blows out the air in the indoor unit chamber (73) into a room from blow-out ports (732, 733) provided in the indoor unit chamber (73); an electric heater that is provided in the indoor unit chamber (73) and can heat the air in the indoor unit chamber (73); a first temperature sensor that measures the temperature of the air sucked in from the suction port (731); a second temperature sensor that measures the temperature of the air blown out from the blow-out ports (732, 733); and a controller (60) that acquires first temperature data and second temperature data from the first temperature sensor and the second temperature sensor in a state in which constant power is supplied to the electric heater to generate heat while rotating the fan (43) at a constant rotation speed, determines that a filter (44) is contaminated when the temperature difference between the acquired first temperature data and second temperature data satisfies a reference condition, and outputs a contamination signal for maintenance of the filter (44).

Description

Air conditioner, air conditioning system, control method and program for an air conditioner

[0001] The present disclosure relates to an air conditioner, an air conditioning system, a control method for an air conditioner, and a program.

[0002] Some air conditioners determine the presence or absence of fouling of a filter provided at an air intake, for example, clogging due to fouling.

[0003] For example, Patent Document 1 discloses an air conditioner that determines that a filter is clogged when the temperature difference between the air at the intake and the air at the outlet exceeds an allowable value.

[0004] Further, Patent Document 2 discloses an air conditioner that, when the integrated operation time of the air conditioner main body exceeds a certain time, obtains the temperature difference between the air at the intake and the air at the outlet, and determines whether or not the filter is clogged based on the obtained temperature difference.

[0005] Japanese Utility Model Publication No. 56-075655, Japanese Patent Publication No. 61-52371

[0006] In the air conditioners described in Patent Documents 1 and 2, the indoor heat exchanger exchanges heat with the air inhaled from the intake. Therefore, the air at the outlet is the air that has been heat-exchanged by the indoor heat exchanger. As a result, the temperature difference between the air at the intake and the air at the outlet is affected by the operating state of the indoor heat exchanger. Thus, there are cases where it is not possible to accurately determine whether or not the filter is clogged.

[0007] The present disclosure has been made to solve the above problems, and an object thereof is to provide an air conditioner, an air conditioning system, a control method for an air conditioner, and a program that accurately determine the presence or absence of fouling of a filter and have high maintainability.

[0008] To achieve the above objectives, the air conditioner according to this disclosure comprises a fan, an electric heater, a first temperature sensor, a second temperature sensor, and a controller. The fan is located in the indoor unit room, draws in indoor air from an intake port having a filter, blows the drawn-in air to an indoor heat exchanger located in the indoor unit room, and blows the air from the indoor unit room into the room from an outlet located in the indoor unit room. The electric heater is located in the indoor unit room and is capable of heating the air in the indoor unit room. The first temperature sensor measures the temperature of the air drawn in from the intake port. The second temperature sensor measures the temperature of the air blown out from the outlet. The controller rotates the fan at a constant speed and supplies a constant power to the electric heater to generate heat, while acquiring first temperature data and second temperature data from the first and second temperature sensors. If the temperature difference between the acquired first and second temperature data satisfies a standard condition, the controller determines that the filter is contaminated and outputs a contaminated signal for filter maintenance.

[0009] According to the configuration of this disclosure, when the controller determines whether or not the filter is contaminated, it rotates the fan at a constant speed to blow air at a constant volume, and further generates a constant amount of heat in the electric heater with a constant power. As a result, the condition of the filter is accurately reflected in the temperature difference between the acquired first temperature data and the second temperature data. Consequently, the controller can accurately determine whether or not the filter is contaminated. In addition, the air conditioner has high maintainability.

[0010] Cross-sectional view of the air conditioner according to Embodiment 1 of this disclosure Hardware configuration diagram of the controller of the air conditioner according to Embodiment 1 of this disclosure Flowchart of the first filter replacement determination process performed by the controller of the air conditioner according to Embodiment 1 of this disclosure Flowchart of the second filter replacement determination process performed by the controller of the air conditioner according to Embodiment 2 of this disclosure Graph showing the change in temperature difference between the temperature of the air taken in from the intake port and the temperature of the air blown out from the outlet port when the fan speed is increased in the second filter replacement determination process performed by the controller of the air conditioner according to Embodiment 2 of this disclosure A graph showing another trend in the temperature difference between the temperature of the air taken in from the intake port and the temperature of the air blown out from the outlet when the fan speed is increased in the second filter replacement determination process. A graph showing yet another trend in the temperature difference between the temperature of the air taken in from the intake port and the temperature of the air blown out from the outlet in the second filter replacement determination process performed by the controller of the air conditioner according to Embodiment 2 of this disclosure. A flowchart of the third filter replacement determination process performed by the controller of the air conditioner according to Embodiment 3 of this disclosure. A graph showing an example of the trend in the temperature difference between the temperature of the air taken in from the intake port and the temperature of the air blown out from the outlet of the frame of the air conditioner according to Embodiment 4 of this disclosure.

[0011] Hereinafter, an air conditioner, an air conditioning system, a control method for the air conditioner, and a program according to embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

[0012] (Embodiment 1) The air conditioner according to Embodiment 1 is an air conditioner that harmonizes the indoor air of a railway vehicle. In order to improve maintainability, this air conditioner has a controller that determines whether or not the filter provided at the intake port is contaminated, for example, whether or not it is clogged. First, with reference to Figure 1, the configuration of the air conditioner that is controlled by the controller will be described.

[0013] Figure 1 is a cross-sectional view of the air conditioner 1 according to Embodiment 1. For ease of understanding, the airflow is indicated by arrows in Figure 1. Also, Figure 1 shows only a typical wiring diagram of the controller 60.

[0014] As shown in Figure 1, the air conditioner 1 comprises a compressor 10 for compressing the refrigerant, outdoor heat exchangers 21 and 22 for exchanging heat between the refrigerant and outside air, expansion valves 31 and 32 for expanding the refrigerant, indoor heat exchangers 41 and 42 for exchanging heat between the refrigerant and indoor air, heaters 51 and 52 capable of heating indoor air, and a controller 60. The compressor 10, outdoor heat exchangers 21 and 22, expansion valves 31 and 32, and indoor heat exchangers 41 and 42 are connected by piping in this order to form a refrigerant circuit.

[0015] The compressor 10 is a device that converts low-pressure refrigerant into high-pressure refrigerant by compressing it. The compressor 10 has an inlet and a discharge port (not shown), which draw in low-pressure refrigerant from the inlet and discharge high-pressure refrigerant from the discharge port. These inlet and discharge ports are connected to a four-way valve (not shown). Outdoor heat exchangers 21 and 22 and indoor heat exchangers 41 and 42 are further connected to this four-way valve.

[0016] Although not shown in the diagram, the four-way valve, under the control of the controller 60, directs the refrigerant from either the outdoor heat exchangers 21, 22 or the indoor heat exchangers 41, 42 to the intake port of the compressor 10. The four-way valve also directs the high-pressure refrigerant discharged from the compressor 10 to the other of the outdoor heat exchangers 21, 22 or the indoor heat exchangers 41, 42. In this way, the four-way valve switches the direction of refrigerant flow in the refrigerant circuit. As a result, the four-way valve switches the operating state of the air conditioner 1 to either cooling operation or heating operation.

[0017] The compressor 10 supplies high-pressure refrigerant to the outdoor heat exchangers 21 and 22 by switching the four-way valve. This causes the compressor 10 to operate the air conditioner 1 in cooling mode. Alternatively, the compressor 10 supplies high-pressure refrigerant to the indoor heat exchangers 41 and 42 by switching the four-way valve. This causes the compressor 10 to operate the air conditioner 1 in heating mode. In this way, the compressor 10 causes the air conditioner 1 to operate in cooling or heating mode by switching the four-way valve. To facilitate understanding, the following explanation will assume that the air conditioner 1 is operating in cooling mode.

[0018] The outdoor heat exchangers 21 and 22 are, for example, fin-and-tube type heat exchangers. The outdoor heat exchangers 21 and 22 exchange heat between outside air taken in from outside the railway vehicle and refrigerant flowing through the tubes. Specifically, the outdoor heat exchangers 21 and 22 have tubes (not shown), and high-pressure refrigerant compressed by the compressor 10 is supplied to these tubes. On the other hand, the outdoor heat exchangers 21 and 22 also have fins (not shown), and outside air is blown onto these fins by the fan 23. The outdoor heat exchangers 21 and 22 exchange heat between the refrigerant flowing through the tubes and the outside air blown onto the fins, thereby condensing the refrigerant. As a result, the outdoor heat exchangers 21 and 22 function as condensers. Each of the outdoor heat exchangers 21 and 22 supplies the condensed refrigerant to the expansion valves 31 and 32, respectively.

[0019] The expansion valves 31 and 32 are, for example, solenoid valves or motorized valves and are equipped with valve bodies. The expansion valves 31 and 32 open and close the flow path of the refrigerant using their valve bodies. A controller 60 is electrically connected to the expansion valves 31 and 32, and the opening degree of the flow path by the valve body is adjusted by the output of the controller 60. The refrigerant is then depressurized according to the opening degree. As a result, the expansion valves 31 and 32 depressurize the refrigerant to a pressure corresponding to the output of the controller 60 and expand it. Each of the expansion valves 31 and 32 flows the expanded refrigerant to the indoor heat exchangers 41 and 42, respectively. Note that the expansion valves 31 and 32 can also be made of capillary tubes with a constant opening degree.

[0020] The indoor heat exchangers 41 and 42, like the outdoor heat exchangers 21 and 22, are, for example, fin-and-tube type heat exchangers. The indoor heat exchangers 41 and 42 exchange heat between the indoor air of the railway vehicle and the refrigerant flowing through the tubes. In detail, the indoor heat exchangers 41 and 42, like the outdoor heat exchangers 21 and 22, have tubes (not shown) through which the refrigerant expanded by expansion valves 31 and 32 flows. The indoor heat exchangers 41 and 42 also have fins (not shown) through which the indoor air of the railway vehicle is blown from a fan 43. As a result, the indoor heat exchangers 41 and 42 exchange heat between the refrigerant flowing through the tubes and the indoor air blown onto the fins. In this way, the indoor heat exchangers 41 and 42 absorb heat from the indoor air and evaporate the refrigerant. The indoor heat exchangers 41 and 42 function as evaporators. As a result, the indoor heat exchangers 41 and 42 cool the indoor air. As a result, the indoor heat exchangers 41 and 42 cool the inside of the railway car.

[0021] On the other hand, heaters 51 and 52 have electric heaters that generate heat when electricity is supplied. Heaters 51 and 52 are positioned near the indoor heat exchangers 41 and 42, respectively. The heaters 51 and 52, under the control of power supply by the controller 60, heat the indoor air blown by the fan 43 during heating operation to assist in heating, and remove frost that accumulates on the indoor heat exchangers 41 and 42 during cooling operation.

[0022] Each component of the air conditioner 1 is housed in a frame 70. More specifically, the frame 70 has an outdoor unit room 71, a compressor room 72, and an indoor unit room 73. Of these rooms, the outdoor unit room 71 houses outdoor heat exchangers 21, 22, a fan 23, and expansion valves 31, 32. The compressor room 72 houses the compressor 10. Furthermore, the indoor unit room 73 houses indoor heat exchangers 41, 42, a fan 43, and heaters 51, 52.

[0023] The outdoor unit room 71 has an intake port (not shown) and outlet ports 712 and 713 shown in Figure 1. In the outdoor unit room 71, an internal fan 23 rotates, drawing in outside air from the intake port (not shown) and supplying it to the outdoor heat exchangers 21 and 22. Furthermore, the outside air that has undergone heat exchange with the outdoor heat exchangers 21 and 22 is discharged from the outlet ports 712 and 713.

[0024] Similarly, the indoor unit room 73 has an intake port 731 and outlet ports 732 and 733 that connect to the interior of the railway vehicle. In the indoor unit room 73, the fan 43 inside rotates, drawing in indoor air from the intake port 731, and supplying the drawn-in indoor air to the indoor heat exchangers 41 and 42. Furthermore, the indoor air that has exchanged heat with the indoor heat exchangers 41 and 42 is returned to the interior through the outlet ports 732 and 733. As a result, the interior of the railway vehicle is air-conditioned.

[0025] Furthermore, the indoor unit room 73 has dampers 734 and 735 for taking outside air into the interior of the railway vehicle, and a damper 736 provided at the fresh air intake 723 of the compressor room 72 for taking in fresh air entering from the communication ports 721 and 722. Of the dampers 734-736, damper 736 is provided for taking in fresh air into the interior of the railway vehicle and is also called a fresh air damper. Damper 736 switches between a state in which the indoor unit room 73 is connected to the outside and a state in which the indoor unit room 73 is isolated from the outside by opening and closing the air passage formed in the fresh air intake 723. As a result, damper 736 switches between a state in which the air conditioner 1 conditioned the air while taking in fresh air, i.e., outside air, and a state in which the air conditioner 1 conditioned the air by circulating the air inside the railway vehicle.

[0026] In this configuration, the air conditioner 1 is equipped with a filter 44 to remove dust from the air in the room being air-conditioned. Specifically, the filter 44 is fitted into the air intake 731. However, when the air conditioner 1 is operated for a certain period of time, the filter 44 becomes clogged with dust, dirt, deformation, damage, etc., resulting in a large pressure loss. As a result, the airflow of the fan 43 decreases, and the air conditioning performance of the air conditioner 1 deteriorates. In some cases, this can lead to poor evaporation of the refrigerant in the indoor heat exchangers 41 and 42, which can adversely affect the refrigeration cycle.

[0027] To resolve these issues, a long-life filter 44 is used. However, even with such a filter 44, it is necessary to replace it with a new one after operating the air conditioner 1 for a certain period of time. The degree of clogging of the filter 44 is affected by the surrounding dust environment, making it difficult for the user to determine the exact replacement time for the filter 44. As a result, it is difficult to perform effective maintenance if the user has to decide when to replace the filter 44. Therefore, in the air conditioner 1, the controller 60 determines whether or not the filter 44 is contaminated and whether or not it needs to be replaced. Next, the configuration of the controller 60 will be explained with reference to Figure 2.

[0028] Figure 2 is a hardware configuration diagram of the controller 60 installed in the air conditioner 1. For ease of understanding, Figure 2 also shows the configuration of the main connections to the controller 60.

[0029] As shown in Figure 2, the controller 60 includes an I / O port (Input / Output Port) 61 and a storage device 62.

[0030] The dampers 734-736, fan 43, and heaters 51 and 52, as well as temperature sensors 81 and 82 for measuring air temperature, are electrically connected to the I / O port 61. Although not shown in Figure 2, various components of the air conditioner 1, such as the fan 23, four-way valve, and motor of the compressor 10, are also electrically connected to the I / O port 61.

[0031] Dampers 734-736, although not shown, are equipped with a drive circuit that drives blades that open and close the air passage. This drive circuit receives commands from the CPU (Central Processing Unit) 63, which will be described later, via the I / O port 61 shown in Figure 2. Based on these commands, the drive circuit drives the blades to open and close the air passage. For example, the drive circuit of damper 736 switches between a state in which outside air can be drawn from damper 736 into the indoor unit room 73 and a state in which the indoor unit room 73 is disconnected from the air passage of damper 736.

[0032] Furthermore, the fan 43 is equipped with a drive circuit (not shown) for driving its blades. The drive circuit of the fan 43 receives commands from the CPU 63 via the I / O port 61 shown in Figure 2. The drive circuit of the fan 43 then rotates the fan 43. As a result, the fan 43 takes in an amount of indoor air from the intake port 731 according to the command from the CPU 63. The fan 43 also sends air at an airflow rate according to the command from the CPU 63 to the indoor heat exchangers 41 and 42.

[0033] Furthermore, the heaters 51 and 52 are equipped with a control circuit, for example, which includes a thyristor. This control circuit receives commands from the CPU 63 via the I / O port 61. Based on the commands from the CPU 63, the control circuit supplies power to the heaters 51 and 52, causing them to generate heat at the time and amount corresponding to the commands. As a result, the heaters 51 and 52 assist in heating by the indoor heat exchangers 41 and 42 or remove frost that has accumulated on the indoor heat exchangers 41 and 42. Alternatively, the heaters 51 and 52 heat the air taken in by the fan 43 from the intake port 731 during the determination process by the controller 60 (described later) to determine whether or not the filter 44 needs to be replaced.

[0034] Temperature sensors 81 and 82 are sensors that measure temperature using methods such as resistance thermometers and thermocouples. Temperature sensor 81 is located near the air intake 731, as shown in Figure 1. More specifically, temperature sensor 81 is located inside the indoor unit room 73, beyond the air intake 731. Temperature sensor 81 measures the temperature of the air taken in from the air intake 731. In contrast, temperature sensor 82 is located near the air outlet 732. More specifically, temperature sensor 82 is located inside the railway vehicle, beyond the air outlet 732. Temperature sensor 82 measures the temperature of the air blown out from the air outlet 732. Temperature sensors 81 and 82 periodically measure these temperatures and transmit the obtained temperature data to the CPU 63 via the I / O port 61.

[0035] Returning to Figure 2, the storage device 62 has an EEPROM (Electrical Erasable Programmable Read-Only Memory) or flash memory, etc. The storage device 62 stores rotation speed data 621 for which the fan 43 should rotate, which is used in the determination process by the controller 60, described later, to determine whether or not the filter 44 needs to be replaced. The storage device 62 also stores power data 622 for which power should be supplied to the heaters 51 and 52, which are used in the same determination process. Furthermore, the storage device 62 stores determination data 623, which is used in the same determination process.

[0036] Furthermore, the controller 60 includes a computer comprising a CPU 63, a ROM (Read-Only Memory) 64, and a RAM (Random Access Memory) 65. The controller 60 performs various processes to control each component of the air conditioner 1 by having the CPU 63 read various programs stored in the storage device 62 or ROM 64 into the RAM 65 and execute them. The CPU 63 is also called a processor because it performs various processes.

[0037] For example, the controller 60 performs a determination process to determine whether the filter 44 needs to be replaced by reading and executing a filter replacement determination program stored in the ROM 64 by the CPU 63. In this determination process, the controller 60 reads rotation speed data 621 and power data 622 from the storage device 62. The controller 60 then rotates the fan 43 at a constant rotation speed based on the read rotation speed data 621. The controller 60 also supplies a constant power to the heaters 51 and 52 based on the read power data 622, causing them to generate a constant amount of heat. Furthermore, the controller 60 acquires temperature data from the temperature sensors 81 and 82 in this state. The controller 60 reads determination data 623 from the storage device 62 and determines whether the temperature difference between the temperature data from the temperature sensors 81 and 82 is greater than the upper limit value included in the read determination data 623. If the temperature difference is greater than the upper limit value, the controller 60 determines that the filter 44 is contaminated and outputs a filter replacement signal.

[0038] The controller 60 has a communication module 66 connected to an I / O port 61. As a result, the CPU 63 can communicate with the management server 2 via the internet 100 using the communication module 66. When the controller 60 determines that the filter 44 is contaminated, it sends a filter replacement signal to the server 2. The server 2 is connected to a display device 3 which has a liquid crystal display. When the server 2 receives the filter replacement signal, it displays on the display device 3 that the filter 44 should be replaced. In this way, the server 2 informs the user of the condition of the filter 44. In other words, the server 2 prompts the user to replace the filter 44. Through this process, the controller 60 determines whether or not the filter is contaminated, thereby improving the maintainability of the air conditioner 1.

[0039] Next, with reference to Figure 3, the process by which the controller 60 determines whether or not the filter 44 needs to be replaced will be explained in more detail. In the following explanation, the process of determining whether or not the filter 44 needs to be replaced will be referred to as the first filter replacement determination process to distinguish it from the determination processes described in Embodiments 2 and 3.

[0040] FIG. 3 is a flowchart of the first filter replacement determination process performed by the controller 60.

[0041] First, when a power switch and an operation mode selection button (not shown) are pressed to start the air conditioner 1 and a cooling operation or a heating operation is selected, a filter replacement determination program is executed by the CPU 63 included in the controller 60, and as a result, the flow of the first filter replacement determination process is started.

[0042] In the flow of the first filter replacement determination process, first, as shown in FIG. 3, the controller 60 closes the damper 736 (step S1). Specifically, the controller 60 transmits a closing command to the drive circuit of the damper 736 described above to close the air passage in the drive circuit of the damper 736. Thereby, the controller 60 narrows the air inflow path to the indoor unit chamber 73 to only the suction port 731.

[0043] Next, the controller 60 starts the operation of the fan 43 (step S2). Specifically, the controller 60 reads the rotation speed data 621 from the storage device 62. Then, the controller 60 transmits a command to the drive circuit of the fan 43 to rotate the fan 43 at the rotation speed defined by the read rotation speed data 621. Further, the controller 60 causes the drive circuit of the fan 43 to maintain that rotation speed.

[0044] Subsequently, the controller 60 starts the operation of the heaters 51 and 52 (step S3). Specifically, the controller 60 reads the power data 622 from the storage device 62. Then, the controller 60 transmits a command to the control circuits of the heaters 51 and 52 described above to supply the heaters 51 and 52 with the power defined by the read power data 622. Thereby, the controller 60 causes the heaters 51 and 52 to generate heat with a certain amount of heat.

[0045] Subsequently, the controller 60 acquires the measured values of the temperature sensors 81 and 82 (step S4). The temperature sensors 81 and 82 perform temperature measurements every time a certain short period of time elapses. The controller 60 acquires the most recent measurement data from such temperature sensors 81 and 82.

[0046] Subsequently, the controller 60 calculates the temperature difference from the acquired measured values of the temperature sensors 81 and 82 (step S5). That is, the controller 60 calculates the temperature difference between the temperature of the air taken in from the suction port 731 measured by the temperature sensor 81 and the temperature of the air blown out from the blowout port 732 measured by the temperature sensor 82.

[0047] Subsequently, the controller 60 determines whether the variation from the previously calculated temperature difference is small (step S6). Specifically, the controller 60 determines whether the temperature difference calculated this time is within a certain value from the temperature difference calculated previously. Thereby, the controller 60 determines whether the temperature inside the indoor unit chamber 73 is in a stable state.

[0048] If the controller 60 determines that the variation from the previously calculated temperature difference is not small (No in step S6), it returns to step S4. Thereby, a series of steps from the acquisition of the measured values of the temperature sensors 81 and 82 to the determination of the variation from the previously calculated temperature difference are repeated.

[0049] On the other hand, if the controller 60 determines that the variation from the previously calculated temperature difference is small (Yes in step S6), it determines whether the temperature difference is within the allowable range (step S7). Specifically, the controller 60 reads the determination data 623 from the storage device 62. Then, the controller 60 determines whether the current temperature difference calculated in step S5 is within the allowable range by using the data of the upper limit value and the lower limit value indicating the allowable range included in the read determination data 623.

[0050] If the controller 60 determines that the temperature difference is not within the acceptable range (No in step S7), it determines whether the temperature difference is greater than the upper limit of the acceptable range (step S8). If the controller 60 determines that the temperature difference is greater than the upper limit of the acceptable range (Yes in step S8), it notifies that clogging has occurred (step S9). Specifically, the controller 60 determines that the filter 44 is contaminated and sends a filter replacement signal to the management server 2 described above. When the server 2 receives the filter replacement signal, it displays on the display device 3 that clogging has occurred in the filter 44 and that the filter 44 should be replaced.

[0051] After notifying the controller 60 of the occurrence of clogging, the controller 60 terminates the flow of the first filter replacement determination process. That is, the controller 60 terminates the operation of the fan 43 and the heaters 51 and 52.

[0052] On the other hand, if the controller 60 determines that the temperature difference is below the upper limit of the allowable range (No. in step S8), the contamination of the filter 44 is within the allowable range and there is no need to replace the filter 44, so the flow of the first filter replacement determination process is terminated.

[0053] Furthermore, if the controller 60 determines that the temperature difference is within an acceptable range (Yes in step S7), it similarly terminates the flow of the first filter replacement determination process because there is no contamination in the filter 44 and there is no need to replace the filter 44.

[0054] When the controller 60 completes the flow of the first filter replacement determination process, it performs a preliminary operation in preparation for cooling or heating operation. That is, the controller 60 lowers or raises the temperature inside the railway vehicle in preparation for the regular cooling or heating operation to conditioned the air to the desired temperature.

[0055] As described above, in the air conditioner 1 according to Embodiment 1, the controller 60 rotates the fan 43 at a constant rotational speed and supplies a constant power to the heaters 51 and 52 to generate heat, while acquiring temperature data from temperature sensors 81 and 82. When the temperature difference of the acquired temperature data meets the standard conditions, specifically when the temperature difference of the acquired temperature data is greater than the upper limit of the allowable range, the controller 60 determines that the filter 44 is contaminated and outputs a filter replacement signal. According to the air conditioner 1, when the controller 60 performs the first filter replacement determination process, it rotates the fan 43 at a constant rotational speed to blow air at a constant volume, and further generates a certain amount of heat in the heaters 51 and 52 with a constant power. Therefore, the state of the filter 44 is accurately reflected in the temperature difference of the acquired temperature data. As a result, the controller 60 can accurately determine whether or not the filter 44 is contaminated. In addition, the air conditioner 1 has high maintainability.

[0056] The controller 60 performs the first filter replacement determination process with only the heaters 51 and 52 generating heat, that is, with the supply of refrigerant to the indoor heat exchangers 41 and 42 stopped. Therefore, the operating status of the indoor heat exchangers 41 and 42 does not affect the determination of whether or not the filter 44 needs to be replaced. As a result, the controller 60 can accurately determine whether or not the filter 44 is contaminated.

[0057] The heaters 51 and 52 described in Embodiment 1 are examples of electric heaters as defined in this disclosure. The temperature sensors 81 and 82 are examples of first and second temperature sensors as defined in this disclosure. The temperature data measured by temperature sensors 81 and 82 are examples of first and second temperature data as defined in this disclosure. Furthermore, the filter replacement signal is an example of a contamination signal as defined in this disclosure. The upper limit of the allowable range used by the controller 60 for determination is an example of a threshold value as defined in this disclosure. The system formed by the air conditioner 1, server 2, and display device 3 is an example of an air conditioning system as defined in this disclosure. The display device 3 is an example of a notification device as defined in this disclosure. The operation of the fan 43 in step S2 and the operation of the heaters 51 and 52 in step S3 performed in the first filter replacement determination process are examples of the first step as defined in this disclosure. Steps S4-S9 performed in the first filter replacement determination process are examples of the second step as defined in this disclosure.

[0058] (Modification) In Embodiment 1, in step S2 of the first filter replacement determination process, the controller 60 rotates the fan 43 at a rotational speed defined by the rotational speed data 621 in the storage device 62. The rotational speed of the fan 43 may be the rotational speed when the air conditioner 1 is in cooling or heating operation. Alternatively, the rotational speed of the fan 43 may be a rotational speed at which the fan 43 can rotate stably. Furthermore, the rotational speed of the fan 43 may be a constant rotational speed. Also, the fan 43 may be a fan that rotates at a constant speed that cannot be changed. In addition, the rotational speed of the fan 43 may be the maximum rotational speed at which the fan 43 can rotate, i.e., the rated rotational speed. This is because at this rated rotational speed, it is possible to reliably determine whether the filter 44 is clogged, i.e., whether the filter 44 is contaminated.

[0059] (Embodiment 2) In the air conditioner 1 according to Embodiment 1, if the temperature difference of the acquired temperature data is greater than the upper limit of the allowable range, it is determined that the filter 44 is contaminated and the user is notified of the occurrence of clogging. As a result, the air conditioner 1 prompts the user to replace the filter 44. However, the air conditioner 1 is not limited to this. The air conditioner 1 may change the rotation speed of the fan 43 in response to the contamination of the filter 44, for example, clogging of the filter 44.

[0060] The air conditioner according to Embodiment 2 ensures the airflow of the fan 43 by changing the rotation speed of the fan 43 in accordance with the clogging of the filter 44.

[0061] The air conditioner according to Embodiment 2 will be described below with reference to Figures 4 and 5A-5C. Embodiment 2 will be described primarily for its configuration, which differs from that of Embodiment 1. In detail, the configuration of the air conditioner according to Embodiment 2 is the same as that of the air conditioner 1 according to Embodiment 1. However, the second filter replacement determination process performed by the air conditioner according to Embodiment 2 differs in some steps from the first filter replacement determination process described in Embodiment 1. For this reason, Embodiment 2 will be described primarily for its second filter replacement determination process.

[0062] Figure 4 is a flowchart of the second filter replacement determination process performed by the controller 60 of the air conditioner according to Embodiment 2.

[0063] As shown in Figure 4, the second filter replacement determination process is the same as the first filter replacement determination process described in Embodiment 1 from steps S1 to S8. That is, steps S1 to S8 of the second filter replacement determination process are the same as the first filter replacement determination process described in Embodiment 1, from closing the damper 736 (step S1) to determining whether the temperature difference is greater than the upper limit of the allowable range (step S8). For this reason, Embodiment 2 will describe the process from the determination whether the temperature difference is greater than the upper limit of the allowable range (step S8) onward.

[0064] If the controller 60 determines that the temperature difference is greater than the upper limit of the allowable range (Yes in step S8), it determines whether the rotational speed of the fan 43 is at its maximum value (step S9). Specifically, the controller 60 reads rotational speed data 621 from the storage device 62. This rotational speed data 621 stores the rated rotational speed of the fan 43, that is, the maximum rotational speed at which the fan 43 can rotate. The controller 60 stores the rotational speed commanded to the fan 43's drive circuit as the current rotational speed in the storage device 62 for each command. As a result, the storage device 62 stores this current rotational speed in the rotational speed data 621. Therefore, the read rotational speed data 621 includes the current rotational speed. The controller 60 uses the maximum rotational speed and the current rotational speed contained in the read rotational speed data 621 to determine whether the current rotational speed is the maximum rotational speed.

[0065] If the controller 60 determines that the rotational speed of the fan 43 is not at its maximum value (No. in step S9), it increases the rotational speed of the fan 43 by a fixed amount (step S10). This increases the airflow of the fan 43 by a fixed amount. Furthermore, although not shown in the diagram, the controller 60 overwrites the current rotational speed stored in the rotational speed data 621 stored in the storage device 62 with the rotational speed of the fan 43 after it has been increased by a fixed amount. This updates the current rotational speed in the rotational speed data 621. After that, the controller 60 returns to step S4. The controller 60 repeats the series of processes from steps S4 to S9. This allows the controller 60 to determine again whether the temperature difference remains below the upper limit of the allowable range while the airflow of the fan 43 has increased by a fixed amount. If the controller 60 determines that the temperature difference remains below the upper limit of the allowable range, it stores the rotational speed data of the fan 43 at that time in the rotational speed data 621 of the storage device 62. When the air conditioner according to Embodiment 2 is performing air conditioning, the controller 60 reads the rotation speed data 621 and rotates the fan 43 at that rotation speed. In this way, the controller 60 prevents a decrease in airflow due to clogging of the filter 44 during air conditioning.

[0066] In step S10, as described above, the rotational speed of the fan 43 is increased by a certain amount. An example of the effect when the rotational speed of the fan 43 is increased is shown in Figure 5A.

[0067] Figure 5A is a graph showing the change in the temperature difference between the air taken in from the intake port 731 and the air blown out from the outlet port 732 when the rotation speed of the fan 43 is increased in the second filter replacement determination process. More specifically, Figure 5A shows the change in the temperature difference when it converges to the allowable range R. Note that Figure 5A is a simplified graph showing the change in the temperature difference when it changes ideally, for the sake of ease of understanding. The same applies to Figures 5B and 5C, which will be described later.

[0068] As shown in Figure 5A, the determination in step S9 is made at time t1. As a result, if the rotation speed of the fan 43 increases by a certain amount from time t1 to step S10, and if the filter 44 is contaminated to a usable degree, the temperature difference will decrease over time and eventually converge to the acceptable range R. Figure 5A is a simplified graph and shows a linear progression, but as the controller 60 repeats the series of processes from step S4 to S10, the temperature difference gradually decreases. As a result, if the filter 44 is contaminated to a usable degree, the temperature difference will fall below the upper limit of the acceptable range R. Step S10 produces this effect.

[0069] Figure 5A is an example of a case where it is determined that the rotational speed of fan 43 is not at its maximum value (No. in step S9), but another example is shown in Figure 5B.

[0070] Figure 5B is a graph showing a different trend of the temperature difference than that shown in Figure 5A. More specifically, Figure 5B shows the trend of the temperature difference when it converges to a state where it is higher than the upper limit of the allowable range R.

[0071] Even if the controller 60 described above determines that the rotational speed of the fan 43 is not at its maximum value (No. in step S9), and the rotational speed of the fan 43 is increased by a fixed amount from time t1 shown in Figure 5B (step S10), if the filter 44 is so contaminated that it is unusable, the temperature difference will remain above the upper limit of the allowable range R, despite the increase in the rotational speed of the fan 43. In such a case, even if the rotational speed of the fan 43 reaches its maximum value, the temperature difference will remain above the upper limit of the allowable range R.

[0072] Therefore, if the controller 60 determines that the rotation speed of the fan 43 is at its maximum value (Yes in step S9), it provides a notification of clogging as described in Embodiment 1 (step S11). In detail, the controller 60 provides a notification of clogging as described in Embodiment 1, and after providing the notification of clogging, it terminates the operation of the fan 43 and the heaters 51 and 52, as in Embodiment 1, thereby terminating the second filter replacement determination process.

[0073] Furthermore, if the controller 60 determines that the temperature difference is below the upper limit of the allowable range (No. in step S8), it terminates the second filter replacement determination process. An example of the temperature difference progression in such a case is shown in Figure 5C.

[0074] Figure 5C is a graph showing a different trend in the temperature difference than that shown in Figure 5A. More specifically, Figure 5C shows the trend of the same temperature difference when the temperature difference is within the allowable range R.

[0075] If the filter 44 is not contaminated and is fully usable, and the fluctuation from the previously calculated temperature difference has become small (Yes in step S6), then the temperature difference is within the acceptable range R, as shown in Figure 5C. In this case, there is no longer any need to increase the rotation speed of the fan 43. Furthermore, it is clear that the filter 44 is not clogged. For this reason, if the controller 60 determines that the temperature difference is below the upper limit of the acceptable range (No in step S8), it terminates the second filter replacement determination process as described above.

[0076] By performing this second filter replacement determination process, the controller 60 adjusts the rotation speed of the fan 43 if the filter 44 is contaminated to a usable degree. This ensures that the airflow of the fan 43 is maintained. As a result, the controller 60 extends the usable time of the filter 44. In other words, the replacement cycle of the filter 44 is optimized, and maintenance can be reduced.

[0077] In Embodiment 2, when the controller 60 determines that the temperature difference is greater than the upper limit of the allowable range and that the rotation speed of the fan 43 is not at its maximum value, the rotation speed of the fan 43 is increased by a fixed amount. However, the rotation speed of the fan 43 corresponding to the temperature difference may be determined by experimentation, and a table associating the temperature difference with the rotation speed corresponding to the temperature difference may be stored in the storage device 62 in advance. Then, when the controller 60 determines that the temperature difference is greater than the upper limit of the allowable range and that the rotation speed of the fan 43 is not at its maximum value, it may read the table and rotate the fan 43 at a rotation speed corresponding to the temperature difference based on the read table. Furthermore, the maximum value when the controller 60 determines that the rotation speed of the fan 43 is at its maximum value is an example of the rated value as referred to in this disclosure.

[0078] As described above, in the air conditioner according to Embodiment 2, the controller 60 increases the rotation speed of the fan 43 when the temperature difference between the temperature of the air taken in from the intake port 731 and the temperature of the air blown out from the outlet port 732 is greater than the upper limit of the allowable range. For example, the controller 60 increases the rotation speed of the fan 43 by a fixed amount. As a result, the controller 60 rotates the fan 43 at a rotation speed corresponding to the temperature difference and at a rotation speed greater than the current rotation speed. Consequently, the controller 60 rotates the fan 43 at a rotation speed corresponding to the degree of contamination of the filter 44, thereby ensuring sufficient airflow. For this reason, in the air conditioner according to Embodiment 2, there is no need to replace the filter 44 frequently, and the filter 44 can be used for a long period of time.

[0079] (Embodiment 3) In embodiments 1 and 2, the controller 60 determines whether or not the filter 44 is contaminated, but the controller 60 may also determine whether or not there is an air leak in the indoor unit room 73.

[0080] In the air conditioner according to Embodiment 3, the controller 60 determines whether or not there is an air leak in the indoor unit room 73 based on the temperature difference it calculates.

[0081] The air conditioner according to Embodiment 3 will be described below with reference to Figure 6. Embodiment 3 will be described primarily for its configuration, which differs from that of Embodiments 1 and 2.

[0082] Figure 6 is a flowchart of the third filter replacement determination process performed by the controller of the air conditioner according to Embodiment 3.

[0083] In Embodiment 1, the temperature difference calculated in step S5 shown in Figure 3 is estimated to be a value corresponding to the rotation speed of the fan 43, provided that the change from the previously calculated temperature difference is small (Yes in step S6), as long as the heaters 51 and 52 generate a constant amount of heat. Therefore, using a usable filter 44, the temperature difference for the rotation speed of the fan 43 as described in Embodiment 1 is determined experimentally in advance.

[0084] In detail, using filters 44 in various states, such as a filter 44 without contamination and a filter 44 that is usable even if contaminated, experiments are conducted to determine in advance what temperature difference will occur when the fan 43 is rotated at the rotation speed defined by the rotation speed data 621 of the storage device 62 described in Embodiment 1. Then, from these experiments, a numerical range containing the temperature difference value corresponding to the rotation speed of the fan 43 is determined. Furthermore, the determined temperature difference value corresponding to the rotation speed of the fan 43 is stored in the judgment data 623 of the storage device 62 shown in Figure 2.

[0085] In this state, the controller 60 of the air conditioner according to Embodiment 3 executes the third filter replacement determination process shown in Figure 6.

[0086] The third filter replacement determination process differs from the first filter replacement determination process described in Embodiment 1 in that steps S31 and S32 are added between steps S6 and S7, as shown in Figure 6. Therefore, steps S31 and S32 will be described below.

[0087] If the controller 60 determines that the change from the previously calculated temperature difference is small (Yes in step S6), it determines whether the temperature difference calculated in step S5 is a value corresponding to the rotation speed of the fan 43 (step S31). Specifically, the controller 60 reads the determination data 623 from the storage device 62 and determines whether the temperature difference is a value corresponding to the rotation speed of the fan 43 based on the value corresponding to the rotation speed of the fan 43 included in the read determination data 623, for example, a numerical range corresponding to the rotation speed of the fan 43.

[0088] For example, if the temperature difference is smaller than the lower limit of the numerical range corresponding to the rotation speed of the fan 43, as contained in the read judgment data 623, the controller 60 determines that the temperature difference is not a value corresponding to the rotation speed of the fan 43 (No. in step S31). In this case, it is thought that air is leaking from the indoor unit room 73 or the filter 44 and the temperature is not rising. In this case, the controller 60 notifies the system of the air leak (step S32). Specifically, the controller 60 transmits an air leak signal to the management server 2 shown in Figure 2. When the server 2 receives the air leak signal, it displays on the display device 3 that there is an abnormal air leak in the indoor unit room 73.

[0089] On the other hand, if the controller 60 determines that the temperature difference is a value corresponding to the rotation speed of the fan 43 (Yes in step S31), it proceeds to step S7 to determine whether or not the filter 44 is contaminated. The processing from step S7 onward is the same as in Embodiment 1, so the explanation is omitted.

[0090] As described above, in the air conditioner according to Embodiment 3, the controller 60 determines that there is an air leak in either the indoor unit chamber 73 or the filter 44 if the temperature difference between the temperature of the air taken in from the intake port 731 and the temperature of the air blown out from the outlet port 732 is not a value corresponding to the rotation speed of the fan 43. For this reason, the air conditioner has high maintainability.

[0091] (Embodiment 4) In Embodiments 1-3, the controller 60 determines whether or not the filter 44 is contaminated, but the controller 60 may also estimate when the filter 44 should be replaced.

[0092] In the air conditioner according to Embodiment 4, the replacement time for the filter 44 is estimated from the temperature difference calculated by the controller 60 and the rotation speed of the fan 43.

[0093] The air conditioner according to Embodiment 4 will now be described with reference to Figure 7. Embodiment 4 will be described primarily for its configuration, which differs from that of Embodiments 1-3.

[0094] Figure 7 is a graph showing an example of the change in the temperature difference between the temperature of the air taken in from the intake port 731 and the temperature of the air blown out from the outlet port 732.

[0095] As shown in Figure 7, the temperature difference between the air temperature and the temperature of the air blown out from the outlet 732 increases with time until the filter 44 is replaced at times t2 and t3. Therefore, when the heaters 51 and 52 generate a constant amount of heat, it is advisable to experimentally obtain data showing the relationship between the rotation speed of the fan 43 and the change in the temperature difference at that time, and then determine the temperature difference at which the filter 44 should be replaced, hereinafter referred to as the replacement criterion value, from the obtained data.

[0096] In the air conditioner according to Embodiment 4, the above-mentioned replacement reference value and a table relating the rotation speed of the fan 43 to the temperature difference at that time are stored in the determination data 623 of the storage device 62 shown in Figure 2. Then, after calculating the temperature difference in step S5 as described in Embodiment 1, the controller 60 reads the determination data 623 from the storage device 62. The controller 60 then determines whether the temperature difference calculated in step S5 exceeds the above-mentioned replacement reference value included in the read determination data 623. If the temperature difference exceeds the replacement reference value, the controller 60 notifies that the filter 44 should be replaced. Specifically, the controller 60 transmits a filter replacement signal to the management server 2 shown in Figure 2, and the server 2 displays on the display device 3 that it is time to replace the filter 44. As a result, the replacement of the filter 44 is prompted at times t4 and t5 shown in Figure 7, and as a result, the air conditioner according to Embodiment 4 is maintained.

[0097] The controller 60 may also estimate the time until the filter 44 needs to be replaced from the table above. The controller 60 may then send the estimated time until the filter 44 needs to be replaced to the server 2, and have the display device 3 display that time.

[0098] As described above, in the air conditioner according to Embodiment 4, the controller 60 estimates the time to replace the filter 44 based on the temperature difference between the temperature of the air taken in from the intake port 731 and the temperature of the air blown out from the outlet port 732, and the rotation speed of the fan 43, and notifies the user that the filter 44 should be replaced. For this reason, the air conditioner has high maintainability.

[0099] The air conditioner 1, air conditioning system, control method for the air conditioner 1, and program according to embodiments of the present disclosure have been described above, but the air conditioner 1, air conditioning system, control method for the air conditioner 1, and program are not limited thereto.

[0100] For example, in Embodiment 1-4, the air conditioner 1 includes two each of the outdoor heat exchangers 21, 22, indoor heat exchangers 41, 42, expansion valves 31, 32, and heaters 51, 52. However, the air conditioner 1 is not limited to this. The air conditioner 1 only needs to have at least one of these components. Furthermore, the air conditioner 1 may have a number of these components corresponding to the desired air conditioning performance.

[0101] Furthermore, in Embodiment 1-4, the temperature sensor 81 is provided near the intake port 731. The temperature sensor 82 is provided near the outlet port 732. However, the temperature sensors 81 and 82 are not limited to these. The temperature sensor 81 only needs to measure the temperature of the air being drawn in from the intake port 731. The temperature sensor 82 only needs to measure the temperature of the air being blown out from the outlet port 732. Here, the air being drawn in includes not only the air that is about to be drawn into the intake port 731, but also the air that has actually been drawn into the intake port 731. The air being blown out includes not only the air that is about to be blown out from the outlet port 732, but also the air that has actually been blown out from the outlet port 732. Therefore, to this extent, their positions are arbitrary. For example, the temperature sensor 81 may be provided inside the intake port 731. The temperature sensor 82 may be provided inside the outlet port 732.

[0102] Furthermore, in Embodiment 1-4, the air conditioner 1, server 2, and display device 3 constitute an air conditioning system. The server 2, upon receiving a filter replacement signal, causes the display device 3 to indicate that the filter 44 should be replaced. However, the air conditioning system is not limited to this. The air conditioning system can consist of the air conditioner 1 and an alerting device that notifies the user that the filter 44 should be replaced when it receives a signal output by the controller 60 of the air conditioner 1, such as a fouling signal or a filter replacement signal. For this reason, the display device 3 may be replaced with a device that notifies the user that the filter 44 should be replaced by sound, such as a speaker. Alternatively, the air conditioner 1 may directly display the message that the filter 44 should be replaced on the display device 3 without going through the server 2.

[0103] In Embodiments 1-4, the air conditioner 1 is installed in a railway vehicle. However, the air conditioner 1 is not limited to this. The air conditioner 1 may also be used in buildings.

[0104] In the above embodiment, the filter replacement determination program is stored in ROM 64, but the filter replacement determination program may also be stored and distributed on a computer-readable recording medium such as a flexible disk, CD-ROM (Compact Disc Read-Only Memory), DVD (Digital Versatile Disc), or MO (Magneto-Optical Disc). In this case, the controller 60 that performs valve control processing may be configured by installing the filter replacement determination program stored on the recording medium onto a computer.

[0105] Furthermore, the filter replacement determination program may be stored on a disk device of a server on the Internet communication network, and the filter replacement determination program may be downloaded, for example, by being superimposed on a carrier wave.

[0106] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. In other words, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure.

[0107] 1 Air conditioner, 2 Server, 3 Display device, 10 Compressor, 21, 22 Outdoor heat exchanger, 23 Fan, 31, 32 Expansion valve, 41, 42 Indoor heat exchanger, 43 Fan, 44 Filter, 51, 52 Heater, 60 Controller, 61 I / O port, 62 Storage device, 63 CPU, 64 ROM, 65 RAM, 66 Communication module, 70 Frame, 71 Outdoor unit room, 72 Compressor room, 73 Indoor unit room, 81, 82 Temperature sensor, 100 Internet, 621 Rotation speed data, 622 Power data, 623 Judgment data, 712, 713 Air outlet, 721, 722 Communication port, 723 Fresh air intake, 731 Inlet, 732, 733 Air outlet, 734, 735, 736 Damper, t1-t5 time, R tolerance range.

Claims

1. An air conditioner comprising: a fan formed in an indoor unit room that draws in indoor air from an intake port having a filter, blows the drawn-in air to an indoor heat exchanger provided in the indoor unit room, and blows the air from the indoor unit room into the room from an outlet provided in the indoor unit room; an electric heater provided in the indoor unit room that is capable of heating the air in the indoor unit room; a first temperature sensor that measures the temperature of the air drawn in from the intake port; a second temperature sensor that measures the temperature of the air blown out from the outlet; and a controller that rotates the fan at a constant rotation speed and supplies a constant power to the electric heater to generate heat, acquires first temperature data and second temperature data from the first temperature sensor and the second temperature sensor, and determines that the filter is contaminated when the temperature difference between the acquired first temperature data and the second temperature data satisfies a standard condition, and outputs a contaminated signal for maintaining the filter.

2. The air conditioner according to claim 1, wherein the standard condition is that the temperature difference is greater than a threshold.

3. The air conditioner according to claim 2, wherein the controller changes the rotation speed of the fan to a rotation speed corresponding to the temperature difference between the first temperature data and the second temperature data, which is greater than the threshold, and rotates the fan at the changed rotation speed when the indoor heat exchanger conditioned the air in the room.

4. The air conditioner according to claim 3, wherein the controller determines that the filter is contaminated when the rotational speed of the fan exceeds a rated value and outputs a contaminated signal for maintaining the filter.

5. The air conditioner according to claim 1 or 2, wherein the controller determines that there is an air leak in either the filter or the indoor unit room and outputs an air leak signal when the temperature difference between the first temperature data and the second temperature data is not the rotation speed corresponding to the temperature difference.

6. The air conditioner according to any one of claims 1 to 5, wherein the indoor heat exchanger exchanges heat between the air in the indoor unit room and the refrigerant, and the controller determines whether the filter is contaminated while the supply of refrigerant to the indoor heat exchanger is stopped.

7. The air conditioner according to any one of claims 1 to 6, wherein the constant rotational speed is the rated rotational speed of the fan.

8. The air conditioner according to any one of claims 1 to 7, wherein the controller estimates the replacement time of the filter from the temperature difference between the acquired first temperature data and the second temperature data and the rotation speed of the fan, and outputs data of the estimated replacement time of the filter.

9. The air conditioner according to any one of claims 1 to 8, wherein the controller, after determining that the filter is contaminated, supplies a refrigerant to the indoor heat exchanger to perform a preliminary operation before air conditioning the room to the desired temperature.

10. The air conditioner according to any one of claims 1 to 9, wherein the interior is the interior of a railway vehicle, and the air conditioner is for use in a railway vehicle.

11. An air conditioning system comprising: an air conditioner according to any one of claims 1 to 10; and a notification device that notifies the user that the filter should be replaced when it receives the fouling signal output by the controller.

12. A control method for an air conditioner comprising: a fan formed in an indoor unit room that draws in indoor air from an intake port having a filter, blows the drawn-in air to an indoor heat exchanger provided in the indoor unit room, and blows the air from the indoor unit room into the room from an outlet provided in the indoor unit room; an electric heater provided in the indoor unit room that is capable of heating the air in the indoor unit room; a first temperature sensor that measures the temperature of the air drawn in from the intake port; and a second temperature sensor that measures the temperature of the air blown out from the outlet, the control method comprising: a first step of rotating the fan at a constant rotation speed and supplying a constant power to the electric heater to generate heat; and a second step of, while the first step is being performed, acquiring first temperature data and second temperature data from the first temperature sensor and the second temperature sensor, and determining that there is contamination in the filter and outputting a contamination signal for maintaining the filter if the temperature difference between the acquired first temperature data and the second temperature data satisfies a standard condition.

13. A program for a computer that controls an air conditioner comprising: a fan formed in an indoor unit room that draws in indoor air from an intake port having a filter, blows the drawn-in air to an indoor heat exchanger provided in the indoor unit room, and blows the air from the indoor unit room into the room from an outlet provided in the indoor unit room; an electric heater provided in the indoor unit room that is capable of heating the air in the indoor unit room; a first temperature sensor that measures the temperature of the air drawn in from the intake port; and a second temperature sensor that measures the temperature of the air blown out from the outlet, to execute the following steps: a first step of rotating the fan at a constant rotation speed and supplying a constant power to the electric heater to generate heat; and a second step of, while the first step has been executed, acquiring first temperature data and second temperature data from the first temperature sensor and the second temperature sensor, and if the temperature difference between the acquired first temperature data and the second temperature data satisfies a standard condition, determining that the filter is contaminated and outputting a contaminated signal for maintaining the filter.

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