EP3447405A1

EP3447405A1 - Air-conditioning device

Info

Publication number: EP3447405A1
Application number: EP16899344.2A
Authority: EP
Inventors: Yuki Mochizuki
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-04-18
Filing date: 2016-04-18
Publication date: 2019-02-27
Anticipated expiration: 2036-04-18
Also published as: JPWO2017183070A1; EP3447405A4; JP6556339B2; EP3447405B1; WO2017183070A1

Abstract

An air-conditioning apparatus includes: a controller which controls a refrigerant circuit; and a temperature detection device which detects a temperature related to the refrigerant circuit as temperature information. The controller calculates a difference between time which is detected as the temperature information when a power recovery is made from a power-failure state and time which is detected as the temperature information when a power-failure detection unit detects a power failure. When the calculated difference is greater than a power-failure reference threshold value, the controller performs compressor protection control of heating a compressor for a fixed period of time, and then rotationally drives the compressor. On the other hand, when the obtained difference is smaller than or equal to the power-failure reference threshold value, the controller rotationally drives the compressor without performing the compressor protection control.

Description

Technical Field

The present invention relates to an air-conditioning apparatus which circulates refrigerant to perform air conditioning.

Background Art

While an operation of an air-conditioning apparatus is stopped, there is a case where refrigerant accumulates in a compressor. When the air-conditioning apparatus is started, with the refrigerant accumulating in the compressor, the compressor may be damaged. In view of this point, a related-art air-conditioning apparatus performs compressor protection control for preventing a compressor from being damaged at the time of starting the air-conditioning apparatus (see, for example, Patent Literature 1).
It should be noted that the compressor protection control is a control that when the compressor is in a stopped state, a heating unit such as a heater heats the compressor to evaporate refrigerant accumulating in the compressor. The air-conditioning apparatus of Patent Literature 1 performs the compressor protection control by supplying power to an electric heater wound around the compressor.
Furthermore, in another related-art air-conditioning apparatus, an operation frequency is restricted for a while after the apparatus is started, and the compressor protection control is performed with heat generated by a coil of an electric motor included in a compressor, in consideration of the case where supplying of power may be stopped for a long period of time, and heating could not be performed using a heating unit such as a heater.

Citation List

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2010-112619

Summary of Invention

Technical Problem

However, in general, it takes several hours that refrigerant accumulates in the compressor after an operation of an air-conditioning apparatus is stopped, and thus the compressor protection control does not need to be performed, for example, in the case where supplying of power is restated after a short time elapses from occurrence of a power failure. However, the related-art air-conditioning apparatus necessarily executes the compressor protection control when it is started, regardless of whether a power failure continues for a short time or supplying of power is stopped for a long time. The compressor cannot be operated at 100% of capacity while the compressor protection control is being performed. Therefore, in the related-art air-conditioning apparatus, even if the time for which a power failure continues is short, it takes long time to restore the state of air in a to-be-air-conditioned space to that prior to occurrence of the power failure.
The present invention has been made to solve the above problem, and an object of the invention is to provide an air-conditioning apparatus capable of rapidly restoring the state of air in a to-be-air-conditioned space to that prior to occurrence of a power failure in the case where supplying of power is restarted after elapses of a short time from occurrence of the power failure.

Solution to Problem

In an air-conditioning apparatus according to one embodiment of the present invention, a compressor, a heat-source-side heat exchanger, an expansion valve and a load-side heat exchanger are coupled to each other by a refrigerant pipe to form a refrigerant circuit. The air-conditioning apparatus includes: a controller which controls the refrigerant circuit; and a temperature detection device which detects a temperature related to the refrigerant circuit as temperature information. The controller includes: a power-failure detection unit which detects a power failure; a temperature difference calculation unit which calculates a difference between a temperature which is detected as the temperature information when a power recovery is made from a power-failure state and a temperature which is detected as the temperature information when the power-failure detection unit detects the power failure; and an operation control unit. The operation control unit performs compressor protection control of heating the compressor for a fixed period of time, and then rotationally drive the compressor when the difference is greater than a power-failure reference threshold value; and rotationally drive the compressor without performing the compressor protection control when the difference is smaller than or equal to the power-failure reference threshold value.

Advantageous Effects of Invention

According to one embodiment of the present invention, when the difference between a temperature which is detected as temperature information when a power failure occurs and a temperature which is detected as temperature information when a power recovery is made is smaller than or equal to a power-failure reference threshold value, a compressor is rotationally driven to proceed to a normal operation control without performing a compressor protection control. Thus, the compressor can be rapidly caused to operate at the capacity at which the compressor was operated before occurrence of the power failure. Accordingly, in the case where supplying of power is restarted after a short time elapses from occurrence of the power failure, the state of air in a to-be-air-conditioned space can be rapidly restored to the air-conditioned state thereof prior to occurrence of the power failure.

Brief Description of Drawings

Fig. 1 is a schematic diagram illustrating a configuration of an air-conditioning apparatus according to the first embodiment of the present invention.
Fig. 2 is a block diagram illustrating a functional configuration of an outdoor-unit control device as illustrated in Fig. 1.
Fig. 3 is a flowchart illustrating an operation of the air-conditioning apparatus as illustrated in Fig. 1.
Fig. 4 is a schematic diagram illustrating a configuration of an air-conditioning apparatus according to the second embodiment of the present invention.
Fig. 5 is a block diagram illustrating a functional configuration of an outdoor-unit control device as illustrated in Fig. 4.
Fig. 6 is a flowchart illustrating an operation of the air-conditioning apparatus as illustrated in Fig. 4.
Fig. 7 is a schematic diagram illustrating a configuration of an air-conditioning apparatus according to the third embodiment of the present invention.
Fig. 8 is a block diagram illustrating a functional configuration of an outdoor-unit control device as illustrated in Fig. 7.
Fig. 9 is a flowchart illustrating an operation of the air-conditioning apparatus as illustrated in Fig. 7.

Description of embodiments

First embodiment

Fig. 1 is a schematic diagram illustrating a configuration of an air-conditioning apparatus according to an embodiment of the present invention. The configuration of an air-conditioning apparatus 100 will be overall described with reference to Fig. 1. As illustrated in Fig. 1, the air-conditioning apparatus 100 includes an outdoor unit 1 and an indoor unit 2. The outdoor unit 1 and the indoor unit 2 are operated by power supplied from a commercial power supply 500 which is an AC power supply.
The outdoor unit 1 includes a compressor 3, a heat-source-side heat exchanger 4, a heat-source-side fan 7, and an outdoor-unit control device 9. The indoor unit 2 includes an expansion valve 5, a load-side heat exchanger 6, a load-side fan 8, and an indoor-unit control device 10. The compressor 3, the heat-source-side heat exchanger 4, the expansion valve 5, and the load-side heat exchanger 6 are coupled to each other by a refrigerant pipe 13 to form a refrigerant circuit which circulates refrigerant.
The compressor 3 is a compressor whose capacity is variable, and is provided to compress the refrigerant. The compressor 3 includes a compressor motor (not shown) to be controlled by an inverter. The heat-source-side heat exchanger 4 is formed of, for example, a fin-and-tube heat exchanger, and causes heat exchange to be performed between the refrigerant and outside air which is a heat medium. The expansion valve 5 is formed of, for example, an electronic expansion valve, and reduces the pressure of the refrigerant. The load-side heat exchanger 6 is formed of, for example, a fin-and-tube heat exchanger, and causes heat exchange to be performed between the refrigerant and air in a to-be-air-conditioned space.
The heat-source-side fan 7 is formed of an axial flow fan such as a propeller fan, and is provided for the heat-source-side heat exchanger 4. The heat-source-side fan 7 sends air to the heat-source-side heat exchanger 4. The load-side fan 8 is formed of a centrifugal fan such as a cross-flow fan, and is provided for the load-side heat exchanger 6. The load-side fan 8 sends air to the load-side heat exchanger 6.
The outdoor unit 1 includes a discharge temperature detection device 3a provided on a discharge side of the compressor 3 to detect a discharge temperature, which is the temperature of refrigerant discharged from the compressor 3. The discharge temperature detection device 3a is, for example, a temperature sensor formed of a thermistor, and is provided at, for example, a discharge port of the compressor 3. The discharge temperature is included in "temperature information" in the present invention.
The indoor unit 2 includes a suction temperature detection device 11 and an input device 12. The suction temperature detection device 11 is, for example, a temperature sensor formed of a thermistor, and is provided to detect an indoor air temperature, which is the temperature of air in the to-be-air-conditioned space. The input device 12 is to be operated by a user. That is, the input device 12 allows the user to, for example, turn on/off a power source, set a target temperature, set the direction of wind, and set the velocity of wind.
The outdoor-unit control device 9 controls operations of various actuators provided in the outdoor unit 1, such as the compressor 3 and the heat-source-side fan 7. The indoor-unit control device 10 controls operations of various actuators provided in the indoor unit 1, such as the expansion valve 5 and the load-side fan 8. The outdoor-unit control device 9 and the indoor-unit control device 10 mutually communicate with each other to execute cooperative control of the air-conditioning apparatus 100. That is, the outdoor-unit control device 9 can control the operations of various actuators provided in the indoor unit 2, using the indoor-unit control device 10.
Fig. 2 is a block diagram illustrating a functional configuration of the outdoor-unit control device 9 as illustrated in Fig. 1. As illustrated in Fig. 2, the outdoor-unit control device 9 includes a power-failure detection unit 91, a temperature storage processing unit 92, a storage unit 93, a temperature difference calculation unit 94 and an operation control unit 95.
The power-failure detection unit 91 constantly monitors the state of supplying of power from the commercial power supply 500 to detect a stop of supplying of power from the commercial power supply 500, that is, a power failure. Also, the power-failure detection unit 91 detects that supplying of the power from the commercial power supply 500 is restarted, that is, a power recovery, and outputs a signal indicating detection of the power recovery to the temperature storage processing unit 92.
The temperature storage processing unit 92 acquires, when the power-failure detection unit 91 detects a power failure, information indicating a discharge temperature from the discharge temperature detection device 3a, and stores the acquired information indicating the discharge temperature in the storage unit 93 as a discharge temperature Td_off. Also, the temperature storage processing unit 92 acquires, when receiving the signal indicating detection of the power recovery from the power-failure detection unit 91, information indicating the discharge temperature from the discharge temperature detection device 3a, and stores the acquired information indicating the discharge temperature in the storage unit 93 as a discharge temperature Td_on.
The storage unit 93 stores, as described above, the discharge temperature Td_off and the discharge temperature Td_on which are temperature information. The storage unit 93 can hold the stored information even during the power failure. It should be noted that the storage unit 93 can be formed of a programmable read only memory (PROM) such as a flash memory or a hard disk drive (HDD).
The temperature difference calculation unit 94 finds out a difference between the discharge temperature Td_on which is detected by the discharge temperature detection device 3a when a power recovery is made from a power failure state and the discharge temperature Td_off which is detected by the discharge temperature detection device 3a when the power-failure detection unit 91 detects the power failure. To be more specific, the temperature difference calculation unit 94 reads out the discharge temperature Td_off and the discharge temperature Td_on from the storage unit 93 when supplying of power from the commercial power supply 500 is restarted after occurrence of the power failure, and calculates a temperature difference ΔTd by subtracting the discharge temperature Td_on from the discharge temperature Td_off. Also, the temperature difference calculation unit 94 has a function of outputting the calculated temperature difference ΔTd to the operation control unit 95.
The operation control unit 95 includes a power-failure time determination unit 95a, a protection control unit 95b and an air-conditioning control unit 95c. The power-failure time determination unit 95a compares the temperature difference ΔTd calculated by the temperature difference calculation unit 94 with a power-failure reference threshold value to determine whether or not the temperature difference ΔTd is greater than the power-failure reference threshold value.
Incidentally, in the air-conditioning apparatus 100, the discharge temperature of the compressor 3 is important operation data for recognizing the operation state thereof. Therefore, the discharge temperature detection device 3a is covered with a heat insulating material (not shown). When the air-conditioning apparatus 100 is in operation, the discharge temperature of the compressor 3 is higher than the temperature of outside air by approximately ten degrees C to several tens of degrees C. When the operation of the air-conditioning apparatus 100 is stopped, the discharge temperature detected by the discharge temperature detection device 3a gradually approaches the temperature of the outside air.
In this case, as a situation in which the variation of the discharge temperature of the compressor 3 is the minimum, for example, the following situation is conceivable: when the air-conditioning apparatus 100 is in operation, the difference between the discharge temperature of the compressor 3 and the temperature of outside air is only approximately 10 degrees C. Under this situation, the discharge temperature of the compressor 3 varies only by approximately 10 degrees C from the time when a power failure occurs to the time when a power recovery is made.
In view of the above circumstances, in the first embodiment, the power-failure reference threshold value is set to 10 degrees C. It should be noted that the time required until the discharge temperature of the compressor 3 lowers by 10 degrees C is several minutes to several tens of minutes, but the time required until refrigerant accumulates in the compressor 3 is generally several hours. Therefore, the refrigerant does not accumulate in the compressor 3 before the discharge temperature of the compressor 3 lowers by 10 degrees C. Thus, in the case where the temperature difference ΔTd is 10 degrees C or smaller, the compressor 3 will not be damaged even if the compressor protection control is not performed.
The power-failure reference threshold value may be varied as appropriate in accordance with, for example, the amount of refrigerant in the air-conditioning apparatus 100, the type of the compressor 3, and the state of attachment of the discharge temperature detection device 3a or the suction temperature detection device 11. For example, the power-failure reference threshold value may be set to a value smaller than 10 degrees C. That is, in the case where the power-failure reference threshold value is set in accordance with, for example, the amount of refrigerant in the air-conditioning apparatus 100, and the temperature difference ΔTd is smaller than or equal to the power-failure reference threshold value, the compressor 3 can be prevented from being damaged, even without the compressor protection control.
Therefore, when the temperature difference ΔTd is greater than the power-failure reference threshold value, the power-failure time determination unit 95a can determine that a power failure time is long, and thus outputs a control command signal to the protection control unit 95b to request the protection control unit 95b to perform the compressor protection control. By contrast, when the temperature difference ΔTd is smaller than or equal to the power-failure reference threshold value, the power-failure time determination unit 95a can determine that the power-failure time is short, and thus outputs a control command signal to the air-conditioning control unit 95c to request the protection control unit 95b to omit the compressor protection control. It should be noted that the power-failure time is time required from occurrence of occurrence of the power failure to restarting of supplying of power.
The protection control unit 95b performs a compressor protection control of heating the compressor 3 only for a fixed period of time in response to the control command signal from the power-failure time determination unit 95a. In the first embodiment, the compressor 3 includes an electric heater (not shown), and the protection control unit 95b energizes the electric heater for a fixed period of time in response to the control command signal from the power-failure time determination unit 95a. Furthermore, the protection control unit 95b outputs the control command signal to the air-conditioning control unit 95c when the compressor protection control is ended, that is, when the fixed period of time elapses.
In response to the control command signal output from the power-failure time determination unit 95a or the protection control unit 95b, the air-conditioning control unit 95c rotationally drives the compressor 3, and performs a normal operation control associated with air conditioning. In the following, the normal operation control associated with air conditioning is also referred to as "normal operation control".
To be more specific, the air-conditioning control unit 95c performs the normal operation control in cooperation with the indoor-unit control device 10 by controlling the operations of the various actuators provided in the outdoor unit 1 and the indoor unit 2. For example, the air-conditioning control unit 95c controls the operations of the various actuators in accordance with settings made using the input device 12 or the like. Also, the air-conditioning control unit 95c controls the operations of the various actuators in such a way as to reduce the difference between a target temperature set using the input device 12 and an indoor-air temperature detected by the suction temperature detection device 11.
That is, in the case where the temperature difference ΔTd is greater than the power-failure reference threshold value, the operation control unit 95 performs the compressor protection control, and then rotationally drives the compressor 3 to execute the normal operation control. By contrast, in the case where the temperature difference ΔTd is smaller than or equal to the power-failure reference threshold value, the operation control unit 95 rotationally drives the compressor 3 to execute the normal operation control without performing the compressor protection control.
As described above, when supplying of power is restarted, the outdoor-unit control device 9 indirectly determines whether or not the power-failure time is short, based on the discharge temperature detected by the discharge temperature detection device 3a, and performs protection necessity determination processing of determining whether or not to perform the compressor protection control before performing the normal operation control.
Although the first embodiment is described above by referring to by way of example the case where the power-failure detection unit 91 has a function of detecting a power recovery, this is an example, and is not limitative. The temperature storage processing unit 92 may be made to have a function of detecting a power recovery. Furthermore, the temperature difference calculation unit 94 may store the temperature difference ΔTd in the storage unit 93 or the like instead of outputting the temperature difference ΔTd to the operation control unit 95. In this case, the power-failure time determination unit 95a may read out the temperature difference ΔTd from the storage unit 93 or the like, and perform determination processing.
In this case, the outdoor-unit control device 9 and the indoor-unit control device 10 can be made of hardware such as a circuit device which fulfills the above functions, or can be made of software to be executed on a microcomputer such as digital signal processor (DSP) or an arithmetic unit such as a central processing unit (CPU).
Fig. 3 is a flowchart illustrating the operation of the air-conditioning apparatus 100 as illustrated in Fig. 1. With reference to Fig. 3, the following description is made by referring to a control operation by the outdoor-unit control device 9, mainly to the protection necessity determination processing.
First, the temperature storage processing unit 92 is on standby until the power-failure detection unit 91 detects a power failure (NO in step S101 in Fig. 3). When the power-failure detection unit 91 detects the power failure (YES in step S101 in Fig. 3), the temperature storage processing unit 92 stores the discharge temperature Td_off detected by the discharge temperature detection device 3a in the storage unit 93 (Step S102 in Fig. 3). The operation of the air-conditioning apparatus 100 is in a stopped state until supplying of power from the commercial power supply 500 is restarted (NO in step S103 in Fig. 3).
When supplying of power from the commercial power supply 500 is restarted (YES in step 103 in Fig. 3), the temperature storage processing unit 92 stores the discharge temperature Td_on detected by the discharge temperature detection device 3a in the storage unit 93 (step S104 in Fig. 3).
Next, the temperature difference calculation unit 94 reads out the discharge temperature Td_off and the discharge temperature Td_on stored in the storage unit 93, and calculates the temperature difference ΔTd by subtracting the discharge temperature Td_on from the discharge temperature Td_off (step S105 in Fig. 3).
The operation control unit 95 compares the temperature difference ΔTd calculated by the temperature difference calculation unit 94 with the power-failure reference threshold value to determine whether or not the temperature difference ΔTd is greater than the power-failure reference threshold value (step S106 in Fig. 3). When the temperature difference ΔTd is greater than the power-failure reference threshold value (YES in step S106 in Fig. 3), the operation control unit 95 executes the compressor protection control (step S107 in Fig. 3), and then rotationally drives the compressor 3 to execute the normal operation control (step S108 in Fig. 3). By contrast, when the temperature difference ΔTd is smaller than or equal to the power-failure reference threshold value (NO in step S106 in Fig. 3), the operation control unit 95 rotationally drives the compressor 3 to execute the normal operation control without executing the compressor protection control (step S108 in Fig. 3).
As described above, in the air-conditioning apparatus 100 according to the first embodiment, when a power failure occurs, the power-failure detection unit 91 detects the power failure, and stores the discharge temperature Td_off in the storage unit 93. Then, when supplying of power is restarted after occurrence of the power failure, the air-conditioning apparatus 100 automatically restarts its operation. At this time, the air-conditioning apparatus 100 compares the discharge temperature Td_on obtained after restarting of supplying of power, with the discharge temperature Td_off to determines whether or not to execute the compressor protection control, based on the result of the comparison.
To be more specific, when the temperature difference ΔTd between the discharge temperature Td_on and the discharge temperature Td_off is smaller than or equal to the power-failure reference threshold value, the air-conditioning apparatus 100 omits the compressor protection control, and returns to the normal operation control which was executed before the power failure. On the other hand, when the temperature difference ΔTd is greater than the power-failure reference threshold value, the air-conditioning apparatus 100 executes the compressor protection control, and after the compressor protection control is ended, returns to the normal operation control which was before occurrence of the power failure. That is, when supplying of power is restarted after elapse of a short time from occurrence of the power failure, the air-conditioning apparatus 100 can omit the compressor protection control, which is unnecessary in this case, and can thus rapidly causes the compressor 3 to be operated at the capacity at which the compressor 3 was operated before occurrence of the power failure, and can also rapidly restore the state of the air in the to-be-air-conditioned space to the air-conditioned state thereof prior to occurrence of the power failure.
Further, since the time required until the discharge temperature of the compressor 3 lowers by the power-failure reference threshold value is shorter than the time required until refrigerant accumulates in the compressor 3, the refrigerant does not accumulate in the compressor 3 within the time required until the discharge temperature of the compressor 3 lowers by the power-failure reference threshold value. Therefore, in the case where the temperature difference ΔTd is smaller than or equal to the power-failure reference threshold value, the air-conditioning apparatus 100 can omit the compressor protection control without damaging the compressor 3.
Therefore, in the air-conditioning apparatus 100, even if a condition during the power failure, for example, the temperature of air during the power failure, changes, it can be rapidly adjusted, and the state of air in the to-be-air-conditioned space can be rapidly restored to the air-conditioned state thereof prior to the power failure. Thus, the reliability is ensured.

Second embodiment

Fig. 4 is a schematic diagram illustrating a configuration of an air-conditioning apparatus according to the second embodiment of the present invention. A configuration of an air-conditioning apparatus 100A will be overall described with reference to Fig. 4. Components which are the same as or similar to those of the air-conditioning apparatus 100 according to the first embodiment described above will be denoted by the same reference signs, and their descriptions will be omitted.
The outdoor unit 1 of the air-conditioning apparatus 100A includes an inverter device 14, a heat-transfer fin 14a, a first inverter device 15, a first heat-transfer fin 15a and a heat-transfer temperature detection device 17. The inverter device 14 and the outdoor unit 1 drive a compressor motor of the compressor 3 in response to a control signal from the outdoor-unit control device 9. The inverter device 14 produces a voltage for operating the compressor 3, and supplies the produced voltage to the compressor motor.
The heat-transfer fin 14a transfers heat generated in the inverter device 14. The heat-transfer fin 14a is formed of, for example, a heatsink, and is provided in the inverter device 14. The heat-transfer fin 14a transfers heat, especially heat generated by a switching element (not shown) included in the inverter device 14.
The heat-transfer temperature detection device 17 is, for example, a temperature sensor formed of a thermistor, and is provided in the heat-transfer fin 14a. The heat-transfer temperature detection device 17 detects a heat-transfer temperature, which is the temperature of the heat-transfer fin 14a provided in the inverter device 14. The heat-transfer temperature is included in the "temperature information" in the present invention.
The first inverter device 15 drives a motor included in the heat-source-side fan 7 in response to a control signal from the outdoor-unit control device 9. The first heat-transfer fin 15a is formed of, for example, a heatsink, and transfers heat generated in the first inverter device 15.
The first inverter device 15 corresponds to the "inverter device" in the present invention, and the first heat-transfer fin 15a corresponds to the "heat-transfer fin" in the present invention.
The indoor unit 2 of the air-conditioning apparatus 100A includes a second inverter device 16 and a second heat-transfer fin 16a. The second inverter device 16 drives a motor included in the load-side fan 8 in response to a control signal from the indoor-unit control device 10. The second heat-transfer fin 16a is formed of, for example, a heatsink, and transfers heat generated in the second inverter device 16.
The second inverter device 16 corresponds to the "inverter device" in the present invention, and the second heat-transfer fin 16a corresponds to the "heat-transfer fin" in the present invention.
The outdoor-unit control device 9A has a function of controlling the operations of the inverter device 14 and the first inverter device 15. The indoor-unit control device 10A has a function of controlling the operation of the second inverter device 16. The other configurations of the outdoor-unit control device 9A and the indoor-unit control device 10A are the same as those of the outdoor-unit control device 9 and the indoor-unit control device 10 in the first embodiment.
Fig. 5 is a block diagram illustrating a functional configuration of the outdoor-unit control device 9A as illustrated in Fig. 4. The outdoor-unit control device 9A includes a temperature storage processing unit 192, a temperature difference calculation unit 194, and an operation control unit 195 including a power-failure time determination unit 195a.
The temperature storage processing unit 192 acquires, when the power-failure detection unit 91 detects a power failure, information indicating the heat-transfer temperature from the heat-transfer temperature detection device 17, and stores the acquired information indicating the discharge temperature in the storage unit 93 as a heat-transfer temperature Tinv_off. Furthermore, the temperature storage processing unit 192 acquires, when a power recovery is made from the power failure state, information indicating the heat-transfer temperature from the heat-transfer temperature detection device 17, and stores the acquired information indicating the heat-transfer temperature in the storage unit 93 as a heat-transfer temperature Tin_on. That is, in the second embodiment, the storage unit 93 stores the heat-transfer temperature Tinv_off and the heat-transfer temperature Tinv_on as temperature information. The other configuration of the temperature storage processing unit 192 is the same as that of the temperature storage processing unit 92 in the first embodiment.
The temperature difference calculation unit 194 calculates a difference between the heat-transfer temperature which is detected by the heat-transfer temperature detection device 17 when the power recovery is made from the power failure state and the heat-transfer temperature which is detected by the heat-transfer temperature detection device 17 when the power-failure detection unit 91 detects the power failure. To be more specific, the temperature difference calculation unit 194 reads out the heat-transfer temperature Tinv_off and the heat-transfer temperature Tinv_on from the storage unit 93 when supplying of power from the commercial power supply 500 is restarted after occurrence of the power failure, and calculates a temperature difference ΔTinv by subtracting the heat-transfer temperature Tinv_on from the heat-transfer temperature Tinv_off. Furthermore, the temperature difference calculation unit 194 has a function of outputting the calculated temperature difference ΔTinv to the operation control unit 195.
The power-failure time determination unit 195a compares the temperature difference ΔTinv calculated by the temperature difference calculation unit 194 with a power-failure reference threshold value to determine whether or not the temperature difference ΔTinv is greater than the power-failure reference threshold value. When the temperature difference ΔTinv is greater than the power-failure reference threshold value, the power-failure time determination unit 195a can determine that the power-failure time is long, and the power-failure time determination unit 195a thus outputs a control command signal to the protection control unit 95b. By contrast, when the temperature difference ΔTinv is smaller than or equal to the power-failure reference threshold value, the power-failure time determination unit 195a can determine that the power-failure time is short, and the power-failure time determination unit 195a thus outputs a control command signal to the air-conditioning control unit 95c.
The power-failure reference threshold value is set to 10 degrees C as in the first embodiment. The power-failure reference threshold value may be varied as appropriate in accordance with, for example, the amount of refrigerant in the air-conditioning apparatus 100A, the type of the compressor 3 and the state of attachment of the heat-transfer temperature detection device 17 or the suction temperature detection device 11. That is, when the temperature difference ΔTinv is smaller than or equal to a power-failure reference threshold value which is set in accordance with, for example, the amount of refrigerant in the air-conditioning apparatus 100, the compressor 3 can be prevented from being damaged even when the compressor protection control is not performed.
As described above, the outdoor-unit control device 9A indirectly determines, when supplying of power is restarted, whether or not the power-failure time is short, based on the heat-transfer temperature detected by the heat-transfer temperature detection device 17, and executes protection necessity determination processing of determining whether or not to execute the compressor protection control before shifting to the normal operation control.
It should be noted that the temperature difference calculation unit 194 may store the temperature difference ΔTinv in the storage unit 93 or the like, instead of outputting the temperature difference ΔTinv to the operation control unit 195. In this case, the power-failure time determination unit 195a may read out the temperature difference ΔTinv from the storage unit 93 or the like, and perform determination processing.
Fig. 6 is a flowchart illustrating the operation of the air-conditioning apparatus 100A as illustrated in Fig. 4. A control operation by the outdoor-unit control device 9A will be described with reference to Fig. 6, by referring mainly to the protection necessity determination processing.
First, the temperature storage processing unit 192 is on standby until the power-failure detection unit 91 detects a power failure (NO in step S201 in Fig. 6). When the power-failure detection unit 91 detects a power failure (YES in step S201 in Fig. 6), the temperature storage processing unit 192 stores information indicating the heat-transfer temperature Tinv_off detected by the heat-transfer temperature detection device 17 in the storage unit 93 (step S202 in Fig. 6). The operation of the air-conditioning apparatus 100A is in a stopped state until supplying of power from the commercial power supply 500 is restarted (NO in step S203 in Fig. 6).
When supplying of power from the commercial power supply 500 is restarted (YES in step S203 in Fig. 6), the temperature storage processing unit 192 stores the heat-transfer temperature Tinv_on detected by the heat-transfer temperature detection device 17 in the storage unit 93 (step S204 in Fig. 6).
Next, the temperature difference calculation unit 94 reads out the heat-transfer temperature Tinv_off and the heat-transfer temperature Tinv_on stored in the storage unit 93, and calculates he temperature difference ΔTinv by subtracting the heat-transfer temperature Tinv_on from the heat-transfer temperature Tinv_off (step S205 in Fig. 6).
The operation control unit 195 compares the temperature difference ΔTinv calculated by the temperature difference calculation unit 94 with the power-failure reference threshold value to determine whether or not the temperature difference ΔTinv is greater than the power-failure reference threshold value (step S206 in Fig. 6). When the temperature difference ΔTinv is greater than the power-failure reference threshold value (YES in step S206 in Fig. 6), the operation control unit 195 performs the compressor protection control (step S207 in Fig. 6), and then rotationally drives the compressor 3 to perform the normal operation control (step S208 in Fig. 6). On the other hand, when the temperature difference ΔTinv is smaller than or equal to the power-failure reference threshold value (NO in step S206 in Fig. 6), the operation control unit 195 rotationally drives the compressor 3 to perform the normal operation control without performing the compressor protection control (step S208 in Fig. 6).
As described above, in the air-conditioning apparatus 100A according to the second embodiment, when a power failure occurs, the power-failure detection unit 91 detects the power failure, and stores the heat-transfer temperature Tinv_off in the storage unit 93. When supplying of power is restarted after occurrence of the power failure, the air-conditioning apparatus 100A automatically restarts to operate. At this time, the air-conditioning apparatus 100A compares the heat-transfer temperature Tinv_on obtained after restating of supplying of power with the heat-transfer temperature Tinv_off to determine whether or not to perform the compressor protection control, based on the result of the comparison.
To be more specific, when the temperature difference ΔTinv between the heat-transfer temperature Tinv_on and the heat-transfer temperature Tinv_off is smaller than or equal to the power-failure reference threshold value, the air-conditioning apparatus 100A omits the compressor protection control, and returns to the normal operation control which was performed before occurrence of the power failure. On the other hand, when the temperature difference ΔTinv is greater than the power-failure reference threshold value, the air-conditioning apparatus 100A executes the compressor protection control, and after the compressor protection control is ended, the air-conditioning apparatus 100A returns to the normal operation control which was executed before occurrence of the power failure. That is, in the case where supplying of power is restarted after a short time elapses from occurrence of the power failure, the air-conditioning apparatus 100A can omit the compressor protection control, which is unnecessary in this case, and can thus rapidly cause the compressor 3 to be operated at the capacity at which the compressor 3 was operated before occurrence of the power failure, and can also rapidly restore the state of the air in the to-be-air-conditioned space to the air-conditioned state thereof prior to occurrence the power failure.
Furthermore, since the time required until the temperature of the heat-transfer fin 14a lowers by the power-failure reference threshold value is shorter than the time required until refrigerant accumulates in the compressor 3, the refrigerant does not accumulate in the compressor 3 within the time required until the temperature of the heat-transfer fin 14a lowers by the power-failure reference threshold value. Therefore, in the case where the temperature difference ΔTinv is smaller than or equal to the power-failure reference threshold value, the air-conditioning apparatus 100A can omit the compressor protection control without damaging the compressor 3.
Therefore, in the air-conditioning apparatus 100A, even if a condition during the power failure, for example, the temperature of air during the power failure, changes, it can be rapidly adjusted, and the state of air in the to-be-air-conditioned space can be rapidly restored to the air-conditioned state thereof prior to the power failure. Thus, the reliability is ensured.
Furthermore, it should be noted that the temperature of the heat-transfer fin 14a provided at the inverter device 14 varies in accordance with the ambient temperature of the inverter device 14 and the operation capacity of the compressor 3, but does not vary in accordance with the amount of refrigerant. Therefore, the air-conditioning apparatus 100A can more accurately determine whether a power recovery is made from the power failure state in a short time period or not.
Fig. 4 illustrates by way of example the case where the heat-transfer temperature detection device 17 is provided at the heat-transfer fin 14a; however, this is an example, and is not limitative. That is, the heat-transfer temperature detection device 17 may be provided at the first heat-transfer fin 15a or the second heat-transfer fin 16a. In this case, the outdoor-unit control device 9A may perform the protection necessity determination processing or the like based on the heat-transfer temperature detected by the heat-transfer temperature detection device 17 provided at the first heat-transfer fin 15a or the second heat-transfer fin 16a.
In particular, since the change of the internal temperature of a room corresponding to the to-be-air-conditioned space is relatively smaller than that of the outside of the room, the protection necessity determination processing can be more accurately performed than in the case where the heat-transfer temperature detection device 17 is provided at the second heat-transfer fin 16a provided in the indoor unit 2.

Third embodiment

Fig. 7 is a schematic diagram illustrating a configuration of an air-conditioning apparatus according to the third embodiment of the present invention. A configuration of a configuration of an air-conditioning apparatus 100B will be overall described with reference to Fig. 7. Components which are the same or similar to those in the air-conditioning apparatus 100 and the air-conditioning apparatus 100A according to the above embodiments described above will be denoted by the same reference signs, and their descriptions will thus be omitted.
As illustrated in Fig. 7, the outdoor unit 1 of the air-conditioning apparatus 100B includes an outdoor-unit control device 9B, a power-failure time measurement device 18, and a standby power supply device 19. The power-failure time measurement device 18 is a timer which measures time, and measures a power-failure time, which is a period of time for which a power-failure state continues. The standby power supply device 19 is, for example, a battery, and supplies power to the power-failure time measurement device 18 during a power failure.
Fig. 8 is a block diagram illustrating a functional configuration of the outdoor-unit control device 9B as illustrated in Fig. 7. The outdoor-unit control device 9B includes a power-failure time processing unit 296 and an operation control unit 295 including a power-failure time determination unit 295a.
The power-failure time processing unit 296 outputs a measurement start command to the power-failure time measurement device 18 when the power-failure detection unit 91 detects a power failure. That is, the power-failure time measurement device 18 starts to measure time in response to the measurement start command from the power-failure time processing unit 296. Furthermore, the power-failure time processing unit 296 outputs a measurement stop command to the power-failure time measurement device 18 when supplying of power from the commercial power supply 500 is restarted. That is, the power-failure time measurement device 18 stops measurement of time in response to the measurement stop command from the power-failure time processing unit 296.
The power-failure time processing unit 296 acquires the time measured by the power-failure time measurement device 18 as a power-failure time Tpf. Furthermore, the power-failure time processing unit 296 has a function of outputting the power-failure time Tpf acquired from the power-failure time measurement device 18 to the power-failure time determination unit 295a.
The power-failure time determination unit 295a compares the power-failure time Tpf with a power-failure reference time to determine whether or not the power-failure time Tpf is longer than the power-failure reference time. When the power-failure time Tpf is longer than the power-failure reference time, the power-failure time determination unit 295a outputs a control command signal to the protection control unit 95b. By contrast, when the power-failure time Tpf is smaller than or equal to the power-failure reference time, the power-failure time determination unit 295a outputs a control command signal to the air-conditioning control unit 95c.
It should be noted that several hours are taken until refrigerant accumulates in the compressor 3. Further, the time required until the refrigerant accumulates in the compressor 3 after occurrence of power failure varies in accordance with, for example, the amount of refrigerant in the air-conditioning apparatus 100B and the type of the compressor 3. Therefore, the power-failure reference time is set in accordance with, for example, the amount of refrigerant in the air-conditioning apparatus 100B and the type of the compressor 3. In the case where it is assumed that the refrigerant accumulates in the compressor 3 relatively early, the power-failure reference time is set to, for example, 60 minutes.
As described above, the outdoor-unit control device 9B directly determines whether or not the power-failure time is short, based on the power-failure time Tpf which is measured by the power-failure time measurement device 18 when supplying of power is restarted, and performs the protection necessity determination processing of determining whether or not to perform the compressor protection control before shifting to the normal operation control.
In this case, at least one of the power-failure time measurement device 18 and the standby power supply device 19 may be provided in the outdoor-unit control device 9B. Furthermore, the power-failure time measurement device 18 and the standby power supply device 19 may be provided in the indoor unit 2. In this case, for example, at least one of the power-failure time measurement device 18 and the standby power supply device 19 may be provided in the indoor-unit control device 10.
The power-failure time processing unit 296 may store the power-failure time Tpf in an internal memory (not shown) or the like, instead of outputting the power-failure time Tpf to the power-failure time determination unit 295a. In this case, the power-failure time determination unit 295a may read out the power-failure time Tpf from the internal memory or the like, and perform the determination processing.
Fig. 9 is a flowchart illustrating the operation of the air-conditioning apparatus 100B as illustrated in Fig. 7. A control operation by the outdoor-unit control device 9B will be described with reference to Fig. 9, by referring mainly to the protection necessity determination processing.
First, the power-failure detection unit 91 is on standby until a power failure is detected (NO in step S301 Fig. 9). When the power-failure detection unit 91 detects a power failure (YES in step S301 in Fig. 9), the power-failure time processing unit 296 outputs a measurement start command to the power-failure time measurement device 18 to cause the power-failure time measurement device 18 to start to measure time (step S302 in Fig. 9). The operation of the air-conditioning apparatus 100B is in the stopped state until supplying of power from the commercial power supply 500 is restarted (NO in step S303 in Fig. 9).
When supplying of power from the commercial power supply 500 is restarted (YES in step S303 in Fig. 9), the power-failure time processing unit 296 outputs a measurement stop command to the power-failure time measurement device 18 to cause the power-failure time measurement device 18 to stop measurement of time. Then, the power-failure time processing unit 296 acquires the power-failure time Tpf measured by the power-failure time measurement device 18 (step S304 in Fig. 9).
Next, the operation control unit 295 compares the power-failure time Tpf with the power-failure reference time to determine whether or not the power-failure time Tpf is greater than the power-failure reference time (step S305 in Fig. 9). When the power-failure time Tpf is greater than the power-failure reference time (YES in step S305 in Fig. 9), the operation control unit 295 performs the compressor protection control (step S306 in Fig. 9), and then rotationally drives the compressor 3 to perform the normal operation control (step S307 in Fig. 9). On the other hand, when the power-failure time Tpf is shorter than or equal to the power-failure reference time (NO in step S305 in Fig. 9), the operation control unit 295 rotationally drives the compressor 3 to perform the normal operation control without performing the compressor protection control (step S307 in Fig. 9).
As described above, in the case where supplying of power is restarted after a short time elapses from the power failure, the air-conditioning apparatus 100B can omit the compressor protection control, which is unnecessary, and can thus rapidly cause the compressor 3 at the capacity at which the compressor 3 was operated before occurrence of the power failure, and also rapidly restore the state of the air in the to-be-air-conditioned space to the air-conditioned state thereof prior to the power failure. That is, in the air-conditioning apparatus 100B, even if a condition during the power failure, for example, the temperature of air during the power failure, changes, it can be rapidly adjusted, and the state of air in the to-be-air-conditioned space can be rapidly restored to the air-conditioned state thereof prior to the power failure. Thus, the reliability is ensured.
It should be noted that the air- conditioning apparatuses 100 and 100A according to the above embodiments store temperature information obtained prior to occurrence of the power failure, and compare the temperature information with temperature information obtained after a power recovery to execute the protection necessity determination processing. In this case, in the case where the time required until the discharge temperature of the compressor 3 or the temperature of the heat-transfer fin 14a or the like lowers is compared with the time required until refrigerant accumulates after occurrence of the power failure, as described above, the time required until the refrigerant accumulates after occurrence of the power failure is longer. Therefore, even when the discharge temperature of the compressor 3 or the temperature of the heat-transfer fin 14a or the like is smaller than or equal to the power-failure reference threshold value, there is a case where a sufficient margin is allowed until the refrigerant accumulates, that is, there is a case where the refrigerant does not accumulate, although this depends on the accuracy of setting the power-failure reference threshold value.
In view of this point, the air-conditioning apparatus 100B according to the third embodiment performs the protection necessity determination processing based on the power-failure time Tpf measured by the power-failure time measurement device 18, that is, an actually measured value of the power-failure time. Then, the power-failure reference time to be compared with the power-failure time Tpf can be set to be longer and in such a way as to prevent the compressor 3 from being damaged, in direct consideration of the time required until the refrigerant accumulates after occurrence of the power failure. That is, the air-conditioning apparatus 100B has a function of directly measuring the power-failure time, and can thus determine whether or not to perform the compressor protection control, with higher accuracy. Thus, an operation omitting the unnecessary compressor protection control can be achieved without losing the reliability.
In this case, the outdoor unit 1 may include an outside-air temperature detection device (not shown), which is, for example, a temperature sensor formed of a thermistor, and detects an outside-air temperature, which is the temperature of outside air. In this case, the power-failure reference time may be set based on an inside-outside temperature difference, which is a difference between the outside-air temperature detected by the outside-air temperature detection device and the temperature of indoor air which is detected by the suction temperature detection device 11.
In the case where such a configuration is adopted, for example, the power-failure time determination unit 295a may acquire information indicating the temperature of outside air and the temperature of indoor air from the outside-air temperature detection device and the suction temperature detection device 11 to find out the inside-outside temperature difference. Then, the power-failure time determination unit 295a may set the power-failure reference time based on the inside-outside temperature difference, and apply the set power-failure reference time to the comparison with the power-failure time Tpf.
In the case where the inside-outside temperature difference is great, the refrigerant more easily accumulates in the compressor 3. Therefore, in this case, the power-failure time determination unit 295a may change the power-failure reference time such that the greater the inside-outside temperature difference, the shorter the power-failure reference time. As a result, the outdoor-unit control device 9B can execute the protection necessity determination processing with higher accuracy. For example, a temperature difference time table in which inside-outside temperature differences and power-failure reference times are associated with each other may be stored in the internal memory or the like, and with respect to the found inside-outside temperature difference, the power-failure time determination unit 295a may refer to the temperature difference time table to determine an associated power-failure reference time.
The embodiments described above are preferable examples of the air-conditioning apparatus, and the technical scope of the present invention is not limited to the embodiments. For example, regarding the above embodiments, a description is made by referring to by way of example the case where the protection control unit 95b energizes the electric heater provided in the compressor 3 to perform the compressor protection control; however, this is an example, and is not limitative. The protection control unit 95b may perform the compressor protection control by applying, to a coil (not shown) of an electric motor included in the compressor 3, a voltage which is set low so as not to cause the electric motor to rotate, and heating the compressor 3 with heat generated by the coil. In the case of adopting such a configuration, it is not necessary to provide the electric heat in the compressor 3.
Furthermore, in the embodiments, the air- conditioning apparatuses 100, 100A and 100B are described above by way of example as air-conditioning apparatuses dedicated to the cooling operation, but they are not limited to such air-conditioning apparatuses. For example, the air- conditioning apparatuses 100, 100A and 100B may be formed to include a four-way valve which switches the flow of refrigerant, and be thus capable of performing a heating operation, a defrosting operation, etc. That is, regarding the above embodiments, it is described above by way of example that the heat-source-side heat exchanger 4 functions as a condenser, and the load-side heat exchanger 6 functions as an evaporator; however, the heat-source-side heat exchanger 4 may function as the evaporator, and the load-side heat exchanger 6 may function as the condenser.
Moreover, regarding the above embodiments, it is described above by way of example that the outdoor-unit control device included in the outdoor unit 1 functions as a main controller, and performs the protection necessity determination processing, etc.; however, this is an example, and is not limitative. For example, the outdoor-unit control device included in the indoor unit 2 may function as the main controller to perform the protection necessity determination processing, etc. In the air-conditioning apparatus according to each of the above embodiments, as its controller, only one controller may be provided, and may be made to have the functions of both the outdoor-unit control device and indoor-unit control device.
In addition, Figs. 1, 4 and 7 illustrate by way of example the air- conditioning apparatuses 100, 100A and 100B as separate-type air-conditioning apparatuses, in which the outdoor unit 1 and the indoor unit 2 are separately provided; however, as each of the air- conditioning apparatuses 100, 100A and 100B, an integrated-type air-conditioning apparatus may be applied in which the function of the outdoor unit 1 and the function of the indoor unit 2 are combined.

Reference Signs List

1 outdoor unit 2 indoor unit 3 compressor 3a discharge temperature detection device 4 heat-source-side heat exchanger 5 expansion valve 6 load-side heat exchanger 7 heat-source-side fan 8 load- side fan 9, 9A, 9B outdoor-unit control device 10 indoor-unit control device 11 suction temperature detection device 12 input device 13 refrigerant pipe 14 inverter device 14a heat-transfer fin 15 first inverter device 15a first heat-transfer fin 16 second inverter device 16a second heat-transfer fin 17 heat-transfer temperature detection device 18 power-failure time measurement device 19 standby power supply device 91 power- failure detection unit 92, 192 temperature storage processing unit 93 storage unit 94, 194 temperature difference calculation unit 95, 195, 295 operation control unit 95a, 195a, 295a power-failure time determination unit 95b protection control unit 95c air- conditioning control unit 100, 100A, 100B air-conditioning apparatus 296 power-failure time processing

Claims

An air-conditioning apparatus in which a compressor, a heat-source-side heat exchanger, an expansion valve and a load-side heat exchanger are coupled to each other by a refrigerant pipe to form a refrigerant circuit, the air-conditioning apparatus comprising:
a controller configured to control the refrigerant circuit; and

a temperature detection device configured to detect a temperature related to the refrigerant circuit as temperature information,

wherein the controller includes:
a power-failure detection unit configured to detect a power failure;

a temperature difference calculation unit configured to calculate a difference between a temperature which is detected as the temperature information when a power recovery is made from a power-failure state and a temperature which is detected as the temperature information when the power-failure detection unit detects the power failure; and

an operation control unit configured to:
perform compressor protection control of heating the compressor for a fixed period of time and then rotationally drive the compressor, when the difference is greater than a power-failure reference threshold value; and

rotationally drive the compressor without performing the compressor protection control, when the difference is smaller than or equal to the power-failure reference threshold value.
The air-conditioning apparatus of claim 1, wherein the temperature detection device is provided on a discharge side of the compressor, and is configured to detect a temperature of refrigerant discharged from the compressor as the temperature information.
The air-conditioning apparatus of claim 1,
wherein the compressor is driven by an inverter circuit,
wherein the inverter circuit includes a heat-transfer fin configured to transfer heat generated by the inverter circuit, and
wherein the temperature detection device is provided at the heat-transfer fin, and is configured to detect a temperature of the heat-transfer fin as the temperature information.
The air-conditioning apparatus of claim 1,
wherein for at least one of the heat-source-side heat exchanger and the load-side heat exchanger, a fan to be driven by an inverter circuit is provided,
wherein the inverter circuit includes a heat-transfer fin configured to transfer heat generated by the inverter circuit, and
wherein the temperature detection device is provided at the heat-transfer fin, and is configured to detect a temperature of the heat-transfer fin as the temperature information.
An air-conditioning apparatus in which a compressor, a heat-source-side heat exchanger, an expansion valve and a load-side heat exchanger are coupled to each other by a refrigerant pipe to form a refrigerant circuit, the air-conditioning apparatus comprising:
a controller configured to control an operation of the refrigerant circuit; and

a power-failure time measurement device configured to measure a power-failure time which is a period of time in which a power-failure state continues,

wherein the controller including an operation control unit configured to:

perform compressor protection control of heating the compressor for a fixed period of time and then rotationally drive the compressor, when the power-failure time is longer than a power-failure reference time; and

rotationally drive the compressor without performing the compressor protection control, when the power-failure time is shorter than or equal to the power-failure reference time.