JP4404420B2 - Air conditioner control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to prevention of freezing of an evaporator in an air conditioner having a dehumidifying function.
[0002]
[Prior art]
As a conventional anti-freezing of an air conditioner, there has been one as described in JP-A-7-4727. What is described in this publication is a refrigeration cycle configured using a variable capacity compressor, an evaporator, a pressure reducing device, and a condenser, and a sensor for detecting the temperature of the evaporator is provided. When the temperature falls below the preset first value, the operating capacity of the compressor is lowered, and then the compressor is detected until the detected temperature exceeds the first value and then exceeds the second value higher than the first value. The increase in driving ability was prohibited.
[0003]
By comprising in this way, the operating range of the compressor could be expanded without freezing the evaporator.
[0004]
[Problems to be solved by the invention]
Such a conventional technique merely suppresses freezing from the temperature of the evaporator, and there is still room for expansion of the operating range of the compressor.
[0005]
In the present invention, when an evaporator and a condenser are provided close to each other, the operating range of the air conditioner is expanded by taking into consideration the factor of the outside air temperature.
[0006]
[Means for Solving the Problems]
In the present invention, the variable operating capacity compressor 1, the outdoor heat exchanger 3, the electric expansion valve 4a, the indoor heat exchanger 6, the electric expansion valve 4b, and the indoor heat exchanger 7 are annularly formed using refrigerant piping. The refrigeration cycle is connected to the refrigeration chamber , and at least the air cooled by the indoor heat exchanger 7 is supplied to the conditioned room, and the temperature of the indoor heat exchanger 7 is less than the first set value. In the control device for an air conditioner having a stop control unit that stops the operation of the compressor 1 when the air is small, the air blowing amount of the air blowing device that supplies the air cooled by the indoor heat exchanger 7 to the conditioned room is usually set. An operation control unit that performs an operation of obtaining a dehumidifying effect of the conditioned room by increasing or decreasing between the amount of air blown and stopped or almost stopped, and the outside air temperature is smaller than the second set value during this operation at the electric expansion valve 4a is fully opened, the diaphragm of the electric expansion valve 4b With adjusting the amount, the compressor is intended and a intermittent operation control unit for ON / OFF in a predetermined cycle.
[0007]
Furthermore, the set value changing unit changes the first set value to the third set value in the second operation mode from 1 degree to the first set value to the third set value in the first operation mode. Change within 3 degrees.
[0008]
Further, the set value changing unit is configured so that a difference between the first set value to the third set value in the first operation mode and the first set value to the third set value in the second operation mode is the first. The setting value of 2 is the largest.
[0009]
Also, it has a refrigeration cycle in which compressors, condensers, decompressors, and evaporators with variable operating capacity are connected in an annular shape using refrigerant piping, and at least supplies air cooled by the evaporator to the conditioned room And the air cooled by the evaporator is supplied to the conditioned chamber in the control device for the air conditioner having a stop control unit that stops the operation of the compressor when the temperature of the evaporator is lower than the first set value. An operation control unit that performs an operation of obtaining the dehumidifying effect of the conditioned room by increasing or decreasing the air flow rate of the air blower between the normal air flow rate and the stop or almost stop, and the outside air temperature is the first during the operation. And an intermittent operation control unit that masks the operation of the stop control unit and turns the compressor on and off at a predetermined period when the value is smaller than 2.
[0010]
The intermittent operation control unit stops the operation of the compressor when the temperature of the evaporator is equal to or lower than the third set value (<first set value).
[0011]
The operation stop unit further includes a decrease control unit for reducing the operation capacity of the compressor when the temperature of the evaporator is larger than the first set value and smaller than the fourth set value (> first set value), and the evaporator An increase prohibition unit for prohibiting an increase in the operation capacity of the compressor when the temperature of the compressor is larger than the fourth set value and smaller than the fifth set value (> the fourth set value) and the operating capacity of the compressor is increasing. It has.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a refrigerant circuit diagram, where 1 is a compressor with variable operation capability, 2 is a four-way switching valve, 3 is an outdoor heat exchanger, 4a and 4b are electrically driven whose throttle amount can be arbitrarily adjusted according to a control signal. An expansion valve (pressure reduction device), 5 is a strainer, 6 and 7 are indoor heat exchangers divided into two, and 8 is an accumulator. Yes.
[0013]
The operating capacity of the compressor 1 is automatically controlled so as to reach a magnitude that balances with the air conditioning load of the conditioned room (indoor) within a predetermined range, for example, the temperature between the room temperature and the set temperature. A deviation e and a change Δe of the temperature deviation e are obtained every predetermined period, and a fuzzy calculation is performed from the values of e and Δe to obtain a correction value of the driving ability. Next, there is a method of setting a value obtained by adding this correction value to the current operating capacity as a new operating capacity. However, the setting of the operating capacity of the compressor 1 is not limited to this method, and only from the temperature deviation e. Other methods such as obtaining may be used.
[0014]
The indoor heat exchangers 6 and 7 are connected in series via the electric expansion valve 4b. When the electric expansion valve 4b is in a fully open state, the indoor heat exchangers 6 and 7 are substantially integrated. is there.
[0015]
When the electric expansion valve 4a is fully opened and the throttle amount (pressure reduction amount) of the electric expansion valve 4b is adjusted, the indoor heat exchangers 6 and 7 are condensed and evaporated (or when the refrigerant circulation direction is reversed) And a dehumidifying operation can be performed.
[0016]
In addition, 9 and 10 are mufflers (silencers), 11 is a blower device (propeller fan) for the outdoor heat exchanger, and 12 is a blower device (cross flow fan) for the indoor heat exchanger. The blower 12 uses a DC brushless motor as a motor so that the amount of blown air can be varied substantially linearly.
[0017]
When the state of the four-way switching valve 2 is shown by a solid line (the state shown in the figure) and the electric expansion valve 4b is fully open, the high-temperature and high-pressure refrigerant discharged from the compressor 1 passes through the muffler 9 and the four-way switching valve 2. After condensing in the outdoor heat exchanger 3, evaporates in the indoor heat exchangers 6 and 7 through the electric expansion valve 4 a and the strainer 5, and then sucked into the compressor 1 again through the muffler 10, the four-way switching valve 2 and the accumulator 8. However, the refrigeration cycle indicated by the solid line arrow is circulated.
[0018]
At this time, the refrigerant evaporates in the indoor heat exchangers 6 and 7 to perform the cooling operation (cooling mode), and the cooled air is supplied to the conditioned room by the blower 12.
[0019]
Further, at this time, the first operation mode for periodically increasing or decreasing the amount of air blown by the blower 12, that is, the cooling effect for supplying the cool air to the conditioned room and the supply of the cool air are reduced to nearly the stop to interrupt the cooling effect. The operation is performed to prevent dehumidification due to the cooling operation without substantially lowering the room temperature while preventing the temperature increase of the conditioned room due to the cooling operation.
[0020]
When the electric expansion valve 4a is fully opened, the blower 11 is stopped and the opening degree (throttle amount) of the electric expansion valve 4b is adjusted, the refrigerant discharged from the compressor 1 is condensed in the indoor heat exchanger 6, It evaporates in the indoor heat exchanger 7. Accordingly, the air heated by the indoor heat exchanger 6 by the blower 12 and the air cooled by the indoor heat exchanger 7 are mixed and supplied to the conditioned room, and therefore dehumidified by the indoor heat exchanger 7. At the same time, the throttle amount is controlled by the electric expansion valve 4b, and the air whose discharge air temperature is controlled is supplied to the conditioned room.
[0021]
That is, the dehumidifying operation in the second operation mode is performed, and the amount of throttle of the electric expansion valve 4b is adjusted to perform the dehumidifying operation with a cool feeling and the dehumidifying operation with a warm feeling.
[0022]
When the four-way switching valve 2 is in the state indicated by the dotted line, the high-temperature and high-pressure refrigerant discharged from the compressor 1 is condensed in the indoor heat exchangers 6 and 7 via the muffler 9, the four-way switching valve 2 and the muffler 10. Then, after evaporating in the outdoor heat exchanger 3 through the strainer 6 and the electric expansion valve 4a, the refrigerant is circulated through the refrigeration cycle indicated by the dotted arrow where it is sucked into the compressor 1 again through the four-way switching valve 2 and the accumulator 8. .
[0023]
At this time, the refrigerant is condensed in the indoor heat exchangers 6 and 7 to perform heating operation, and the heated air is supplied to the conditioned room by the blower 12.
[0024]
FIG. 2 is a schematic block diagram of a control circuit provided in the indoor unit of the air conditioner (unit in which the indoor heat exchanges 6 and 7 are mounted).
[0025]
In this figure, reference numeral 21 denotes a plug to which 100V AC power is supplied, and is connected to a 100V commercial AC power supply. This AC power is supplied to the power supply circuit 23 via the switch 22.
[0026]
Reference numeral 24 is a current fuse, 25 is a rectifier circuit, 26 is a motor power supply, 27 is a control power supply, and 28 is a serial power supply. These components constitute the power supply circuit 23.
[0027]
The current fuse 24 is blown to protect the circuit when the current supplied to the power supply circuit 23 exceeds a predetermined current, and the rectifier circuit 25 converts the AC power obtained through the current fuse 24 into a full wave. The motor power supply circuit (switching power supply circuit) 26 generates a driving power supply for the fan motor (DC sensorless motor) 29 that constitutes the blower 12 and has a switching waveform based on a signal from a microcomputer to be described later. The output voltage is varied between DC12V and DC48V by controlling the ON duty.
[0028]
The control power supply 27 generates and stabilizes the drive power supply (DC5V) of the control unit 30, and the serial power supply 28 transmits a signal (four-way switching valve 2) to be transmitted to the outdoor unit (in which the outdoor heat exchanger 3 is mounted). The switching signal, the setting value of the operating capacity of the compressor 1, etc.) is a circuit for sharing the common line with the AC power supplied to the outdoor unit.
[0029]
Reference numeral 31 denotes a terminal plate. The first terminal, the second terminal, and the third terminal are provided on a resin-made terminal block, and a temperature fuse 32 that melts at a predetermined temperature or more and opens a circuit is provided on the terminal block. It is attached so that the temperature, that is, the temperature of the terminal board 31 can be detected.
[0030]
A normally open contact piece 37 of the power relay 36 is interposed between the first terminal of the terminal board 31 and the plug 21, and the normally open contact piece 37 is closed by the output of the microcomputer 33 (the driver is not shown). The AC power output from 31 to the outdoor unit is controlled.
[0031]
The second terminal of the terminal board 31 is connected to the plug 21 and is a common line with the third terminal (signal output terminal).
[0032]
The third terminal is a terminal for outputting a signal output from the microcomputer 33 via the serial circuit 28 a and the serial power supply 28.
[0033]
In addition, the 1st terminal-3rd terminal of the terminal board 31 is connected so that the same terminal number may connect with the terminal board of the electric circuit mounted in the outdoor unit of FIG. 3 mentioned later.
[0034]
The thermal fuse 32 is inserted into the drive line of the power relay 36, and when the temperature of the terminal board 31 rises, the power relay 36 is cut off and the normally open contact piece 37 is opened to supply AC power to the outdoor unit. It is a thing to cut off.
[0035]
Reference numeral 39 denotes a wireless remote controller, which performs various settings and function selections such as operation control of the air conditioner and setting of setting values based on the operation of the switch, and the operation signal is provided on the display board 40. Sent to the receiving circuit.
[0036]
The microcomputer 33 receives this operation signal and controls the operation of the air conditioner. The display board 40 displays the operation state of the air conditioner (operation mode such as cooling / heating / drying, set values, room temperature, etc.).
[0037]
Reference numeral 41 denotes a switch board, which is provided with switches for services such as the switch 22 and a test operation switch.
[0038]
An external ROM 42 stores an initial setting value of the microcomputer 33.
[0039]
Reference numerals 43 and 44 denote a temperature sensor for detecting the temperature of the room and a temperature sensor for detecting the temperature of the indoor heat exchanger 6, which are connected to an A / D input terminal of the microcomputer 33. The microcomputer 33 controls the operation of the air conditioner based on these detected temperatures.
[0040]
A humidity sensor 45 detects the humidity in the room and is connected to an A / D input terminal of the microcomputer 33. The microcomputer 33 controls the operation of the air conditioner based on the detected temperature and humidity.
[0041]
A step motor 46 changes the opening degree of the electric expansion valve 4b, and changes the opening degree of the electric expansion valve 4b in response to a signal from the microcomputer 33.
[0042]
A motor drive circuit 47 has an inverter circuit in which switching elements are connected in a three-phase bridge shape. When a DC sensorless motor is used, the output of this inverter circuit is matched with the rotational position of the rotor of the fan motor 29. It is to switch. A signal for switching the output of the inverter circuit is output by the microcomputer 33 judging from the rotational position of the rotor, and the rotational speed of the fan motor 29 is controlled by the voltage of the DC voltage output from the motor power supply 26.
[0043]
The electric expansion valves 4 a and 4 b are configured such that the refrigerant throttle amount is controlled by a built-in drive unit (step motor or the like), and the throttle amount is arbitrarily controlled according to a signal output from the microcomputer 33. Further, when one of the electric expansion valves 4a and 4b is a control target, the rest is fully opened. The electric expansion valves 4a and 4b are controlled so that the temperature of the heat exchanger acting as an evaporator becomes constant.
[0044]
FIG. 3 is a block diagram showing an outline of a control circuit mounted on the outdoor unit, and is connected to the terminal board 31 shown in FIG.
[0045]
In this figure, reference numeral 52 denotes a power circuit, which rectifies and smoothes 100V AC power from the indoor unit obtained through the first and second terminals of the terminal board 51 by double voltage rectification, and a varistor and noise filter. A reactor, a current fuse, etc. are added.
[0046]
The DC power output from the power supply circuit 52 is output to an inverter circuit 53 in which switching elements are connected in a three-phase bridge shape, and a three-phase alternating current of a pseudo sine wave based on the PWM theory (the compressor 1 uses an induction motor). Or after being converted to a system in which the stator winding is energized with the energization pattern corresponding to the rotation position (when the compressor 1 uses a DC brushless motor). , And supplied to the compressor 1.
[0047]
Accordingly, in any case, the operating speed of the compressor 1 can be controlled by changing the rotation speed of the compressor 1.
[0048]
Reference numeral 55 denotes a microcomputer, which forms the control unit 54. Based on the control signal received from the microcomputer 33 of the indoor unit via the third terminal of the terminal board 51 and the serial circuit 56, the microcomputer 55 controls the driving ability (the number of revolutions) of the compressor 1 by the above operation, and further switches four-way. Controls the switching of the valve 2 and the blower 11 (fan motor that drives the propeller fan), and compresses so that the current value detected by a CT (current detector) 58 connected to the current detection circuit 57 does not exceed a predetermined value. The operating capacity of the compressor 1 is controlled so that the temperature of a temperature sensor 59 that detects the temperature of the compressor 1 does not exceed a predetermined value.
[0049]
Reference numeral 60 denotes an outside air temperature sensor that detects the temperature of outside air. The outside air temperature detected by this sensor is transmitted to the microcomputer 33 of the indoor unit via the serial circuit 56.
[0050]
Note that 61 is a temperature sensor that detects the temperature of the outdoor heat exchanger, and 62 is a switching power supply that generates DC power for control.
[0051]
In the air conditioner configured as described above, the operation of each device is controlled based on a program stored in the microcomputer 33 of the indoor unit.
[0052]
FIG. 4 is a flowchart showing a driving operation according to the present invention, which is a subroutine of a program stored in the microcomputer 33.
[0053]
In this flowchart, first, in step S1, it is determined whether or not the room temperature tin is T3 or less. When this condition is satisfied, the process proceeds to step S2, and it is determined whether or not the outside air (temperature detected by the outside air temperature sensor 60) is T4 or less. I do.
[0054]
When the condition of step S2 is satisfied, that is, when the room temperature is T3 or less and the outside air is T4 or less, the process proceeds to step S3, and whether or not the temperature of the heat exchanger 6 (temperature detected by the temperature sensor 44) t is greater than T5. When the determination is made and these conditions are satisfied, the process proceeds to step S5.
[0055]
In step S5, the operating capacity of the compressor 1 is set within a predetermined range (about 10% to 30% of the maximum operating capacity) according to the magnitude of the air conditioning load at that time. The intermittent operation is performed and corresponds to the operation of the intermittent operation control unit.
[0056]
This intermittent operation is set to, for example, an operation in which a 120-second operation and a 150-second stop are alternately repeated. However, the intermittent operation is not limited to this, and the air conditioner operating capacity and the air conditioning load of the conditioned room These times are arbitrarily set based on the above.
[0057]
At this time, the blast volume to the conditioned room may be maintained at the set wind speed or at a constant wind speed, and the conditioned room may be periodically increased or decreased between the constant wind speed and the stop or almost stopped. The operation for obtaining the dehumidifying effect may be performed.
[0058]
When the condition of step S3 is not satisfied, the process proceeds to step S4 and the operation of the compressor 1 is stopped.
[0059]
After step S4 and step S5, the process returns to the main program of the microcomputer 33.
[0060]
When the condition of step S1 is not satisfied or when the condition of step S2 is not satisfied, the process proceeds to step S6, where the temperature t of the evaporator 6 (the heat exchanger 6 acting as an evaporator, hereinafter referred to as the evaporator 6) is It is determined whether or not T0 or less, and when this condition is satisfied, the operation of the compressor 1 is stopped in step S7. In other words, regardless of the required capacity calculated by the microcomputer 33, a signal indicating that the operating capacity of the compressor 1 is “0” is transmitted to the outdoor unit.
[0061]
In step S8, it is determined whether or not the temperature t of the evaporator 6 is equal to or higher than T2. If this condition is satisfied, the process proceeds to step S9, and the operation of the compressor 1 is set to the normal operation (restricted state). Return to the main program.
[0062]
When step S8 is not satisfied, that is, when the temperature t of the evaporator 6 is lower than T2, it is determined in step S10 whether or not the operating capacity of the compressor 1 is increasing. Thus, the increase in the driving capacity is prohibited, and correction is made so that the signal indicating the driving capacity of the compressor 1 does not increase regardless of the signal from the microcomputer 33.
[0063]
When the operating capacity of the compressor 1 is not increasing, that is, when it is decreasing or operating at a constant capacity, the process proceeds to step S12.
[0064]
In step S12, it is determined whether or not the temperature t of the evaporator 6 is equal to or lower than T1, and when this condition is satisfied, the process proceeds to step S13 to perform correction for decreasing the operating capacity of the compressor 1, and when this condition is not satisfied. In step S14, normal operation is performed.
[0065]
That is, when the temperature of the evaporator 6 is greater than T0 and less than or equal to T1, correction is performed to reduce the operating capacity of the compressor 1.
[0066]
By configuring in this way, the operating capacity of the compressor 1 is corrected in response to the temperature drop of the evaporator 6 to prevent the evaporator 6 (the heat exchanger 6 acting as an evaporator) from freezing. It is something that can be done.
[0067]
At the same time, when the outside air temperature is lowered, the compressor 1 is intermittently operated within the range where the evaporator 6 is not frozen regardless of these anti-freezing controls, and the range of the dehumidifying operation can be expanded even when the outside temperature falls. It can be done.
[0068]
As an example, the values shown in the flowchart of FIG. 4 are set as T0 = 2 degrees, T1 = 6 degrees, T2 = 8 degrees, T3 = 13 degrees, T4 = 10 degrees, and T5 = -15 degrees. However, the present invention is not limited to this, and is arbitrarily set based on the minimum operating capacity of the compressor, the capacity of the heat exchanger, the size of the conditioned room, and the like.
[0069]
【The invention's effect】
In the air conditioner configured as described above, the outside air temperature, the room temperature, and the like are detected, and the compressor is intermittently operated when both the room temperature and the outside air temperature are low. Therefore, the evaporator does not freeze when the outside air temperature is low. The range can be expanded, and the operating range of the dehumidifying operation can be expanded.
[0070]
Furthermore, when the outside air temperature and room temperature are high, the operation capacity of the compressor is corrected so that the evaporator does not freeze according to the temperature of the evaporator. The range can be expanded.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram showing a refrigeration cycle of an air conditioner showing an embodiment of the present invention.
FIG. 2 is a schematic block diagram of a control circuit used for controlling an indoor unit.
FIG. 3 is a schematic block diagram of a control circuit used for controlling an outdoor unit.
FIG. 4 is a flowchart showing an operation for preventing freezing.
[Explanation of symbols]
1 Compressor 6 Heat exchanger 7 Heat exchanger 33 Microcomputer 45 Temperature sensor 60 Outside air temperature sensor

Claims (5)

Refrigeration in which the compressor 1, variable heat capacity 3, outdoor heat exchanger 3, electric expansion valve 4a, indoor heat exchanger 6, electric expansion valve 4b, and indoor heat exchanger 7 are connected annularly using refrigerant piping. An operation of supplying at least air cooled by the indoor heat exchanger 7 to the conditioned room, and the compression when the temperature of the indoor heat exchanger 7 is lower than a first set value. In the control device for an air conditioner having a stop control unit that stops the operation of the machine 1 , the air flow rate of the air blower that supplies the air cooled by the indoor heat exchanger 7 to the conditioned room is defined as a normal air flow rate. An operation control unit that performs an operation to obtain a dehumidifying effect of the conditioned chamber by increasing or decreasing between stop and almost stop, and an electric expansion valve when the outside air temperature is lower than the second set value during this operation 4a is fully opened and the throttle amount of the electric expansion valve 4b is adjusted. Rutotomoni, control device for an air conditioner which is characterized by comprising said compressor intermittent operation control unit for ON / OFF in a predetermined cycle.   2. The air according to claim 1, wherein the intermittent operation control unit stops the operation of the compressor when the temperature of the evaporator is equal to or lower than a third set value (<first set value). Harmonic machine control device.   The operation stop unit further includes a decrease control unit that reduces the operation capacity of the compressor when the temperature of the evaporator is larger than the first set value and smaller than the fourth set value (> first set value). The air conditioner control device according to claim 2. The shutdown unit further the temperature of the evaporator is larger than the fourth set value fifth set value the compressor when operating capacity of the (> 4th set value) smaller than and the compressor is on the increase The control apparatus for an air conditioner according to claim 3, further comprising an increase prohibition unit that prohibits an increase in the operating capacity of the air conditioner.   The control apparatus for an air conditioner according to claim 1, wherein the intermittent operation control unit sets the operation capability of the compressor based on the humidity of the conditioned room.

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