JP2001133021A - Controller for air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen the operating range of an air conditioner by lowering the temperature for operating antifreezing when the atmospheric temperature is low. SOLUTION: The controller for an air conditioner constitutes a refrigerating cycle having a compressor 1, a condenser 3, a pressure reducing unit 4a and an evaporator 6 annularly connected by using refrigerant piping; and a stop control unit for stopping the operation of the compressor when the temperature of the evaporator is lower than a first set value. Further, the controller comprises an operation control unit for conducting an operation for obtaining a dehumidifying effect of room to be conditioned by increasing or decreasing the supply air amount of a blower for supplying the air cooled by the evaporator to the room between a normal supply air amount and the stop or substantially stop, and an intermittent operation control unit for turning ON/OFF the compressor at a predetermined period by masking the operation of the stop control unit, when the atmospheric temperature is lower than a second set value in case of conducting the previous operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the prevention of freezing of an evaporator in an air conditioner having a dehumidifying function.

[0002]

2. Description of the Related Art A conventional air conditioner has been disclosed in Japanese Patent Application Laid-Open No. 7-4727 as a method for preventing freezing. What is described in this publication is to provide a sensor for detecting the temperature of an evaporator in a refrigeration cycle configured using a variable capacity compressor, an evaporator, a decompression device, and a condenser. When the temperature falls below a first value set in advance, the operating capacity of the compressor is reduced, and thereafter the compressor is operated until the detected temperature exceeds a second value higher than the first value after exceeding the first value. This prohibits an increase in the driving ability of the vehicle.

[0003] With this configuration, the operating range of the compressor can be expanded without freezing the evaporator.

[0004]

In such a conventional technique, 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 in which the operating range of an air conditioner is expanded by providing an evaporator and a condenser close to each other and further taking into account the factors of the outside air temperature.

[0006]

SUMMARY OF THE INVENTION The present invention has a refrigerating cycle in which a compressor, a condenser, a decompression device, and an evaporator of variable operation capacity are connected in a ring by using a refrigerant pipe, and is cooled by the evaporator. A first operation mode for continuously increasing or decreasing the amount of air blown by a blower for supplying air to the conditioned room to obtain a dehumidifying effect of the conditioned room, and the air cooled by the evaporator and the air heated by the condenser. And a second operation mode in which the temperature of the evaporator is adjusted to a first set value by selecting a second operation mode for controlling the second operation mode for obtaining the dehumidifying effect of the conditioned room A stop control unit for stopping the operation of the compressor when the temperature is smaller than the first set value, and reducing the operation capacity of the compressor when the temperature of the evaporator is larger than the first set value and smaller than a second set value (> first set value) A decrease control unit, wherein the temperature of the evaporator is higher than the second set value, and An increase prohibition unit for prohibiting an increase in the compressor's operating capacity when the compressor's operating capacity is smaller than a fixed value (> second set value), and a first setting in the first operation mode A setting value changing unit that changes the value to the third set value to be larger than the first to third set values in the second operation mode, respectively.

Further, the set value changing section changes the first to third set values in the second operation mode from the first to third set values in the first operation mode. It is changed within a range of 1 to 3 degrees.

[0008] Further, the set value changing unit is configured to change the first to third set values in the first operation mode and the first to third set values in the second operation mode. The difference is the largest at the second set value.

In addition, a compressor with a variable operating capacity, a condenser,
A refrigerating cycle in which a decompression device and an evaporator are connected in a ring using a refrigerant pipe, and an operation of supplying at least the air cooled by the evaporator to the conditioned room is performed, and the temperature of the evaporator becomes the first temperature.
In the control device for an air conditioner having a stop control unit for stopping the operation of the compressor when the value is smaller than the set value of the air conditioner, the blowing amount of the blowing device for supplying the air cooled by the evaporator to the conditioned room is determined as a normal blowing amount. And an operation control unit that performs an operation of increasing or decreasing between stop and almost stop to obtain a dehumidifying effect of the conditioned room, and a stop control unit that performs an operation when the outside air temperature is smaller than the second setting during the operation. And an intermittent operation control unit for turning on / off the compressor at a predetermined cycle while masking the operation.

Further, the intermittent operation control section 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).

The operation stop unit further includes a reduction control unit that reduces the operation capability of the compressor when the temperature of the evaporator is higher than the first set value and lower than a fourth set value (> first set value). When the temperature of the evaporator is higher 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, the increase in the operating capacity of the compressor is prohibited. And an increase prohibition unit.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a refrigerant circuit diagram. 1 is a compressor of a variable operating capacity, 2 is a four-way switching valve, 3 is an outdoor heat exchanger, 4a and 4b are electric motors whose throttle amount can be arbitrarily adjusted according to a control signal. Expansion valve (pressure reducing device), 5 is strainer,
Reference numerals 6 and 7 denote an indoor heat exchanger divided into two, and 8 denotes an accumulator, which is annularly connected by refrigerant pipes as shown in the drawing to constitute a refrigeration cycle.

The operating capacity of the compressor 1 is automatically controlled so as to reach a size balanced with the air conditioning load of the conditioned room (room) within a predetermined range. And the variation of the temperature deviation e.
e is obtained at predetermined intervals, 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 the correction value to the current operating capacity as a new operating capacity, but the setting of the operating capacity of the compressor 1 is not limited to this method. Other methods, such as finding, may be used.

The indoor heat exchangers 6 and 7 are connected in series via an electric expansion valve 4b. When the electric expansion valve 4b is fully opened, the indoor heat exchangers 6 and 7 are substantially integrated. It becomes.

When the electric expansion valve 4a is fully opened and the throttle amount (pressure reduction amount) of the electric expansion valve 4b is adjusted, when the indoor heat exchangers 6 and 7 are reversed in the condenser and evaporator (or the circulation direction of the refrigerant). Can function as an evaporator and a condenser), thereby enabling a dehumidifying operation.

Reference numerals 9 and 10 denote mufflers (mufflers), 11 denotes a blower (propeller fan) for an outdoor heat exchanger, and 12 denotes a blower (cross flow fan) for an indoor heat exchanger. The blower 12 is configured to use a DC brushless motor as a motor so that the blower amount can be varied substantially linearly.

When the four-way switching valve 2 is in a state shown by a solid line (shown in the figure) and the electric expansion valve 4b is fully opened, the high-temperature and high-pressure refrigerant discharged from the compressor 1 is supplied to the muffler 9 and the four-way switching valve. After being condensed in the outdoor heat exchanger 3 through the outdoor heat exchanger 3 and evaporated in the indoor heat exchangers 6 and 7 through the electric expansion valve 4a and the strainer 5, the compressor 1 is again passed through the muffler 10, the four-way switching valve 2 and the accumulator 8. Circulates through the refrigeration cycle indicated by the solid arrow drawn into the refrigeration cycle.

At this time, the refrigerant is evaporated in the indoor heat exchangers 6 and 7 to perform a cooling operation (cooling mode), and the cooled air is supplied to the conditioned room by the blower 12.

Further, at this time, the first operation mode in which the amount of air blown by the air blower 12 is periodically increased or decreased, that is, the cooling effect of supplying the cool air to the conditioned room and the cooling effect of reducing the supply of the cool air almost to near the stop, is achieved. Is performed to prevent the temperature of the conditioned room from increasing due to the cooling operation, and to perform the operation for effectively dehumidifying by the cooling operation without substantially lowering the room temperature.

When the electric expansion valve 4a is fully opened, the blower 11 is stopped, and the opening (throttle amount) of the electric expansion valve 4b is adjusted, the refrigerant discharged from the compressor 1 passes through the indoor heat exchanger 6. It condenses and evaporates in the indoor heat exchanger 7. Therefore, the air heated in the indoor heat exchanger 6 by the blower 12 and the air cooled in the indoor heat exchanger 7 are mixed and supplied to the conditioned room, so that the indoor heat exchanger 7 dehumidifies. At the same time, the air whose controlled amount is controlled by the electric expansion valve 4b and the temperature of the discharge air is controlled is supplied to the conditioned room.

That is, the dehumidifying operation in the second operation mode is performed, and the throttle amount of the electric expansion valve 4b is adjusted to perform the cooling dehumidifying operation and the warming dehumidifying operation.

When the state of the four-way switching valve 2 is in the state shown by the dotted line, the high-temperature and high-pressure refrigerant discharged from the compressor 1 passes through the muffler 9, the four-way switching valve 2, and the muffler 10, and the indoor heat exchanger 6, 7, condensed, strainer 6, electric expansion valve 4
After evaporating in the outdoor heat exchanger 3 through a, the four-way switching valve 2
The refrigerant is circulated through a refrigerating cycle indicated by a dotted arrow which is sucked into the compressor 1 again through the accumulator 8.

At this time, the refrigerant is condensed in the indoor heat exchangers 6 and 7 to perform a heating operation, and the heated air is supplied to the conditioned room by the blower 12.

FIG. 2 is a schematic block diagram of a control circuit provided in an indoor unit of the air conditioner (a unit on which indoor heat exchanges 6 and 7 are mounted).

In this figure, reference numeral 21 denotes a plug to which 100 V AC power is supplied, which is connected to a 100 V commercial AC power supply. This AC power is supplied to the power supply circuit 23 via the switch 22.

24 is a current fuse, 25 is a rectifier circuit, 2
Reference numeral 6 denotes a motor power supply, 27 denotes a control power supply, and 28 denotes a serial power supply. These components constitute a power supply circuit 23.

The current fuse 24 serves to protect the circuit by fusing when the current supplied to the power supply circuit 23 exceeds a predetermined current.
The motor power circuit (switching power circuit) 26 generates a driving power for a fan motor (DC sensorless motor) 29 included in the blower 12 and is described later. The ON duty of the switching waveform is controlled based on a signal from the microcomputer, and the output voltage is varied between DC12V and DC48V.

The control power supply 27 is for generating and stabilizing a drive power supply (5 V DC) for the control unit 30, and the serial power supply 28 is for transmitting a signal (four-way) to be transmitted to an outdoor unit (where the outdoor heat exchanger 3 is mounted). This is a circuit for sharing a common line with the AC power to supply the switching signal of the switching valve 2 and the set value of the operating capacity of the compressor 1 to the outdoor unit.

Reference numeral 31 denotes a terminal plate. The first terminal, the second terminal, and the third terminal are provided on a terminal block made of resin, and a thermal fuse 32 that blows at a predetermined temperature or higher to open a circuit. It is attached so that the temperature of the terminal block, that is, the temperature of the terminal plate 31 can be detected.

A normally open contact 37 of the power relay 36 is interposed between the first terminal of the terminal plate 31 and the plug 21, and the normally open contact 37 is closed by an output of the microcomputer 33 (the driver is not shown). And the AC power output from the terminal plate 31 to the outdoor unit.

The second terminal of the terminal plate 31 is connected to the plug 21 and serves as a common line with the third terminal (signal output terminal).

The third terminal is a terminal for outputting a signal output from the microcomputer 33 via the serial circuit 28a and the serial power supply 28.

The first to third terminals of the terminal board 31 are connected to terminal boards of an electric circuit mounted on the outdoor unit shown in FIG. 3 described later so that the same terminal numbers are connected to each other.

The temperature fuse 32 is inserted into the drive line of the power relay 36. When the temperature of the terminal plate 31 rises, the power supply to the power relay 36 is cut off, the normally open contact 37 is opened, and the AC power to the outdoor unit is released. To shut off the supply.

A wireless remote controller 39 selects various settings and functions, such as operation control of the air conditioner and setting of set values, based on the operation of a switch. Is transmitted to the receiving circuit provided in the.

The microcomputer 33 receives the operation signal and controls the operation of the air conditioner. The display substrate 40
Indicates the operating state of the air conditioner (operating modes such as cooling / heating / drying, set values, room temperature, etc.).

Reference numeral 41 denotes a switch substrate, and a switch 22
There are switches for services, such as a switch for trial operation and trial operation.

An external ROM 42 stores an initial set value of the microcomputer 33.

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 the A / D input terminal of the microcomputer 33.
The microcomputer 33 controls the operation of the air conditioner based on the detected temperatures.

Reference numeral 45 denotes a humidity sensor for detecting indoor humidity. The humidity sensor 45 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. It is.

Reference numeral 46 denotes a step motor for changing the opening of the electric expansion valve 4b, which changes the opening of the electric expansion valve 4b in response to a signal from the microcomputer 33.

Reference numeral 47 denotes a motor drive circuit, which has an inverter circuit in which switching elements are connected in a three-phase bridge form. When a DC sensorless motor is used, the output of the inverter circuit is used to output the rotational position of the rotor of the fan motor 29. Is switched in accordance with. The microcomputer 33 determines and outputs the signal for switching the output of the inverter circuit from the rotational position of the rotor, and the rotational speed of the fan motor 29 is controlled by the DC voltage output from the motor power supply 26.

The motor-operated expansion valves 4a and 4b control the throttle amount of the refrigerant by a built-in drive unit (step motor or the like). The throttle amount is arbitrarily controlled according to a signal output from the microcomputer 33. You. Also, the electric expansion valve 4a,
Reference numeral 4b indicates that when one of them is to be controlled, the other is fully opened. Electric expansion valves 4a, 4b
Is controlled so that the temperature of the heat exchanger acting as an evaporator becomes constant.

FIG. 3 is a block diagram schematically showing a control circuit mounted on the outdoor unit. The control circuit is connected to the terminal plate 31 shown in FIG.

In this figure, 52 is a power supply circuit,
This rectifies and smoothes 100 V AC power from the indoor unit obtained through the first and second terminals of the terminal plate 51 by double voltage rectification, and is provided with a varistor, a noise filter, a reactor, a current fuse, and the like. .

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 form, and a pseudo-sine-wave three-phase AC based on PWM theory (the compressor 1 induces A method in which the rotation position of the rotor is determined and the stator winding is energized in an energization pattern corresponding to the rotation position (when the compressor 1 uses a DC brushless motor).
, And supplied to the compressor 1.

Therefore, in any case, the operating capacity of the compressor 1 can be controlled by changing the rotation speed of the compressor 1.

Reference numeral 55 denotes a microcomputer, which forms the control unit 54. The microcomputer 55 controls the operation capability (the number of revolutions) of the compressor 1 by the above operation based on the control signal received from the microcomputer 33 of the indoor unit via the third terminal of the terminal plate 51 and the serial circuit 56, and further switches four directions. The switching of the valve 2 and the control of the blower 11 (fan motor for driving the propeller fan) are controlled 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 operation capability of the compressor 1 is controlled so that the temperature of the temperature sensor 59 for detecting the temperature of the compressor 1 does not exceed a predetermined value.

An outside air temperature sensor 60 detects the outside air temperature. The outside air temperature detected by this sensor is transmitted to the microcomputer 33 of the indoor unit via the serial circuit 56.

Reference numeral 61 denotes a temperature sensor for detecting the temperature of the outdoor heat exchanger, and reference numeral 62 denotes a switching power supply for generating DC power for control.

In the air conditioner configured as described above, the operation of each device is controlled based on the program stored in the microcomputer 33 of the indoor unit.

FIG. 4 is a flowchart showing the driving operation according to the present invention, which is a subroutine of a program stored in the microcomputer 33.

In this flowchart, it is first determined in step S1 whether or not the room temperature tin is equal to or lower than T3. If this condition is satisfied, the flow advances to step S2 to determine whether or not the outside air (the temperature detected by the outside air temperature sensor 60) is equal to or lower than T4. Is determined.

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, step S2 is performed.
3 and further determines whether the temperature t of the heat exchanger 6 (the temperature detected by the temperature sensor 44) is greater than T5,
When these conditions are satisfied, the process proceeds to step S5.

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 of the machine 1 is performed, and corresponds to the operation of the intermittent operation control unit.

The intermittent operation is set to, for example, an operation in which the operation for 120 seconds and the stop for 150 seconds are alternately repeated. However, the present invention is not limited to this, and the operation capacity of the air conditioner and the air conditioning load of the conditioned room are not limited to this. These times can be arbitrarily set based on the size of the data.

At this time, the amount of air blown to the conditioned room may be maintained at the set air speed or at a constant air speed, and the air flow may be periodically increased or decreased between the constant air speed and the stop or almost stop. The operation for obtaining the dehumidifying effect of the conditioned room may be performed.

When the condition of step S3 is not satisfied, the operation proceeds to step S4 to stop the operation of the compressor 1.

After the steps S4 and S5, the program returns to the main program of the microcomputer 33.

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, in which the evaporator 6 (the heat exchanger 6 acting as an evaporator, hereinafter referred to as the evaporator 6) is operated. It is determined whether or not the temperature t is equal to or lower than T0.
At 7, the operation of the compressor 1 is stopped. That is, the microcomputer 3
A signal indicating that the operating capacity of the compressor 1 is "0" is transmitted to the outdoor unit regardless of the required capacity calculated in step 3.

In step S8, the temperature t of the evaporator 6 is set to T2.
It is determined whether or not the above is satisfied. If this condition is satisfied, the process proceeds to step S9, where the operation of the compressor 1 is set to the normal operation (in a state where the regulation is released), and then the process returns to the main program.

If step S8 is not satisfied, that is, if the temperature t of the evaporator 6 is lower than T2, step S1
At 0, it is determined whether or not the operating capacity of the compressor 1 is increasing. When the operating capacity is increasing, the increase of the operating capacity is prohibited at step S11, and the operation of the compressor 1 is operated regardless of the signal from the microcomputer 33. The correction is performed so that the signal indicating the capability does not increase.

When the operating capacity of the compressor 1 is not increasing,
That is, when the vehicle is running at a reduced capacity or with a constant capacity, the process proceeds to step S12.

In step S12, it is determined whether or not the temperature t of the evaporator 6 is equal to or lower than T1. If this condition is satisfied, the process proceeds to step S13, where a correction is made to reduce the operating capacity of the compressor 1, and this condition is satisfied. If not, step S14
For normal operation.

That is, when the temperature of the evaporator 6 is greater than T0 and equal to or less than T1, a correction is made to reduce the operating capacity of the compressor 1.

With this configuration, the operating capacity of the compressor 1 is corrected in accordance with the temperature decrease of the evaporator 6 to freeze the evaporator 6 (the heat exchanger 6 acting as an evaporator). Can be prevented.

At the same time, when the outside air temperature decreases, the compressor 1 is operated intermittently within a range in which the evaporator 6 does not freeze, regardless of these freezing prevention controls. It can be expanded.

The values shown in the flowchart of FIG. 4 are, for example, T0 = 2 degrees, T1 = 6 degrees, and T2 =
8 °, T3 = 13 °, T4 = 10 °, T5 = −15 °, but not limited thereto, the minimum operating capacity of the compressor, the capacity of the heat exchanger, the size of the conditioned room Arbitrarily based on the above.

[0069]

According to the air conditioner thus configured,
Detects the outside air temperature, room temperature, etc., and when both the room temperature and the outside air temperature are low, the compressor is operated intermittently, so that the range where the evaporator does not freeze when the outside air temperature is low can be expanded, and the operation of the dehumidifying operation can be performed. The range can be expanded.

Further, when the outside air temperature and room temperature are high, the operating capacity of the compressor is corrected so that the evaporator does not freeze in accordance with the temperature of the evaporator, so that the dehumidification can be performed both when the outside air temperature is high and when the outside air temperature is low. The driving range of driving can be expanded.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram illustrating a refrigeration cycle of an air conditioner according to 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 of preventing freezing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 6 Heat exchanger 7 Heat exchanger 33 Microcomputer 45 Temperature sensor 60 Outside air temperature sensor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takahiro Suzuki 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. (Reference) 3L060 AA07 CC02 CC03 CC04 CC06 DD02 EE04 EE05

Claims (5)

[Claims] 1. A refrigeration cycle in which a compressor, a condenser, a decompression device, and an evaporator of a variable operation capacity are connected in a ring using a refrigerant pipe, and at least air cooled by the evaporator is subjected to the harmony. An air conditioner control device having a stop control unit for stopping the operation of the compressor when the temperature of the evaporator is lower than a first set value. An operation control unit that performs an operation of obtaining a dehumidifying effect of the conditioned room by increasing or decreasing the blowing amount of a blowing device that supplies air to the conditioned room between a normal blowing amount and stopping or almost stopping, and An intermittent operation control unit that masks the operation of the stop control unit when the outside air temperature is lower than a second set value and turns the compressor on and off at a predetermined cycle. Harmonizer control device. 2. The intermittent operation control section 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). 2. The control device for an air conditioner according to 1. 3. The method according to claim 1, further comprising the step of reducing the operation capacity of the compressor when the temperature of the evaporator is higher than the first set value and lower than a fourth set value (> first set value). The control device for an air conditioner according to claim 2, further comprising a control unit. 4. The operation stopping unit further comprises: a temperature of the evaporator is lower than a fourth set value and lower than a fifth set value (> fourth set value), and the operating capacity of the compressor is increased. The control device for an air conditioner according to claim 3, further comprising an increase prohibition unit that prohibits an increase in the operating capacity of the compressor when the air conditioner is running. 5. The control device 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.