JP2903898B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having an inverter.

[0002]

2. Description of the Related Art Conventionally, in this type of air conditioner, the operating frequency of a motor driving a compressor is controlled by an inverter according to the indoor load, and the output voltage V with respect to the output frequency F of the inverter is controlled by control means. It is controlled by one V / F pattern. This V / F
The pattern is shaped as shown by the curve in FIG.
It consists of a straight line rising to the right representing the constant torque mode and a straight line substantially parallel to the horizontal axis representing the constant output mode. The straight line in the constant torque mode is represented by V = aF + b. Here, V is the output voltage of the inverter, F is the output frequency of the inverter, and a and b are constants. The V / F pattern is selected so that the efficiency is maximized under the standard load condition of the compressor during cooling or heating.

[0003]

However, in the above-mentioned conventional air conditioner, one V / F is controlled by the control means.
Since the output voltage V is controlled with respect to the output frequency F of the inverter according to the pattern, there is a problem that the efficiency becomes poor and the power consumption increases except in the selected standard load state. For example, V / according to the standard load during cooling
When the output voltage V is controlled with respect to the output frequency F at the time of the standard load at the time of heating in the F pattern, the standard load at the time of heating is larger than the standard load at the time of cooling, so that the power consumption increases. Further, in a multi-type air conditioner, the load on the compressor greatly varies, and therefore, a single V / F pattern cannot cope with the load.

Therefore, an object of the present invention is to provide a plurality of V / Fs.
An object of the present invention is to provide an air conditioner capable of reducing power consumption by selecting an optimum V / F pattern from patterns according to a load of a compressor.

[0005]

In order to achieve the above object, the present invention is directed to a refrigerant circuit having a compressor, an outdoor heat exchanger, expansion means and an indoor heat exchanger, and a motor for driving the compressor. In an air conditioner including an inverter that controls an operation frequency and a control unit that controls an output voltage according to an output frequency of the inverter, a load sensor that detects a load of the compressor, and an output voltage corresponding to an output frequency of the inverter. V / F pattern storage means for storing at least two V / F patterns to be represented, and the V / F pattern based on the output of the load sensor.
V / F pattern selection means for selecting one V / F pattern from the pattern storage means and outputting the selected V / F pattern to the control means, and causing the control means to control the output voltage according to the output frequency in accordance with the V / F pattern. And the refrigerant used in the refrigerant circuit is R32, R125, or R134.
a, or a mixed refrigerant of R32 and R125, or R32
And R134a.

According to a second aspect of the present invention, the refrigerant circuit has a four-way switching valve, and the air conditioner can perform a cooling operation and a heating operation, and performs a cooling operation or a heating operation. And a V / F pattern selecting means, based on a result of the determination by the cooling / heating determining means.
/ F pattern is selected.

[0007]

According to the first aspect of the present invention, the V / F pattern storage means stores at least two V / F patterns. The load sensor detects the load of the compressor,
Based on the output of the load sensor, the V / F pattern selection means selects one V / F pattern from a plurality of V / F patterns stored in the V / F pattern storage means. The control means controls the output voltage V with respect to the output frequency F of the inverter according to the selected V / F pattern.

As described above, one V / F pattern is selected from a plurality of V / F patterns in accordance with the load of the compressor, and the output voltage of the inverter is controlled according to the V / F pattern. Improve the coefficient of performance (CO
P) is improved.

According to the first aspect of the present invention, the refrigerant is R32, R125, or R134a, or a mixed refrigerant of R32 and R125, or R32 and R13.
4a is a mixed refrigerant. These refrigerants make the load fluctuation on the compressor larger than R22, which is a normal refrigerant, but one V / F pattern among a plurality of V / F patterns.
Since the / F pattern is selected, it is possible to cope with a change in load and reduce power consumption.

Further, according to the invention of claim 2, the air conditioner has a four-way switching valve and is used for both cooling and heating, and the cooling / heating determining means determines whether to perform the cooling operation or the heating operation. The V / F pattern selection means selects one V / F pattern from the V / F pattern storage means based on the determination result of the cooling / heating determination means. Therefore, even if the load fluctuates between cooling and heating, one optimal V / F pattern can be selected, and the efficiency is increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

In FIG. 1, 1 is a compressor, 2 is a four-way switching valve, 3 is an outdoor heat exchanger, 4 is an electric expansion valve as expansion means, 5 is a capillary tube as expansion means,
Reference numeral 6 denotes an indoor heat exchanger, and reference numeral 7 denotes an accumulator, which are connected by piping to form a refrigerant circuit.

Reference numeral 21 denotes a high pressure sensor as a load sensor for detecting the pressure on the discharge side of the compressor 1, 22 denotes a discharge temperature thermistor as a load sensor for detecting the temperature of refrigerant discharged from the compressor 1, and 23 denotes outdoor heat exchange. Vessel 3
The outdoor heat exchange temperature thermistor as a load sensor for detecting the temperature of the outside air, the outside air temperature thermistor 24 as a load sensor for detecting the outside air temperature, and the indoor heat exchange temperature 25 as a load sensor for detecting the temperature of the indoor heat exchanger 6 Thermistor, 2
Reference numeral 6 denotes an indoor temperature thermistor as a load sensor for detecting the indoor temperature, and reference numeral 27 denotes a low-pressure pressure sensor as a load sensor for detecting the pressure on the suction side of the compressor 1.

Reference numeral 31 denotes an inverter which drives a three-phase induction motor (not shown) for driving the compressor 1 at a frequency corresponding to the indoor load, and 32 normally outputs a signal of a frequency F corresponding to the indoor load from the inverter 31. Is a control device that causes the inverter 31 to output an output voltage V according to the output frequency F in a selected V / F pattern described later.

The control device 32 operates as shown in FIG.

First, in step S1, the load of the compressor 1 is calculated by multiplying the difference between the output of the high pressure sensor 21 and the output of the low pressure sensor 27 by a constant. In this embodiment, the load of the compressor 1 is calculated based on the difference between the pressure on the discharge side and the pressure on the suction side of the compressor 1. The load of the compressor 1 may be calculated in consideration of the indoor heat load. further,
Discharge temperature thermistor 22, indoor heat exchange temperature thermistor 23
The indoor heat load may be determined by using the output of the outside air temperature thermistor 24.

Next, in step S2, it is determined whether a cooling operation or a heating operation is being performed based on an output from a remote controller (not shown). This step S2 constitutes a cooling / heating determining means. If it is determined that the cooling operation is being performed, the process proceeds to step S3.

In step S3, the load calculated in step S1 is compared with a predetermined threshold to determine whether the load is large, medium, or small. If it is determined that the load is small, the process proceeds to step S4, where the V / F shown in FIG.
Select the pattern S4. The V / F pattern S4 may be stored in the form of a table in the memory, or a coefficient of a mathematical expression representing the V / F pattern S4 may be stored.

If it is determined in step S3 that the load is medium, the V / F pattern S5 shown in FIG.
Select If it is determined in step S3 that the load is large, that is, it is in an overload state at the time of cooling, it is determined from the memory that FIG.
The V / F pattern S6 shown in FIG.

On the other hand, if it is determined in step S2 that the heating operation is being performed, the process proceeds to step S9, where the load calculated in step 1 is compared with a predetermined threshold value, and whether the load is large, medium, or small. Is determined. If the load is small, the process proceeds to step S10, where the V / F pattern S10 shown in FIG. 3 is selected. If the load is medium, the process proceeds to step S1.
1 to select the V / F pattern S11 shown in FIG.
If the load is large, the process proceeds to step S12, and the V / F pattern S12 shown in FIG. 3 is selected. As shown in FIG. 3, the V / F pattern includes S4, S10, S5, S11,
The output voltage increases in the order of S6 and S12. Steps S3, S4, S5, S6, S9, S10, S11, and S12 constitute V / F pattern selection means.

In step S7, steps S4, S5, S
6, One V / F selected in S10, S11 or S12
Based on the pattern, control is performed such that an output voltage V of the inverter according to the output frequency F of the inverter 31 is obtained. This control is the same as the conventional normal control.

As described above, the air conditioner of this embodiment is
Based on the outputs of the high pressure sensor 21 and the low pressure sensor 27, the load of the compressor 1 is calculated in step S1.
Since the optimum V / F pattern is selected in steps S6 to S6 and steps S9 to S12, the compressor 1 is driven by inputting the output voltage V corresponding to the load of the compressor 1 from the inverter 31 to the three-phase induction motor. The efficiency is higher and the power consumption is lower.

Further, the air conditioner of this embodiment is provided with a four-way switching valve 2, and can switch between the four-way switching valve 2 to perform the cooling operation and the heating operation. And the V / F pattern S during the cooling operation
4, S5, and S6 are selected, and the V / F patterns S10, S11, and S12 are selected during the heating operation.
An optimum output voltage can be obtained both during cooling and during heating, thus increasing efficiency and reducing power consumption.

In the above embodiment, a single-chamber type air conditioner has been described. However, the present invention is also applied to a multi-chamber type, that is, a multi-type air conditioner in which a plurality of indoor heat exchangers are connected in parallel. can do. In a multi-type air conditioner, since the load fluctuation of the compressor is large,
If one V / F pattern is selected from the / F patterns according to the load, the effect of reducing power consumption is extremely large.

The refrigerant used in the air conditioner is not limited to a special refrigerant, but may be R32 or R32.
In the case of using the refrigerant 125 or R134a, or the refrigerant mixture of R32 and R125, or the refrigerant mixture of R32 and R134a, the load fluctuation of the compressor 1 becomes particularly large. If the / F pattern is selected according to the load, the effect of reducing power consumption is extremely large.

[0026]

As is clear from the above, according to the first aspect of the present invention, at least two V / F patterns are stored in the V / F pattern storage means, and the output of the load sensor for detecting the load of the compressor is stored. Based on the V / F pattern selection means, one V / F pattern is selected from the plurality of V / F patterns stored in the V / F pattern storage means, and the V / F pattern is selected according to the selected V / F pattern. Since the output voltage V with respect to the output frequency F of the inverter is controlled by the control means, efficiency can be improved and power consumption can be reduced.

According to the first aspect of the present invention, the refrigerant is R32, R125, or R134a, a mixed refrigerant of R32 and R125, or R32 and R13.
4a is a mixed refrigerant. These refrigerants make the load fluctuation on the compressor larger than R22, which is a normal refrigerant, but one V / F pattern among a plurality of V / F patterns.
Since the / F pattern is selected, it is possible to cope with a change in load and reduce power consumption.

According to the second aspect of the present invention, the cooling / heating determining means determines whether the cooling / heating air conditioner performs the cooling operation or the heating operation, and the V / F pattern selecting means includes the cooling / heating determining means. Since one V / F pattern is selected from the V / F pattern storage means based on the determination result, even if the load fluctuates between cooling and heating, one optimal V / F pattern can be selected. And power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the control device of the embodiment.

FIG. 3 is a diagram showing a plurality of V / F patterns of the embodiment.

FIG. 4 is a diagram showing one V / F pattern of a conventional air conditioner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way switching valve, 3 ... Outdoor heat exchanger, 4 ... Electric expansion valve, 6 ... Indoor heat exchanger, 21 ... High pressure sensor, 27 ... Low pressure sensor, 31 ... Inverter, 32 …Control device.

Continuation of the front page (56) References JP-A-61-18392 (JP, A) JP-A-61-223446 (JP, A) JP-A-64-16297 (JP, A) JP-A-2-70291 (JP) , A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F25B 13/00 F25B 1/00

Claims (2)

(57) [Claims] A refrigerant circuit having a compressor, an outdoor heat exchanger, an expansion means, and an indoor heat exchanger; an inverter for controlling an operation frequency of an electric motor for driving the compressor; and an output voltage corresponding to an output frequency of the inverter. A load sensor for detecting a load on the compressor; and a V / F pattern storing means for storing at least two V / F patterns representing an output voltage with respect to an output frequency of the inverter. Based on the output of the load sensor, one V / F pattern is selected from the V / F pattern storage means and output to the control means, and the control means responds to the output frequency in accordance with the V / F pattern. V / F pattern selection means for controlling the output voltage, wherein the refrigerant used in the refrigerant circuit is R32 or Is R12
5. An air conditioner comprising R134a, or a mixed refrigerant of R32 and R125, or a mixed refrigerant of R32 and R134a. 2. The air conditioner according to claim 1, wherein
The refrigerant circuit has a four-way switching valve, the air conditioner is capable of performing a cooling operation and a heating operation, and includes a cooling / heating determination unit configured to determine whether to perform the cooling operation or the heating operation. An air conditioner characterized in that the V / F pattern selection means selects a V / F pattern based on the result of the judgment by the cooling / heating judgment means.