KR20000057057A - Air-conditioner - Google Patents

Abstract

PURPOSE: An air conditioner is provided to prevent dryness of a heat exchanger of an indoor unit by controlling an opening degree of an electric expansion valve mounted on a freezing cycle appropriately. CONSTITUTION: In an air conditioner, the opening degree of the electric expansion valve is controlled to increase a temperature of a refrigerant discharged from a compressor to a target discharge temperature, and amending the target discharge temperature on the basis of a temperature value of the heat exchanger, the temperature value of the refrigerant discharged from the compressor and the temperature value of the refrigerant inhaled by the compressor, wherein the amendment is performed to decrease the target discharge temperature when a value operated from the heat exchanger temperature and the suction refrigerant temperature exceeds a predetermined temperature.

Description

Air Conditioner {AIR-CONDITIONER}

The present invention relates to a separate type air conditioner installed by dividing a unit into an outdoor unit and an outdoor unit such as a compressor, a condenser, a pressure reducing device (electric expansion valve), and an evaporator constituting a refrigeration cycle.

In an air conditioner (hereafter abbreviated as "air conditioner") that harmonizes indoor air, the refrigerant circulates in the refrigeration cycle formed between the indoor unit and the outdoor unit, thereby controlling the temperature of the air discharged from the indoor unit. have.

Such an air conditioner controls the degree of opening of the electric expansion valve installed in the refrigeration cycle, thereby cooling the heat exchanger installed in the indoor unit (acting as an evaporator during cooling operation and as a condenser during heating operation). Volume and heating rate are controlled.

In the air conditioner, the target discharge temperature, which is the target temperature of the refrigerant discharged from the compressor, is set, and the electric expansion valve is controlled so that the temperature (discharge temperature) of the refrigerant discharged from the compressor becomes the target discharge temperature.

However, in the case where the electric expansion valve is controlled only by the target discharge temperature, when the refrigerant pressure decreases due to the temperature decrease of the evaporator while operating in the cooling mode, the reaction temperature increases near the heat exchanger outlet of the indoor unit ( Heat exchangers begin to dry).

When drying occurs in the heat exchanger of the indoor unit, cooling (and dehumidification) of the air at this part is not performed, and dew condensation occurs in the crossflow fan for blowing, causing frosting to which water droplets adhere.

If the air is blown while the frost has occurred, there is a problem that water is scattered in the indoor unit or discharged into the room from the outlet.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and by controlling the electric expansion valve installed in an air conditioner appropriately, for example, a control method of an electric expansion valve for preventing drying from occurring in a heat exchanger of an indoor unit in a cooling mode. The purpose is to propose.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows the refrigerating cycle of the air conditioner applied to this embodiment.

2 is a schematic configuration diagram showing an indoor unit of an air conditioner.

3 is a block diagram showing a schematic configuration of an indoor unit electric circuit of an air conditioner.

4 is a block diagram showing a schematic configuration of an outdoor unit electric circuit of an air conditioner.

5 is a flowchart showing an outline of a correction amount setting for correcting a target discharge temperature.

6 is a flowchart showing an outline of setting a target discharge temperature.

7 is a flow chart showing an example of the rotational speed limit of the compressor based on the dryness of the indoor unit heat exchanger.

(Explanation of symbols for the main parts of the drawing)

10. Air conditioner 12. Indoor unit

14. Outdoor unit 18. Heat exchanger (use side heat exchanger)

26. Compressor 30. Heat exchanger (heat source side heat exchanger)

36. Electric expansion valve 44. Cross-flow fan

74. Microcomputer (abbreviated as microcomputer)

86. Heat exchanger temperature sensor (coil temperature detection means)

96.Control panel, 98.Microcomputer

108. Compressor Motor

112. Outside temperature sensor (outside temperature detection means)

150. Refrigerant temperature sensor (discharge temperature detection means)

152. Refrigerant temperature sensor (suction temperature detection means)

The air conditioner of the present invention controls the flow rate of the refrigerant circulating in the refrigeration cycle composed of at least a compressor, a use side heat exchanger, an electric expansion valve, and a heat source side heat exchanger by changing the opening degree of the electric expansion valve. In the air conditioner, the opening degree of the electric expansion valve is controlled so that the temperature of the refrigerant discharged from the compressor reaches the target discharge temperature, the temperature value of the heat exchanger on the use side, the temperature value of the refrigerant discharged from the compressor, and The target discharge temperature is corrected based on some values of the temperature values of the refrigerant drawn into the compressor.

According to the present invention, the target discharge temperature is corrected on the basis of the discharge temperature which is the temperature of the refrigerant discharged from the compressor, the suction temperature which is the temperature of the refrigerant sucked into the compressor, and the coil temperature which is the temperature of the use-side heat exchanger.

The electric expansion valve is operated in the opening direction by lowering the target discharge temperature, whereby the coil temperature, which is the temperature of the heat exchanger, rises, and the suction temperature falls.

Here, the target discharge temperature is corrected based on the discharge temperature, the suction temperature, and the coil temperature, and the opening degree of the electric expansion valve is controlled based on the target discharge temperature, thereby making it possible to suppress drying of the use-side heat exchanger. It is possible to prevent dew adhering to a cross flow fan or the like due to drying occurring in the use-side heat exchanger.

In the present invention as described above, the above correction corrects the target discharge temperature low when the value calculated based on the coil temperature and the suction temperature exceeds a predetermined value.

As the heat exchanger has a high suction temperature, drying is likely to occur.

From this, it is judged by comparing the coil temperature and the discharge temperature to determine whether drying is likely to occur in the heat exchanger, and when the drying is to occur, the target discharge temperature is lowered.

Thereby, drying of a heat exchanger can be suppressed.

Further, in the present invention, when the suction temperature is higher than the coil temperature, the correction corrects the target discharge temperature so that the electric expansion valve is opened.

When the discharge temperature exceeds the target discharge temperature, drying is likely to occur in the use-side heat exchanger.

Here, when the discharge temperature is high, the target discharge temperature is corrected to decrease.

As a result, the electric expansion valve is operated in the open direction, the discharge temperature is lowered, the coil temperature is slightly increased, and the suction temperature is lowered, so that drying of the heat exchanger is suppressed.

In addition, the present invention includes an outside air temperature detecting means for detecting the outside air temperature, wherein the correcting means corrects the target discharge temperature according to the outside air temperature.

According to the present invention, when the outside air temperature is lowered, the refrigerant pressure is also lowered. Therefore, when the outside air temperature is low, the target discharge temperature is corrected to be lower than when the outside air temperature is high.

Thereby, drying of the utilization side heat exchanger which becomes easy to generate | occur | produce when external temperature is comparatively low can be suppressed.

In the present invention, it is preferable to include limiting means for limiting the refrigerant discharge capacity of the compressor based on the coil temperature and the suction temperature.

By increasing the number of revolutions of the compressor, the cooling capacity is increased.

However, if the cooling capacity is raised in a state where drying is likely to occur in the heat exchanger, the refrigerant liquefies and the heat exchanger is more likely to dry.

For this reason, in a state in which the heat exchanger is easy to dry, it is preferable to lower the cooling capacity. However, at least the cooling capacity can be suppressed from rising, so that frost adhesion due to drying of the heat exchanger can be suppressed.

(Example)

EMBODIMENT OF THE INVENTION Embodiment of this invention is described below.

1, the schematic structure of the air conditioner (henceforth "air-conditioner 10") applied to this embodiment is shown.

The air conditioner 10 is constituted by an indoor unit 12 and an outdoor unit 14.

In addition, a plurality of indoor units 12 may be connected to the outdoor unit 14.

The indoor unit 12 and the outdoor unit 14 of the air conditioner 10 are connected by a thick pipe refrigerant pipe 16A for circulating a gas refrigerant and a refrigerant pipe 16B for a thin tube circulating a liquid refrigerant. .

The indoor unit 12 is provided with a heat exchanger 18 as a use-side heat exchanger, and one end of each of the refrigerant pipes 16A and 16B is connected to the heat exchanger 18.

The other end of the refrigerant pipe 16A is connected to the valve 20A of the outdoor unit 14.

The valve 20A is connected to the four-way valve 24 via the muffler 22A, and the accumulator 28 and the muffler 22B are connected to the four-way valve 24. Each of the accumulator 28 and the muffler 22B is connected to the compressor 26.

In addition, the outdoor unit 14 is provided with a heat exchanger 30 as a heat source side heat exchanger.

One side of the heat exchanger 30 is connected to the four-way valve 24, and the other side of the heat exchanger 30 is connected to the valve 20B through the capillary tube 32, the filter 34, and the modulator 38.

In addition, an electric expansion valve 36 is provided between the filter 34 and the modulator 38.

In addition, the other end of the refrigerant pipe 16B is connected to the valve 20B, whereby a closed circulation path of the refrigerant forming a refrigeration cycle is formed between the indoor unit 12 and the outdoor unit 14. .

In the air conditioner 10, when the compressor 26 is driven, the refrigerant is circulated during the refrigeration cycle.

As shown by the arrow in FIG. 1, the flow of the refrigerant during heating operation (heating mode) and cooling or dehumidification operation (cooling mode), the air conditioner 10 is changed to the operation mode by switching the four-way valve 24. Is switched to the cooling mode (including the dehumidification mode) and the heating mode, and the evaporation temperature of the refrigerant in the refrigerating cycle is adjusted by controlling the valve opening degree of the electric expansion valve 36.

As shown in FIG. 2, the indoor unit 12 is provided with the casing 42 in which the inlet 48 and the outlet 50 were formed, and is provided in the base board 40 provided in the back surface of this casing 42. As shown in FIG. It is fixed to a predetermined height on the wall surface of the room where air conditioning is to be performed.

In the casing 42, a cross flow fan 44 is disposed together with the heat exchanger 18, and indoor air passes through the filter 48 from the inlet 46 by the operation of the cross flow fan 44. Is sucked into the casing 42.

The air sucked into the casing 42 passes through the heat exchanger 18, and then is discharged from the discharge port 50 into the room.

By passing through the heat exchanger 18, this air heat-exchanges with the refrigerant | coolant which circulates in the heat exchanger 18, and becomes air (air-conditioning wind) with the temperature which air-conditions the room.

The upper and lower flaps 54 and the left and right flaps 52 are provided at the discharge port 50 of the indoor unit 12, and are discharged from the discharge port 50 by the left and right flaps 52 and the upper and lower flaps 54. The direction of the air conditioning wind is changed.

In the air conditioner 10, the left and right flaps 52 change direction manually, and mainly control the direction of the upper and lower flaps 54, and control the wind direction of the air conditioning wind blown from the discharge port 50.

In addition, the indoor unit 12 may control the direction of the left and right flaps 52 together with the upper and lower flaps 54.

As shown in FIG. 3, the indoor unit 12 is provided with a power supply board 56, a control board 58, and a power relay board 60.

The power supply board 56 is provided with a motor power supply 62, a control circuit power supply 64, a series power supply 66, and a drive circuit 68. The power for driving the air conditioner 10 (for example, single phase) is provided. AC power of 100V) is supplied.

In addition, the controller board 58 is provided with a series circuit 70, a drive circuit 72, and a microcomputer 74.

A fan motor 76 (for example, a DC brushless motor) for driving the cross flow fan 44 is connected to the drive circuit 68 of the power supply board 56 and installed on the control board 58. The driving power is supplied from the motor power source 62 in accordance with the control signal from the microcomputer 74.

At this time, the microcomputer 74 controls by changing the output voltage from the drive circuit 68 to 256 steps in the range of 12V to 36V, and adjusts the air volume of the air conditioning wind discharged from the outlet port 50 of the indoor unit 12. do.

The upper and lower flap motors 78 for operating the power relay substrate 60 and the upper and lower flaps 54 are connected to the drive circuit 72 of the control board 58.

The power relay substrate 60 is provided with a power relay 80 and a temperature fuse. The power relay 80 is operated by a signal from the microcomputer 74 to supply power to the outdoor unit 14. In order to open and close the contact 80A.

The air conditioner 10 can supply electric power to the outdoor unit 14 by closing the contact 80A.

In addition, when electric power is supplied to the outdoor unit 14 separately from the indoor unit 12, the operation of the outdoor unit 14 is controlled by serial communication described later.

The upper and lower flap motor 78 is operated in accordance with the control signal of the microcomputer 74 to operate the upper and lower flaps 54.

As a result, the air-conditioning wind is discharged from the discharge port 50 of the indoor unit 12 toward the desired area.

In addition, the microcomputer 74 is connected to a room temperature sensor 84 for detecting the room temperature and a heat exchange temperature sensor 86 for detecting the coil temperature of the heat exchanger 18, and is provided on the controller board 58. The service LED and the operation changeover switch 88 are connected.

The operation switching switch 88 is switched to "normal operation" and "test operation" performed during maintenance, and "stop" to stop the operation of the air conditioner 10.

The air conditioner 10 is used by setting the operation switching switch 88 to "normal operation".

As a result, the contact 88A is closed, and driving electric power is supplied to the indoor unit 12.

In addition, by setting the operation switching switch 88 to the "stop" position, the contact 88A is opened to stop the power supply to the indoor unit 12.

In addition, the service LED lights up during maintenance, so that maintenance personnel are notified of the result of the self-diagnosis.

The indoor unit 12 is provided with a terminal block 90 to which wiring to the outdoor unit 14 is connected.

Power supply wiring supplied from the indoor unit 12 to the outdoor unit 14 is connectable to the terminals 90A, 90B, 90C of the terminal block 90.

Further, wirings for performing serial communication between the indoor unit 12 and the outdoor unit 14 are connected to the terminals 90B and 90C.

The series circuit 70 connected to the microcomputer 74 and the series power supply 66 of the power supply circuit 56 is connected to the outdoor unit 14 through the terminals 90B and 90C. Serial communication is possible between the 12 and the outdoor unit 14.

On the other hand, the display substrate 82 is connected to the microcomputer 74.

The display substrate 82 is provided with a display unit provided with a display LED for driving display and the like, and a light receiving unit including a light receiving element for receiving an operation signal transmitted from a remote control switch 120 (not shown).

As a result, in the air conditioner 10, the remote control switch is operated so as to perform direct current communication between the indoor unit 12 and the outdoor unit 14, and perform the air conditioning operation so that the indoor is in the air conditioning state set by the remote control switch. .

4, the schematic structure of the outdoor unit 14 is shown.

The outdoor unit 14 is provided with a terminal block 92, and wiring for serial communication is connected to the terminals 92B and 92C among the terminals 92A, 92B and 92C of the terminal block 92.

In addition, the driving power is supplied to the outdoor unit 14 through the terminals 90A and 90B.

The outdoor unit 14 is provided with a rectifying board 94 and a control board 96.

In addition to the microcomputer 98, the control board 96 is provided with noise filters 100A, 100B, 100C, a series circuit 102, a switching power supply 104, and the like.

The rectifying substrate 94 rectifies the power supplied through the noise filter 100A, smoothes it through the noise filters 100B and 100C, and outputs it to the switching power supply 104.

An inverter circuit 106 is connected to the switching power supply 104 together with the microcomputer 98, and the power of the frequency corresponding to the control signal output from the microcomputer 98 is transferred from the inverter circuit 106 to the compressor motor 108. It outputs and rotates the compressor 26. As shown in FIG.

In addition, the microcomputer 98 limits the power output from the inverter circuit 106 to a predetermined range (upper limit) of not less than (off) or 14 Hz (in terms of rotational frequency), so that the operating current does not exceed a predetermined value. The rotation speed of the compressor motor 108, that is, the compressor 26, is changed, thereby controlling the capacity of the compressor 26 (cooling capacity of the air conditioner 10).

As a method of changing the rotation speed of the compressor 26, when an induction motor is used for the drive source of the compressor 26, the controlled pseudo sine wave of the frequency is output from the inverter circuit 106 based on the PWM theory. do.

The rotation speed of the compressor 26 can be changed by changing the frequency of the pseudo sine wave.

In addition, when using a direct current motor (DC brushless motor) as a drive source of the compressor 26, it energizes with a predetermined stator winding through the inverter circuit 106 in a predetermined conduction pattern corresponding to the rotational position of the rotor of this motor. To maintain rotation.

At this time, energization to the stator windings is chopped at a predetermined cycle to reduce the load on the switching elements constituting the inverter circuit 106.

The rotation speed is performed by changing the ON duty of the chopping waveform.

The control board 96 is connected with a fan motor 110 and a fan motor condenser 110A for driving a fan (not shown) for cooling the four-way valve 24 and the heat exchanger 30.

The microcomputer 98 switches the four-way valve 24 in accordance with the operation mode and turns on the fan motor 110 based on the control signal from the indoor unit 12 and the detection results of various sensors described later. To control the ON / OFF and the rotation speed of the compressor motor 108.

In addition, a micro expansion valve 36 is connected to the microcomputer 98.

The stepping motor (not shown) is provided in this electric expansion valve 36, and the opening degree of the electric expansion valve 36 is opened and closed by the drive of this stepping motor.

The microcomputer 98 arbitrarily controls the opening degree of the electric expansion valve 36 by controlling the rotation amount of this stepping motor in the range of 0-512 steps, for example.

On the other hand, the outdoor unit 14 detects the temperature of the ambient temperature sensor 112 for detecting the outside temperature, the coil temperature sensor 114 for detecting the temperature of the refrigerant coil of the heat exchanger 30, and the compressor 26. Along with the compressor temperature sensor 116, refrigerant temperature sensors 150 and 152 for detecting the refrigerant temperature in the refrigeration cycle are provided, and these are connected to the microcomputer 98.

The microcomputer 98 converts the outputs of these temperature sensors to A / D (analog / digital), and then introduces them to the inside for use in the control.

As shown in FIG. 1, the refrigerant temperature sensor 150 is provided on the discharge side of the refrigerant from the compressor 26, and detects the temperature of the refrigerant discharged from the compressor 26 as the discharge temperature.

In addition, the refrigerant temperature sensor 152 is provided between the valve 20A and the four-way valve 24, for example, and is sucked into the compressor 26 when the air conditioner 10 is operated in the cooling mode. The refrigerant temperature is detected as the suction temperature.

In the air conditioner 10, the rotation speed of the compressor 26 is set according to the room temperature and the set temperature, and the compressor 26 is driven.

At this time, the microcomputer 98 of the outdoor unit 14 sets the target discharge temperature, and controls the electric expansion valve 36 so that the discharge temperature detected by the refrigerant temperature sensor 150 becomes the target discharge temperature.

By the way, in the air conditioner 10, when controlling the opening degree of the electric expansion valve 36 during operation in the cooling mode, the coil temperature, the refrigerant temperature sensor (detected by the heat exchange temperature sensor 86 of the indoor unit 12) ( Correction is made based on the discharge temperature detected by 150, the suction temperature detected by the refrigerant temperature sensor 152, and the ambient air temperature detected by the outside air temperature sensor 112.

Accordingly, in the air conditioner 10, the frost of the cross flow fan 44 due to the drying occurring in the heat exchanger 18 of the indoor unit 12, ie, the drying of the heat exchanger 18 is prevented. have.

Frost attachment of the cross flow fan 44 occurs when the humid air passing through the dry place of the heat exchanger 18 hits the cooled cross flow fan.

In the air conditioner 10, the opening degree of the electric expansion valve 36 is corrected by correcting the target discharge temperature.

For this reason, in the air conditioner 10, from the last target discharge temperature Tgt-dism, discharge temperature T-dis, suction temperature T-sh, and coil temperature T-coil, the indoor unit 12 is carried out. Together with the dryness degree D-sh of the heat exchanger 18 of the heat exchanger 18, the operation degree D-dis of the electric expansion valve 36 at the time of correcting the opening degree of the electric expansion valve 36 is obtained.

This drying degree (D-sh) and operation degree (deviation) (D-dis) are set as follows as an example.

D-dis = T-dis-Tgt-dism

D-sh = T-sh-(T-coil-α)

In the microcomputer 98, the operation amount USH of the electric expansion valve 36 is set from this drying degree D-sh and operation degree D-dis, and the target discharge temperature Tgt- is set from this operation amount USH. Set the correction amount (CSH) to correct dis).

The correction amount CSH is calculated based on the following equation from the operation amount USH and the previous correction amount CSHm.

CSH = USH + CSHm

In addition, the initial value of the correction amount CSHm is "0" (CSHm = 0).

In the air conditioner 10, the operation amount USH is based on the operation degree D-dis and the drying degree D-sh. In this embodiment, it sets as an example as shown in Table 1, and operates The set value of the manipulated value USH in accordance with the degrees D-dis and D-sh is stored in a memory (not shown) provided in the microcomputer 98.

Table 1

D-dis ＞ 2 2 D-dis ＞ 1 One D-dis -One －1 ＞ D-dis D-sh 2 0 -A -B -C 2 ＞ D-sh One 0 0 0 -D 1 ＞ D-sh -One 0 0 0 0 －1 ＞ D-sh E F G 0

In addition, each value of A to G sets an optimum value according to the capacity of the refrigeration cycle, and a range of 1 to 5 is more preferable.

On the other hand, the target discharge temperature Tgt-dis is set by correcting the previous target discharge temperature Tgt-dis by the outside air temperature To and the correction amount CSH, as shown by the following equation.

Tgt-dis = Tgt-dis + C (To) + CSH

C (To) is a function based on the outside temperature and is adjusted for each unit of the air conditioner.

That is, in the air conditioner 10, the target discharge temperature Tgt-dis is shifted based on the outside temperature To, and is increased or decreased using the correction amount CSH.

When the discharge temperature T-dis is lower than the target discharge temperature Tgt-dism, the operation degree D-dis becomes negative.

According to Table 1, USH is corrected in the downward direction, and the electric expansion valve 36 is operated in the closing direction.

When the discharge temperature T-dis is higher than the target discharge temperature Tgt-dism, and the operation degree D-dis is positive, the operation amount USH is corrected in the upward direction. 36 is operated in the opening direction.

Also, the actual USH is corrected again according to the value of D-sh. The dryness degree D-sh, which is the difference between the suction temperature T-sh and the coil temperature T-coil, becomes negative when the heat exchanger 18 is wet, and the heat exchanger 18 When drying is occurring, the constant α is set to be positive.

Thereby, the operation amount USH is set to correct in the direction of lowering the target discharge temperature Tgt-dis when the dryness D-sh is positive, and the target discharge when the dryness D-sh becomes negative. The temperature Tgt-dis is set to be corrected in the direction of raising.

In addition, in this embodiment, 1 D-dis －1，1.0 ＞ D-sh With -1.0 as the dead zone, the correction by the correction amount CSH is not performed in the heating mode (correction amount CSH = 0).

C (To) is a numerical value previously determined according to the ambient temperature To. In this embodiment, as an example thereof, C (To) is set as shown in Table 2, and this value is set together with the operation amount USH and the microcomputer 98 Is stored in a memory (not shown).

Note that this correction C (To) may be omitted.

TABLE 2

Outdoor temperature Cooling mode Nanbang Mode 44 To H 0 38 To <44 I 32 To <38 0 26 To <32 -J 20 To <26 -K 5 To <20 -L -One To <5 -M To <-1 -N

Moreover, since each value of H-N sets an optimum value according to the capability of a refrigeration cycle, the range of 1-30 is more preferable.

When the outside air temperature To is changed in a decreasing direction, C (To) is set to the outside air temperature To by adding 1 ° C to the outside air temperature To detected by the outside air temperature sensor 112 as the outside air temperature To. ) To select.

In the air conditioner 10, the control step of the electric expansion valve 36 (stepping motor of the electric expansion valve 36) is set based on the target discharge temperature Tgt-dis set in this way, and the set control step The electric expansion valve 36 is operated.

Further, in the air conditioner 10, the target discharge temperature Tgt-dis is calculated for each predetermined time ts1 (e.g. 120 sec), and the discharge temperature T-dis is converted to the target discharge temperature Tgt- by the PI operation. Step control of the electric expansion valve 36 is performed every predetermined time ts2 (for example, 10 sec) so as to be dis).

The correction of the target discharge temperature Tgt-dis for controlling the electric expansion valve 36 mainly executed by the microcomputer 98 of the outdoor unit 14 will be described below with reference to the flowcharts of FIGS. 5 to 7. ．

In the air conditioner 10, when the air conditioning operation starts, the target discharge temperature Tgt-dis is calculated.

The target discharge temperature Tgt-dis can be calculated and set based on, for example, the rotational speed of the compressor 26 (past average frequency to the current rotational speed).

In the air conditioner 10, the discharge temperature T-dis detected by the target temperature Tgt-dis by the refrigerant temperature sensor 150, and the suction temperature T-sh detected by the refrigerant temperature sensor 152. , The outside air temperature To detected by the outside temperature sensor 112 and the coil temperature T-coil of the heat exchanger 18 of the indoor unit 12 detected by the heat exchange temperature sensor 86 of the indoor unit 12. ), A target discharge temperature (Tgt-dis) for controlling the opening degree of the electric expansion valve (36) is obtained.

In FIG. 5, when the air conditioning operation of the air conditioner 10 starts, the setting routine routine of the correction amount CSH performed by predetermined time ts1 (for example, 120 sec interval) is shown.

In the first step 200 of this flowchart, after the correction amount CSH is cleared, whether or not the compressor 26 is stopped in the step 202 (the rotation speed f of the compressor 26 is " 0 "or not."

That is, the setting of the correction amount CSH is started each time the compressor 26 starts driving.

Here, if the compressor 26 is driven, it is affirmatively determined by the staff 202 and the process proceeds to the staff 204.

In this step 204, the operation degree D-dis is calculated.

The operation degree D-dis is a temperature difference between the discharge temperature T-dis and the previous target discharge temperature Tgt-dism. The step 204 detects by the refrigerant temperature sensor 150. Reading the discharge temperature (T-dis) calculates the difference between this discharge temperature (T-dis) and the previous target discharge temperature (Tgt-dism).

In the next step 206, it is checked whether or not the absolute value of the calculated operation degree D-dis is within a predetermined value.

That is, it is checked whether or not the temperature difference between the discharge temperature T-dis and the previous target discharge temperature Tgt-dism is within a predetermined range (which is set to 5 ° C as one example in this embodiment).

As a result, when the temperature difference between the discharge temperature T-dis and the target discharge temperature Tgt-dism set last time is within a predetermined value range (affirmative determination at step 206), calculation of the correction value CSH is performed. In order to do so, the process proceeds to step 208.

In this step 208, the suction temperature T-sh detected by the refrigerant temperature sensor 182, the coil temperature detected by the heat exchange temperature sensor 86, and sent out from the indoor unit 12 by serial communication ( T-coil) is read and the dryness (D-sh) of the heat exchanger 18 is calculated.

Next, the operation amount (USH) is set from the calculated operation degree (D-dis) and the drying degree (D-sh) and Table 1, and the current correction amount (CSH) is calculated from the operation amount (USH) and the previous correction amount (CSHm). ) Is calculated.

When the correction amount CSH is obtained in this manner, the next step 210 confirms whether or not the calculated correction amount CSH is smaller than the predetermined value, and in the step 212, the calculated correction amount CSH is the predetermined value. Check if the limit is exceeded.

That is, the steps 210 and 212 confirm whether or not the calculated correction amount CSH is within a predetermined range (in this embodiment, -15 &lt; CSH &lt; 0).

Here, when the calculated correction amount CSH is within a predetermined range (positive determination at steps 210 and 212), the correction amount CSH calculated by shifting to the step 214 is calculated as the target discharge temperature Tgt-dis. It is set as the correction amount used for the calculation of.

In contrast, the calculated correction amount CSH is equal to or less than the predetermined value (CSH). -15) (negative determination by the step 210), the process proceeds to the step 216, and sets the correction amount CSH to the lower limit value (CSH = -15).

The calculated correction amount CSH is equal to or greater than the predetermined value (0). CSH) (negative determination by the step 212), the process proceeds to the step 218, and the correction amount CSH is set to an upper limit value (CSH = 0).

That is, the correction amount (CSH) is a predetermined range (-15 CSH Limited to 0).

When the correction amount CSH used for the calculation of the target discharge temperature Tgt-dis is set in this manner, the step 220 uses the correction amount CSH as the previous correction amount used for the calculation of the next correction amount CSH. CSHm) (CSH = CSHm).

6, the outline of setting of the target discharge temperature Tgt-dis used for the step control of the electric expansion valve 36 in the air conditioner 10 is shown. In the first step 230, the target discharge temperature ( Tgt-dis).

The next step 232 reads the outside air temperature To detected by the outside air temperature sensor 112, and the step 234 reads the correction amount C based on the operation mode and the outside air temperature To from Table 2 above. Set (To).

The staff 236 then checks whether or not correction is performed using the correction amount CSH.

Here, when performing correction using the correction amount CSH, the process proceeds to the step 238, and after reading the correction amount CSH set by the flowchart shown in FIG. 5, the outside air temperature To is stored in the step 238. ) And calculation of target discharge temperature Tgt-dis using the correction amount CSH, that is, correction of target discharge temperature Tgt-dis.

In the air conditioner 10, under the condition that the correction is not performed using the correction amount CSH of the target discharge temperature Tgt-dis, for example, in the heating mode or when the rotation speed of the compressor 26 is greatly changed. It is determined indefinitely by the staff 236, and the process proceeds to the staff 240.

As a result, the target 240 calculates the target discharge temperature Tgt-dis so as to perform correction only based on the outside temperature To.

In this way, when the target discharge temperature Tgt-dis is calculated, the next step 242 is whether the target discharge temperature Tgt-dis is lower than or equal to a predetermined temperature (for example, 86 ° C) set as the upper limit temperature. When the target discharge temperature Tgt-dis has not exceeded the upper limit temperature (affirmative determination at the step 242), the process proceeds to the step 246, and the target discharge temperature Tgt-dis is changed. Step control of the electric expansion valve (36).

When the target discharge temperature Tgt-dis exceeds this upper limit temperature (the negative determination by the step 242), the target discharge temperature Tgt-dis is set to the upper limit temperature (for example, Tgt-dis). dis = 68 ° C.), and step control of the electric expansion valve 36 is performed based on this target discharge temperature Tgt-dis.

When the air conditioner 10 is operating in the cooling mode, from the coil temperature T-coil, which is the temperature of the heat exchanger 18 of the suction temperature T-sh and the indoor unit 16, to the heat exchanger 18; In a state in which drying is unlikely to occur, that is, in a state in which the heat exchanger 18 is wet to the outlet, the dryness degree D-sh is negative.

In contrast, when the coil temperature T-coil rises, drying tends to occur near the outlet of the heat exchanger 18.

When drying occurs in the heat exchanger 18, dew adhesion occurs in the cross flow fan 44.

At this time, the coil temperature (T-coil) increases relative to the suction temperature (T-sh), and the dryness (D-sh) also increases.

On the other hand, when the discharge temperature T-dis is higher than the target discharge temperature Tgt-dis, the operation degree D-dis becomes a positive value, and the discharge temperature T-dis is the target discharge temperature (T-dis). When it is lower than Tgt-dis, the operation degree D-dis becomes a negative value.

Moreover, when the rotation speed of the compressor 26 is constant, the discharge temperature T-dis can be lowered by opening the electric expansion valve 36 to increase the flow rate of the refrigerant, thereby reducing the opening degree of the electric expansion valve 36. It can be made narrow by raising the flow volume of refrigerant | coolant.

The target discharge temperature Tgt-dis is increased by increasing the correction amount CSH and decreases by decreasing the correction amount CSH.

The operation amount USH of the correction amount CSH is set in the direction of decreasing the correction amount CSH as the dryness D-sh increases.

As a result, the heat exchanger 18 is in a state in which moisture is likely to be wet, and when the dryness D-sh becomes high, the target discharge temperature Tgt-dis is raised to the direction in which the electric expansion valve 36 opens. Manipulated.

Therefore, drying of the heat exchanger 18 is suppressed.

On the other hand, the refrigerant pressure is quite affected by the outside temperature (To).

In other words, when the outside temperature increases, the refrigerant pressure increases, and when the outside temperature decreases, the refrigerant pressure also decreases.

For this reason, even if the opening degree of the electric expansion valve 36 is the same, when the outdoor temperature To is low, the refrigerant tends to accumulate in the outdoor heat exchanger 30, and as a result, the refrigerant supplied to the heat exchanger 18. Is reduced, so that drying occurs easily in the heat exchanger (18).

In contrast, in the present invention, when the outside temperature To is high, the target discharge temperature Tgt-dis is shifted to be high.

Thereby, the electric expansion valve 36 does not open more than necessary when the outdoor air temperature To is low, and at the same time, it is possible to suppress the drying of the heat exchanger 18 when the outdoor air temperature To is high. .

On the other hand, in the air conditioner 10, the rotation speed of the compressor 26 is limited based on the dryness degree D-sh.

FIG. 7 shows an example of the rotational speed limitation of the compressor 26 based on the dryness level D-sh used to correct the target discharge temperature Tgt-dis.

In this flowchart, after the initial setting of the timer or flag used in this flowchart is performed in the first step 250, the step 252 calculates the dryness degree calculated in the flowchart shown in FIG. D-sh).

In the next step 254, it is checked whether or not the dryness level D-sh exceeds a predetermined value (3.0 as an example), and the control step of the electric expansion valve 36 is removed from the step 256. It reads and checks in step 258 whether the control step reaches the upper limit.

Here, when dryness degree D-sh is less than predetermined value (D-sh <3.0), or when the control staff of the electric expansion valve 36 does not reach the upper limit (in the step 254 or the step 258). Negative determination], the process proceeds to the step 260 and checks whether the compressor 26 is in a stopped state from the rotational speed of the compressor 26, and when the compressor 26 is in a stopped state (negative determination in the step 260). ], Complete this flowchart once.

That is, this flowchart is executed only during the operation of the compressor 26, and is reset every time the compressor 26 is stopped.

On the other hand, the dryness (D-sh) is a predetermined value (D-sh 3.0), and when the control staff of the electric expansion valve 36 reaches an upper limit (affirmative determination in the staff 254 and the staff 258), the process shifts to the staff 262 and the rotation speed of the compressor 26 is increased. Reset / start the timer to limit.

Thereafter, in the steps 264, 266, 268, and 270, as in the steps 252, 254, 256, and 258, whether the dryness degree D-sh is equal to or greater than a predetermined value and the electric expansion valve 36 Check whether the control staff has reached the upper limit.

In addition, the staff 272 checks whether or not the time measured by the timer has reached a predetermined time (for example, 30 minutes).

That is, in the steps 264 to 272, it is checked whether the state where the control step of the electric expansion valve 26 reaches the upper limit while the dryness D-sh is greater than or equal to the predetermined value continues for a predetermined time.

Thus, if either of the dryness level D-sh and the control staff falls within a predetermined time (negative determination by the staff 266 or the staff 270 in the state of being negatively determined by the staff 272), the compressor ( It returns to the step 252 without restricting the rotation speed of 26).

On the other hand, if the dryness degree D-sh is more than a predetermined value and the state in which the control staff of the electric expansion valve 26 reaches the upper limit continues for a predetermined time (affirmative determination in the steps 266, 270 and 272), the compressor The rotation speed of (26) is limited.

Restriction of the rotation speed of the compressor 26 lowers the rotation speed of the compressor 26 at the step 274 to a predetermined value (for example, 75% of the current rotation speed), and the rotation speed at the step 276. Prohibit the rise of.

As a result, in the air conditioner 10, the rotation speed of the compressor 26 is lowered, and the increase in the rotation speed, that is, the increase in the discharge pressure of the refrigerant is prohibited.

As a result, the discharge pressure of the refrigerant decreases with the rotation speed of the compressor 26. For example, during the freezing cycle, the liquefied refrigerant stays in the heat exchanger 30 of the outdoor unit. Even if the heat exchanger 18 is in a state where drying is likely to occur, drying of the heat exchanger 18 can be suppressed and frost can be prevented from occurring in the cross flow fan 44.

In the next step 278, it is checked whether or not a flag is set, and when the flag is reset, the process shifts to the step 280 to set a flag indicating that the increase in the rotation speed is set.

In this way, if the rotation speed of the compressor 26 is limited, the next staff 282 reads the dryness level D-sh, and the dryness level D-sh is a predetermined value (e.g. -1 0) Check if it goes down below.

Here, when the dryness degree D-sh falls below a predetermined value and the heat exchanger 18 is in a wet state, it is affirmatively determined by the staff 284.

As a result, the process proceeds to the step 286 and releases the increase in the rotation speed of the compressor 26.

As described above, the air conditioner 10 prevents drying from occurring in the heat exchanger 18 of the indoor unit 12 by correcting the target discharge temperature Tgt-dis. When the drying is being continued, the rotation speed of the compressor 26 is lowered, and the increase in the rotation speed of the compressor 26 is prohibited, thereby preventing the drying of the heat exchanger 18 more reliably. have.

When the heat exchanger 18 reaches a state where no drying occurs, the prohibition of the increase in the rotation speed of the compressor 26 is released.

On the other hand, when the prohibition of the increase in the rotation speed of the compressor 26 is set and the flag is already set, affirmative determination is made by the staff 278, the process proceeds to the staff 288, and whether or not the compressor 26 is in a stopped state. Check it.

As a result, when the compressor 26 is in the stopped state, the flow proceeds to the step 290 to release the prohibition of the increase in the rotation speed of the compressor 26, and then the flowchart is finished once.

Thus, in the air conditioner 10, when the rotation speed of the compressor 26 reaches the 2nd time in order to prevent drying of the heat exchanger 18, the increase of the rotation speed is prohibited until the compressor 26 stops. Do not release it.

In addition, in the air conditioner 10 applied to this embodiment demonstrated above, the structure of the air conditioner to which this invention is applied is not limited.

The present invention can be applied to an air conditioner of any configuration in which the flow rate of the refrigerant in the refrigeration cycle is adjusted by the electric expansion valve.

As described above, according to the present invention, by adjusting the target discharge temperature based on the discharge temperature, the suction temperature, and the coil temperature, the electric expansion valve can be controlled in response to the drying of the heat exchanger of the indoor unit. An excellent effect can be obtained that can prevent the adhesion of frost due to.

Claims (5)

In the air conditioner which controls the flow volume of the refrigerant | coolant circulating in the refrigeration cycle comprised using a compressor, a utilization side heat exchanger, an electric expansion valve, and a heat source side heat exchanger by changing the opening degree of the said electric expansion valve, While controlling the opening degree of the electric expansion valve so that the temperature of the refrigerant discharged from the compressor reaches the target discharge temperature, And the target discharge temperature is corrected on the basis of several values of the temperature value of the use-side heat exchanger, the temperature value of the refrigerant discharged from the compressor, and the temperature value of the refrigerant sucked into the compressor. The method of claim 1, And the correction is to correct the target discharge temperature low when a value calculated from the temperature of the use-side heat exchanger and the temperature of the refrigerant drawn into the compressor exceeds a predetermined value. The method according to claim 1 or 2, And when the temperature of the refrigerant drawn into the compressor is higher than the target discharge temperature, the correction corrects the target discharge temperature to open the electric expansion valve. The method according to any one of claims 1 to 3, The correction is an air conditioner, characterized in that for correcting the target discharge temperature in accordance with the outside air temperature. The method according to any one of claims 1 to 4, And the movement capacity of the compressor is limited based on the temperature of the use-side heat exchanger and the temperature of the refrigerant drawn into the compressor.