JP2011257079A - Air conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioning device that can equalize room temperature and prevent excessive current in a PTC heater.SOLUTION: In an air conditioning device 1 that includes: a PTC heater 55 in which, in a stable region S1, when the temperature of the PTC heater 55 is increased, a resistance is decreased or is substantially constant whereas, in a rise region S2, the resistance is rapidly increased when the temperature exceeds a rise temperature T1; and an air blower 25 that generates an air current which exchanges heat with the PTC heater 55, and that performs a heating operation by discharging air heated by the PTC heater 55 into the room, when the temperature within the room is within a low-temperature range including a region whose temperature is lower than a set temperature, the DUTY ratio is set at 100% and the PTC heater 55 is driven in the rise region S2, and when the temperature within the room is within a high-temperature range whose temperatures are higher than the set temperature, the PTC heater 55 is stopped, and when the temperature within the room is within an intermediate-temperature range between the low-temperature range and the high-temperature range, the DUTY ratio is set at a predetermined DUTY ratio and the PTC heater 55 is driven in the stable region S1.

Description

  The present invention relates to an air conditioner including a PTC heater.

  A conventional air conditioner is disclosed in Patent Document 1. This air conditioner is configured as an integrated type in which an indoor part arranged indoors is arranged at the front part and an outdoor part arranged outside the room is arranged at the rear part. A compressor for operating the refrigeration cycle and an outdoor heat exchanger connected to the compressor are arranged outside the room. A suction port and an air outlet are opened in the room, and a blower, an indoor heat exchanger, and a PTC (Positive Temperature Coefficient) heater are arranged inside. The indoor heat exchanger is connected to the compressor via a refrigerant pipe. The blower sucks air from the suction port and sends out the air exchanged with the indoor heat exchanger and the PTC heater from the blower outlet.

  When the cooling operation is started, the refrigeration cycle is operated by driving the compressor, the indoor heat exchanger becomes an evaporator on the low temperature side of the refrigeration cycle, and the outdoor heat exchanger becomes a condenser on the high temperature side of the refrigeration cycle. The indoor air flows into the room through the suction port by driving the blower, and the air that has been cooled down by exchanging heat with the indoor heat exchanger is sent into the room through the air outlet. Thereby, indoor cooling is performed.

  When the heating operation is started, the refrigeration cycle is operated by driving the compressor, the indoor heat exchanger becomes a condenser on the high temperature side of the refrigeration cycle, and the outdoor heat exchanger becomes an evaporator on the low temperature side of the refrigeration cycle. The indoor air flows into the room through the suction port by driving the blower, and is heated by exchanging heat with the indoor heat exchanger. In addition, the temperature of the air flowing into the room is further increased by driving the PTC heater. The heated air is sent into the room through the outlet and the room is heated.

  The PTC heater is formed by sandwiching a heating element having PTC characteristics between electrodes, and is driven by applying a voltage between the electrodes. The heating element has a characteristic in which a resistance value decreases or is substantially constant with respect to a temperature rise and a rising region in which the resistance value increases rapidly when the rising temperature is exceeded.

  The PTC heater is driven in the rising region, and when the temperature rises, the resistance value of the heating element increases rapidly and the current value and the amount of heat generation decrease, and when the temperature drops, the resistance value of the heating element decreases rapidly and the current value and heat generation. The amount increases. Thereby, the calorific value of the PTC heater can be stabilized and hot air at a predetermined temperature can be easily generated, and overheating of the PTC heater can be prevented.

JP-A-8-152179 (pages 3-5, FIG. 2)

  However, according to the conventional air conditioner, the heating capability of the PTC heater is lowered when the room temperature rises above the set temperature, and the heating capability of the PTC heater is raised when it falls below the set temperature. At this time, if the heating capacity of the PTC heater is varied depending on the voltage, the resistance value of the heat generating element rapidly decreases due to the temperature drop when the voltage is lowered, and an overcurrent flows through the PTC heater, resulting in a problem of exceeding the power supply capacity.

  On the other hand, if the heating capacity of the PTC heater is varied depending on the air volume of the blower, the rotational speed of the blower is lowered when the room temperature rises, and the rotational speed of the blower is raised when it falls. At this time, since the PTC heater continues to generate a certain amount of heat, there is a problem that the temperature in the vicinity of the air conditioner becomes high and the room temperature becomes non-uniform.

  For this reason, if the compressor is stopped during the heating operation and the average heating capability of the PTC heater is maintained high and heating is performed only by the PTC heater, overcurrent and non-uniform room temperature occur. Therefore, it is common to reduce the average heating capacity of the PTC heater and use the PTC heater as an auxiliary by driving the compressor. Thereby, the capability of a PTC heater cannot fully be demonstrated, and heating capability may become low, when an external temperature is low.

  An object of the present invention is to provide an air conditioner that can equalize indoor temperature and prevent overcurrent of a PTC heater.

  In order to achieve the above object, the present invention provides a PTC heater having a characteristic that a resistance value decreases or is substantially constant with respect to a temperature rise, and a rising region where the resistance value increases rapidly when the rising temperature is exceeded, A heater control unit that performs DUTY control of the PTC heater, a temperature detection unit that detects a room temperature, and a blower that generates an air flow that exchanges heat with the PTC heater, and the air heated by the PTC heater is placed indoors In an air conditioner that performs heating operation by sending out, when the room temperature is in a low temperature range including a low temperature region than the set temperature, the PTC heater is driven in the rising region with a DUTY ratio of 100%, and the indoor temperature is The PTC heater is stopped at a high temperature zone that is higher than the set temperature, and a predetermined temperature is applied at an intermediate temperature zone between the low temperature zone and the high temperature zone. In the UTY ratio it is characterized in that driving the PTC heater in the stable region.

  According to this configuration, when the heating operation is started, the PTC heater and the blower are driven. The airflow generated by the blower exchanges heat with the PTC heater, and the air heated by the PTC heater is sent into the room. The PTC heater is DUTY controlled by the heater controller, and is driven at a DUTY ratio of 100% when the room temperature detected by the temperature detector is in a low temperature range including a lower temperature region than the set temperature. At this time, the PTC heater is maintained at the temperature in the rising region where the resistance value changes rapidly with respect to the temperature change. As a result, the amount of heat generated by the PTC heater is stabilized and overheating is prevented.

  When the room temperature rises to an intermediate temperature range, the PTC heater is driven at a predetermined DUTY ratio. At this time, the resistance value of the PTC heater decreases with increasing temperature or is maintained at a substantially constant temperature in a stable region, and the amount of heat generated by the PTC heater decreases. Since the DUTY ratio is lowered to the temperature in the stable region, the resistance value of the PTC heater is reduced, but the current is reduced and overcurrent is prevented. When the room temperature further rises to a high temperature zone, the PTC heater is stopped and the PTC heater is cooled.

  In the air conditioner having the above-described configuration, the intermediate temperature zone is further divided into a plurality of auxiliary temperature zones, and the PTC is more in the auxiliary temperature zone on the high temperature side than in the auxiliary temperature zone on the low temperature side. It is preferable to reduce the DUTY ratio of the heater. According to this configuration, the PTC heater is driven at a predetermined DUTY ratio when the room temperature becomes an auxiliary temperature zone on the low temperature side of the intermediate temperature zone. When the room temperature rises and becomes an auxiliary temperature zone on the high temperature side of the intermediate temperature zone, the PTC heater is driven at a DUTY ratio that is lower than the auxiliary temperature zone on the low temperature side by a predetermined amount.

  In the air conditioner configured as described above, it is preferable that the rotational speed of the blower be smaller when the auxiliary temperature zone is on the high temperature side than when the auxiliary temperature zone is on the low temperature side. According to this configuration, when the temperature of the PTC heater is lowered due to a decrease in the DUTY ratio in the auxiliary temperature zone on the high temperature side, the rotational speed of the blower is reduced and the delivery of cold air is prevented.

  In the air conditioner configured as described above, it is preferable that the rotational speed of the blower be smaller in the high temperature zone than in the low temperature zone. According to this configuration, when the temperature of the PCT heater is lowered by stopping in the high temperature temperature range, the rotational speed of the blower is reduced and the delivery of cold air is prevented. In addition, you may stop an air blower in a high temperature zone.

  In the air conditioner having the above-described configuration, the present invention further includes a current detection unit that detects the current value of the PTC heater, and sets the DUTY ratio to the DUTY ratio in the intermediate temperature range at an early stage when the room temperature is in the low temperature range. It is preferable to repeat the process of increasing the DUTY ratio by a predetermined amount when the current value detected by the current detection unit is smaller than a predetermined value until the DUTY ratio reaches 100%.

  According to this configuration, when the room temperature is in the low temperature range, the heater control unit applies a voltage having a duty ratio of 50%, for example, to the PTC heater. The current detection unit detects the current value of the PTC heater at a predetermined period, and increases the DUTY ratio by, for example, 10% when the current value of the PTC heater is smaller than the predetermined value. By repeating this process, the DUTY ratio gradually increases, and the PTC heater is driven when the DUTY ratio is 100%.

  According to the present invention, in the air conditioner configured as described above, until the indoor temperature is shifted to the low temperature range, the blower is driven at the first rotational speed, and the DUTY ratio of the PTC heater reaches 100%. During this time, the rotational speed of the blower is gradually decreased from the first rotational speed, and when the DUTY ratio of the PTC heater reaches 100%, the blower is rotated at a second rotational speed that is greater than the first rotational speed. It is preferable to drive by.

  According to this configuration, when the room temperature is in the low temperature range, the blower rotates at the first rotation speed, and the rotation speed gradually decreases and rotates at a low speed. When the DUTY ratio of the PTC heater reaches 100%, the blower rotates at the second high speed.

  In the air conditioner configured as described above, it is preferable that the duty ratio of the PTC heater is decreased by a predetermined amount when the current value detected by the current detection unit is larger than a predetermined value. According to this configuration, when the current value detected by the current detection unit becomes larger than a predetermined value, the DUTY ratio of the PTC heater is reduced by, for example, 10%. Thereby, the overcurrent of the PTC heater is prevented.

  Further, the present invention, in the air conditioner having the above-described configuration, includes a compressor that operates the refrigeration cycle, and a heat exchanger that is arranged in a high temperature portion of the refrigeration cycle and performs heat exchange with the airflow generated by the blower. The heating operation by driving the compressor and the heating operation by driving the PTC heater can be switched. When the heating operation by driving the compressor is performed, the PTC heater is used when the room temperature is lower than a predetermined temperature. It is preferable to switch to heating operation by driving.

  According to this configuration, the compressor and the blower are driven to perform the heating operation, and the compressor is driven to operate the refrigeration cycle. The airflow generated by the blower exchanges heat with the heat exchanger, and the air heated by the heat exchanger is sent out indoors. The room temperature is detected by the temperature detector at a predetermined time after heating operation is performed by driving the compressor. When the room temperature is lower than the predetermined temperature, the compressor is stopped and the PTC heater is driven, and the air exchanged with the PTC heater is sent into the room.

  In the air conditioner configured as described above, the heating operation is performed by driving the PTC heater when starting the heating operation. When the indoor temperature becomes higher than a predetermined temperature, the heating operation is performed by driving the compressor. It is preferable to switch. According to this configuration, when the heating operation by the air conditioner is started, the PTC heater is driven and the air exchanged with the PTC heater is sent into the room. When the room temperature becomes higher than the predetermined temperature, the PTC heater is stopped and the compressor is driven, and the air exchanged with the heat exchanger is sent into the room. When the room temperature becomes lower than the predetermined temperature, the compressor is stopped and the PTC heater is driven.

  According to the present invention, the PTC heater is driven in the rising region by setting the DUTY ratio to 100% in the low temperature range, and the PTC heater is stopped in the high temperature range, and the PTC heater is stabilized at the predetermined DUTY ratio in the intermediate temperature range. Since driving is performed in the region, it is possible to stabilize the amount of heat generated by the PTC heater in the low temperature range and prevent overheating, and to prevent overcurrent in the intermediate temperature range. Further, since the PTC heater is not maintained at a high temperature, the temperature rise in the vicinity of the air conditioner can be prevented, and the room temperature can be made uniform.

The perspective view which shows the air conditioner of 1st Embodiment of this invention. Side surface sectional drawing which shows the air conditioner of 1st Embodiment of this invention. The block diagram which shows the structure of the air conditioner of 1st Embodiment of this invention. The figure which shows the temperature characteristic of the resistance value of the PTC heater of the air conditioner of 1st Embodiment of this invention. The flowchart which shows operation | movement of the heating operation of the air conditioner of 1st Embodiment of this invention. The flowchart which shows operation | movement of the heating operation of the air conditioner of 2nd Embodiment of this invention. The flowchart which shows operation | movement of the heating operation of the air conditioner of 3rd Embodiment of this invention. The flowchart which shows the operation | movement of the DUTY variable process of the air conditioner of 3rd Embodiment of this invention. Time chart of DUTY variable processing of air conditioner of third embodiment of the present invention The flowchart which shows operation | movement of the heating operation of the air conditioner of 4th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a perspective view and a side sectional view of the air conditioner of the first embodiment. FIG. 1 shows a state in which the exterior cover 30 (see FIG. 2) is removed. The air conditioner 1 is configured as an integrated type having an indoor part 2 arranged indoors and an outdoor part 4 arranged adjacent to the indoor part 2 and outdoor.

  A suction port 21 is provided in front of the indoor portion 2, and an outdoor heat exchanger 42 is provided in front of the outdoor portion 4. In the following description, the inlet 21 side is referred to as the front side, and the outdoor heat exchanger 42 side is referred to as the rear side (back side). Moreover, the right side and the left side when facing the suction port 21 are referred to as the right side and the left side of the air conditioner 1.

  The indoor part 2 and the outdoor part 4 are installed on the bottom plate 3 and separated by a partition wall 5 in the front-rear direction. The indoor portion 2 forms a housing 20 surrounded on the outside by the bottom plate 3, the partition wall 5 and the exterior cover 30. Similarly, the exterior 4 forms a casing 40 surrounded by the bottom plate 3, the partition wall 5, and an exterior cover (not shown).

  A compressor 41 that operates the refrigeration cycle is disposed at the right end of the outdoor unit 4. An outdoor heat exchanger 42 connected to the compressor 41 via the refrigerant pipe 47 is disposed on the back surface of the outdoor exterior 4. The outdoor fan 43 made up of a propeller fan is arranged in the center in the left-right direction so as to face the outdoor heat exchanger 42 and cools the outdoor heat exchanger 42. The outdoor fan 43 and the outdoor heat exchanger 42 are disposed in the housing 44, and the housing 44 forms a duct that guides airflow from the outdoor fan 43 to the outdoor heat exchanger 42. The housing 44 is supported on the partition wall 5 via a bracket 45.

  A suction port 21 is opened on the front surface of the exterior cover 30 that covers the indoor portion 2, and an air outlet 22 is opened above the suction port 21. A blower passage 23 is formed in the indoor portion 2 by a blower duct 24 that connects the suction port 21 and the blower port 22. The air duct 24 has a duct member 29 that is detachable when the exterior cover 30 is removed, and a lower wall near the air outlet 22 of the air passage 23 is formed by the duct member 29.

  An indoor fan 25 (blower) composed of a cross flow fan is provided in the air passage 23. A louver 26 that varies the air direction is provided in the vicinity of the air outlet 22 in the air passage 23. An indoor heat exchanger 27 connected to the compressor 41 via the refrigerant pipe 47 is disposed between the indoor fan 25 and the suction port 21.

  A heating unit 28 having a plurality of PTC heaters 55 (see FIG. 3) is disposed between the indoor fan 25 and the indoor heat exchanger 27. An air flow that exchanges heat with the PTC heater 55 and the indoor heat exchanger 27 is formed in the air passage 23 from the suction port 21 by the indoor fan 25. The upper part of the indoor heat exchanger 27 and the heating unit 28 is covered with a duct member 29. The heating member 28 is detachable by removing the duct member 29.

  FIG. 3 is a block diagram showing the configuration of the air conditioner 1. The air conditioner 1 includes a control unit 50 that controls each unit. A compressor 41, an indoor fan 25 (blower), an outdoor fan 43, an operation unit 51, a storage unit 52, a current detection unit 53, a heater control unit 54, and a temperature detection unit 56 are connected to the control unit 50. A PTC heater 55 of the heating unit 28 is connected to the heater control unit 54.

  The operation unit 51 includes operation buttons and a remote controller provided on the surface of the housing 20, and performs operation instructions and setting inputs for the air conditioner 1. The storage unit 52 includes a ROM and a RAM, and stores an operation program, setting conditions, and the like of the air conditioner 1 and temporarily stores calculations of the control unit 50. Although the storage unit 52 is connected to the outside of the control unit 50, the storage unit 52 may be provided inside the control unit 50.

  The current detection unit 53 detects the value of the current flowing through the PTC heater 55. The heater control unit 54 controls driving of the PTC heater 55. The temperature detector 56 detects the room temperature. The heater control unit 54 includes a triac circuit and a relay circuit, and performs DUTY control of the PTC heater 55. If the heater control unit 54 is formed by a triac circuit, switching on / off sound can be reduced more than a relay circuit, which is more desirable.

  The PTC heater 55 is formed by sandwiching a heating element having PTC characteristics between electrodes, and a heater control unit 54 applies a driving voltage between the electrodes to generate heat. FIG. 4 shows the temperature characteristics of the resistance value of the PTC heater 55. The vertical axis represents the resistance value, and the horizontal axis represents the temperature. The PTC heater 55 has a characteristic of having a stable region S1 in which the resistance value decreases or is substantially constant with respect to a temperature rise, and a rising region S2 in which the resistance value increases rapidly when the rising temperature T1 is exceeded.

  In the air conditioner 1 having the above configuration, when the cooling operation is started, the refrigeration cycle is operated by driving the compressor 41. Thereby, the indoor heat exchanger 27 becomes an evaporator on the low temperature side of the refrigeration cycle, and the outdoor heat exchanger 42 becomes a condenser on the high temperature side of the refrigeration cycle. The outdoor heat exchanger 42 is cooled by the outdoor fan 43 and dissipates heat. Indoor air flows into the air passage 23 from the suction port 21 by driving the indoor fan 25, and air cooled by the heat exchange with the indoor heat exchanger 27 is sent out from the air outlet 22 into the room. Thereby, indoor cooling is performed.

  Further, the air conditioner 1 can be switched between a heating operation by driving the compressor 41 and a heating operation by driving the PTC heater 55. When the compressor 41 is driven, the refrigeration cycle is operated. Thereby, the indoor heat exchanger 27 becomes a condenser on the high temperature side of the refrigeration cycle, and the outdoor heat exchanger 42 becomes an evaporator on the low temperature side of the refrigeration cycle. The outdoor heat exchanger 42 absorbs heat by exchanging heat with the outside air by the outdoor fan 43. Indoor air flows into the air passage 23 from the suction port 21 by driving the indoor fan 25, and heat is exchanged with the indoor heat exchanger 27 to raise the temperature. The air heated by the indoor heat exchanger 27 is sent into the room through the outlet 22.

  When the PTC heater 55 is driven, the air in the air passage 23 is heated by the PTC heater 55. The air heated by the PTC heater 55 is sent into the room through the outlet 22.

  The heating operation by driving the compressor 41 can consume less power than the heating operation by driving the PTC heater 55, but the heat absorption by the outdoor heat exchanger 42 becomes insufficient when the outside air temperature is low, so that the heating capacity is lowered. . For this reason, the heating operation by driving the compressor 41 is performed when the outside air temperature is high, and the heating operation by driving the PTC heater 55 is performed when the outside air temperature is low.

  FIG. 5 is a flowchart showing the heating operation by driving the PTC heater 55. The PTC heater 55 and the indoor fan 25 are controlled differently in a low temperature zone, an intermediate temperature zone, and a high temperature zone where the indoor temperature is divided. The low temperature zone consists of a predetermined temperature range including a region that is lower than the set temperature of the room temperature. The high temperature zone consists of a predetermined temperature range that is higher than the set temperature of the room temperature. The intermediate temperature zone consists of a temperature range between a low temperature zone and a high temperature zone.

  For example, the boundary temperature between the low temperature zone and the intermediate temperature zone is set to the set temperature of the room temperature, and the boundary temperature between the intermediate temperature zone and the high temperature zone is set to 2 ° C. higher than the set temperature of the room temperature. Thus, the low temperature range is a temperature range below the set temperature, the intermediate temperature range is a temperature range from the set temperature to the set temperature + 2 ° C., and the high temperature range is a temperature range above the set temperature + 2 ° C. The boundary temperature between the low temperature zone and the intermediate temperature zone may be set higher than the set temperature of the room temperature. The boundary temperature at the time of temperature decrease may be lowered by a predetermined temperature (for example, 1 ° C.) relative to the boundary temperature at the time of temperature increase. Thereby, the operation of the PTC heater 55 near the boundary temperature can be stabilized.

  In step # 21, the room temperature is detected by the temperature detector 56. In step # 22, it is determined whether or not the room temperature is in a low temperature range. If the room temperature is in the low temperature range, in step # 23, the PTC heater 55 is driven with the DUTY ratio set to 100%. In step # 36, the indoor fan 25 is driven by a strong wind (eg, 1140 RPM), and the process returns to step # 21.

  At this time, the PTC heater 55 is maintained at the temperature of the rising region S2 (see FIG. 4). As a result, when the temperature of the PTC heater 55 rises, the resistance value of the heating element rapidly increases and the current value and the amount of heat generation decrease, and when the temperature drops, the resistance value of the heating element rapidly decreases and the current value and the amount of heat generation become smaller. To increase. Accordingly, the amount of heat generated by the PTC heater 55 can be stabilized and hot air at a predetermined temperature can be easily generated, and overheating of the PTC heater 55 can be prevented.

  If it is determined in step # 22 that the room temperature is not in the low temperature range, the process proceeds to step # 31. In step # 31, it is determined whether or not the room temperature is in an intermediate temperature range. If the room temperature is in the intermediate temperature range, the PTC heater 55 is driven with the DUTY ratio set to 40% in step # 35. In step # 36, the indoor fan 25 is driven by a strong wind, and the process returns to step # 21.

  At this time, the PTC heater 55 is maintained at a temperature in the stable region S1 (see FIG. 4), and the heat generation amount of the PTC heater 55 is reduced. Since the DUTY ratio is lowered to the temperature of the stable region S1, the resistance value of the PTC heater 55 is reduced, but the current is reduced and overcurrent is prevented.

  If it is determined in step # 31 that the room temperature is not in the intermediate temperature range, the temperature is in the high temperature range, and the process proceeds to step # 41. In step # 41, the PTC heater 55 is stopped (DUTY ratio 0%). In step # 42, the indoor fan 25 is driven with a light breeze (for example, 300 RPM), and the process returns to step # 21. Thereby, the delivery of cold air due to the temperature drop of the PTC heater 55 is prevented.

  The indoor fan 25 may be stopped at step # 42. At this time, it is more desirable to stop the indoor fan 25 after a predetermined time (for example, 30 seconds) has elapsed after the PTC heater 55 is stopped, because heat does not accumulate in the indoor portion 2.

  According to the present embodiment, the PTC heater 55 is driven in the rising region S2 by setting the DUTY ratio to 100% in the low temperature zone, and the PTC heater 55 is stopped in the high temperature zone, and the predetermined DUTY ratio is set in the intermediate temperature zone. Since the PTC heater 55 is driven in the stable region S1, the amount of heat generated by the PTC heater 55 in the low temperature range can be stabilized to prevent overheating, and overcurrent in the intermediate temperature range can be prevented. Further, since the PTC heater 55 is not maintained at a high temperature, the temperature rise in the vicinity of the indoor portion 2 of the air conditioner 1 can be prevented, and the indoor temperature can be made uniform.

  Thereby, the compressor 41 can be stopped and only the PTC heater 55 can be driven to perform the heating operation. Therefore, the capability of the PTC heater 55 can be fully exhibited, and a decrease in the heating capability can be prevented when the outside air temperature is low.

  In addition, since the rotational speed of the indoor fan 25 (blower) is smaller in the high temperature range than in the low temperature range, it is possible to prevent the cool air from being sent out due to the stop of the PCT heater 55 and to make the user uncomfortable. Can be prevented.

  Next, FIG. 6 is a flowchart showing the operation of the heating operation by driving the PTC heater 55 of the air conditioner 1 of the second embodiment. The air conditioner 1 of the present embodiment is configured in the same manner as the first embodiment shown in FIGS. 1 to 5 described above, and the control when the room temperature is in the intermediate temperature range is different. In the present embodiment, the intermediate temperature zone obtained by dividing the room temperature is further divided into two auxiliary temperature zones, and different control is performed on the PTC heater 55 and the indoor fan 25. In the figure, steps # 21 to # 23 and # 41 are the same as those in FIG.

  If it is determined in step # 31 that the room temperature is in the intermediate temperature range, the process proceeds to step # 32. In step # 32, it is determined whether or not the room temperature is in the low temperature side auxiliary temperature zone. When the room temperature is in the auxiliary temperature zone on the low temperature side, the PTC heater 55 is driven with the DUTY ratio set to 40% in step # 35. In step # 36, the indoor fan 25 is driven by a strong wind, and the process returns to step # 21.

  If it is determined in step # 32 that the room temperature is not in the low temperature side auxiliary temperature zone, it is in the high temperature side auxiliary temperature zone, and the process proceeds to step # 37. In step # 37, the PTC heater 55 is driven with the DUTY ratio set to 30%. In step # 42, the indoor fan 25 is driven by the light wind, and the process returns to step # 21.

  According to this embodiment, the intermediate temperature zone is further divided into a plurality of auxiliary temperature zones, and when the auxiliary temperature zone is on the high temperature side, the DUTY ratio is set to 30% lower than the auxiliary temperature zone on the low temperature side, and the PTC heater 55 is driven. is doing. Thereby, the amount of heat given to the room can be adjusted more finely according to the room temperature, and the room temperature can be maintained more stably.

  In addition, since the rotational speed of the indoor fan 25 (blower) is smaller than that in the low temperature side auxiliary temperature zone in the high temperature side auxiliary temperature zone, it is possible to prevent the cool air from being sent out due to the temperature drop of the PCT heater 55. User discomfort can be prevented. If the room temperature further increases even if the DUTY ratio is 30%, the PTC heater 55 is stopped in step # 41. At this time, the indoor fan 25 may be stopped.

  In the present embodiment, the intermediate temperature zone is divided into two auxiliary temperature zones, but the PTC heater 55 may be driven at different DUTY ratios by dividing it into three or more auxiliary temperature zones.

  Next, FIG. 7 is a flowchart showing the heating operation by driving the PTC heater 55 of the air conditioner 1 of the third embodiment. The air conditioner 1 of the present embodiment operates in the same manner as the second embodiment shown in FIG. 6 described above, and the control is different when the room temperature is in the low temperature range. In the figure, steps # 21 to # 22 and # 31 to # 42 are the same as those in FIG.

  If it is determined in step # 22 that the room temperature is in the low temperature range, the process proceeds to step # 25, and the DUTY variable process shown in FIG. 8 is performed. FIGS. 9A and 9B are time charts during the DUTY variable processing. FIG. 9A shows the DUTY ratio (unit:%) of the drive voltage of the PTC heater 55. FIG. 9B shows the current value (indicated by I in the figure) detected by the current detector 53 and the temperature of the PTC heater 55 (indicated by T in the figure).

  At the beginning of the DUTY variable processing, the indoor fan 25 is driven in step # 51 with a weak wind having a first rotational speed (for example, 600 RPM). In step # 52, the PTC heater 55 starts to be driven at a duty ratio of 50% which is larger than the duty ratio in the intermediate temperature range (time t0). Thereby, the temperature of the PTC heater 55 rises, and the current flowing through the PTC heater 55 increases until the heating element reaches the rising temperature T1 (see FIG. 4).

  The heater control unit 54 acquires the detection result of the current detection unit 53 at a cycle of a predetermined time (1 second in the present embodiment), and waits until the predetermined time elapses in step # 53. When the predetermined time has elapsed, the current value detected by the current detection unit 53 is acquired in step # 54. In step # 55, it is determined whether or not the current value acquired from the current detector 53 is greater than a predetermined current value I1. The current value I1 is set based on the power supply capacity. When the current value I1 is exceeded, the current flowing through the PTC heater 55 is large, and an overcurrent state that may exceed the power supply capacity occurs.

  In addition, if the predetermined time used as the period which acquires the detection result of the electric current detection part 53 of step # 53 is too short, control will be loaded. On the other hand, if the predetermined time is too long, the current flowing through the PTC heater 55 during standby may be too large or too small. Therefore, in the present embodiment, the predetermined time is set to 1 second, but it is preferable to determine an appropriate time experimentally according to the configuration of the air conditioner 1.

  When the current value acquired from the current detection unit 53 is larger than the current value I1, the duty ratio of the PTC heater 55 is decreased by 10% (representing 10% with respect to 100%) in step # 56. Thereby, it can escape from an overcurrent state and returns to step # 53.

  If the current value acquired from the current detector 53 is not greater than the current value I1, it is determined in step # 57 whether or not it is smaller than the predetermined current value I2. The current value I2 is set lower than the current value I1. When the current value acquired from the current detection unit 53 is smaller than the current value I2, the process proceeds to step # 58.

  When the temperature of the PTC heater 55 rises and the heating element rises and exceeds the temperature T1, the resistance value of the heating element increases, and the current value of the PTC heater 55 takes the maximum value P (see FIG. 9B). For this reason, when the current value acquired from the current detection unit 53 decreases with respect to the current value acquired last time, it is determined that the maximum value P has occurred, and the process proceeds to step # 59. If the current value acquired from the current detection unit 53 is not lower than the current value acquired last time, the process returns to step # 53.

  In step # 59, the DUTY ratio of the PTC heater 55 is increased by 10% (representing 10% with respect to 100%). As the DUTY ratio increases, the current value of the PTC heater 55 rises again. Note that the amount of increase in the DUTY ratio may be other than 10%.

  In step # 60, it is determined whether or not the DUTY ratio of the PTC heater 55 has reached 100%. If the DUTY ratio of the PTC heater 55 has not reached 100%, the process returns to step # 53, and steps # 53 to # 60 are repeated. Similarly to the above, when the temperature of the PTC heater 55 rises, the resistance value increases and the current value of the PTC heater 55 takes the maximum value P. As a result, the DUTY ratio of the PTC heater 55 increases by 10% at step # 59, and the current value gradually increases.

  When the DUTY ratio of the PTC heater 55 reaches 100%, the process returns to the flowchart of FIG. In step # 36 in FIG. 7, the indoor fan 25 is driven by a strong wind having a second rotational speed (for example, 1140 RPM) larger than the first rotational speed. At this time, the cooling amount of the PTC heater 55 increases and the temperature T of the PTC heater 55 slightly decreases.

  If the current value acquired from the current detection unit 53 is not smaller than the current value I2 as determined in step # 57, the process returns to step # 53. That is, regardless of the occurrence of the maximum value P, the DUTY ratio of the PTC heater 55 is maintained. As a result, the DUTY ratio is not increased or decreased between the current value I1 and the current value I2, and an overcurrent state can be prevented in advance.

  According to this embodiment, the DUTY ratio is set when the current value of the PTC heater 55 is lower than the predetermined current value I2 when it is driven at a DUTY ratio larger than the DUTY ratio in the intermediate temperature zone at the beginning of the transition to the low temperature zone. Since it repeats until the DUTY ratio reaches 100% by a fixed amount, even when the PTC heater 55 is at a low temperature such as when the PTC heater 55 is started, the current is gradually increased to prevent overcurrent, and the current value Can be prevented from exceeding the power capacity.

  Further, since the DUTY ratio is increased when the current value of the PTC heater 55 reaches the maximum value P, the timing for increasing the DUTY ratio is not fast, and an overcurrent such as when the PTC heater 55 is started is reliably prevented. be able to.

  Further, when the indoor fan 25 is driven at the first rotation speed (for example, 600 RPM) at the initial stage of the DUTY variable processing, and the DUTY ratio of the PTC heater 55 reaches 100%, the second rotation speed that is larger than the first rotation speed. (For example, 1140 RPM). By reducing the air volume of the initial indoor fan 25, heat exchange between the PTC heater 55 and air is promoted. Therefore, the temperature rise of the PTC heater 55 can be accelerated.

  Further, when the current value acquired from the current detection unit 53 is larger than the current value I1, the duty ratio is decreased in step # 57, so that the overcurrent state of the PTC heater 55 is removed and the current value exceeds the power supply capacity. It can prevent more reliably.

  Next, FIG. 10 is a flowchart showing the heating operation of the air conditioner 1 of the fourth embodiment. The air conditioner 1 according to the present embodiment can be switched between a heating operation by driving the compressor 41 and a heating operation by driving the PTC heater 55. The heating operation by driving the PTC heater 55 operates in the same manner as in the third embodiment shown in FIGS. 7 to 9 described above, and steps # 21 to # 42 are the same as those in FIG.

  When the heating operation is started, the indoor fan 25 is driven with strong wind in step # 11. In step # 12, the temperature detection unit 56 detects the room temperature. In step # 13, it is determined whether or not the room temperature is in a high temperature range. If the room temperature is not in the high temperature range, in step # 14, the PTC heater 55 is driven with the DUTY ratio set to 100%. Thereby, the heating operation by the drive of the PTC heater 55 is performed. And it returns to step # 11 and steps # 11- # 14 are repeated.

  When the room temperature becomes a high temperature zone, the process proceeds to step # 15, and the PTC heater 55 is stopped. In step # 16, the compressor 41 is driven. Thereby, the heating operation by the drive of the compressor 41 is performed. In step # 17, the room temperature is detected by the temperature detector 56. In step # 18, it is determined whether or not the room temperature is in a low temperature range.

  If the room temperature is not in the low temperature range, steps # 17 and # 18 are repeated. The compressor 41 is driven such that the capacity is varied according to the room temperature and the room temperature is maintained in the vicinity of the set temperature. At this time, since the room temperature changes in the vicinity of the set temperature, the boundary temperature between the low temperature zone and the intermediate temperature zone is a predetermined temperature (for example, 1 ° C.) rather than the set temperature of the room temperature so as not to frequently shift to the low temperature zone. Set lower.

  When the room temperature is in the low temperature range, the compressor 41 is stopped in step # 19. And it switches to the heating operation by the drive of the PTC heater 55 by step # 21- # 42. If the room temperature is in the high temperature range when the PTC heater 55 is driven, the process proceeds to step # 15 based on the determination in step # 31. As a result, the PTC heater 55 is stopped and switched to the heating operation by driving the compressor 41.

  According to the present embodiment, when the heating operation by driving the compressor 41 is performed, the operation is switched to the heating operation by driving the PTC heater 55 when the room temperature is lower than the predetermined temperature. It is possible to reduce the power consumption by performing the heating operation. If the room temperature cannot be maintained near the set temperature by driving the compressor 41, the PTC heater 55 is driven and can be maintained at the set temperature.

  Further, when the heating operation is started, the heating operation is performed by driving the PTC heater 55, and when the room temperature becomes higher than a predetermined temperature, the operation is switched to the heating operation by driving the compressor 41. The room temperature can be raised quickly by driving the PTC heater 55 at a low temperature.

  According to this invention, it can utilize for the air conditioner which has a PTC heater.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Indoor part 3 Bottom plate 4 Outdoor exterior 5 Partition wall 20 Housing | casing 21 Suction inlet 22 Outlet 23 Blower passage 24 Blower duct 25 Indoor fan 26 Louver 27 Indoor heat exchanger 28 Heating part 30 Exterior cover 41 Compressor 42 Outdoor heat exchanger 43 Outdoor fan 47 Refrigerant pipe 50 Control unit 51 Operation unit 52 Storage unit 53 Current detection unit 54 Heater control unit 55 PTC heater 56 Temperature detection unit

Claims (9)

  A PTC heater having a characteristic in which a resistance value decreases or is substantially constant with respect to a temperature rise and a rising region in which the resistance value increases rapidly when the rising temperature is exceeded; and a heater control unit that performs DUTY control of the PTC heater; An air conditioner that includes a temperature detection unit that detects a room temperature and a blower that generates an air flow that exchanges heat with the PTC heater, and that performs heating operation by sending air heated by the PTC heater into the room When the room temperature is in a low temperature range including a lower temperature range than the set temperature, the DUTY ratio is set to 100% and the PTC heater is driven in the rising area, and the room temperature is higher than the set temperature. Sometimes the PTC heater is stopped, and the PTC heater is set to a predetermined DUTY ratio in the intermediate temperature zone between the low temperature zone and the high temperature zone. An air conditioner characterized by being driven by serial stable region.   The intermediate temperature zone is further divided into a plurality of auxiliary temperature zones, and the DUTY ratio of the PTC heater is made smaller in the auxiliary temperature zone on the high temperature side than in the auxiliary temperature zone on the low temperature side. Item 2. An air conditioner according to Item 1.   3. The air conditioner according to claim 2, wherein the rotational speed of the blower is set to be smaller in the auxiliary temperature zone on the high temperature side than in the auxiliary temperature zone on the low temperature side.   The air conditioner according to any one of claims 1 to 3, wherein the rotational speed of the blower is made smaller in the high temperature zone than in the low temperature zone.   A current detection unit for detecting a current value of the PTC heater, wherein the DUTY ratio is set to be larger than the DUTY ratio in the intermediate temperature range at the initial stage when the room temperature has shifted to the low temperature range, and the current detected by the current detection unit 5. The air conditioner according to claim 1, wherein when the value is smaller than a predetermined value, the process of increasing the DUTY ratio by a predetermined amount is repeated until the DUTY ratio reaches 100%.   The blower is driven at the first rotational speed at the initial stage when the room temperature has shifted to the low temperature zone, and the rotational speed of the blower is set to the first rotational speed until the DUTY ratio of the PTC heater reaches 100%. 6. The fan is driven at a second rotational speed greater than the first rotational speed when the DUTY ratio of the PTC heater reaches 100%. Air conditioner.   The air conditioner according to claim 5 or 6, wherein when the current value detected by the current detection unit is larger than a predetermined value, the DUTY ratio of the PTC heater is decreased by a predetermined amount.   A compressor that operates the refrigeration cycle, and a heat exchanger that is arranged in a high temperature part of the refrigeration cycle and exchanges heat with the airflow generated by the blower, and heating operation by driving the compressor and the PTC heater The heating operation by driving can be switched, and the heating operation by driving the PTC heater is switched when the room temperature is lower than a predetermined temperature when the heating operation by driving the compressor is performed. The air conditioner in any one of Claims 1-7.   9. The air according to claim 8, wherein when the heating operation is started, the heating operation is performed by driving the PTC heater, and when the indoor temperature becomes higher than a predetermined temperature, the operation is switched to the heating operation by driving the compressor. Harmony machine.

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