JP2016099095A - Control device, air conditioner and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a crank case heater for reducing electric power consumption while a compressor is stopped.SOLUTION: A control device includes: a temperature acquisition section for acquiring a temperature of a compressor, a temperature of a heat exchanger and an outside air temperature in a refrigerant circuit having the heat exchanger and the compressor connected to the heat exchanger; and an energization control section for performing on-control or off-control of a crank case heater for heating the compressor on the basis of a temperature difference between the temperature of the compressor and the temperature of the heat exchanger, when the outside air temperature acquired by the temperature acquisition section is a temperature included in one range of a plurality of preset temperature zones, while the compressor is stopped.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a crankcase heater control device, an air conditioner, and a control method.

  The compressor provided outside the room with the air conditioning equipment is cooled by the outside air while the operation is stopped. Since the refrigerant has the property of moving to a lower temperature place in the air conditioning equipment, when the temperature of the compressor drops, the refrigerant present in other devices such as the outdoor heat exchanger moves to the compressor, and the compressor This causes a phenomenon in which the refrigerant accumulates. If the refrigerant accumulates, liquid compression of the refrigerant may occur, or the compressor lubricating oil may dissolve in the refrigerant and the oil film of the compressor may not be formed, resulting in a compressor failure when starting the compressor . Therefore, a heater called a crankcase heater is provided in the compressor, and the crankcase heater is operated to warm the stopped compressor, thereby preventing the refrigerant from accumulating in the compressor.

  As for the operation of the crankcase heater, for example, the crankcase heater is controlled to be uniformly started while the compressor is stopped, or the crankcase heater is turned on / off according to the outside air temperature. Further, for example, in Patent Document 1, the temperature of the compressor, the temperature of the indoor heat exchanger, and the temperature of the outdoor heat exchanger are acquired, and the temperature of the compressor is the temperature of the indoor heat exchanger, or A control method is described in which the crankcase heater is turned on when the temperature is lower than the temperature of the outdoor heat exchanger by a predetermined temperature or more.

JP 2008-170052 A

  However, since the method of Patent Document 1 controls the relative relationship between the temperature of the compressor and the temperature of the indoor heat exchanger or the outdoor heat exchanger regardless of the outside air temperature, for example, when the outside air temperature is low However, the crankcase heater may not work. In that case, there is a possibility that the accumulation of the refrigerant causing the above-described compressor failure may occur. Moreover, since there is a possibility of turning on the crankcase heater even in a temperature range where it is not necessary to operate the crankcase heater, there remains a problem from the viewpoint of energy saving.

  Then, this invention aims at providing the control apparatus, air conditioning apparatus, and control method which can solve the above-mentioned subject.

  A first aspect of the present invention acquires a temperature of the compressor, a temperature of the heat exchanger, and an outside air temperature in a refrigerant circuit including a heat exchanger and a compressor connected to the heat exchanger. And the temperature of the compressor when the outside temperature acquired by the temperature acquisition unit is a temperature included in one of a plurality of predetermined temperature zones while the compressor is stopped. And an energization control unit that performs on-control or off-control of a crankcase heater that heats the compressor based on a temperature difference between the temperatures of the heat exchanger.

  The energization control unit according to the second aspect of the present invention turns on the crankcase heater when the temperature difference obtained by subtracting the temperature of the heat exchanger from the temperature of the compressor is equal to or greater than a first threshold, The crankcase heater is turned off when the temperature is lower than the second threshold value, which is lower than the threshold value.

  The energization control unit according to the third aspect of the present invention turns on the crankcase heater when the acquired outside air temperature continues to rise for a predetermined time regardless of the temperature difference.

  In the fourth aspect of the present invention, three temperature zones are set as the plurality of predetermined temperature zones, and one of the plurality of predetermined temperature zones is an intermediate of the three temperature zones. In the temperature zone, the energization control unit turns on the crankcase heater when the acquired outside air temperature is a temperature included in the temperature zone having the lowest temperature among the three temperature zones. When the temperature is within the high temperature range, the crankcase heater is turned off.

  The first threshold value in the fifth aspect of the present invention is 1.5 ° C.

  The second threshold value in the sixth aspect of the present invention is 0 ° C.

  The compressor temperature according to the seventh aspect of the present invention is the temperature under the dome of the compressor or the discharge port temperature of the compressor.

  According to an eighth aspect of the present invention, there is provided an air conditioner having a refrigerant circuit including a compressor, a crankcase heater provided in the compressor, and an outdoor heat exchanger connected to the compressor. It is an air conditioner provided with the control apparatus as described in any one of these.

  According to a ninth aspect of the present invention, there is provided a crankcase heater control method for heating a compressor in a refrigerant circuit including a heat exchanger and a compressor connected to the heat exchanger, the temperature of the compressor being When the temperature of the heat exchanger and the outside air temperature are acquired, and the acquired outside air temperature is a temperature included in one of a plurality of predetermined temperature zones, the temperature of the compressor It is a control method which performs on control or off control of the crankcase heater based on the temperature difference of the temperature of the heat exchanger.

  According to the present invention, it is possible to save energy by optimizing the on / off control of the crankcase heater while the compressor is stopped.

It is a figure which shows an example of the refrigerant circuit in one Embodiment of this invention. It is a schematic block diagram of the control apparatus in one Embodiment of this invention. It is a figure explaining the temperature zone of the outside temperature used for on / off control of the crankcase heater in one embodiment of the present invention. It is a processing flowchart of the control apparatus in one Embodiment of this invention. It is a flowchart of the judgment process of condition B1 in one Embodiment of this invention. It is a flowchart of the judgment process of condition B2 in one Embodiment of this invention. It is a figure explaining the ON area | region and OFF area | region used for determination of condition B2 in one Embodiment of this invention. It is a figure which shows an example of the behavior of the temperature of the compressor at the time of external temperature rise, and an outdoor heat exchanger.

<First embodiment>
Hereinafter, a control device for a crankcase heater according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram illustrating an example of a refrigerant circuit according to an embodiment of the present invention.
As shown in FIG. 1, the refrigerant circuit includes a compressor 1, an indoor heat exchanger 2, an expansion valve 3, an outdoor heat exchanger 4, a four-way valve 5, and a pipe 6 connecting them.
The compressor 1 compresses the refrigerant and supplies the compressed refrigerant to the refrigerant circuit. The indoor heat exchanger 2 performs heat exchange between the refrigerant and indoor air. The indoor heat exchanger 2 is used as an evaporator during the cooling operation and absorbs heat from the room, and is used as a condenser during the heating operation and dissipates heat to the room. The outdoor heat exchanger 4 performs heat exchange between the refrigerant and the outdoor air. The expansion valve 3 reduces the pressure by expanding the high-pressure refrigerant liquefied by exchanging heat with the condenser. The outdoor heat exchanger 4 is used as a condenser to radiate heat to the outside during cooling operation, and is used as an evaporator to absorb heat from the outside during heating operation. The four-way valve 5 switches the direction in which the refrigerant flows between the heating operation and the cooling operation. The refrigerant flows in the direction of arrow 7 during the cooling operation, and flows in the direction of arrow 8 during the heating operation.

The compressor 1 is provided with a temperature thermistor under the dome (casing) of the compressor 1 or at least one of the vicinity of the discharge port of the compressor 1. Reference numeral 11 denotes a temperature thermistor provided under the dome of the compressor 1. Reference numeral 12 denotes a temperature thermistor provided at the discharge port of the compressor 1. In addition, a temperature thermistor 13 for measuring the outside air temperature is provided outside, and the temperature thermistors 14A and 14B are provided in the outdoor heat exchanger 4 to measure the temperature of the outdoor heat exchanger 4. It is provided at a different position of the vessel 4.
Further, the compressor 1 is provided with a crankcase heater 9 for heating the compressor 1. Reference numeral 20 denotes a control device that controls on / off of the crankcase heater 9. The crankcase heater 9 is provided in order to prevent a failure of the compressor 1 due to liquid compression and no oil film formation caused by the accumulation of refrigerant in the compressor 1. The accumulation of refrigerant in the compressor usually increases when the outside air temperature decreases. When the outside air temperature decreases, the temperature of the compressor 1 and the outdoor heat exchanger 4 also decreases. However, the temperature of the outdoor heat exchanger 4 decreases first, and the refrigerant accumulates in the outdoor heat exchanger 4 at first. . However, when the outside air temperature rises, the heat capacity of the compressor 1 is large and the temperature rise of the compressor 1 is slow, so that the refrigerant moves from the outdoor heat exchanger 4 to the compressor 1 and accumulates in the compressor 1. Become. Next, changes in the temperature of the compressor 1 and the temperature of the outdoor heat exchanger 4 will be specifically described with reference to FIG.

FIG. 8 is a diagram illustrating an example of temperature behavior of the compressor and the outdoor heat exchanger when the outside air temperature rises.
The vertical axis in FIG. 8 is temperature, and the horizontal axis is time. FIG. 8 shows a state in which the temperatures of the compressor 1 and the outdoor heat exchanger 4 that have become low temperature during the night rise as the sun rises. The graph of FIG. 8 shows the behavior of the temperature of the compressor 1 and the like from the morning to several hours in the morning.
Reference numeral 81 indicates a temperature measured by the temperature thermistor 14 (14A or 14B) provided in the vicinity of the outdoor heat exchanger 4. Reference numeral 82 indicates the behavior of the outside air temperature measured by the temperature thermistor 13. Reference numeral 83 denotes a temperature measured by the temperature thermistor 12 provided at the discharge port of the compressor 1. Reference numeral 84 indicates a measured value of the temperature of the oil of the compressor 1. Reference numeral 85 denotes a temperature measured by the temperature thermistor 11 provided under the dome of the compressor 1.
As shown in FIG. 8, as the outside air temperature 82 rises, the temperature 81 of the outdoor heat exchanger 4, the discharge port temperature 83 of the compressor 1, the oil temperature 84, and the under-dome temperature 85 of the compressor 1 also rise. However, the divergence between the temperature 81, the temperature 84, and the temperature under the dome 85 starts around time T1, and the difference increases with the passage of time. Further, the divergence between the outside air temperature 82 and the discharge port temperature 83 starts from around time T2, and the difference increases with time. Thus, when the outside air temperature rises, the temperature of the outdoor heat exchanger 4 rises first, and the temperature of the compressor 1 rises later than that of the outdoor heat exchanger 4. In such a state, the refrigerant moves from the outdoor heat exchanger 4 to the compressor 1, and the refrigerant accumulates in the compressor 1.

The control device 20 in the present embodiment turns on the crankcase heater 9 and heats the compressor 1 in order to prevent the refrigerant from accumulating in the compressor 1. Next, the control device 20 will be described with reference to FIG.
FIG. 2 is a schematic block diagram of a control device according to an embodiment of the present invention.
The control device 20 is, for example, a microcomputer that controls the crankcase heater 9, and includes at least a temperature acquisition unit 21, an energization control unit 22, and a storage unit 23, as shown in FIG.
The temperature acquisition unit 21 acquires the temperature of the compressor 1 from the temperature thermistor 11 and the temperature thermistor 12, the outdoor air temperature from the temperature thermistor 13, and the temperature of the outdoor heat exchanger 4 from the temperature thermistor 14 (14A, 14B). .
The energization control unit 22 performs on / off control of the crankcase heater 9. The accumulation of refrigerant in the compressor 1 causes a failure of the compressor 1. Therefore, it is necessary to turn on the crankcase heater 9 to heat the compressor 1 to prevent the refrigerant from being accumulated, but on the other hand, reduction of standby power is required from the viewpoint of energy saving. The energization control unit 22 controls the on / off of the crankcase heater 9 based on each temperature acquired by the temperature acquisition unit 21 so as to make the off state as long as possible while preventing the refrigerant from accumulating in the compressor 1. I do. In particular, in the present embodiment, when the compressor 1 is stopped and the outside air temperature is within a predetermined range, the temperature difference between the temperature of the compressor 1 and the temperature of the outdoor heat exchanger 4 or an increase in the outside air temperature. Based on the above, the control to turn on / off the crankcase heater 9 is performed.
The storage unit 23 stores various temperatures acquired by the temperature acquisition unit 21 and various parameters used by the energization control unit 22 for on / off control.

Next, on / off control of the crankcase heater 9 performed by the control device 20 will be described with reference to FIGS.
FIG. 3 is a view for explaining a temperature zone of the outside air temperature used for on / off control of the crankcase heater in one embodiment of the present invention.
The control device 20 switches the crankcase heater 9 on / off control method based on the outside air temperature when the compressor 1 is stopped. Specifically, three temperature zones A, B, and C are set in order from the lowest temperature. The “A temperature zone” is a temperature zone having the lowest temperature among the three temperature zones (for example, −1 ° C.). The “B temperature zone” is an intermediate temperature zone (for example, −1 ° C. to 30 ° C.) among the three temperature zones. The “C temperature zone” is a temperature zone having the highest temperature among the three temperature zones (for example, 30 ° C.). As shown in FIG. 3, a hysteresis width of 2 ° C. is provided at the switching temperature between the “A temperature zone” and the “B temperature zone” and the “B temperature zone” and the “C temperature zone”. When the outside air temperature rises from a temperature lower than −1 ° C., the control device 20 determines that the outside air temperature is “B temperature zone” when the outside air temperature becomes −1 ° C., and conversely, is in the “B temperature zone”. When outside temperature falls, when outside temperature will be -3 degreeC, it will determine with being in "A temperature range." Similarly, when the outside air temperature in the “B temperature zone” rises, the control device 20 determines that it is in the “C temperature zone” at 30 ° C., and the outside air temperature in the “C temperature zone” decreases. When the outside air temperature reaches 28 ° C., it is determined that the temperature is in the “B temperature zone”. By providing the hysteresis width in this way, measurement errors and fluctuations of the temperature thermistor 13 can be absorbed and stable control can be performed.

  The present embodiment is directed to on / off control of the crankcase heater 9 when the compressor 1 is stopped. However, when the outside air temperature is in the “A temperature zone”, the refrigerant circuit performs heating operation. There are many. Further, when the outside air temperature is in the “C temperature zone”, the refrigerant circuit is often in a cooling operation. On the other hand, the “B temperature zone” is a daily temperature, and there are many times when the refrigerant circuit is stopped without cooling and heating. In this embodiment, the on / off control of the crankcase heater 9 is optimized particularly in the “B temperature range”, and the energy saving effect is improved.

Specifically, the control device 20 controls the crankcase heater 9 to be turned on when the compressor 1 is stopped and the outside air temperature is in the “A temperature zone”. Further, the control device 20 turns off the crankcase heater 9 when the compressor 1 is stopped and the outside air temperature is in the “C temperature zone”. Further, when the compressor 1 is stopped and the outside air temperature is in the “B temperature zone”, the control device 20 controls the crankcase heater 9 based on the temperature difference between the compressor 1 and the outdoor heat exchanger 4. Perform on / off control. Alternatively, when the outside air temperature is in the “B temperature zone” and the outside air temperature continues to rise for a predetermined time, the control device 20 turns on the crankcase heater 9.
Even when the compressor 1 is not stopped, the control device 20 turns on the crankcase heater 9 based on a predetermined condition such as turning on the crankcase heater 9 while the defrost operation is in progress. / Off control is performed, but the description is omitted because it is not related to the present embodiment.

FIG. 4 is a process flow diagram of the control device according to the embodiment of the present invention.
A flow of processing in which the control device 20 controls on / off of the crankcase heater 9 when the compressor 1 is stopped will be described with reference to FIG.
As a premise, the temperature acquisition unit 21 acquires measurement temperatures at predetermined time intervals from at least one of the temperature thermistor 11 and the temperature thermistor 12, the temperature thermistor 13, and the temperature thermistor 14 (14A, 14B). It is assumed that the temperature is recorded in the storage unit 23.
First, the energization control unit 22 reads the outside air temperature measured by the temperature thermistor 13 from the storage unit 23 and determines whether the outside air temperature is A to “C temperature zone” based on the hysteresis diagram of FIG. Step S11). When the outside air temperature is in the “A temperature zone”, the energization control unit 22 turns on the crankcase heater 9 (step S12). When the outside air temperature is sufficiently low, the crankcase heater 9 is turned on because liquid compression of the refrigerant may occur regardless of the temperature difference between the outdoor heat exchanger 4 and the compressor 1. When the outside air temperature is in the “C temperature zone”, the energization control unit 22 turns off the crankcase heater 9 (step S13). When the outside air temperature is sufficiently high, the crankcase heater 9 is turned off because there is no possibility that the refrigerant will cause liquid compression. When the outside air temperature is in the “B temperature zone”, the energization control unit 22 turns off the crankcase heater 9 after a predetermined time (for example, about 10 minutes or less) has elapsed (step S14). Here, in order to reduce standby power, it is preferable to control the crankcase heater 9 to be turned off as much as possible and to turn it on only when necessary. The energization control unit 22 determines whether or not a condition B1 and a condition B2 to be described later are satisfied (step S15), and turns on the crankcase heater 9 only when necessary. Condition B1 and condition B2 are conditions for determining whether the crankcase heater 9 needs to be activated. When the condition B1 or the condition B2 is satisfied, the energization control unit 22 turns on the crankcase heater 9 (step S17). When both the condition B1 and the condition B2 are not established, the energization control unit 22 turns off the crankcase heater 9 (step S16). Next, it is determined whether or not the outside air temperature is in the “B temperature zone” (step S18). While the outside air temperature is in the “B temperature zone” (step S18; Yes), the processing of step S15 to step S17 is repeated. When the outside air temperature is not in the “B temperature zone” (step S18; No), the processing from step S11 is repeated.
With this control, when the compressor 1 is stopped, the crankcase heater 9 can be turned on only when necessary due to the outside air temperature conditions, etc., and while waiting for efficient accumulation of refrigerant in the compressor 1, Electric power can be reduced.

Next, details of the control when the outside air temperature is in the “B temperature zone” will be described. First, the condition B1 will be described.
FIG. 5 is a flowchart of the condition B1 determination process according to the embodiment of the present invention.
The condition B1 is one of the determination conditions in step S15 in the flowchart described in FIG. Condition B1 is a condition for performing control to turn on the crankcase heater 9 based on a rise in outside air temperature.
First, the energization control unit 22 initializes the counter N by substituting 0 (step S21). Next, the energization control unit 22 reads out the outside air temperature measured by the temperature thermistor 13 from the storage unit 23 for 10 minutes and monitors the transition of the outside air temperature (step S22). Next, the energization control unit 22 determines whether or not the outside air temperature has increased during 10 minutes (step S23). For example, the outside air temperature sampled for 10 minutes is classified into the first half and the second half according to the acquisition time, and the average value of the outside air temperature acquired in the first half is compared with the average value of the outside air temperature acquired in the second half. If the average value of the outside temperature is high, it is determined that the outside temperature has increased.

  If it is determined that the outside air temperature has risen, the energization control unit 22 adds 1 to the counter N and counts up (step S24). When it is determined that the outside air temperature has not risen, the processing from step S21 is repeated. Next, the energization control unit 22 determines whether the counted value of N has reached 10 (step S25). If the value of N has not reached 10, the processing from step S22 is repeated. When the value of N reaches 10, the energization control unit 22 determines that the condition B1 is satisfied (step S26). If it determines with condition B1 having been satisfied, the electricity supply control part 22 will perform control which turns on the crankcase heater 9 according to the processing flow of FIG.

  Here, for convenience of explanation, the case where the outside air temperature is always within the “B temperature zone” has been described as an example. However, in the determination of step S23, the outside air temperature monitored for 10 minutes is outside the “B temperature zone”. If this happens, the value of N is set to 0, and execution of this processing flow is stopped. Since the present embodiment is based on the premise that the compressor 1 is stopped, the value of N is set to 0 even when the compressor 1 starts operating, and the execution of this processing flow is stopped.

  In step S23, even if the external temperature does not increase for 10 minutes and is constant, the process for initializing the counter N to 0 is temporarily suspended and the temperature starts to increase in the next 10 minutes. , N can be counted up and the determination process of the condition B1 can be continued as it is. Further, the determination of the increase in the outside air temperature may be made from the rate of change of the temperature measured by the temperature thermistor 13 without depending on the method shown in FIG. 5, or the temperature difference for each predetermined time interval is calculated. When the temperature acquired in time is higher than a predetermined value, it may be determined that the outside air temperature has increased.

Next, the condition B2 will be described with reference to FIGS.
FIG. 6 is a flowchart of the condition B2 determination process according to the embodiment of the present invention.
First, the energization control unit 22 reads the temperature of the outdoor heat exchanger 4 and the temperature under the dome of the compressor 1 measured by the temperature thermistor 14 </ b> A and the temperature thermistor 14 </ b> B from the storage unit 23. In the refrigerant circuit where the temperature thermistor 11 is not provided under the dome of the compressor 1, the outlet temperature of the compressor 1 measured by the temperature thermistor 12 is read. Next, the energization control unit 22 selects a lower temperature from the temperature measured by the temperature thermistor 14A and the temperature measured by the temperature thermistor 14B, and the temperature difference obtained by subtracting the under-dome temperature (or the discharge port temperature) from the selected temperature. ΔT is calculated. And the electricity supply control part 22 determines whether the calculated temperature difference (DELTA) T exists in the "on area | region" mentioned later (step S31). When the temperature difference is in the “on region”, the energization control unit 22 determines that the condition B2 is satisfied (step S32). When the temperature difference is in an “off region” described later, the energization control unit 22 determines that the condition B2 is not satisfied (step S33).
If it determines with condition B2 being materialized, the electricity supply control part 22 will perform the control which turns on the crankcase heater 9 according to the processing flow of FIG.
The processing flow of FIG. 6 is control until a predetermined time (for example, 10 hours) elapses after the compressor 1 is stopped, and the energization control unit 22 does not depend on the magnitude of the temperature difference ΔT. When the predetermined time elapses after the compressor 1 is stopped, the crankcase heater 9 may be controlled to be turned on.

FIG. 7 is a diagram illustrating an on region and an off region used for determination of the condition B2 in one embodiment of the present invention.
FIG. 7 shows a temperature obtained by subtracting the temperature under the dome of the compressor 1 (or the outlet temperature of the compressor 1) from the lower temperature of the temperatures of the outdoor heat exchanger 4 measured by the temperature thermistor 14A and the temperature thermistor 14B. A graph used for determining whether the temperature difference ΔT is a temperature difference that requires the crankcase heater 9 to be turned on based on the difference ΔT is shown. In FIG. 7, the “on region” is a region of temperature difference where the crankcase heater 9 needs to be turned on. The “off region” is a region of temperature difference where the crankcase heater 9 can be turned off. For example, if the temperature difference ΔT is 1.5 ° C., ΔT is “on region”, and if the temperature difference ΔT is 0 ° C., ΔT is “off region”. Specifically, when the temperature of the outdoor heat exchanger 4 becomes higher by 1.5 ° C. or more than the temperature under the dome of the compressor 1, the energization control unit 22 turns on the crankcase heater 9 and turns on the outdoor heat exchanger 4. When the temperature is equal to or lower than the temperature below the dome of the compressor 1, the energization control unit 22 turns off the crankcase heater 9. By adopting such control, even when the outside air temperature rises as illustrated in FIG. 8, the difference between the temperature of the outdoor heat exchanger 4 and the temperature under the dome (or the discharge port temperature) of the compressor 1 is detected. Then, the compressor 1 can be warmed so that the refrigerant does not move to the compressor 1.

In addition, as shown in FIG. 7, a hysteresis width is also provided in the determination of “on region” and “off region”. In the situation where the temperature difference ΔT gradually increases from a state where there is not much difference between the temperature of the outdoor heat exchanger 4 and the temperature under the dome of the compressor 1 when the outside air temperature exemplified in FIG. When the temperature difference ΔT is 1.5 ° C. or more, the energization control unit 22 determines that the temperature difference ΔT is in the “on region”. On the other hand, in a situation where the temperature difference ΔT becomes smaller, when the temperature difference ΔT becomes 0 ° C., the energization control unit 22 determines that the temperature difference ΔT is in the “off region”. By providing the hysteresis width, it is repeatedly determined whether the temperature difference ΔT is in the “on region” or the “off region” due to fluctuations in the temperature difference ΔT due to detection errors of the temperature thermistors 11, 14, etc. It is possible to prevent switching and unstable control.
When the outside air temperature is included in the “B temperature zone” and the temperature difference ΔT is determined for the first time, if the temperature difference ΔT is within the hysteresis width, it is determined that the temperature difference ΔT is in the “on region”. Good.

  In addition, the following is mentioned as a meaning which determines conditions B1 and B2 together. Although it is preferable that the relationship between the temperature of the compressor 1 and the temperature of the outdoor heat exchanger 4 can always be determined according to the condition B2, the temperature thermistor 14 measures even if the temperature of the outdoor heat exchanger 4 starts to increase due to the influence of the installation location, for example. There is a possibility that the temperature of the compressor 1 or the outdoor heat exchanger 4 cannot be properly captured due to a situation where the temperature of the compressor 1 or the outdoor heat exchanger 4 is not easily raised due to a failure of the temperature thermistor. In such a situation, from the acquired temperature information, even if the condition B2 is not satisfied, the actual temperature of the compressor 1 and the outdoor heat exchanger 4 as illustrated in FIG. There is a possibility that a temperature difference occurs and the refrigerant moves to the compressor 1. Condition B1 is a determination condition prepared for such a situation. By performing the determination of condition B1 in addition to condition B2, the accumulation of refrigerant in the compressor 1 due to the temperature rise as illustrated in FIG. 8 is performed. It can be surely prevented.

  According to this embodiment, the on / off control method of the crankcase heater 9 in a state where the compressor 1 is stopped can be switched according to the temperature zone of the outside air temperature. Further, when the outside air temperature is in a predetermined range (“B temperature zone”) (for example, −1 ° C. to 30 ° C.), only when the temperature of the outdoor heat exchanger 4 is higher than the temperature of the compressor 1 by a predetermined value When the case heater 9 is turned on and the temperature of the outdoor heat exchanger 4 is lower than the temperature of the compressor 1, the crankcase heater 9 can be turned off, so that the refrigerant can efficiently accumulate in the compressor. It can prevent and save energy. Even if the temperature of the outdoor heat exchanger 4 or the compressor 1 cannot be measured due to an abnormality in the temperature thermistors 11 and 14 or the like, if the outside air temperature is monitored and a rise in the outside air temperature is detected, the crankcase heater 9 Since the refrigerant is turned on, the refrigerant can be prevented from accumulating in the compressor 1. Further, when the outside air temperature is in a predetermined range (“B temperature zone”), the crankcase heater 9 can be turned off depending on the temperature difference between the temperature of the compressor 1 and the temperature of the outdoor heat exchanger 4. In particular, when the outside air temperature decreases or when the outside air temperature does not change, energy saving can be achieved by performing the off control.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention. The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. The temperature difference 1.5 ° C. for determining the “on region” described in FIG. 7 is an example of the first threshold value, and the temperature difference 0 ° C. for determining the “off region” It is an example of a two threshold value.

DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Indoor heat exchanger 3 ... Expansion valve 4 ... Outdoor heat exchanger 5 ... Four-way valve 6 ... Piping 11, 12, 13, 14 ... Temperature Thermistor 20 ... Control device 21 ... Temperature acquisition unit 22 ... Energization control unit 23 ... Storage unit

Claims (9)

A temperature acquisition unit for acquiring the temperature of the compressor, the temperature of the heat exchanger, and the outside air temperature in a refrigerant circuit including a heat exchanger and a compressor connected to the heat exchanger;
When the outside air temperature acquired by the temperature acquisition unit is a temperature included in one of a plurality of predetermined temperature zones while the compressor is stopped, the temperature of the compressor and the heat exchanger An energization control unit that performs on-control or off-control of a crankcase heater that heats the compressor based on a temperature difference;
A control device comprising: The energization control unit turns on the crankcase heater when a temperature difference obtained by subtracting the temperature of the heat exchanger from the temperature of the compressor is equal to or greater than a first threshold, and is a temperature lower than the first threshold. Turning the crankcase heater off when below a threshold,
The control device according to claim 1. The control device according to claim 1, wherein the energization control unit turns on the crankcase heater when the acquired outside air temperature continues to rise for a predetermined time regardless of the temperature difference. Three temperature zones are set as the plurality of predetermined temperature zones, and one of the plurality of predetermined temperature zones is an intermediate temperature zone of the three temperature zones,
The energization control unit turns on the crankcase heater and is included in the highest temperature zone when the acquired outside air temperature is a temperature included in the lowest temperature zone of the three temperature zones. The control device according to any one of claims 1 to 3, wherein the crankcase heater is turned off when the temperature is reached. The first threshold is 1.5 ° C.
The control device according to claim 2. The second threshold is 0 ° C.
The control device according to claim 2. The control device according to any one of claims 1 to 6, wherein the temperature of the compressor is a temperature under a dome of the compressor or a discharge port temperature of the compressor. In an air conditioner having a refrigerant circuit comprising a compressor, a crankcase heater provided in the compressor, and an outdoor heat exchanger connected to the compressor,
The control device according to any one of claims 1 to 7,
An air conditioner. A control method of a crankcase heater for heating a compressor in a refrigerant circuit comprising a heat exchanger and a compressor connected to the heat exchanger,
Obtaining the temperature of the compressor, the temperature of the heat exchanger, and the outside air temperature;
When the acquired outside air temperature is a temperature included in one of a plurality of predetermined temperature zones, the crankcase heater is based on a temperature difference between the compressor temperature and the heat exchanger temperature. ON / OFF control of
Control method.

Images