JPH0144908B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air conditioner equipped with a refrigeration cycle having a variable capacity compressor.

Generally, in an air conditioner, when the power supply voltage decreases, the torque of the compressor motor that drives the compressor decreases, causing a breakdown and making it impossible to continue operation.

Therefore, the compressor motor torque obtained at the rated power supply voltage is designed to have a margin for the load, and even if the power supply voltage drops, sufficient torque can be exerted for the load to maintain a stable air conditioner. There are some that are designed to maintain operating conditions.

However, when using a compressor motor designed to output more than necessary,
It is impossible to operate the compressor motor efficiently, and as a matter of course there is a problem in that electric power is wasted, making it unsuitable for the current situation where there is a strong demand for energy conservation.

Further, when the power supply voltage increases, the operating current of the compressor motor increases, and there is a risk of burning out the windings of the compressor motor.

This invention was made in view of the above circumstances, and its purpose is to be able to efficiently operate a compressor according to the power supply voltage, thereby ensuring stable operation regardless of fluctuations in the power supply voltage. An object of the present invention is to provide an air conditioner that can maintain the same condition, reduce power consumption, and further ensure the safety of a compressor motor.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a compressor 1, a condenser 2,
The capillary tube 3, the gas-liquid separator 4, the capillary tube 5, and the evaporator 6 are connected in sequence,
A refrigeration cycle is configured.

The gas refrigerant separated by the gas-liquid separator 4 is then injected into the compressor 1 via an injection cycle 7.

An injection valve 8 is provided in the middle of the injection cycle 7 to adjust the flow rate of the refrigerant.

On the other hand, outdoor air is circulated through the condenser 2 by an outdoor blower 9. Further, indoor air is circulated through the evaporator 6 by an outdoor blower 10.

Figure 2 shows the main parts of the control circuit.

20 is an AC power supply, and the power supply circuit 3 is connected to the power supply 20.
0 is connected.

The power supply circuit 30 consists of a power supply transformer 31 and diodes 32 and 33. The transformer 31 steps down the AC power supply voltage, and the diode 3
2 and 33 for full wave rectification and output.

One end of a relay 50 is connected to the positive output terminal P of the power supply circuit 30, and the other end of the relay 50 is connected to the power supply circuit 30 through the collector and emitter of a switching element such as an NPN transistor 51.
It is connected to the negative side output terminal N of 0.

The base of the transistor 51 is connected to the output terminal of a comparator 62, which will be described later, via a resistor 52. A diode 53 for preventing back electromotive force is connected in parallel to the relay 50.

Therefore, the normally closed contact 50b of the relay 50 is connected between the positive output terminal P and the negative output terminal N of the power supply circuit 30.
The electromagnetic coil 8 ₁ of the injection valve 8 is connected through the injection valve 8 .

On the other hand, a compressor motor 1 ₁ that drives the compressor 1 is connected to a power source 20 via operation control contacts 63 , 63 .

A current detection coil 60 is provided in the energization path to the compressor motor 1 ₁ so that the voltage induced in the current detection coil 60 and the reference voltage emitted from the reference device 61 are compared by a comparator 62 . It's getting old.

In this case, when the voltage induced in the coil 60 becomes larger than the reference voltage, the comparator 62 outputs a logic "1" signal.

That is, the coil 60, the reference device 61, the comparator 6
2 constitutes a voltage fluctuation detection circuit.

Although not shown, the power supply 20 is also connected to a blower motor 9 ₁ of the outdoor blower 9, a blower motor 10 ₁ of the indoor blower 10, and the like.

Next, the operation in the above configuration will be explained.

Now, when the power supply 20 has reached the rated voltage,
The operating current flowing through the compressor motor ₁₁ is not large, so the output of the comparator 62 is a logic "0" signal.

Therefore, the relay 50 is not energized, the rear point 50b remains closed, and the electromagnetic coil 8 ₁ is energized. In other words, injection valve 8
opens.

In this way, if the operation is carried out, the refrigerant discharged from the compressor 1 flows sequentially to the condenser 2, the capillary tube 3, the liquid separator 4, the capillary tube 5, and the evaporator 6. The gas refrigerant separated in the separator 4 is injected into the compressor 1 via an injection cycle 7.

By the way, as shown in FIG. 3, when the power supply voltage increases or decreases from the rated voltage, the operating current of the compressor motor 1 increases significantly, and the current density of the windings in the compressor motor 1 becomes excessive. There is a risk of burnout due to heat generation.

In addition, in Figure 3, the solid line indicates that the power supply frequency is 50
The broken line shows the characteristics when the power supply frequency is 60Hz.

Therefore, if the voltage of the power supply 20 drops to, for example, around 90% of the rated voltage, the coil 60
The voltage induced in the comparator 6 (that is, the voltage obtained by rectifying and integrating the current generated in the coil 60 by the current flowing in the current path) becomes large.
The output of 2 becomes a logic "1" signal. Then, the relay 50 is energized, the contact 50b is opened, and the electromagnetic coil 8 ₁ is no longer energized. In other words, the injection valve 8 is closed. In this way, the injection of gas refrigerant into the compressor 1 is interrupted and the capacity of the compressor 1 is reduced.

In this way, even if the torque of the compressor motor 1 ₁ decreases when the power supply voltage drops, the capacity of the compressor 1 is simultaneously reduced to reduce the load on the compressor motor 1 ₁ , so that breakdown is prevented. This eliminates the need to design the output of the compressor motor 1 ₁ more than necessary, making it possible to reduce power consumption, and moreover, enabling efficient operation of the compressor motor 1 ₁ according to the power supply voltage. Become.

Moreover, as a result, the operating current of the compressor motor 1 ₁ is reduced, and the risk of burnout of the windings in the compressor motor 1 ₁ can be prevented.

On the other hand, even when the voltage of the power supply 20 rises above the rated voltage, the current flowing through the compressor ₁₁ increases more than the current at the rated voltage, as shown in FIG. Then,
When this voltage exceeds the reference voltage issued by the reference device 61, the output of the comparator 62 becomes a logic "1" signal and the performance of the compressor 1 is reduced. Thereby, the risk of burnout of the windings in the compressor motor ₁₁ can be prevented, and it is safe.

Next, other embodiments of the invention will be described with reference to the drawings. In this case, the same parts as in FIGS. 1 and 2 are given the same reference numerals, and detailed explanation thereof will be omitted.

As shown in FIG. 4, a capillary tube 11 is inserted between the condenser 2 and the evaporator 6. Further, a release cycle 12 is provided between the compressor 1 and the refrigerant suction side of the compressor 1, and a release valve 13 is provided in the middle of the release cycle 12.

Furthermore, as shown in FIG. 5, the electromagnetic coil ₁₃₁ of the release valve 13 is connected between the output ends P and N via the normally open contact 50a of the relay 50.

Therefore, in this case, if the voltage of the power supply 20 has reached the rated value, the release valve 13 is maintained in the closed state and the normal refrigeration cycle operation is performed.

When the voltage of the power supply 20 decreases or increases from the rated voltage, the release valve 18 opens and the gas refrigerant in the compressor 1 is released to the refrigerant suction side of the compressor 1 via the release cycle 12. In this way, the capacity of the compressor 1 can be reduced, and the windings of the compressor motor 1 ₁ can be prevented from burning out.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways without changing the gist.

As described above, according to the present invention, there is provided a refrigeration cycle having a variable capacity compressor, a detection means for detecting a decrease or increase in the power supply voltage for the drive motor of the compressor, and a detection means for detecting a decrease or increase in the power supply voltage for the drive motor of the compressor. Since the variable capacity compressor is equipped with a control means that reduces the capacity of the variable capacity compressor when detected, the compressor can be efficiently operated according to the power supply voltage, thereby maintaining a stable operating state regardless of fluctuations in the power supply voltage. In addition, it is possible to provide an air conditioner that can reduce power consumption and also ensure the safety of the compressor motor.

[Brief explanation of drawings]

1, 2, and 3 show an embodiment of the present invention, in which FIG. 1 is a block diagram of a refrigeration cycle, FIG. 2 is a block diagram of the main part of a control circuit, and FIG.
The figure shows the characteristics of the power supply voltage and the operating current of the compressor motor. Figures 4 and 5 show other embodiments of the present invention. Figure 4 is a configuration diagram of a refrigeration cycle. The figure is a configuration diagram of the main parts of the control circuit. 1... variable capacity compressor, 2... condenser, 6...
Evaporator, 7... Injection cycle, 8... Injection valve, 12... Release cycle, 13... Release valve, 20... AC power supply.

Claims (1)

[Claims] 1. A refrigeration cycle having a variable capacity compressor, a detection means for detecting a decrease or increase in the power supply voltage for the drive motor of the compressor, and a detection means that reduces the capacity of the variable capacity compressor when the detection means detects a decrease or increase in the power supply voltage. An air conditioner characterized by comprising a control means for controlling the air conditioner.