JP5071371B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner.

The operating frequency of the compressor of the air conditioner is normally controlled to be equal to or lower than the upper limit frequency (Patent Document 1). The upper limit frequency is uniformly determined in accordance with the horsepower of the air conditioner from the viewpoint of protecting the compressor components and preventing noise from operating noise of the compressor.
JP 2008-075979 A

  By the way, when the outside air temperature is remarkably lowered during the heating operation, the heating capacity of the air conditioner may not be sufficiently exhibited.

The subject of this invention is providing the air conditioning apparatus which can fully ensure a heating capability also under low external temperature conditions.

The air conditioning apparatus according to the first invention includes a refrigerant circuit and an upper limit frequency setting unit. The refrigerant circuit includes a compressor, an indoor heat exchanger, a decompression mechanism, and an outdoor heat exchanger. The upper limit frequency setting unit sets the upper limit frequency of the compressor to be higher as the outside air temperature is lower during the heating operation . When the upper limit frequency setting unit determines that the outside air temperature is equal to or lower than the first temperature and the room temperature does not exceed the third temperature during the heating operation in a state where the upper limit frequency is set to the first frequency, The upper limit frequency is set to a second frequency that is higher than the first frequency . The upper limit frequency setting unit sets the upper limit frequency to a frequency lower than the second frequency when it is determined that the room temperature is equal to or higher than the second temperature during the heating operation in a state where the upper limit frequency is set to the second frequency. Set.

  Here, the upper limit frequency of the compressor is set to be relatively high during heating operation and under low outside air temperature conditions. Therefore, sufficient heating capacity can be ensured even under low outside air temperature conditions.

Further, here, when it is determined that the outside air temperature is equal to or lower than the predetermined temperature (first temperature) and the room temperature does not exceed the third temperature during the heating operation, the upper limit frequency of the compressor is reset to a higher value. Is done. Therefore, sufficient heating capacity can be ensured even under low outside air temperature conditions.

Further, here, when it is determined that the room temperature is equal to or higher than the predetermined temperature (second temperature) , the compressor operating frequency set higher under the low outside air temperature condition is reset to a lower value. . Therefore, when the indoor temperature is high and the high / low differential pressure of the compressor is expected to increase, the operating frequency of the compressor can be suppressed and the compressor can be protected.

An air conditioner according to a second aspect of the present invention is the air conditioner according to the first aspect of the present invention, wherein the upper limit frequency setting unit sets the indoor temperature to the first during the heating operation in a state where the upper limit frequency is set to the second frequency . When it is determined that the temperature is two or more and the outside air temperature is higher than the first temperature, the upper limit frequency is set to a first frequency lower than the second frequency.

Here, if it is determined that the room temperature is equal to or higher than the second temperature and the outside air temperature is higher than the predetermined temperature (first temperature) during the heating operation, the upper limit frequency of the compressor is reset to a lower value. Therefore, sufficient heating capacity can be ensured even under low outside air temperature conditions.

An air conditioner according to a third aspect of the present invention is the air conditioner according to the first or second aspect of the present invention , further comprising an operating frequency determination unit. The operating frequency determining unit determines the operating frequency of the compressor according to the difference between the set temperature and the room temperature so as to be equal to or lower than the upper limit frequency set by the upper limit frequency setting unit.

  Here, the operating frequency of the compressor is determined according to the difference between the set temperature and the room temperature.

An air conditioner according to a fourth aspect of the present invention is the air conditioner according to any of the first to third aspects of the present invention, further comprising a refrigerant heating unit. The refrigerant heating unit heats the refrigerant flowing through the refrigerant circuit.

  Here, in addition to the compressor, a refrigerant heating unit is provided as a heat source. Therefore, when the upper limit frequency of the compressor is increased during heating operation and under low outside air temperature conditions, the amount of refrigerant flowing through the refrigerant circuit is increased, and as a result, the function of the refrigerant heating unit is increased, and the heating capacity can be further improved.

An air conditioner according to a fifth aspect of the present invention is the air conditioner according to the fourth aspect of the present invention, further comprising an output control unit. The output control unit controls the output of the refrigerant heating unit so as to increase as the outside air temperature decreases.

  Here, the output of the refrigerant heating unit is set to be relatively large under low outside air temperature conditions. Therefore, it is possible to further ensure the heating capacity even under a low outside air temperature condition.

The air conditioning apparatus according to Supplementary Note 1 includes a refrigerant circuit and an upper limit frequency setting unit. The refrigerant circuit includes a compressor, an indoor heat exchanger, a decompression mechanism, and an outdoor heat exchanger. The upper limit frequency setting unit sets the upper limit frequency of the compressor to be higher as the outside air temperature is lower during the heating operation. The upper limit frequency can be set to a first frequency and a second frequency higher than the first frequency. When it is determined that the outside air temperature is lower than the first temperature during the heating operation, the upper limit frequency setting unit sets the upper limit frequency to the second frequency.

  Here, when it is determined that the outside air temperature is lower than the predetermined temperature (first temperature) during the heating operation, the upper limit frequency of the compressor is set to a higher value among a plurality of values of the upper limit frequency that the compressor can take. Therefore, sufficient heating capacity can be ensured even under low outside air temperature conditions.

The control method for an air conditioner according to appendix 2 is a control method for an air conditioner having a refrigerant circuit including a compressor, an indoor heat exchanger, a decompression mechanism, and an outdoor heat exchanger. The step of setting the upper limit frequency so as to increase as the outside air temperature decreases is provided.

  Here, if it is determined that the outside air temperature is low during the heating operation, the upper limit frequency of the compressor is reset to a higher value. Therefore, sufficient heating capacity can be ensured even under low outside air temperature conditions.

  In the air conditioner and the control method thereof according to the present invention, the upper limit frequency of the compressor is set to be relatively high during heating operation and under a low outside air temperature condition. Therefore, sufficient heating capacity can be ensured even under low outside air temperature conditions.

  Hereinafter, an air-conditioning apparatus 1 and a control method thereof according to an embodiment of the present invention will be described with reference to the drawings.

<Configuration of air conditioner>
(overall structure)
FIG. 1 is a configuration diagram of the air conditioner 1. As shown in FIG. 1, in the air conditioner 1, an outdoor unit 2 as a heat source side device and an indoor unit 4 as a usage side device are connected by a refrigerant pipe, and a refrigerant circuit 10 that performs a vapor compression refrigeration cycle is provided. Is formed.

  The outdoor unit 2 accommodates a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion valve 24, an accumulator 25, an outdoor fan 26, a hot gas bypass valve 27, a capillary tube 28, and an electromagnetic induction heating unit 6. ing. The indoor unit 4 houses an indoor heat exchanger 41 and an indoor fan 42.

  The refrigerant circuit 10 includes a discharge pipe 10a, a gas pipe 10b, a liquid pipe 10c, an outdoor liquid pipe 10d, an outdoor gas pipe 10e, an accumulator pipe 10f, a suction pipe 10g, and a hot gas bypass 10h.

  The discharge pipe 10 a connects the compressor 21 and the four-way switching valve 22. The gas pipe 10 b connects the four-way switching valve 22 and the indoor heat exchanger 41. The liquid pipe 10 c connects the indoor heat exchanger 41 and the expansion valve 24. The outdoor liquid pipe 10 d connects the expansion valve 24 and the outdoor heat exchanger 23. The outdoor gas pipe 10 e connects the outdoor heat exchanger 23 and the four-way switching valve 22.

  The accumulator pipe 10 f connects the four-way switching valve 22 and the accumulator 25. The electromagnetic induction heating unit 6 is attached to a part of the accumulator tube 10f. Of the accumulator tube 10f, at least a heated portion covered by the electromagnetic induction heating unit 6 has a stainless steel tube covering the periphery of the copper tube. Of the piping constituting the refrigerant circuit 10, the portion other than the stainless steel tube is a copper tube.

  The suction pipe 10g connects the accumulator 25 and the suction side of the compressor 21. The hot gas bypass 10h connects a branch point A1 provided in the middle of the discharge pipe 10a and a branch point D1 provided in the middle of the outdoor liquid pipe 10d.

  A hot gas bypass valve 27 is provided in the middle of the hot gas bypass 10h. The control unit 11 opens and closes the hot gas bypass valve 27 to switch the hot gas bypass 10h between a state where the refrigerant flow is allowed and a state where the hot gas bypass 10h is not allowed. Further, a capillary tube 28 for reducing the cross-sectional area of the refrigerant flow passage is provided downstream of the hot gas bypass valve 27, and the refrigerant flowing through the outdoor heat exchanger 23 and the hot gas bypass 10h during the defrosting operation. The ratio of the refrigerant that circulates is kept constant.

  The four-way switching valve 22 can switch between a cooling operation cycle and a heating operation cycle. In FIG. 1, the connection state for performing the heating operation is indicated by a solid line, and the connection state for performing the cooling operation is indicated by a dotted line. During the heating operation, the indoor heat exchanger 41 functions as a condenser, and the outdoor heat exchanger 23 functions as an evaporator. During the cooling operation, the outdoor heat exchanger 23 functions as a condenser, and the indoor heat exchanger 41 functions as an evaporator.

  An outdoor fan 26 that sends outdoor air to the outdoor heat exchanger 23 is provided in the vicinity of the outdoor heat exchanger 23. An indoor fan 42 that sends room air to the indoor heat exchanger 41 is provided in the vicinity of the indoor heat exchanger 41.

  The control unit 11 includes an outdoor control unit 11 a that controls equipment disposed in the outdoor unit 2 and an indoor control unit 11 b that controls equipment disposed in the indoor unit 4. The outdoor control unit 11a and the indoor control unit 11b are connected by a communication line 11c.

(Appearance of outdoor unit)
FIG. 2 is an external perspective view of the outdoor unit 2 viewed from the front right side. As shown in FIG. 2, the outer shell of the outdoor unit 2 includes a top plate 2a, a bottom plate 2b (see FIG. 4) facing the top plate 2a, a front panel 2c, a fan guard 2k, a right side panel 2f, and a right side panel 2f. Are formed in a substantially rectangular parallelepiped shape by a left side panel (invisible) facing the front panel, a front panel 2c and a rear panel (invisible) facing the fan guard 2k.

(Internal structure of outdoor unit)
3 is a perspective view seen from the front right side of the outdoor unit 2 with the front panel 2c, the right side panel 2f, and the rear panel removed, and FIG. 4 is a diagram other than the bottom plate 2b, the outdoor heat exchanger 23, and the outdoor fan 26. It is the perspective view of the outdoor unit 2 seen from the front right side which removed the member. As shown in FIG. 3, the outdoor unit 2 is divided into a fan room and a machine room by a partition plate 2h. An outdoor heat exchanger 23 and an outdoor fan 26 (see FIG. 4) are arranged in the blower room, and an electromagnetic induction heating unit 6, a compressor 21 and an accumulator 25 are arranged in the machine room.

  As shown in FIG. 4, the outdoor heat exchanger 23 is a fin-and-tube heat exchanger formed in an L shape. Two outdoor fans 26 are arranged between the fan guard 2k (see FIG. 3) and the outdoor heat exchanger 23 so as to be adjacent to each other in the vertical direction via a support base. As the outdoor fan 26 rotates, outdoor air is sucked from the vents of the left side panel and the rear panel, passes between the fins of the outdoor heat exchanger 23, and is blown out from the fan guard 2k.

  The hot gas bypass 10h is disposed on the bottom plate 2b, extends from the machine room side where the compressor 21 is located to the blower room side, goes around the blower room side bottom, and returns to the machine room side. About half of the total length of the hot gas bypass 10 h is located below the outdoor heat exchanger 23.

(Structure of electromagnetic induction heating unit)
FIG. 5 is a cross-sectional view of the electromagnetic induction heating unit 6. As shown in FIG. 5, the electromagnetic induction heating unit 6 is disposed so as to cover the heated portion of the accumulator tube 10f from the outside in the radial direction, and heats the heated portion by electromagnetic induction heating. The heated portion of the accumulator tube 10f has a double tube structure with an inner copper tube and an outer stainless steel tube 100f. The stainless steel material used for the stainless steel pipe 100f is a ferritic stainless steel containing 16 to 18% chromium, or a precipitation hardening stainless steel containing 3 to 5% nickel, 15 to 17.5% chromium, and 3 to 5% copper. Is selected.

  The electromagnetic induction heating unit 6 is first positioned on the accumulator tube 10 f, then the vicinity of the upper end is fixed by the first hex nut 61, and finally the vicinity of the lower end is fixed by the second hex nut 66.

  The coil 68 is wound around the outside of the bobbin main body 65 in a spiral shape with the direction in which the accumulator tube 10f extends as an axial direction. The coil 68 is accommodated inside the ferrite case 71. The ferrite case 71 further accommodates the first ferrite portion 69 and the second ferrite portion 70.

  The first ferrite portion 69 is formed of ferrite having a high magnetic permeability, and collects magnetic flux generated in portions other than the stainless steel tube 100f when a current is passed through the coil 68 to form a path for the magnetic flux. The first ferrite part 69 is located on both ends of the ferrite case 71.

  The second ferrite portion 70 is different in position and shape from the first ferrite portion 69, but its function is the same as that of the first ferrite portion 69, and is arranged in the vicinity of the outside of the bobbin main body 65 in the housing portion of the ferrite case 71. Is done.

(Configuration of control unit)
A detailed configuration of the control unit 11 including the outdoor control unit 11a and the indoor control unit 11b will be described with reference to FIG.

  The indoor control unit 11b is a control circuit having a CPU (not shown) and a memory (not shown), and is mainly accommodated in the indoor unit 4 by reading and executing a program stored in the memory on the CPU. Various electric devices such as the indoor fan 42 are controlled. An indoor temperature sensor 60 that detects the indoor temperature Tr of the room in which the indoor unit 4 is installed is connected to the indoor control unit 11b. The indoor temperature sensor 60 is attached in the vicinity of the air inlet of the casing of the indoor unit 4. A remote controller 44 is connected to the indoor control unit 11b. The remote controller 44 inputs various operation commands (such as a power-on command, a power-off command, a command for changing the set temperature Ts, a command for setting operation modes such as a heating operation mode and a cooling operation mode) to the indoor unit 4. Is for.

  Similarly, the outdoor control unit 11a is also a control circuit having a CPU 12 and a memory 13, and reads a program stored in the memory 13 onto the CPU 12 and executes it, so that the compressor accommodated mainly in the outdoor unit 2 is used. 21, various electric devices such as the four-way switching valve 22, the outdoor expansion valve 24, and the outdoor fan 26 are controlled. In particular, the outdoor control unit 11a operates as the upper limit frequency setting unit 12a and the operation frequency determination unit 12b with respect to the control of the compressor 21, and as the upper limit output setting unit 12c and the output determination unit 12d with respect to control of the electromagnetic induction heating unit 6. Operate. Details of the operation of each unit 12a, 12b, 12a, 12b will be described later. An outdoor temperature sensor 62 that detects an outdoor temperature Ta is connected to the outdoor control unit 11a.

  The outdoor control unit 11a communicates with the indoor control unit 11b, refers to information acquired by the indoor control unit 11b (related to the indoor temperature Tr and various operation commands input to the remote control 44, etc.), and via the remote control 44. The overall operation of the air conditioner 1 is integrated so as to operate according to various input operation commands.

<Operation of air conditioner>
The air conditioner 1 can be switched to either the cooling operation or the heating operation by the four-way switching valve 22.

(Cooling operation)
During the cooling operation, the four-way switching valve 22 is set to the state indicated by the dotted line in FIG. When the compressor 21 is driven in this state, the refrigerant circuit 10 performs a vapor compression refrigeration cycle in which the outdoor heat exchanger 23 serves as a condenser and the indoor heat exchanger 41 serves as an evaporator.

  The high-pressure refrigerant discharged from the compressor 21 is condensed by exchanging heat with outdoor air in the outdoor heat exchanger 23. The refrigerant that has passed through the outdoor heat exchanger 23 is decompressed when passing through the expansion valve 24, and then evaporates by exchanging heat with indoor air in the indoor heat exchanger 41. Then, the air whose temperature has decreased due to heat exchange with the refrigerant is blown out into the air conditioning target space. The refrigerant that has passed through the indoor heat exchanger 41 is sucked into the compressor 21 and compressed.

(Heating operation)
During the heating operation, the four-way switching valve 22 is set to the state indicated by the solid line in FIG. When the compressor 21 is driven in this state, in the refrigerant circuit 10, a vapor compression refrigeration cycle is performed in which the outdoor heat exchanger 23 serves as an evaporator and the indoor heat exchanger 41 serves as a condenser.

  The high-pressure refrigerant discharged from the compressor 21 is condensed by exchanging heat with indoor air in the indoor heat exchanger 41. Then, the air whose temperature has increased due to heat exchange with the refrigerant is blown into the air-conditioning target space. The condensed refrigerant is decompressed when passing through the expansion valve 24, and then evaporates by exchanging heat with outdoor air in the outdoor heat exchanger 23. The refrigerant that has passed through the outdoor heat exchanger 23 is sucked into the compressor 21 and compressed.

  When the compressor 21 is not sufficiently warm at the time of heating operation, particularly at the time of start-up, the electromagnetic induction heating unit 6 heats the accumulator tube 10f, so that the compressor 21 can compress the warmed refrigerant. . As a result, the temperature of the gas refrigerant discharged from the compressor 21 rises, and the lack of heating capacity at startup is compensated.

(Defrosting operation)
When the heating operation is performed, moisture contained in the air is condensed on the surface of the outdoor heat exchanger 23, becomes frost or freezes, covers the surface of the outdoor heat exchanger 23, and the heat exchange performance is deteriorated. For this reason, defrosting operation is performed in order to melt frost or ice adhering to the outdoor heat exchanger 23. The defrosting operation is performed in the same cycle as the cooling operation.

  The high-pressure refrigerant discharged from the compressor 21 is condensed by exchanging heat with outdoor air in the outdoor heat exchanger 23. The frost or ice covering the outdoor heat exchanger 23 is melted by the heat radiation from the refrigerant. The condensed refrigerant is decompressed when passing through the expansion valve 24, and thereafter evaporates by exchanging heat with indoor air in the indoor heat exchanger 41. At this time, the indoor fan 42 is stopped. This is because when the indoor fan 42 is operated, the cooled air is blown into the air-conditioning target space and the comfort is impaired. Then, the refrigerant that has passed through the indoor heat exchanger 41 is sucked into the compressor 21 and compressed.

  Further, during the defrosting operation, the electromagnetic induction heating unit 6 heats the accumulator tube 10f, so that the compressor 21 can compress the warmed refrigerant. As a result, the temperature of the gas refrigerant discharged from the compressor 21 increases, and the defrosting capability is improved.

  Further, during the defrosting operation, the high-pressure refrigerant discharged from the compressor 21 is also passed through the hot gas bypass 10h. Even when ice is growing on the bottom plate 2b of the outdoor unit 2, the ice is melted by heat radiation from the refrigerant passing through the hot gas bypass 10h.

(Control of compressor operating frequency)
The upper limit frequency setting unit 12 a and the operation frequency determination unit 12 b control the operation frequency F of the compressor 21. More specifically, the upper limit frequency setting unit 12a sets the upper limit frequency Fu of the compressor 21, and the operation frequency determination unit 12b determines the operation frequency F so as to be equal to or lower than the upper limit frequency Fu.

The upper limit frequency Fu is set with reference to an upper limit frequency table 13a (see FIG. 7) stored in the memory 13. In the upper limit frequency table 13a, three stages of frequencies (specifically, the first frequency L, the second frequency M, and the third frequency H) are defined for each of the horsepowers of the multi-stage outdoor unit. Here, when the frequencies H, M, and L corresponding to the same horsepower are compared,
Third frequency H ≧ second frequency M ≧ first frequency L
And
Third frequency H> First frequency L
It has become.

  More specifically, the setting process of the upper limit frequency Fu will be described. The upper limit frequency setting unit 12a sets the value of the first frequency L from the upper limit frequency table 13a except during heating operation, that is, during cooling operation and defrosting operation. And set as the upper limit frequency Fu. Note that when a power-on command is input to the remote controller 44, that is, in accordance with the activation of the outdoor unit 2, the outdoor control unit 11a immediately stores the basic configuration of the air conditioner 1 stored in the nonvolatile area of the memory 13. It is configured to read information. The basic configuration information includes information indicating the horsepower of the outdoor unit 2. The upper limit frequency setting unit 12a refers to the information indicating the horsepower of the outdoor unit 2, and among the values of the plurality of first frequencies L in the upper limit frequency table 13a, the upper limit is set to a value corresponding to the horsepower of the outdoor unit 2. Adopted as the frequency Fu.

  On the other hand, during the heating operation, the upper limit frequency setting unit 12a uses the outside temperature Ta and the room temperature Tr as parameters, and the first frequency L, the second frequency M, and the horsepower of the outdoor unit 2 in the upper limit frequency table 13a. Any value of the third frequency H is set as the upper limit frequency Fu. Which value of the first frequency L, the second frequency M, and the third frequency H is adopted is determined by the following logic.

  That is, the upper limit frequency setting unit 12a logically transitions between three states (see FIG. 8). The upper limit frequency setting unit 12a sets the upper limit frequency Fu to the first frequency L in the first state, sets the upper limit frequency Fu to the second frequency M in the second state, and sets the upper limit frequency Fu in the third state. Set to the third frequency H.

  When the upper limit frequency setting unit 12a is in the first state, the “outside air temperature Ta is 4 ° C. or lower and the indoor temperature Tr is 25 ° C. or lower at predetermined time intervals (for example, every 30 seconds). ”(First condition). When the first condition is satisfied, the state transits to the second state.

  Further, when the upper limit frequency setting unit 12a is in the second state, the “upper temperature Ta is −6 ° C. or lower and the indoor temperature Tr is 21 ° C. at predetermined time intervals (for example, every 30 seconds). It is determined whether or not (the second condition) or “the outside air temperature Ta is 5 ° C. or higher, or the room temperature Tr is 26 ° C. or higher” (third condition). When the second condition is satisfied, the state transitions to the third state, and when the third condition is satisfied, the state transitions to the first state.

  Further, when the upper limit frequency setting unit 12a is in the third state, the “upper temperature Ta is −5 ° C. or more and the indoor temperature Tr is 22 ° C. at predetermined time intervals (for example, every 30 seconds). It is determined whether or not it is “the above” (fourth condition). When the fourth condition is satisfied, the state transits to the second state.

  In addition, when the compressor 21 is started, first, the first state is set. In other words, when the compressor 21 is started, the minimum third frequency L becomes the default value of the upper limit frequency Fu.

  On the other hand, the operating frequency determination unit 12b determines the operating frequency F so as to be equal to or lower than the upper limit frequency Fu set by the upper limit frequency setting unit 12a while using the temperature difference between the set temperature Ts and the room temperature Tr as a parameter. The determination process of the operating frequency F is executed at any time while the compressor 21 is being driven. The operating frequency F determined by the operating frequency determining unit 12b is immediately passed to the inverter board 21a of the compressor 21, and the compressor 21 is driven at the operating frequency F.

  The reason why the operating frequency F of the compressor 21 is controlled in this manner is as follows.

  In general, from the viewpoint of protecting the components of the compressor, it is important not to excessively increase the operating frequency of the compressor, and thus not excessively increase the upper limit frequency of the compressor. This is because if the operating frequency of the compressor becomes too high, there is a concern that the components of the compressor will be excessively heated. In addition, it is important not to excessively increase the upper limit frequency of the compressor from the viewpoint of preventing noise derived from the operation sound of the compressor. However, if the outside air temperature is excessively lowered during the heating operation, sufficient heating capacity may not be exhibited depending on the degree of restriction imposed on the upper limit frequency of the compressor. On the other hand, when the outside air temperature is too low, it is expected that the components of the compressor accommodated in the outdoor unit will not be excessively heated.

  Therefore, in the present embodiment, the upper limit frequency Fu of the compressor 21 during the heating operation is designed to be set higher as the outside air temperature Ta is lower (see FIG. 9). FIG. 9 summarizes the conditions regarding the outside air temperature Ta for the upper limit frequency setting unit 12a to transition from the first state to the third state, with the upper limit frequency Fu on the vertical axis and the outdoor air temperature Ta on the horizontal axis. It is a graph.

  That is, in the present embodiment, during the heating operation, when the outside air temperature Ta falls below a certain reference level and the necessity for increasing the capacity of the air conditioner 1 becomes strong, the indoor temperature Tr does not exceed a certain reference level. Control for increasing the upper limit frequency Fu of the compressor 21 is executed. The reason for the condition that the room temperature Tr does not exceed a certain reference level is that if the room temperature Tr becomes too large, the high / low differential pressure of the compressor is expected to increase, so the operating frequency F is increased. This is because it is not desirable.

  On the other hand, the upper limit frequency Fu of the compressor 21 is set to be relatively large (that is, set to the second frequency M or the third frequency H) due to the necessity of increasing the heating capacity of the air conditioner 1. When it is determined that the outside air temperature Ta does not fall below a certain reference level or the room temperature Tr exceeds a certain reference level (specifically, when the third condition or the fourth condition is satisfied) ) To restore the upper limit frequency Fu (that is, from the third frequency H to the second frequency M, or the second frequency M, in order to protect the compressor 21 and avoid noise originating from the compressor 21). To the first frequency L) is being executed.

  Therefore, in this embodiment, the balance between the problem regarding the heating capability of the air conditioning apparatus 1 and the problem regarding the protection of the components of the compressor 21 and the noise prevention derived from the compressor 21 are traded off. The rational control of the compressor 21 is realized.

(Control of output of electromagnetic induction heating unit)
The upper limit output setting unit 12 c and the output determination unit 12 d control the output O of the electromagnetic induction heating unit 6.

  More specifically, the upper limit output setting unit 12c sets the upper limit output Ou of the electromagnetic induction heating unit 6 while using the upper limit frequency Fu of the compressor 21 as a parameter. At this time, the upper limit output Ou is set to increase as the upper limit frequency Fu increases.

  On the other hand, the output determination unit 12d determines the output O so as to be equal to or less than the upper limit output Ou set by the upper limit output setting unit 12c as needed. The output O determined by the output determination unit 12d is immediately passed to the electromagnetic induction heating unit 6.

  Therefore, at the start of the heating operation in which the electromagnetic induction heating unit 6 is driven, the upper limit output Ou of the electromagnetic induction heating unit 6 is set to be larger as the outside air temperature Ta is lower and the upper limit frequency Fu of the compressor 21 is set higher. As a result, the output O is also increased. That is, as the heating capacity of the air conditioner 1 needs to be increased, the amount of refrigerant flowing through the refrigerant circuit 10 and thus the electromagnetic induction heating unit 6 increases, and the output O of the electromagnetic induction heating unit 6 increases. Therefore, the electromagnetic induction heating unit 6 can rationally assist the increase in the heating capacity of the air conditioner 1.

<Features>
The air conditioner 1 is configured such that the upper limit frequency Fu of the compressor 21 is set relatively higher as the outside air temperature Ta is lower during the heating operation. Therefore, even when the outside air temperature Ta is remarkably lowered, a sufficient heating capacity can be ensured.

  Further, the operating frequency Fu of the compressor 21 that is determined to be low and the outside air temperature Ta is set high is reset to the original value when the indoor temperature Tr is determined to be high. Therefore, when the indoor temperature Tr is high and the high / low differential pressure of the compressor 21 is expected to increase, the operating frequency F of the compressor 21 is suppressed, and the components of the compressor 21 are sufficiently protected. ing.

<Modification>
(1)
The setting process of the upper limit frequency Fu of the compressor 21 in the embodiment can be applied to other types of air conditioners. For example, the present invention can be applied to a type of air conditioner that does not have the electromagnetic induction heating unit 6, and can also be applied to a multi-type air conditioner.

(2)
The mode of the setting process of the upper limit output Ou of the electromagnetic induction heating unit 6 is not limited to the above. For example, the upper limit output setting unit 12c may use the outside air temperature Ta as a parameter, and the upper limit output Ou may be set to increase as the outside air temperature Ta decreases.

(3)
In the above embodiment, when the compressor 21 is started, the upper limit frequency setting unit 12a first enters the first state, and then transitions to the second state for the first time when the first condition is satisfied, and further when the second condition is satisfied. The transition to the third state is made for the first time. However, when the compressor 21 is started, first, the first condition and the second condition are determined. If only the first condition is satisfied, the second state is entered without passing through the first state, and the first condition and the second condition are satisfied. If both are satisfied, the third state may be entered without going through the first state and the second state.

  Further, the setting process for setting the upper limit frequency Fu to the second frequency M or the third frequency equal to or higher than the first frequency L may be executed only when the compressor 21 is started.

INDUSTRIAL APPLICABILITY The present invention is useful as an air conditioner that can sufficiently ensure heating capacity even under low outside air temperature conditions.

The refrigerant circuit figure of the air conditioning apparatus which concerns on one Embodiment of this invention. The external appearance perspective view of the outdoor unit seen from the front right side. The perspective view of the outdoor unit which removed the front panel, the right side panel, and the back panel. The perspective view of the outdoor unit which removed members other than a baseplate, an outdoor heat exchanger, and an outdoor fan. Sectional drawing of an electromagnetic induction heating unit. The control block diagram of an air conditioning apparatus. The figure which shows an upper limit frequency table. The state transition diagram of the upper limit frequency setting part at the time of heating operation. The figure which put together the state transition conditions of the upper limit frequency setting part regarding external temperature.

1 Air Conditioner 6 Electromagnetic Induction Heating Unit (Refrigerant Heating Unit)
DESCRIPTION OF SYMBOLS 10 Refrigerant circuit 11 Control part 11a Outdoor control part 12a Upper limit frequency setting part 12b Operation frequency determination part 12c Upper limit output setting part (output control part)
12d Output determination unit (output control unit)
21 Compressor 23 Outdoor heat exchanger 24 Expansion valve (pressure reduction mechanism)
41 Indoor heat exchanger

Claims (5)

A refrigerant circuit (10) including a compressor (21), an indoor heat exchanger (41), a decompression mechanism (24), and an outdoor heat exchanger (23);
An upper limit frequency setting unit (12a) for setting the upper limit frequency of the compressor (21) to be higher as the outside air temperature is lower during heating operation;
Equipped with a,
The upper limit frequency setting unit (12a) is configured such that, during a heating operation in a state where the upper limit frequency is set to the first frequency, the outside air temperature is equal to or lower than the first temperature and the room temperature does not exceed the third temperature. Is determined, the upper limit frequency is set to a second frequency higher than the first frequency ,
The upper limit frequency setting unit (12a) is in the heating operation in a state where the upper limit frequency is set to the second frequency, when the indoor temperature is judged to be higher than or equal to the second temperature, the upper limit frequency Set to a frequency lower than the second frequency;
Air conditioner (1). The upper limit frequency setting unit (12a) is in the heating operation in a state where the upper limit frequency is set to the second frequency, the indoor temperature is higher than or equal to the second temperature and the outside air temperature is higher than the first temperature Is determined, the upper limit frequency is set to the first frequency,
The air conditioner (1) according to claim 1. An operation frequency determination unit (12b) that determines an operation frequency of the compressor (21) according to a difference between a set temperature and a room temperature so as to be equal to or lower than the upper limit frequency set by the upper limit frequency setting unit (12a). ),
Further comprising
The air conditioner (1) according to claim 1 or 2 . A refrigerant heating unit (6) for heating the refrigerant flowing through the refrigerant circuit (10);
Further comprising
The air conditioner (1) according to any one of claims 1 to 3 . An output control section (12c, 12d) for controlling the output of the refrigerant heating unit (6) so as to increase as the outside air temperature decreases;
Further comprising
The air conditioner (1) according to claim 4 .

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