JP5511867B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus.

  In the heating operation of the heat pump refrigeration cycle apparatus, frost may form on the heat exchanger of the outdoor unit depending on outdoor temperature and humidity conditions. There is a control system (defrost operation) in which the refrigeration cycle is operated as a reverse cycle as a method for recovering the heating performance deterioration due to frost formation. The defrost operation does not require additional parts such as a heater and can easily remove frost, and various proposals have been made for methods of effectively performing this operation.

  For example, the technology described in Patent Document 1 below improves the defrost effect by controlling the fan motor rotation speed so as to offset the outside wind during the defrost operation.

JP 2010-169292 A

  However, in the conventional technique represented by the above-mentioned Patent Document 1, since the outdoor heat exchanger or the indoor heat exchanger that functions as an evaporator generates heat during defrost operation, the inside of the heat exchanger in a state where the attached frost has been melted is high.・ High humidity atmosphere. At this time, since the temperature around the heat exchanger is lower than that of the atmosphere, the humidity in the atmosphere is cooled to cause condensation, which may accelerate corrosion and the like. In particular, in an outdoor unit or a fan motor mounted on an indoor unit, copper wires, boards, and the like are arranged inside, and there is a possibility that the function of the refrigeration cycle apparatus itself may be lost if a conduction failure due to corrosion occurs. As a method of preventing moisture from entering the fan motor, it is conceivable to change to a waterproof structure, but there is a problem that the cost increases due to an increase in the size of the fan motor.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the refrigerating-cycle apparatus which can aim at the improvement of reliability, without increasing cost.

  In order to solve the above-described problems and achieve the object, the present invention provides a compressor, an expansion mechanism, a four-way valve, an indoor heat exchanger that functions as a condenser or an evaporator, and a condenser or an evaporator. A refrigeration cycle apparatus in which a functioning outdoor heat exchanger is connected by a refrigerant pipe, an outdoor fan that blows air to the outdoor heat exchanger, an indoor fan that blows air to the indoor heat exchanger, and the outdoor fan An outdoor fan motor that drives the indoor fan, an outdoor fan drive unit that drives the outdoor fan motor, an indoor fan drive unit that drives the indoor fan motor, the four-way valve, An expansion mechanism, the outdoor fan drive unit, and a control unit for controlling the indoor fan drive unit, wherein the outdoor heat exchanger functions as an evaporator. When receiving a predetermined command for inhibiting condensation of the outdoor fan motor during defrosting operation when the voltage for driving the outdoor fan, and outputs to the outdoor fan motor.

  According to the present invention, there is an effect that the reliability can be improved without increasing the cost.

FIG. 1 is a structural diagram of a refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the relationship between the heating operation time and the heating capacity. FIG. 3 is a diagram illustrating an operation mode at a low temperature. FIG. 4 is a diagram illustrating a temperature change in the outdoor unit during the defrost operation by the refrigeration cycle apparatus. FIG. 5 is a diagram showing a temperature change in the outdoor unit during the defrost operation by the refrigeration cycle apparatus according to the embodiment of the present invention. FIG. 6 is a circuit diagram of the outdoor fan drive unit. FIG. 7 is a flowchart showing the operation of the outdoor fan drive unit. FIG. 8 is a time chart of the outdoor fan rotation speed. FIG. 9 is a structural diagram of the outdoor unit.

  Embodiments of a refrigeration cycle apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a structural diagram of a refrigeration cycle apparatus 1 according to an embodiment of the present invention. The refrigeration cycle apparatus 1 has an outdoor unit 6 and an indoor unit 7 as main components. The outdoor unit 6 includes a four-way valve 2, an outdoor heat exchanger 3 that functions as a condenser or an evaporator, an expansion mechanism 4, an outdoor fan drive unit 8, a control unit 10, a refrigerant pipe 11, a compressor 13, an outdoor fan 61, and An outdoor fan motor 62 that drives the outdoor fan 61 is included. The indoor unit 7 includes an indoor heat exchanger 5 that functions as a condenser or an evaporator, an indoor fan drive unit 9, a refrigerant pipe 11, an indoor fan 71, and an indoor fan motor 72 that drives the indoor fan 71. ing.

  The outdoor fan 61 is a blower fan for blowing air to the outdoor heat exchanger 3 to promote heat exchange, and the indoor fan 71 is a blower fan for blowing air to the indoor heat exchanger 5 to promote heat exchange. is there. The outdoor fan motor 62 is a motor that rotates the outdoor fan 61, and the indoor fan motor 72 is a motor that rotates the indoor fan 71. The outdoor fan drive unit 8 is a circuit that supplies power to the outdoor fan motor 62, and the indoor fan drive unit 9 is a circuit that supplies power to the indoor fan motor 72. The control unit 10 is a control unit that controls the four-way valve 2, the compressor 13, the expansion mechanism 4, the outdoor fan drive unit 8, and the indoor fan drive unit 9 according to the temperature and humidity desired by the user. The refrigerant pipe 11 connects the compressor 13, the four-way valve 2, the indoor heat exchanger 5, the expansion mechanism 4, and the outdoor heat exchanger 3 so that the refrigerant can be circulated. Note that the four-way valve 2 shown in FIG. 1 is in a state where a discharge pipe (not shown) of the compressor 13 and the indoor heat exchanger 5 are connected, that is, in a heating operation state.

  Next, the basic operation during the heating operation of the refrigeration cycle apparatus 1 in a low temperature environment will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram illustrating a relationship between the heating operation time and the heating capacity, and FIG. 3 is a diagram illustrating an operation mode at a low temperature. The horizontal axis represents time, and the vertical axis represents the heating capacity of the refrigeration cycle apparatus 1.

  When the surface temperature of the outdoor heat exchanger 3 is less than 0 degrees under low outdoor air conditions, moisture in the air adheres to the surface of the outdoor heat exchanger 3 as frost. Part A of FIG. 2 shows a point in time when frost formation on the surface of the outdoor heat exchanger 3 has started. When this frost grows until it blocks the air path of the outdoor heat exchanger 3, heat exchange between the outside air and the refrigerant is performed. Is not performed sufficiently, the heating capacity rapidly decreases as shown in part B of FIG. In the refrigeration cycle apparatus 1, the defrost operation is started as shown in part C of FIG.

  The defrosting operation is realized by switching the four-way valve 2 in the reverse direction by the expansion mechanism 4. That is, the four-way valve 2 shown in FIG. 1 is performed by connecting a discharge pipe (not shown) of the compressor 13 and the outdoor heat exchanger 3 as indicated by a dotted line. Thereby, a high-temperature and high-pressure refrigerant is supplied to the outdoor heat exchanger 3 side, and frost adhering to the outdoor heat exchanger 3 can be melted by this heat. When the frost is removed, the defrosting operation is terminated as shown in part D of FIG. 3, the four-way valve 2 is switched again as shown in FIG. 1, and the heating operation is resumed.

  During the defrost operation, the outdoor heat exchanger 3 generates heat, and the adhering ice is melted to become water, and a part of it becomes water vapor. That is, since the temperature rise and the moisture increase occur at the same time, the internal atmosphere of the outdoor heat exchanger 3 becomes partially hot and humid compared to the surroundings.

  Next, the temperature change in the outdoor unit 6 during the defrost operation will be described with reference to FIG. FIG. 4 is a diagram illustrating a temperature change in the outdoor unit 6 during the defrost operation by the refrigeration cycle apparatus 1. The horizontal axis represents time, and the vertical axis represents temperature. The solid line represents the temperature in the outdoor heat exchanger 3, the dotted line represents the motor temperature (the temperature of the outdoor fan motor 62), and the alternate long and short dash line represents the dew point temperature.

  The refrigeration cycle apparatus 1 actively drives the outdoor fan 61 to blow air to the outdoor heat exchanger 3 in the normal operation mode (rotation control mode) other than the defrost operation. Promotes heat exchange with the outside air. When the rotation control mode is the heating operation, the outdoor heat exchanger 3 may be frosted as described above. Therefore, the refrigeration cycle apparatus 1 is operated from the heating operation to the defrost operation as shown in part P of FIG. Switch to. When the defrost operation is started (t1), since the high-temperature refrigerant is supplied to the outdoor heat exchanger 3, the temperature of the outdoor heat exchanger 3 rises as shown in the Q part of FIG. As the frost melts, some of it becomes water vapor and the humidity increases. Note that the outdoor fan 61 is stopped after the defrost operation is started. Further, as the temperature and humidity of the outdoor heat exchanger 3 increase, the dew point temperature in the outdoor unit 6 increases as shown in the R part of FIG.

  The outdoor fan motor 62 is cooled to a low temperature by the outside air immediately before the defrost operation and has a larger heat capacity than the air, so that the motor temperature is kept lower than the atmosphere even after the start of the defrost operation. Therefore, as shown in S part of FIG. 4, when the dew point temperature of the atmosphere in the outdoor unit 6 becomes higher than the motor temperature, the outdoor fan motor 62 condenses water vapor and causes condensation. Since the amount of dew condensation depends on the dew point temperature and the motor temperature, as shown in FIG. 4, the area of the shaded portion corresponding to the difference between the dew point temperature and the motor temperature corresponds to the dew amount. Hereinafter, the shaded area is referred to as a motor dew generation area. The outdoor fan motor 62 is generally made of a metal such as a circuit board, iron, or copper, and therefore metal corrosion tends to proceed more easily as the condensation increases.

  Next, the temperature change at the time of the defrost driving | operation by the refrigerating-cycle apparatus 1 which concerns on embodiment of this invention using FIG. 5 is demonstrated. FIG. 5 is a diagram showing a temperature change in the outdoor unit 6 during the defrost operation by the refrigeration cycle apparatus 1 according to the embodiment of the present invention.

  The control unit 10 and the outdoor fan drive unit 8 prevent the high-temperature and high-humidity atmosphere generated by the outdoor heat exchanger 3 from drifting in the vicinity of the motor when the defrost operation is started as shown in part P of FIG. Blow operation (condensation prevention operation) is performed. In this dew condensation prevention operation, for example, an AC voltage is applied to the windings of the outdoor fan motor 62 from the outdoor fan drive unit 8 so that the outdoor fan 61 gently flows air from the outdoor fan motor 62 side to the outdoor heat exchanger 3 side. It is realized by doing.

  By this dew condensation prevention operation, outside air is introduced into the vicinity of the outdoor fan motor 62 even after defrosting. For this reason, the temperature and humidity of the atmosphere in the vicinity of the motor do not change greatly before and after the defrost, and the dew condensation condition shown in FIG. 4 is not reached. That is, according to the dew condensation prevention operation of the refrigeration cycle apparatus 1 according to the embodiment, it is possible to reduce the dew amount of the outdoor fan motor 62 or to prevent dew condensation.

  It should be noted that the amount of air required to prevent the fan motor dew condensation is sufficient if the atmosphere in the vicinity of the outdoor heat exchanger 3 does not contact the outdoor fan motor 62. If the amount of air is large, the defrost of the outdoor heat exchanger 3 It is desirable that the outdoor fan motor 62 be operated at the minimum necessary number of rotations because this results in a decrease in effect and an increase in power consumption.

  Next, a specific method of the dew condensation preventing operation will be described with reference to FIGS. FIG. 6 is a circuit diagram of the outdoor fan drive unit 8, FIG. 7 is a flowchart showing the operation of the outdoor fan drive unit 8, and FIG. 8 is a time chart of the outdoor fan rotation speed during heating of the control unit 10. FIG. 9 is a structural diagram of the outdoor unit 6.

In FIG. 9, the general internal structure of the outdoor unit 6 will be described. The outdoor fan 61, the outdoor fan motor 62, and the outdoor heat exchanger 3 are arranged in this order when viewed from the front side (lower part of the figure).
During the cooling / heating operation), the outdoor fan 61 is operated in such a direction as to blow air from the outdoor fan 61 to the front side.

  In FIG. 6, the outdoor fan drive unit 8 includes an outdoor fan control circuit 81 and an inverter 82 as main components. The inverter 82 applies a voltage to the outdoor fan motor 62, and the position sensor 63 built in the outdoor fan motor 62 detects the rotor position (magnetic pole position of the rotor) of the outdoor fan motor 62 or the rotation speed of the rotor. The outdoor fan control circuit 81 outputs a PWM signal to the inverter 82 based on information from the control unit 10 and the position sensor 63.

  The position sensor 63 of the outdoor fan motor 62 is composed of elements that output electrical signals, such as Hall ICs, photocouplers, photointerrupters, and their associated circuits, and is therefore fixed and built in the motor stator with a structure with a printed circuit board. Is done.

  Next, the operation of the outdoor fan drive unit 8 will be described with reference to FIG. The outdoor fan control circuit 81 controls generation of an AC voltage for rotationally driving the outdoor fan motor 62 based on the operation mode (air blowing mode) and the rotation speed command (rotation speed command). As shown in FIG. 7, the outdoor fan control circuit 81 first checks the operation mode output from the control unit 10 (step S1), and determines whether or not the operation mode corresponds to the fan motor dew condensation prevention operation, for example. (Step S2), the direction in which the outdoor fan motor 62 should rotate is determined according to the received operation mode. That is, when the operation mode is the normal operation mode (step S2, No), the outdoor fan control circuit 81 rotates the outdoor fan 61 in the forward direction so that air flows from the outdoor heat exchanger 3 to the outdoor fan 61. The energization order to each phase of the outdoor fan motor 62 is determined (step S3). On the other hand, when the operation mode is the fan motor dew condensation prevention operation mode (step S2, Yes), the outdoor fan control circuit 81 sets the outdoor fan 61 so that, for example, the wind flows from the outdoor fan 61 to the outdoor heat exchanger 3. The order of energization of each phase of the outdoor fan motor 62 is determined so as to rotate in the direction (step S4). Next, the outdoor fan control circuit 81 receives the rotor position information obtained from the position sensor 63 provided in the outdoor fan motor 62 as an input, calculates the current rotational position and rotational speed, and obtains the rotational speed obtained from the control unit 10. The rotational speed is controlled by comparing the number command and the current rotational speed (step S5), and determining and outputting the duty and frequency of the PWM signal so that the rotational speed difference is reduced (step S6). The outdoor fan control circuit 81 converts the voltage command into a PWM control signal for each element in the inverter 82 and outputs it to the inverter 82. The outdoor fan control circuit 81 repeats the above operation (Step S7, No) except when the operation is finished (Step S7, Yes).

  As described above, in the present embodiment, the outdoor fan drive unit 8 issues a predetermined command for suppressing the condensation of the outdoor fan motor 62 during the defrost operation when the outdoor heat exchanger 3 functions as an evaporator. When received, the outdoor fan 61 is driven to introduce the wind toward the inside of the outdoor unit 6, for example, so that the reliability can be improved without increasing the cost.

  Note that the air volume in the fan motor dew condensation prevention mode only needs to be enough to prevent air from coming into contact with the high-temperature, high-humidity heat exchanger near the low-temperature fan motor surface. Is sufficiently small compared to the airflow required for Further, if the air volume is excessive, the temperature of the outdoor heat exchanger 3 during the defrosting operation is lowered, which may hinder the defrosting of the outdoor heat exchanger 3 and cause a reduction in heating capacity. For this reason, the refrigeration cycle apparatus 1 with high reliability and high heating capacity can be obtained by setting the value of the frequency command in the fan motor dew condensation prevention mode to a value smaller than the lower limit value of the normal frequency command. FIG. 8 shows, for example, the fan rotation speed during heating operation and the fan rotation speed during defrost operation. The operation frequency (fan rotation speed) at the time of defrost operation is set to a value smaller than the minimum rotation speed at the time of air conditioning operation (only the heating operation is shown in the illustrated example).

  Further, it is preferable that the fan motor dew condensation prevention mode is kept to the minimum necessary in order to reduce power consumption. As a typical example, it may be possible to add whether or not the defrost operation is being performed during the heating operation as determination information. Usually, such determination information (cooling / heating) or the like cannot be detected by the fan motor and is recognized by the control unit 10, so that the start / stop determination of the fan motor condensation prevention mode is performed by the control unit 10, There is an advantage that the refrigeration cycle apparatus 1 can be configured at low cost without increasing the number of sensors and signal lines. It should be noted that the start / stop determination of the fan motor dew condensation prevention mode can be performed by other than the control unit 10.

  Further, the driving direction of the outdoor fan 61 during the defrost operation is preferably a direction in which air is introduced from the outdoor fan 61 into the outdoor unit, but it is also possible to select a direction opposite to this. However, since air moves inside the outdoor unit, it is effective in preventing condensation of the outdoor fan motor 62. That is, the outdoor fan drive unit 8 outputs a voltage for driving the outdoor fan 61 to the outdoor fan motor 62 when receiving a predetermined command for suppressing condensation of the outdoor fan motor 62 during the defrost operation. By setting to, there is an effect in preventing condensation of the outdoor fan motor 62. As described above, conventionally, the outdoor fan 61 is stopped during the defrost operation.

  Note that the refrigeration cycle apparatus 1 according to the embodiment of the present invention shows an example of the content of the present invention, and can be combined with another known technique, and departs from the gist of the present invention. Of course, it is possible to change and configure such as omitting a part within the range.

  As described above, the present invention is applicable to a refrigeration cycle apparatus, and is particularly useful as a refrigeration cycle apparatus that can improve reliability without increasing costs.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle apparatus 2 Four-way valve 3 Outdoor heat exchanger 4 Expansion mechanism 5 Indoor heat exchanger 6 Outdoor unit 7 Indoor unit 8 Outdoor fan drive part 9 Indoor fan drive part 10 Control part 11 Refrigerant piping 13 Compressor 61 Outdoor fan 62 Outdoor Fan motor 63 Position sensor 71 Indoor fan 72 Indoor fan motor 81 Outdoor fan control circuit 82 Inverter

Claims (5)

A refrigeration cycle in which a compressor, an expansion mechanism, a four-way valve, an indoor heat exchanger that functions as a condenser or an evaporator, and an outdoor heat exchanger that functions as a condenser or an evaporator are connected by a refrigerant pipe. A device,
An outdoor fan that blows air to the outdoor heat exchanger;
An indoor fan for blowing air to the indoor heat exchanger;
An outdoor fan motor for driving the outdoor fan;
An indoor fan motor for driving the indoor fan;
An outdoor fan driving unit for driving the outdoor fan motor;
An indoor fan drive unit for driving the indoor fan motor;
A control unit for controlling the four-way valve, the expansion mechanism, the outdoor fan driving unit, and the indoor fan driving unit;
With
The outdoor fan drive unit is configured to drive the outdoor fan when receiving a predetermined command for preventing dew condensation of the outdoor fan motor during defrost operation when the outdoor heat exchanger functions as an evaporator. A refrigeration cycle apparatus that outputs a voltage to the outdoor fan motor.   When the outdoor fan driving unit receives the predetermined command during the defrost operation, the outdoor fan driving unit outputs a voltage for driving the outdoor fan in a direction to introduce wind into the outdoor unit to the outdoor fan motor. The refrigeration cycle apparatus according to claim 1, wherein:   3. The refrigeration cycle apparatus according to claim 1, wherein an operating frequency of the outdoor fan motor for preventing dew condensation of the outdoor fan motor is smaller than a minimum number of rotations during air-conditioning operation.   The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the outdoor fan motor incorporates a position sensor for detecting a magnetic pole position or a rotation speed of the rotor. The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the control unit performs the start and stop of a predetermined command for suppressing dew condensation of the outdoor fan motor.

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