JP4229546B2 - 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]
In such a conventional technique, the freezing is simply suppressed based on the temperature of the evaporator, and there is still room for expansion of the operating range of the compressor.
[0005]
The present invention provides an air conditioner that can expand the operating range of a compressor when an evaporator and a condenser are provided nearby.
[0006]
[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 in a ring shape using refrigerant piping, and air that is cooled by the evaporator is supplied to the conditioned room. The first operation mode for obtaining the dehumidifying effect of the conditioned room by continuously increasing / decreasing the blast volume of the apparatus, and the air cooled by the evaporator and the air heated by the condenser are mixed and then supplied to the conditioned room Then, in the control device for the air conditioner that selects and controls the second operation mode for obtaining the dehumidifying effect of the conditioned room, the operation of the compressor is stopped when the temperature of the evaporator is lower than the first set value. A stop control unit that reduces the operating capacity of the compressor when the evaporator temperature is greater than the first set value and less than the second set value (> first set value), and the evaporator temperature Is greater than the second set value and greater than the third set value (> second set value) Further, an increase prohibiting unit for prohibiting an increase in the operation capacity of the compressor when the operation capacity of the compressor is increasing, and a first setting value to a third setting value in the first operation mode are respectively set to the second setting value. And a set value changing unit that changes larger than the first to third set values in the operation mode.
[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]
In addition, the present invention has a refrigeration cycle in which a compressor, condenser, decompressor, and evaporator with variable operation capability are connected in an annular shape using refrigerant piping, and air cooled by the evaporator is supplied to the conditioned chamber. The first operation mode for obtaining the dehumidifying effect of the conditioned room by continuously increasing / decreasing the amount of air blown from the blower, and after mixing the air cooled by the evaporator and the air heated by the condenser In the control device of the air conditioner that selects and controls the second operation mode to be supplied to the conditioned room and obtain the dehumidifying effect of the conditioned room, based on the temperature and the set value of the evaporator, A controller for preventing the evaporator from freezing is provided, and the set value is made different between the first operation mode and the second operation mode.
[0010]
Furthermore, the set value used in the first operation mode is set higher than the set value used in the second operation mode.
[0011]
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.
[0012]
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.
[0013]
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.
[0014]
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.
[0015]
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.
[0016]
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.
[0017]
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.
[0018]
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.
[0019]
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.
[0020]
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.
[0021]
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. .
[0022]
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.
[0023]
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).
[0024]
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.
[0025]
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.
[0026]
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.
[0027]
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.
[0028]
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.
[0029]
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.
[0030]
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).
[0031]
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.
[0032]
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.
[0033]
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.
[0034]
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.
[0035]
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.).
[0036]
Reference numeral 41 denotes a switch board, which is provided with switches for services such as the switch 22 and a test operation switch.
[0037]
An external ROM 42 stores an initial setting value of the microcomputer 33.
[0038]
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.
[0039]
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.
[0040]
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.
[0041]
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.
[0042]
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.
[0043]
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.
[0044]
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.
[0045]
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.
[0046]
Accordingly, in any case, the operating speed of the compressor 1 can be controlled by changing the rotation speed of the compressor 1.
[0047]
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.
[0048]
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.
[0049]
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.
[0050]
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.
[0051]
FIG. 4 is a flowchart showing the freeze prevention operation of the heat exchanger of the indoor unit, and is a subroutine constituting a part of the main program.
[0052]
The outline will be described with reference to FIG. 5. When the temperature of the heat exchanger 6 acting as an evaporator decreases in the first operation mode and enters the range of 8 to 6 degrees (the operation capacity of the compressor 1). When the signal for increasing is output from the indoor unit), first, the increase in the operating capacity of the compressor 1 is prohibited. Despite this prohibition, when the temperature of the heat exchanger 6 continues to decrease and enters the range of 6 degrees to 2 degrees, correction is performed to decrease the operating capacity of the compressor 3.
[0053]
Moreover, when the temperature of the heat exchanger 6 becomes 2 degrees or less, the operation of the compressor 1 is stopped.
[0054]
At this time, if the temperature of the heat exchanger 6 starts to rise and exceeds the regulation range, the regulation applied to the operating capacity of the compressor 1 is released.
[0055]
These controls are for preventing the heat exchangers 6 and 7 acting as an evaporator in the first operation mode from freezing due to a temperature drop.
[0056]
In the flowchart of FIG. 4, first, in step S1, whether or not the temperature (temperature detected by the temperature sensor 44) t of the evaporator 6 (the heat exchanger 6 acting as an evaporator, hereinafter referred to as the evaporator 6) t is equal to or lower than T0. When this condition is satisfied, the operation of the compressor 1 is stopped in step S2. 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.
[0057]
In step S3, 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 S4, and after setting the operation of the compressor to the normal operation (the state where the restriction is released), the main Return to the program.
[0058]
When step S3 is not satisfied, that is, when the temperature t of the evaporator 6 is lower than T2, it is determined in step S5 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.
[0059]
When the operating capacity of the compressor 1 is not increasing, that is, when the operating capacity is decreasing or operating at a constant capacity, the process proceeds to step S7.
[0060]
In step S7, 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 S8 to perform correction for decreasing the operating capacity of the compressor 1, and when this condition is not satisfied. In step S9, normal operation is performed.
[0061]
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.
[0062]
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.
[0063]
In the flowchart of FIG. 4, the values used in the cooling mode and the first operation mode are set to T0 = 2 degrees, T1 = 6 degrees, and T2 = 8 degrees. In the second operation mode, T0 = 1 degree, T1 = 3 degrees, and T2 = 6 degrees are set. T0 corresponds to the first set value, T1 corresponds to the second set value, and T2 corresponds to the third set value.
[0064]
The values of T0 to T2 in the first operation mode are changed larger than the values of T0 to T2 in the second operation mode, respectively. This change is switched by a set value changing unit configured by a program in the microcomputer 33. This set value changing unit switches the set values based on a signal transmitted from the remote control 39 that determines the operation mode of the air conditioner.
[0065]
Note that these set values are not limited to the values shown in the above-described embodiments, but within a range where the heat exchanger does not freeze depending on the maximum operating capacity, the minimum operating capacity of the compressor, the capacity of each heat exchanger, and the like. It is set arbitrarily.
[0066]
In the second operation mode, the heat exchanger 7 acts as a condenser and dissipates heat. Therefore, the heat exchangers 6 and 7 both function as evaporators, and thus the interior of the indoor unit Therefore, the temperature at which the heat exchanger is frozen is lowered accordingly.
[0067]
Therefore, in the second operation mode, the set value can be set lower than that in the first operation mode, and in the second operation mode, the temperature range in which the operation can be performed without operating the freeze prevention. Can be expanded.
[0068]
In addition, the setting value changing unit has a larger effect in setting the value of T0 to T2 in the second operation mode in the range of 1 degree to 3 degrees than the value of T0 to T2 in the first operation mode. If it was 1 degree or less, sufficient effects could not be obtained, and if it was 3 degrees or more, the possibility of freezing the heat exchanger was high.
[0069]
Further, the set value changing unit makes the difference between the value of T0 to T2 in the first operation mode and the value of T0 to T2 in the second operation mode the largest in the value of T1, so that the compressor The range in which the driving ability is reduced is widened, and it is possible to act in a direction to suppress the ease of freezing that occurs when the set value is lowered as a whole.
[0070]
【The invention's effect】
By configuring the present invention as described above, the range in which the heat exchanger can be operated without freezing in the second operation mode 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.
FIG. 5 is an explanatory diagram showing a schematic operation of anti-freezing control.
[Explanation of symbols]
1 Compressor 6 Heat exchanger 7 Heat exchanger 33 Microcomputer 45 Temperature sensor

Claims (5)

A compressor, a condenser, a pressure reducing device, a variable operating capacity type, a refrigeration cycle in which an evaporator is connected in an annular shape using a refrigerant pipe, and a blower that supplies air cooled by the evaporator to a conditioned room The first operation mode in which the air volume is continuously increased and decreased to obtain the dehumidifying effect of the conditioned room, and the air cooled by the evaporator and the air heated by the condenser are mixed and then the conditioned room In the control device for the air conditioner that selects and controls the second operation mode for supplying and obtaining the dehumidifying effect of the conditioned room, when the temperature of the evaporator is lower than the first set value, A stop control unit for stopping the operation, and a reduction control unit for reducing the operating capacity of the compressor when the temperature of the evaporator is larger than a first set value and smaller than a second set value (> first set value); The evaporator temperature is greater than the second set value and third An increase prohibition unit for prohibiting an increase in the operation capacity of the compressor when it is smaller than a set value (> second set value) and the operation capacity of the compressor is increasing, and a first in the first operation mode An air conditioner comprising: a set value changing unit that changes the set value through the third set value larger than the first set value through the third set value in the second operation mode, respectively. Control device. The set value changing unit changes the first set value to the third set value in the second operation mode from 1 to 3 from the first set value to the third set value in the first operation mode. The air conditioner control device according to claim 1, wherein the air conditioner control device changes within a range. The set value changing unit is configured such 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 second. The control device for an air conditioner according to claim 1, wherein the control value is set to the largest value. A compressor, a condenser, a pressure reducing device, a variable operating capacity type, a refrigeration cycle in which an evaporator is connected in an annular shape using a refrigerant pipe, and a blower that supplies air cooled by the evaporator to a conditioned room The first operation mode in which the air volume is continuously increased and decreased to obtain the dehumidifying effect of the conditioned room, and the air cooled by the evaporator and the air heated by the condenser are mixed and then the conditioned room In the control device for an air conditioner that selects and controls the second operation mode for supplying and obtaining the dehumidifying effect of the conditioned room, the evaporator is prevented from freezing based on the temperature and the set value of the evaporator. A control device for an air conditioner is provided, wherein a controller for performing the above operation is provided, and the set value is made different between the first operation mode and the second operation mode. The control device for an air conditioner according to claim 4, wherein a set value used in the first operation mode is set higher than a set value used in the second operation mode.

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