JP2008232500A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an economical refrigerating cycle device of high reliability by preventing degradation of operational efficiency caused by frost formation on an evaporation-side heat exchanger when an operation is performed under a low-temperature environment. <P>SOLUTION: This refrigerating cycle device capable of switching a normal operation and a defrosting operation by a four-way valve, is provided with a constant torque control mode for controlling the torque of a motor of an outdoor or indoor air blower constant at a prescribed torque value, or a constant electric current control mode for controlling electric current of the motor of the outdoor or indoor air blower constant at a prescribed electric current value, and the evaporator-side air blower as the air blower at a heat exchanger side operated as the evaporator of the refrigerating cycle in the normal operation is operated in the constant torque control mode or the constant electric current control mode, when the normal operation is operated under a low temperature environment requiring a defrost operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus capable of switching between normal operation and defrosting operation.

  As a conventional refrigeration cycle device, a compressor, a four-way valve, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger are connected in sequence to form a refrigeration cycle. By switching the four-way valve, an outdoor heat exchanger is used during heating. There is a refrigeration air conditioner that operates as an evaporator and an indoor heat exchanger as a condenser, and operates as an outdoor heat exchanger as a condenser and an indoor heat exchanger as an evaporator during cooling.

  When this type of refrigeration air conditioner is heated under low temperature and high humidity conditions, frost adheres to the evaporation side heat exchanger (outdoor heat exchanger). If the operation is continued as it is, frost grows, obstructs the air passage of the evaporation side heat exchanger, and the refrigeration and air conditioning capacity is reduced. In general, in order to recover this decrease in air conditioning capacity, an operation for defrosting, that is, a defrosting operation is periodically performed. Since the energy during the defrosting operation is mainly consumed for melting the frost, frequent defrosting operation results in a decrease in operating capacity. On the other hand, if the timing of performing the defrosting operation is late, there is a possibility that problems such as a liquid back phenomenon due to a decrease in the evaporation temperature and an overcurrent stop of the blower due to the air path of the evaporation side heat exchanger being blocked may occur.

Therefore, conventionally, when the temperature difference between the temperature of the evaporation side heat exchanger and the ambient outside air temperature becomes a preset defrosting start temperature difference, defrosting is started and defrosting operation is performed at an appropriate timing. Thus, there has been a technique that appropriately maintains the frosting state of the evaporation side heat exchanger (see, for example, Patent Document 1).
JP 2004-116796 A

  However, in the technique of the above-mentioned Patent Document 1, control is performed only focusing on the start timing of the defrosting operation, and the blower control according to the frosting state of the evaporation side heat exchanger is insufficient, so that frosting prevention is performed. There was room for further improvement in the effect. In the above description, when the refrigeration cycle apparatus is a refrigeration air conditioner, the defrosting on the outdoor fan side that operates as an evaporator during heating operation has been described. However, the same applies to the case where the refrigeration cycle apparatus is a refrigeration / refrigeration apparatus. There was a problem of frost formation, and it was necessary to perform defrosting. In the case of a refrigeration / refrigeration system, frost forms on the indoor fan side, contrary to the refrigeration and air conditioning system.

  The present invention has been made in view of the above points, and prevents a reduction in operation efficiency due to frost formation on the evaporation side heat exchanger when operating in a low temperature environment, and is economical and highly reliable. An object is to obtain a refrigeration cycle apparatus.

  A refrigeration cycle apparatus according to the present invention includes a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger are connected by a refrigerant pipe, and an outdoor fan that promotes heat exchange of the outdoor heat exchanger; Refrigeration having an indoor blower that promotes heat exchange of the indoor heat exchanger and a control unit that controls the refrigeration cycle, outdoor blower, and indoor blower, and switching between normal operation and defrosting operation by switching the four-way valve In the cycle device, the control unit controls the constant torque control mode so that the torque of the motor of the outdoor or indoor fan becomes constant at a predetermined torque value, or the current of the motor of the outdoor or indoor fan becomes a predetermined current value. It has a constant current control mode that controls it to be constant, and when performing normal operation in a predetermined low-temperature environment, the heat exchanger side that operates as the evaporator of the refrigeration cycle during normal operation The evaporator blower is machine is intended to operate at a constant torque control mode or the constant current control mode.

  According to the present invention, a constant torque control mode or a constant current control mode for controlling the blower motor to have a constant torque or current is provided, and when performing normal operation in a low temperature environment where frost formation occurs, evaporation is performed. Since the evaporator-side fan is driven in the constant torque control mode or the constant current control mode, the evaporator-side fan can be driven at the maximum permissible rotational speed corresponding to the load condition (frosting state). For this reason, the capability of normal operation can be improved and the progress of frost adhesion can be suppressed. As a result, it is possible to prevent a reduction in operating efficiency due to frost formation, and to obtain an economical and highly reliable refrigeration cycle apparatus.

Embodiment 1 FIG.
FIG. 1 shows a configuration of a refrigeration cycle apparatus according to an embodiment of the present invention. Hereinafter, a case where the refrigeration cycle apparatus is a refrigeration air conditioner will be described as an example.
In the figure, the refrigeration air conditioner includes a refrigeration cycle in which a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an expansion mechanism 4, and an indoor heat exchanger 5 are connected by a refrigerant pipe 11, and during the heating operation, the compressor The refrigerant from 1 is caused to flow from the indoor heat exchanger 5 to the expansion mechanism 4 and the outdoor heat exchanger 3 by the four-way valve 2, and during the defrosting operation, the refrigerant flows in the opposite direction to that in the heating operation by switching the four-way valve 2. It is supposed to be. The four-way valve 2 shown in FIG. 1 is in a state in which the discharge side of the compressor 1 and the indoor heat exchanger 5 are connected, and is in a state corresponding to a heating operation.

  Further, the refrigerating and air-conditioning apparatus further includes an outdoor fan 6 and an indoor fan 7 for sending air to the outdoor heat exchanger 3 and the indoor heat exchanger 5 to promote heat exchange, and the outdoor fan 6 and the indoor fan 7. Control of the entire refrigerating and air-conditioning apparatus while exchanging operation command signals and monitor signals between the outdoor fan driving means 8 and the indoor fan driving means 9 and the outdoor fan driving means 8 and the indoor fan driving means 9 for driving each of them. The control part 10 which performs is provided.

  The outdoor blower 6 includes an outdoor blower blade 61 and an outdoor blower motor 62 that rotationally drives the outdoor blower blade 61. The outdoor blower motor 62 is connected to the control unit 10 via the outdoor blower driving means 8. Based on a control signal from the control unit 10, the outdoor fan driving means 8 is rotationally driven. Similarly, the indoor blower 7 includes an indoor blower blade 71 and an indoor blower motor 72 that drives the indoor blower blade 71, and the indoor blower motor 72 is connected to the control unit via the indoor blower driving means 9. Based on the control signal from the control unit 10, it is rotationally driven by the indoor fan driving means 9.

  Here, the present invention prevents a reduction in operating capacity due to frost on the side of the heat exchanger operating as the evaporator of the refrigeration cycle in the outdoor heat exchanger 3 or the indoor heat exchanger 5, In the refrigeration air-conditioning apparatus having the configuration, during heating operation, particularly under low outdoor air conditions (for example, a low temperature environment of 5 ° C. or lower), heating operation under low outdoor air conditions is used to distinguish from normal heating operation. Frosting occurs on the outdoor heat exchanger 3 side.

 Hereinafter, first, the basic operation during the low-temperature heating operation will be described with reference to FIGS.

FIG. 2 is a diagram showing a basic operation during a low-temperature heating operation.
In the low-temperature heating operation, when the surface temperature of the outdoor heat exchanger 3 that operates as an evaporator is less than 0 degrees, moisture in the air adheres to the surface of the outdoor heat exchanger 3 as frost. And if frost grows until it blocks the air path of the outdoor heat exchanger 3, the heat exchange between the outside air and the refrigerant cannot be sufficiently performed, and the heating capacity rapidly decreases as shown in FIG. A defrosting operation is performed in order to recover this reduced capability. As described above, the defrosting operation is performed, for example, by switching the four-way valve 2 of FIG. 1 to operate in the reverse direction, that is, so as to connect the discharge pipe of the compressor 1 and the outdoor heat exchanger 3. Thereby, a high-temperature and high-pressure refrigerant is supplied to the outdoor heat exchanger 3 side, and frost can be melted by this heat. After the frost is removed, the four-way valve 2 is switched again to resume the heating operation. In addition, since heating stops during the defrosting operation, it is better that the defrosting operation time and frequency are as small as possible.

  It is known that the heat exchange performance varies depending on the air volume of the evaporator-side fan (outdoor fan 6). FIG. 3 is a diagram illustrating a difference in heating capacity due to a difference in the rotational speed of the outdoor blower 6 and a difference in timing for reducing the capacity due to frost formation. The dotted line in FIG. 3 shows the case where the rotational speed of the outdoor blower 6 is high, and the solid line shows the case where the rotational speed of the outdoor blower 6 is low. From FIG. 3, when the air volume is large, that is, when the rotational speed of the outdoor fan 6 is high, the heat transfer of the outdoor heat exchanger 3 is promoted to obtain a high heating capacity, and the effect of suppressing frost formation is high. It turns out that the generation | occurrence | production timing of the capability fall by frost can be delayed.

  Next, the effect by the delay of frost formation timing is demonstrated using FIG. FIG. 4 is a diagram illustrating an operation cycle of heating / defrosting operation during low-temperature heating operation. The upper bar graph in the figure shows the case where the rotational speed of the outdoor blower 6 is high, and the lower bar graph shows the case where the rotational speed of the outdoor blower 6 is low. As shown in FIG. 3, when the rotational speed of the outdoor fan 6 is high, the time from the start of heating to frosting becomes longer, so the defrosting time ratio during the predetermined time is low as shown in FIG. It becomes smaller than during rotation. As a result, the heating capacity is improved and a heating operation with little temperature unevenness can be performed. Therefore, it is preferable that the rotational speed of the outdoor fan 6 can be maintained as high as possible.

  Next, a description will be given of an operation control method for the outdoor blower 6 that is effective for preventing frost formation when a propeller fan having a propeller type blade shape of the outdoor blower 6 is used as the outdoor blower 6.

FIG. 5 is a diagram showing a general rotational speed-load torque characteristic in a propeller fan, and FIG. 6 is a diagram showing a general frost formation area-load torque characteristic when a propeller fan is used.
As shown in FIG. 5, the torque of the propeller fan increases according to the rotational speed and pressure loss. Therefore, when the pressure loss increases, the rotational speed decreases under the same torque condition. As the frosting progresses, the pressure loss of the air passage increases, so the relationship between the frosting area and the load torque of the motor has a characteristic of rising right shoulder as shown in FIG.

  Here, it is assumed that the maximum rated torque of the motor is τm, the rotational speed that generates the torque τm when the frost area is 100%, ω1, and the rotational speed that generates the torque τm when the frost area is 0%, ω2. Then, when the motor speed is controlled to be constant at ω1 until the frosting area ratio is from 0% to 100%, and when the motor speed is controlled to be constant at ω2, As for the relationship with the motor load torque, the graph in the case of constant ω2 as shown in FIG. 6 is drawn above the graph of ω1.

  It should be noted that under the condition that the frost formation area is less than 100%, the load torque of the motor does not reach the maximum rated torque τm as shown in FIG. For this reason, there is room for increasing the rotational speed. In other words, if the propeller fan (outdoor fan 6) is operated with the output torque kept constant at τm, the rotational speed immediately after the start of the heating operation (frosting area 0%) can be increased to ω2. And when frosting progresses with progress of time, a rotation speed will fall naturally toward (omega) 1 according to the load. For this reason, even if it operates with output torque (tau) m maintained, the driving | operation which does not exceed the maximum rated torque of a motor is realizable.

  In order to improve the prevention of frost formation by arranging the above contents, it is preferable that the rotational speed of the outdoor fan 6 can be maintained as high as possible. In order to realize this, the output torque of the outdoor fan motor 62 as described above. May be controlled to be constant at the maximum rated torque τm. By performing such constant torque control, the outdoor fan 6 can be driven at the maximum number of rotations commensurate with the load at that time, and a high frosting prevention effect can be obtained.

  The relationship between frost formation and load torque when the blade shape of the blower is sirocco, line flow, or turbo type will be described. FIG. 7 shows a general rotational speed-load torque characteristic in the case of these fans, and FIG. 8 shows a frost formation area-load torque characteristic. The relationship between the rotational speed and the torque has a positive correlation, but the relationship between the pressure loss and the torque is reversed from that in the case of the propeller type, and has a characteristic of low load torque at the time of high pressure loss. For this reason, the relationship between the frost formation area and the load torque is lowered to the right as shown in FIG. Therefore, when such a fan-shaped blower is used, the rotational speed when frosting is made higher than the rotational speed ω1 immediately after the start of heating operation (frosting area 0%) under the same maximum rated torque of the motor. Is possible. That is, if the output torque is controlled to be constant τm, it is possible to mitigate the decrease in the air volume due to frost formation, and the progress of frost formation can be delayed.

  In addition, although the air volume control of the outdoor fan 6 is performed by the outdoor fan driving means 8, speed control is generally used as the control method. Also in the outdoor blower 6 of this example, speed control is used during normal heating operation, and the constant torque control described above is used during low-temperature heating operation. As described above, by using the speed control and the constant torque control in combination, a more functional outdoor fan 6 is realized. Hereinafter, an example of a specific realization configuration of the outdoor fan driving means 8 will be described with reference to FIG.

FIG. 9 is a block diagram of the outdoor fan driving means 8 of FIG. The configuration in FIG. 9 shows a configuration example when position sensorless vector control is used as the control method.
The outdoor fan drive unit 8 includes an outdoor fan drive control unit 81, an outdoor fan inverter 82, and a current detection unit 83. The outdoor fan drive control unit 81 receives a command from the control mode command and the speed command given from the control unit 10 to create a PWM control signal, drives the transistor of the outdoor fan inverter 82, and drives the outdoor fan motor 62 and the outdoor fan motor 62. The outdoor fan blade 61 fixed to the shaft is rotated. The outdoor fan drive control unit 81 returns the rotational speed information of the outdoor fan motor 62 to the control unit 10.

  Next, the internal configuration of the outdoor fan drive control unit 81 will be described. The outdoor fan drive control unit 81 includes an A / D converter 811 that converts motor current information of the outdoor fan motor 62 into a digital signal, a coordinate converter 812 that converts the current from a stationary coordinate to a rotating coordinate, a rotor position, A position / speed estimator 813 for estimating the speed, a speed controller 814 for controlling the speed to be constant, a constant torque controller 815 for controlling the output torque to be constant, and a constant torque control based on a control mode command from the outside. Control mode switching means 816 for selecting either speed control, d-axis current controller 817 and q-axis current controller 818 for calculating voltage commands Vd * and Vq * so that the current approaches the current command, and voltage command Vd Coordinate converter 819 that converts *, Vq * into voltage commands Vu *, Vv *, Vw * in stationary coordinates, and voltage commands Vu *, Vv *, Vw * into PWM control signals for driving the outdoor fan inverter P to do And M control unit 820, in constructed.

Next, a schematic operation of the outdoor fan drive control unit 81 will be described. First, the position θ and the speed ω are estimated from the current information Id, Iq obtained from the A / D converter 811 and the coordinate converter 812 and the current output voltage commands Vd, Vq. Here, the speed controller 814 obtains the output Iq * based on the speed command ω ^* given from the outside (control unit 10) and the current speed ω so that the current speed ω approaches the speed command ω ^* . It is output to the control mode switching means 816. The constant torque controller 815 outputs a predetermined Iq * (here, for convenience, the q-axis current command value Iq_max at the time of the maximum rated torque of the outdoor fan motor 62) to the control mode switching means 816. When the control mode command is the speed control mode, the control mode switching means 816 is switched to the speed controller 814 side, and the output of the speed controller 814 is input to the q-axis current controller 818. On the other hand, when the control mode command is the constant torque control mode, the control mode switching means 816 is switched to the constant torque controller 815 side, and the output of the constant torque controller 815 is input to the q-axis current controller 818.

  The outdoor fan drive control unit 81 further obtains a predetermined excitation current command Id * (here, fixed to zero for convenience) according to the outdoor fan motor 62 and operating conditions, and a d-axis current controller 817 and a q-axis current controller At 818, the voltage commands Vd * and Vq * are controlled so that the currents Id and Iq approach the command values Id * and Iq *, respectively. Next, the coordinate converter 819 converts the voltage commands Vd *, Vq * into voltage commands Vu *, Vv *, Vw * of the stationary coordinate system, and converts them into control signals for each transistor of the outdoor fan inverter 82 by the PWM control means 820. Convert. The outdoor fan inverter 82 applies an AC voltage corresponding to the control signal of each transistor to the outdoor fan motor 62 to control the rotation of the outdoor fan motor 62.

When operating in the speed control mode, the speed controller 814 is controlled so that the outdoor fan motor 62 has a predetermined speed ω because ω = ω ^* is in a steady state (a stable state when τ → ∞). . On the other hand, when operating in the constant torque control mode, since Id = 0 and Iq = Iq_max are in a steady state, control is performed so that constant current and constant torque are obtained.

  Next, the frost formation detection sequence of the outdoor fan 6 during the low-temperature heating operation by the outdoor fan driving means 8 and the control unit 10 described above will be described with reference to FIG. FIG. 10 is a control flowchart of the outdoor blower 6 during the low-temperature heating operation when the outdoor blower blade shape is a propeller type. The low-temperature heating operation is performed when the outside temperature detected by the outside temperature sensor 3a corresponds to a low outside air condition of a predetermined temperature (for example, 5 ° C.) or less when a heating operation start instruction is input. If it does not correspond to the low outside air condition, normal heating operation (that is, speed control mode) is performed. In addition, although predetermined temperature is 5 degreeC, this is frosting temperature obtained experimentally.

  In the low temperature heating operation, as described above, the outdoor fan 6 is operated in the constant torque control mode. Specifically, constant torque control is performed with the q-axis current command as the maximum rated value Iq_max so that the maximum rated torque of the outdoor fan motor 62 is constant (step 1). Note that the start timing of the low-temperature heating operation includes the end of the defrosting operation in addition to the instruction to start the heating operation at the low temperature.

  Thereby, the rotation speed of the outdoor fan motor 62 rises rapidly to the maximum rotation speed that can be operated. The controller 10 monitors the speed (hereinafter referred to as the rotational speed) ω immediately after the start of the constant torque operation, and obtains the rotational speed filter value ωfil. The rotational speed filter value ωfil is obtained, for example, by a first-order lag function with the rotational speed ω as an input. The following formula (1) shows an example in which the first-order lag function is realized by a microcomputer or the like.

ωfil ← ωfil + K ・ {ω (t)-ωfil} (1)
Where K is the filter coefficient (0 <K <1)

  The control unit 10 determines whether the acceleration has been completed with the start of operation (step 3). This is determined, for example, by the fact that the rotational speed ω and the rotational speed filter value ωfil coincide. The frost detection preparation process is completed in steps 1 to 4 described above.

  If it is determined in step 3 that acceleration has ended, the process enters frosting detection processing. First, the current rotation speed filter value ωfil is set to the initial rotation speed ωnom for frosting detection (step 4).

  Here, the outdoor fan driving means 8 is controlled in the constant torque control mode. However, in this mode, the speed control does not work, and the speed and the rotational speed of the outdoor fan motor 62 change according to the increase or decrease of the load. When the shape of the outdoor fan blade 61 is a propeller type, if the outdoor heat exchanger 3 is frosted during operation, the pressure loss increases, the load torque of the outdoor fan motor 62 increases, and the rotational speed gradually decreases. .

  In the frosting detection process, the rotational speed filter value ωfil is continuously calculated (step 5), and the decrease of the rotational speed filter value from the initial value ωnom is monitored (step 6). When the difference is decreased by a predetermined difference Δω1 or more, it is determined that frost is formed, the heating operation is stopped, and the defrosting operation is started. Here, the start timing of the defrosting operation is determined using the rotation speed filter value ωfil instead of the rotation speed ω, but this is because the rotation speed of the outdoor fan motor 62 is determined by the outdoor fan 6. This is based on consideration of the fact that there is a fluctuation due to the air volume of the installation environment, and if there is no problem with the fluctuation of the rotation speed data, it may be performed based on the rotation speed ω. In addition, the defrosting operation start condition is here when the amount of change in the rotational speed filter value is decreased by a predetermined difference Δω1 or more, but may be when the rotational speed filter value is decreased to a predetermined rotational speed or less.

  In general, since the time interval from the start of heating to frost formation is on the order of several minutes to several hours, the time constant of the filter for obtaining the rotation speed filter value in the above is generally shorter than the above time. If set, the time from frost formation to the start of the defrosting operation can be shortened. Further, if the time constant of the filter is set to be substantially longer than the acceleration time from the start of heating operation to acceleration, good frost detection can be performed without erroneously determining completion of acceleration as frost formation.

  As described above, according to the first embodiment, during the low-temperature heating operation, the outdoor fan 6 on the outdoor heat exchanger 3 side where frost formation occurs is operated in the constant torque control mode. The outdoor blower 6 can be operated at the maximum allowable number of rotations according to the above. For this reason, while being able to improve a heating capability, the adhesion progress of frost can be suppressed. As a result, it is possible to prevent a reduction in operating efficiency due to frost formation, and to obtain an economical and highly reliable refrigeration cycle apparatus.

  In addition, since the frosted state is determined by looking at the amount of time change in the rotational speed of the outdoor fan motor 62 and the start or end of the defrosting operation is determined, the actual operating environment (air volume, humidity, etc.) Therefore, it is possible to accurately determine the start timing of the defrosting operation. For this reason, it is possible to improve the heating capacity by increasing the average rotational speed of the blower, and it is possible to suppress temperature unevenness by reducing the defrost frequency.

  In Embodiment 1, since the control method of the outdoor fan driving means 8 is vector control (position sensorless vector control), switching between the speed control mode and the constant torque control mode can be realized with a simple configuration.

Embodiment 2. FIG.
In this Embodiment 2, control of the outdoor fan 6 at the time of a defrost operation is demonstrated. FIG. 11 is a control flowchart of the outdoor blower 6 during the defrosting operation when the blade is a propeller type. In FIG. 11, steps having the same operations as those in the flowchart of FIG. 10 described above are denoted by the same reference numerals and description thereof is omitted.

  Steps 1 to 3 in FIG. 11 are defrost detection preparation processing, which accelerates with the maximum torque, stores the rotation speed at the end of acceleration in ωnom, and shifts to defrost detection processing. In the defrosting detection process, the rotational speed filter value ωfil is calculated and the change with time is confirmed. When the rotational speed difference Δω2 is increased by more than a predetermined rotational speed Δω2 (step 16), it is determined that the frost has been removed and the process proceeds to low temperature heating operation again. To do.

  According to the second embodiment, since the outdoor fan 6 is operated in the constant torque mode during the defrosting operation, it can be operated at the maximum allowable speed according to the load condition (frosting state), and the defrosting operation time can be reduced. It can be shortened. Further, since the frost formation is judged by looking at the increase in the rotational speed of the outdoor blower motor 62 of the outdoor blower 6, it is possible to accurately judge the end timing of the defrosting operation, thereby increasing the temperature unevenness and the average heating. It becomes possible to prevent a decline in ability.

  In the second embodiment, the constant torque control mode is used during the defrosting operation, but the speed control mode may be used.

  In the first and second embodiments, the constant torque control mode is performed only during the low-temperature heating operation. However, this constant torque control mode is an effective control method for controlling the blower with the maximum output. Therefore, it may be used even when heating is started. In this case, there is an effect that the controllability of the room temperature can be further improved.

  In the first and second embodiments, an example of constant torque control that keeps the motor torque constant at the maximum rated torque has been shown. However, a constant current that keeps the current that changes in proportion to the torque constant at the maximum rated current is shown. It is good also as control.

  In Embodiments 1 and 2 described above, the determination of the start or end of the defrosting operation is performed using the temporal change in the rotational speed of the outdoor fan 6, but in proportion to the rotational speed. The determination may be made based on other operating physical quantities that change (current / voltage (including a voltage commanded by a voltage command)).

Embodiment 3 FIG.
In the third embodiment, as a further usage of the constant torque control mode, a case where clogging is detected in the air passage (the air passage of the blower operating in the constant torque control mode) will be described. FIG. 12 is a control flowchart for detecting clogging when the fan blade shape is a propeller type. In the constant torque control mode, when there is an object that becomes air path resistance in the air path, a load is applied to the blower and the rotational speed is reduced. This characteristic is used to detect clogging. Therefore, the clogging here includes frost adhering to the heat exchanger existing in the air passage, and dust adhering to the dust collecting filter installed outside the heat exchanger. In FIG. 12, ωsh is the threshold value for determining the clogging when constant torque control is performed with the rated maximum torque of the motor. Immediately after acceleration, the rotational speed filter values ωfil and ωsh are compared (step 20). If ωfil> ωsh, it is determined that there is no clogging (step 21), and if ωfil <ωsh, it is determined that clogging occurs. (Step 22).

  Thus, the constant torque control mode can be used for clogging determination.

  In each of the above-described embodiments, examples relating to the heating operation and the defrosting operation in the case where the fan blade shape is a propeller type have been described. For example, the same effect can be obtained even if the outdoor unit blade shape is a line flow, sirocco, turbo type, or the like. Is possible. In the case of these blades, the load torque decreases with an increase in pressure loss. Therefore, the reverse of the above embodiment, that is, the low temperature heating operation may be controlled as shown in FIG. 11 and the defrosting operation as shown in FIG.

  In each of the above embodiments, an example of a refrigeration air-conditioning apparatus has been described as a refrigeration cycle apparatus. However, the present invention is not limited to this and may be a refrigerator or a refrigerator. In this case, the four-way valve 2 is switched to the side opposite to the state shown in FIG. 1 and the indoor heat exchanger 5 is operated as an evaporator, and the above-described control method is adopted for the indoor blower 7. Thereby, there can exist an effect similar to the above.

  When the refrigeration cycle apparatus is a refrigerator or a refrigerator as described above, the indoor unit blade shape of the indoor blower 7 may be any of a line flow, a sirocco, and a turbo type. An effect can be obtained.

It is a block diagram of the refrigerating air conditioning apparatus as a refrigerating cycle apparatus in Embodiment 1 of this invention. It is a figure which shows the basic operation at the time of low-temperature heating operation. It is a figure which shows the difference in the heating capability by the difference in the rotation speed of the outdoor air blower 6, and the difference in the capability fall timing by frost formation. It is a figure which shows the driving | running cycle of heating / defrosting operation in low temperature heating operation. It is a figure which shows the relationship between the rotation speed and torque in a propeller fan. It is a figure which shows the general frost formation area-load torque characteristic at the time of using a propeller fan. It is a figure which shows the rotation speed-load torque characteristic in a sirocco, a line flow, and a turbo type fan. It is a figure which shows the frost formation area-load torque characteristic in a sirocco, a line flow, and a turbo type fan. It is a block diagram of the outdoor fan drive means 8 of Embodiment 1. FIG. It is a control flowchart of the outdoor air blower at the time of low-temperature heating operation in case a fan blade shape is a propeller type. It is a flowchart regarding the defrost operation in case a blade | wing is a propeller type. It is a control flowchart of clogging detection when a fan blade shape is a propeller type.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Four way valve, 3 Outdoor heat exchanger, 3a Outside air temperature sensor, 4 Expansion mechanism, 5 Indoor heat exchanger, 6 Outdoor blower, 7 Indoor blower, 8 Outdoor blower drive means, 9 Indoor blower drive means, 10 Control unit, 11 refrigerant pipe, 61 outdoor fan blade, 62 outdoor fan motor, 71 indoor fan blade, 72 indoor fan motor.

Claims (25)

A refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger are connected by a refrigerant pipe, an outdoor fan that promotes heat exchange of the outdoor heat exchanger, and heat of the indoor heat exchanger In a refrigeration cycle apparatus having an indoor blower that promotes replacement, a control unit that controls the refrigeration cycle, the outdoor blower, and the indoor blower, and capable of switching between a normal operation and a defrosting operation by switching the four-way valve ,
The control unit is a constant torque control mode for controlling the motor torque of the outdoor or indoor fan to be constant at a predetermined torque value, or the current of the motor of the outdoor or indoor fan is constant at a predetermined current value. When the normal operation is performed in a predetermined low-temperature environment, heat that operates as an evaporator of the refrigeration cycle during normal operation of the outdoor or indoor fan is provided. An refrigeration cycle apparatus, wherein an evaporator-side fan, which is an exchanger-side fan, is operated in the constant torque control mode or the constant current control mode.   2. The refrigeration cycle according to claim 1, wherein the predetermined torque value is a maximum rated torque of a motor of the evaporator side blower, and the predetermined current value is a maximum rated current of a motor of the evaporator side blower. apparatus.   The normal operation is a heating operation, and the outdoor fan is operated in the constant torque control mode or the constant current control mode during a low temperature heating operation in which an outside air temperature is equal to or lower than a predetermined temperature value. Or the refrigerating-cycle apparatus of Claim 2.   The refrigeration cycle apparatus according to claim 3, wherein the predetermined temperature value is 5 ° C.   The said control part judges the start or completion | finish of the said defrost operation using the temporal change of the operation | movement physical quantity of the said outdoor air blower, The refrigeration cycle apparatus of Claim 3 characterized by the above-mentioned.   6. The refrigeration cycle apparatus according to claim 5, wherein a blade shape of the outdoor fan is a propeller type, and a defrosting operation start condition is that an operation physical quantity of the outdoor fan becomes a predetermined value or less.   6. The refrigeration cycle according to claim 5, wherein a blade shape of the outdoor fan is a propeller type, and a defrosting operation start condition is that a decrease amount of an operation physical quantity of the outdoor fan is equal to or greater than a predetermined amount. apparatus.   The blade shape of the outdoor blower is a propeller type, and an operation physical quantity of the outdoor blower during the defrosting operation is a predetermined value or more is set as a defrosting operation end condition. Refrigeration cycle equipment.   The blade shape of the outdoor blower is a propeller type, and an end condition of the defrosting operation is that the amount of increase in the operation physical quantity of the outdoor blower during the defrosting operation is a predetermined amount or more. 5. The refrigeration cycle apparatus according to 5.   The refrigeration cycle apparatus according to any one of claims 5 to 9, wherein the operating physical quantity is at least one of a rotational speed, a current, and a voltage of the outdoor blower.   The refrigeration cycle apparatus according to claim 3, wherein during the defrosting operation, the outdoor fan is operated in the constant torque control mode or the constant current control mode.   4. The refrigeration cycle apparatus according to claim 3, wherein the outdoor fan is operated in a constant torque control mode or the constant current control mode at the start of a normal heating operation other than the low-temperature heating operation.   4. The refrigeration cycle apparatus according to claim 3, wherein the normal heating operation other than the low-temperature heating operation is driven in a speed control mode with a constant speed, and the control method of the outdoor fan is a vector control method. .   The clogged state in the air passage through which the wind of the outdoor blower passes is detected based on an operation physical quantity of the outdoor blower operating in the constant torque control mode or the constant current control mode. Item 4. The refrigeration cycle apparatus according to item 3.   The normal operation is a refrigeration / freezing operation, and the indoor blower is operated in the constant torque control mode or the constant current control mode at a low temperature refrigeration / freezing operation in which the room temperature is a predetermined temperature value or less. The refrigeration cycle apparatus according to claim 1 or 2.   The refrigeration cycle apparatus according to claim 15, wherein the control unit determines the start or end of the defrosting operation using a temporal change in an operation physical quantity of the indoor blower.   The blade shape of the indoor blower is either a line flow, sirocco or turbo type, and the defrosting operation start condition is that the operating physical quantity of the indoor blower during the low-temperature refrigeration / freezing operation exceeds a predetermined value. The refrigeration cycle apparatus according to claim 16.   The fan shape of the indoor blower is either line flow, sirocco or turbo type, and the defrosting operation start condition is that the increase in the physical quantity of operation of the indoor blower during the low-temperature refrigeration / freezing operation exceeds a predetermined amount The refrigeration cycle apparatus according to claim 16, wherein   The blade shape of the indoor blower is either a line flow, sirocco or turbo type, and the defrosting operation end condition is that the operation physical quantity of the indoor blower during the defrosting operation is equal to or less than a predetermined value. The refrigeration cycle apparatus according to claim 16.   The blade shape of the indoor blower is either a line flow, sirocco, or turbo type, and the defrosting operation end condition is that the amount of decrease in the operation physical quantity of the indoor blower during the defrosting operation exceeds a predetermined amount. The refrigeration cycle apparatus according to claim 16.   The refrigeration cycle apparatus according to any one of claims 16 to 20, wherein the operating physical quantity is at least one of a rotation speed, a current, and a voltage of the indoor blower.   The refrigeration cycle apparatus according to claim 15, wherein the indoor blower is operated in the constant torque control mode or the constant current control mode during a defrosting operation.   The refrigeration cycle apparatus according to claim 15, wherein the indoor blower is operated in the constant torque control mode or the constant current control mode at the start of normal refrigeration / refrigeration operation other than the low-temperature refrigeration / refrigeration operation.   16. The normal refrigeration / freezing operation other than the low-temperature refrigeration / freezing operation is driven in a speed control mode with a constant speed, and the control method of the indoor blower is a vector control method. Refrigeration cycle equipment.   The clogged state in the air passage through which the wind of the indoor blower passes is detected based on an operation physical quantity of the indoor blower operating in the constant torque control mode or the constant current control mode. The refrigeration cycle apparatus described.

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