JPH0633896B2 - Defrost control method for air conditioner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for controlling a defrosting operation of an air conditioner having a refrigeration cycle.

(B) Conventional Technology Generally, conventional defrosting control methods for air conditioners are described in JP-B-59-26860, JP-A-58-16141, and JP-A-60-114671. There was something like that.

First, the former publication describes that the end line of the defrosting operation is corrected using only the temperature of the outdoor heat exchanger or the outdoor temperature and the outdoor temperature so that unnecessary defrosting operation is not performed. there were.

What is described in the second publication calculates the set time of the optimum defrosting operation according to the outside air temperature before the defrosting operation starts or after the defrosting operation starts so that unnecessary defrosting operation is not performed. It was something that was done.

Moreover, the one described in the latter publication is such that the compressor is not driven while the operation of the compressor is temporarily stopped due to switching of the four-way valve at the start of the defrosting operation. Was applied to heat the compressor, and the heat generation amount was used during the defrosting operation to shorten the defrosting time.

(C) Problems to be Solved by the Invention In the conventional technique configured as described above, the defrosting operation time is shortened by suppressing unnecessary defrosting operation. It depends on the amount of frost on the outside heat exchanger (evaporator during heating operation) and the temperature of the outside air. In some cases, this defrosting operation time becomes relatively long, and during this time, the room to be conditioned There was a case where the temperature of the product decreased and the user felt uncomfortable. Also when shortening the defrosting operation as described in the latter publication,
There is a limit to the defrosting operation time that can be shortened, and the temperature of the conditioned room drops substantially during this defrosting operation time, causing the user to feel uncomfortable as in the above case.

It has been attempted to perform a heating operation by an electric heater in order to suppress the temperature decrease of the conditioned room during the defrosting operation, but in such a case, the heating amount by the electric heater is substantially limited. Therefore, a sufficient effect cannot be obtained. That is, the air blown to the electric heater is once cooled by the indoor heat exchanger and its temperature drops. Therefore, the amount of air blown to the electric heater is reduced to suppress the temperature drop of the discharge air, or the electric heater of large capacity is used. It was necessary to increase the calorific value using. In this case, the compressor is operating for defrosting, and the operating current and the electric heater current are simultaneously consumed by the air conditioner, so the capacity of the breaker that supplies the current to the air conditioner is increased. Considering this, the capacity of this electric heater could not be increased so much.
Therefore, a sufficient heating effect cannot be obtained despite the large power consumption.

In view of such a problem, the present invention provides a defrosting control method capable of suppressing a temperature decrease in a conditioned room due to a defrosting operation and performing comfortable air conditioning.

(D) Means for Solving the Problems The present invention has a refrigeration cycle in which a compressor, a condenser, a decompression device, and an evaporator are connected by a refrigerant pipe, and the defrosting operation of the evaporator is performed when the evaporator is frosted. In the defrosting control method for an air conditioner configured to perform, when the continuous defrosting operation is maintained for a predetermined time or longer, the heating operation by the electric heater is started, and after the heating operation is finished, the defrosting operation is performed. Is to be restarted.

(E) Action In the control method of the air conditioner configured as described above, the heating operation by the electric heater is performed during one defrosting operation to raise the temperature of the conditioned room to some extent, and then the defrosting operation is performed again. It is possible to suppress a large temperature drop in the room to be conditioned.

(F) Example An example of the present invention will be described below with reference to the drawings.
The figure is a schematic view of an air conditioner using the present invention. 1 in the figure
Is a compressor, 2 is a four-way valve, 3 is an indoor heat exchanger, 4, 5 is a pressure reducer (pressure reducing device), 6 is an outdoor heat exchanger, 7 is an accumulator, and the four-way valve 2 is shown during heating operation. In the state of the solid line, the high-temperature high-pressure refrigerant discharged from the discharge port of the compressor 1 is the four-way valve 2, the indoor heat exchanger 2, the pressure reducers 4, 5,
The outdoor heat exchanger 6, the four-way valve 2, and the accumulator 7 sequentially flow in the direction of the solid arrow and are sucked from the suction port of the compressor 1. At this time, the indoor heat exchanger 3 acts as a condenser to heat the room. The outdoor heat exchanger 6 functions as an evaporator.

During the cooling operation, the four-way valve 2 is in the state shown by the dotted line in the figure, and the high-temperature high-pressure refrigerant discharged from the discharge port of the compressor 1 is
The outdoor heat exchanger 6, the pressure reducer 5, the check valve 8, the indoor heat exchanger 3, the four-way valve 2, and the accumulator 7 sequentially flow in the direction of the dotted arrow and are sucked from the suction port of the compressor 1. At this time, the indoor heat exchanger 3 acts as an evaporator to perform indoor cooling operation. The outdoor heat exchanger 6 acts as a condenser.

Also, by using the check valve 8 to change the resistance values of the pressure reducers 4 and 5,
The optimum decompression value is obtained during the heating operation and the cooling operation.

Reference numeral 9 denotes an electromagnetic on-off valve (hereinafter referred to as an electromagnetic valve), which connects the discharge port D and the suction port S of the compressor 1 via the pressure reducer 10 and the accumulator 7. Therefore, this solenoid valve 9
When is open, the pressure of the refrigerant discharged from the discharge port D decreases, and the operating capacity of the compressor 1 decreases. Electric heaters 11 and 12 are provided on the secondary side of the indoor heat exchanger 3. Reference numeral 13 denotes a fan motor on the indoor side, which can switch the wind speed between three levels of weak wind (L), medium wind (M), and strong wind (H). Reference numeral 14 denotes a fan motor on the outdoor side, which can switch the wind speed between two stages of weak wind (L) and strong wind (H).

FIG. 3 is an electric circuit diagram used in the refrigerant circuit diagram shown in FIG. Terminals in the figure An AC power supply 15 is connected between them. Reference numeral 16 is a varistor for absorbing noise, and 17 is a current fuse.

18 and 19 are interlocking switching contacts (RFI2).
(RFI2) 18 normally open contact and normally closed contact are fan motor 1 respectively
Connected to weak wind (L) terminal and strong wind (H) terminal of 3 and switching contact piece
The normally open contacts of (RFI2) 19 are each a weak wind of the fan motor 13.
It is connected to the (L / L) terminal and its normally closed contact is open. Reference numeral 20 denotes a switching contact (RFI1), and the normally open contact and the normally closed contact are connected to the switching contact (RFI2) 18 and the switching contact (RFI2) 19, respectively.

Reference numeral 21 denotes a switching contact (RFO2), and the normally open contact and the normally closed contact are connected to the weak wind (L) terminal and the strong wind (H) terminal of the fan motor 14, respectively. Reference numeral 22 is a normally open contact piece connected to the switching contact piece (RFO2).

23 and 24 are normally open contact pieces (REV2) and normally open contacts (REV4),
The solenoid valve 9 and the four-way valve 2 are energized respectively. Reference numeral 25 is a normally open contact piece (RCM) for energizing the compressor 1. 27, 28
Are normally open contact pieces (RHA) and normally open contacts (RHB) for energizing the electric heaters 11 and 12, respectively. Reference numerals 29, 30, and 31 are condensers for driving the compressor 1 and the fan motors 30 and 31, respectively.

FIG. 4 is an electronic circuit diagram for controlling the various sections shown in FIG. Relay (RFO1) 32 is normally open contact piece (RFO1) 2
2, the relay (RFO2) 33 has a switching contact (RFO2) 21, the relay (RFI1) 34 has a switching contact (RFI1) 20, and the relay (RFI2) 35 has a switching contact (RFI2). ) 18 and switching contact (RFI
2) 19, the relay (RHB) 36 has a normally open contact piece (RHB) 28, the relay (RHA) 37 has a normally open contact piece (RHA) 27, and the relay (RCM) 38 is normally open. It has a contact piece (RCM) 25 and a relay (REV
2) 39 has a normally open contact piece (REV2) 23 and a relay (REV4) 40
Has a normally open contact piece (REV4) 24. These relays 3
2 to 40 are terminals R5 to R of the microprocessor 41
It is connected to 13 and is energized when each terminal becomes H (HIGH) level voltage. The operation of the microprocessor 41 will be described later based on the flowchart. 42 to 50
Is an output resistance of the microprocessor 41, and 51 to 59 are inverters, which convert the H level voltage into the L (LOW) level voltage and the L level voltage into the H level voltage. The relay is energized when the output of these inverters is at the L level voltage (the output of the microprocessor is at the H level voltage).

67 is a rectifier circuit, which is composed of a diode bridge. A smoothing capacitor 68 smoothes the output of the rectifier circuit 67. Reference numeral 69 denotes a constant voltage circuit, which supplies a positive voltage to the terminal VSS of the microprocessor 41 and a terminal VAS.
S is the first reference voltage, terminal VREF is the second reference voltage,
The reset output is output to the terminal RESET and the negative voltage is output to the terminal VDD.

Reference numeral 70 denotes a crystal oscillator, which forms an oscillation circuit by combining resistors 71, 72, 73 and capacitors 74, 75. The oscillation output of this oscillation circuit is the microprocessor 41.
Is connected between the terminals OSC1 and OSC2.

Reference numerals 76 to 79 are sensors for detecting temperature, which are room temperature,
It is provided at a position where the outside air temperature, the temperature of the indoor heat exchanger, and the temperature of the outdoor heat exchanger can be detected. The sensors 76 to 79 are connected to the positive voltage VSS via the resistors 80 to 83, respectively.
Is connected to the ground, and the connection points between the sensor and the resistor are connected to the terminals A1 to A4 of the microprocessor 41, respectively. The terminals A1 to A4 are input terminals for analog voltage, and have an A / D (analog / digital) converter inside. A thermistor is used as each of the sensors 76 to 79.

Input resistors 97 to 100 are connected to scan input terminals K1, K2, K4, and K8 of the microprocessor 41, respectively. On the other hand, the microprocessor 41
The terminals R0, R1, and R3 are scan output terminals. The operation switch 92, the diode 101 and the resistor 97 are connected in series between the terminal R1 and the terminal K1, and the cooling / heating switch 102, the diode 103 and the resistor 100 are connected in series between the terminal R1 and the terminal K8. It is connected.

Reference numerals 105 and 106 denote grayout put code switches for setting the wind speed of the fan motor on the indoor side and for setting the indoor temperature set value, respectively, and wiring as shown in FIGS. 5 and 6. Has become. 107 to 1
Reference numeral 13 is a diode that regulates the flow direction of the scan output.

FIG. 7 is a main flowchart showing the main operation of the microprocessor 41 shown in FIG. 4, and the program starts when a reset signal is given to the terminal RESET of the microprocessor 41. Step S1 is initialization, which initializes and initializes the microprocessor. Step S2 is a key scan and data input subroutine, and the operation switch (OPSW) 9
2, the open / close state of the cooling / heating changeover switch 102, the setting state of the grayout put code switch 105 for setting the wind speed of the indoor fan, the setting state of the grayout put code switch 106 for selecting the indoor temperature set value,
The room temperature, the outside air temperature, the temperature of the indoor heat exchanger, and the temperature of the outdoor heat exchanger detected by the sensors 76 to 79 are input and stored internally. Thereafter, in step S3, it is determined whether or not the operation switch 92 is closed. If the switch 92 is open, the air conditioner is held in a stopped state, and if the switch 92 is closed, the process proceeds to step S4. In S4, it is determined whether the cooling / heating switch 102 is in the open / closed state, that is, the cooling operation or the heating operation, and the process proceeds to one of the cooling operation steps S5, S6 or the heating operation steps S7, S8, S9.
Incidentally, S10 is a subroutine for protection.

In the "cooling operation" in step S5, the compressor is operated when the room temperature is higher than the set value, and the wind speed of the indoor fan at this time is set to the wind speed determined in S6. When the room temperature falls below the set value, the compressor operation is stopped and the indoor fan wind speed is set to low (L / L) operation. The compressor is kept stopped by a 3-minute timer for at least 3 minutes.

The "blower setting" in step S6 sets the wind speed of the indoor fan based on the set value, and when the "AUTO" mode is set, the wind speed is set to a strong (H) wind speed based on the difference between the room temperature and the set value. Set to three levels, low (L) wind speed and weak (L / L) wind speed.

Further, the wind speed of the outdoor fan is set to be strong or weak based on the outside temperature. It should be noted that the "blower setting" in step S8 in the heating operation performs substantially the same operation, but there is a difference in that the set value differs between the cooling operation and the heating operation.

The "protection" in step S10 is to stop the operation of the air conditioner based on the outputs of various protection switches such as a refrigerant pressure switch and an electric heater overheat switch (not shown).

In the "heating operation" in step S7, the room temperature and the set value are compared with each other in the same manner as the cooling operation to operate the compressor and the electric heater A.
The energization of 11 is controlled. When frost formation on the outdoor heat exchanger 6 (acting as an evaporator) exceeds a certain amount during such a heating operation, the frost detection unit outputs a defrost signal. This defrost signal is released when certain conditions are met. As the frost detection method of the frost detection unit, the temperature change of the outdoor heat exchanger 6, the temperature change of the indoor heat exchanger 3, or the outdoor fan 1
The frost formation is determined by the change in the current flowing through the sensor 4, the detector attached to the outdoor heat exchanger 6, and the like. To release the defrost signal, it is determined that the frost has melted when the temperature of the outdoor heat exchanger 6 becomes a certain temperature or higher (for example, about 12 ° to 15 ° C or higher).

FIG. 1 is a flowchart showing the defrosting operation. In this flowchart, step S11 is a step for detecting frost formation as described above, and is connected to the heating operation flowchart. When frost formation is detected in step S11, it is determined in step S12 whether or not the mask time has elapsed, and if the mask time has elapsed, the following defrost control is performed. First, in step S13, the compressor 1 and the outdoor fan 14 are stopped, and the electric heaters A, B11, 1
Energize 2. At this time, since the indoor fan 13 is operating, the heating operation by the electric heaters A, B 11, 12 is performed. Such heating operation is maintained for 60 seconds to increase the room temperature. Next, the four-way valve 2 is reversed to form a refrigeration cycle for hot gas defrosting. After 2 seconds has elapsed, the operation of the compressor 1 is started in step S14, the power supply to the indoor fan 13 and the electric heaters A, B11, 12 is stopped, and the defrosting operation by hot gas is performed. In step S15, the outdoor heat exchanger 6
The temperature (T) is detected, and when this temperature becomes "T≥12 ° C", it is judged that defrosting has ended, and step S16 is performed to restart the heating operation. If the temperature of the outdoor heat exchanger does not satisfy "T≥12 ° C", the defrosting operation by this hot gas is maintained as it is, and when this defrosting operation is timed for 5 minutes in step S17, step S18 Then, the compressor 1 is stopped, the indoor fan 13 and the electric heater B12 are powered,
The heating operation by the electric heater B12 is maintained. At this time, if "room temperature ≤ set temperature -1.8 ° C", the electric heater A11 is also energized. In the heating operation by such an electric heater, it is determined in step S19 whether the room temperature is equal to or higher than the set value or is maintained for 10 minutes, and step S14 is performed.
And the defrosting operation is performed again. After this, the temperature of the outdoor heat exchanger is judged to be "T" when it is judged in step S15.
The defrosting operation with hot gas and the heating operation with the electric heater are alternately repeated until the condition of ≧ 12 ° C ”is satisfied.

In the control of the defrosting operation as described above, after the defrosting operation for a certain time (5 minutes), the defrosting operation is interrupted once, and the heating operation by the electric heater is performed, and the temperature of the controlled room that is lowered by the defrosting operation To some extent. After this, the defrosting operation is restarted again.

In the above embodiment, a predetermined time (5
After that, the heating operation by the electric heater is performed, but the heating operation by the electric heater may be performed when the temperature of the conditioned room becomes low.

(G) Effect of the Invention The present invention has a refrigeration cycle in which a compressor, a condenser, a decompression device, and an evaporator are connected by a refrigerant pipe, and the defrosting operation of the evaporator is performed when the evaporator is frosted. In the defrosting control method of the air conditioner that has been formed, when the continuous defrosting operation is continued for a predetermined time or longer, the heating operation by the electric heater is started, and the defrosting operation is restarted after the end of this heating operation. When the amount of frost on the vessel is large and the defrosting time becomes long, the defrosting operation is suspended once and the heating operation by the electric heater is performed to suppress the temperature decrease of the controlled room during the defrosting operation. Therefore, even when the heating operation is interrupted by the defrosting operation, the temperature drop in the conditioned room is suppressed,
Comfortable air conditioning is continuously maintained.

[Brief description of drawings]

FIG. 1 is a flow chart showing a defrosting operation, FIG. 2 is a schematic view of an air conditioner using the present invention, FIG. 3 is an electric circuit diagram for controlling the equipment shown in FIG. 2, and FIG. FIG. 5 is an electronic circuit diagram for controlling the relay contact piece shown in FIG. 3, FIG. 5 is a wiring diagram of a grayout put code switch for setting the wind speed of the indoor fan shown in FIG. 4, and FIG. 4 is a wiring diagram of the grayout put code switch for setting the room temperature shown in FIG. 4, and FIG. 7 is a main flow chart showing the main operation of the microprocessor shown in FIG. 1 ... Compressor, 3 ... Indoor heat exchanger, 4, 5 ... Pressure reducing device, 6 ... Outdoor heat exchanger, 11, 12 ... Electric heater.

Claims (3)

[Claims] 1. An air conditioner having a refrigeration cycle in which a compressor, a condenser, a pressure reducing device, and an evaporator are connected by a refrigerant pipe, and the defrosting operation of the evaporator is performed when the evaporator is frosted. In the defrosting control method for a machine, when continuous defrosting operation is continued for a predetermined time or more, heating operation by an electric heater is started, and after the heating operation is finished, the defrosting operation is restarted. Defrosting control method for air conditioner. 2. The defrosting control method for an air conditioner according to claim 1, wherein the heating operation by the electric heater is terminated when the temperature of the conditioned room exceeds a predetermined temperature. 3. The defrosting control method for an air conditioner according to claim 1, wherein the heating operation by the electric heater ends after a lapse of a certain time after the electric heater is energized.