JPH0599519A - Heat pump type air conditioner - Google Patents

Abstract

PURPOSE:To enable an abnormal stopping of a compressor to be prohibited by a method wherein a heat pump type air conditioner is provided with a frequency changing means for decreasing an inverter frequency when a surrounding air temperature sensor for use in sensing a surrounding air temperature is mounted and the detected surrounding air temperature is more than its set temperature. CONSTITUTION:A sensed value of a surrounding air temperature sensor 21 for use in sensing a surrounding air temperature is inputted to a comparing means 22 of a control device 20 and compared with a set temperature inputted from a temperature setting means 23. In the case that the surrounding air temperature is more than the set temperature, a frequency changing means 24 receives a signal from the comparing means 22 and determines to decrease an invertor frequency to a value less than a predetermined value, and the result of this decision is outputted to an inverter 7 through an outputting means 25 so as to decrease a frequency of current to be supplied to a motor for driving the compressor. In this way, the number of rotations of the compressor is decreased, an amount of refrigerant discharged from the compressor is decreased and further an amount of refrigerant circulating within a refrigerant circuit is also decreased, resulting in that a high pressure within the refrigerant circuit is decreased to decrease the load in the compressor and so the compressor may not be over-heated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner.

[0002]

2. Description of the Related Art An example of a refrigerant circuit of a conventional heat pump type air conditioner is shown in FIG. During the cooling operation, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 enters the outdoor heat exchanger 3 via the four-way switching valve 2 as shown by the solid line arrow, and is then driven by the fan motor 9 to the outside. By radiating heat to the outside air blown by the fan 10, it is condensed and liquefied into a high-pressure liquid refrigerant. This liquid refrigerant is adiabatically expanded by being throttled in the process of passing through the throttling mechanism 4 such as an expansion valve and becomes a low-temperature low-pressure gas-liquid two-phase. Next, this refrigerant enters the indoor heat exchanger 5, where it absorbs heat from the indoor air blown by the indoor fan 12 driven by the fan motor 11 to evaporate and become a low-temperature low-pressure gas refrigerant, which is switched in all directions. Compressor 1 through valve 2 and accumulator 6
Return to.

During the heating operation, the refrigerant discharged from the compressor 1 passes through the four-way switching valve 2 to be condensed and liquefied in the indoor heat exchanger 5 and adiabatically expanded in the throttle mechanism 4 as indicated by a dashed arrow, so that the outdoor heat After evaporating and vaporizing in the exchanger 3, it returns to the compressor 1 through the four-way switching valve 2 and the accumulator 6. In addition, in FIG.
Reference numeral 7 is an inverter that changes the frequency of the current supplied to the drive motor of the compressor 1.

[0004]

In the above conventional heat pump type air conditioner, when the outside air temperature becomes abnormally high during the heating operation, the heat absorption amount of the outdoor heat exchanger 3 becomes large, so that the refrigerant at the outlet thereof. The degree of superheat increases and the temperature of the refrigerant gas drawn into the compressor 1 rises accordingly, so that the compressor 1 is overheated. Further, when the amount of heat absorbed by the outdoor heat exchanger 3 increases, the high pressure in the refrigerant circuit rises, so the discharge pressure of the compressor 1 also increases, and the compressor 1 accordingly.
As the load increases, the compressor 1 is also overheated. On the other hand, when the outside air temperature becomes abnormally high during the cooling operation, the condensing pressure of the refrigerant increases, and the high pressure in the refrigerant circuit increases accordingly, so that the discharge pressure of the compressor 1 increases and the load of the compressor 1 increases. Since it increases, the compressor 1 is overheated. When the compressor 1 is overheated, the compressor 1 is abnormally stopped.

[0005]

SUMMARY OF THE INVENTION The present invention has been invented to solve the above problems, and its gist is to provide an electric compressor driven through an inverter for changing the frequency. In the heat pump type air conditioner, the outside temperature sensor for detecting the outside temperature is installed, and the frequency changing means for lowering the inverter frequency is provided when the outside temperature is equal to or higher than the set temperature. On the plane.

[0006]

In the present invention, because of the above-mentioned configuration, when the outside air temperature detected by the outside air temperature sensor is equal to or higher than the set temperature, the inverter frequency is lowered and the rotation speed of the electric compressor is lowered. Along with this, the amount of refrigerant discharged from the electric compressor is reduced and the amount of refrigerant circulating in the refrigerant circuit is reduced, so that the high pressure in the refrigerant circuit is reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the control block diagram shown in FIG. The refrigerant circuit is the same as the conventional one shown in FIG. The detection value of the outside air temperature sensor 21 for detecting the outside air temperature is the comparison means of the control device 20.
It is input to 22 and is compared here with the set temperature input from the temperature setting means 23. When the outside air temperature is equal to or higher than the set temperature, the frequency changing means 24 receives the signal from the comparing means 22.
Determines that the inverter frequency should be reduced to a predetermined value or less, and the determination result is output to the inverter 7 via the output means 25, and the inverter 7 reduces the frequency of the current supplied to the motor that drives the compressor 1. .

Thus, the number of revolutions of the compressor 1 decreases, the amount of refrigerant discharged from the compressor 1 decreases, and the amount of refrigerant circulating in the refrigerant circuit decreases, so that the high pressure in the refrigerant circuit decreases. Since the load on the compressor 1 is small, the compressor 1 will not be overheated.

[0009]

According to the present invention, when the outside air temperature detected by the outside air temperature sensor is equal to or higher than the set temperature, the inverter frequency is reduced and the rotation speed of the electric compressor is reduced. The amount of discharged refrigerant decreases and the amount of refrigerant circulating in the refrigerant circuit decreases, so that the high pressure in the refrigerant circuit decreases. Thus, the abnormal stop of the compressor can be prevented even when the outside air temperature is high, so that the operation of the air conditioner can be continued.

[Brief description of drawings]

FIG. 1 is a control block diagram showing an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram of a heat pump type air conditioner.

[Explanation of symbols]

 1 Compressor 7 Inverter 20 Controller 21 Outside Air Temperature Sensor 23 Temperature Setting Means 22 Comparing Means 24 Frequency Changing Means 25 Output Means

Claims (1)

[Claims] 1. A heat pump type air conditioner equipped with an electric compressor driven via an inverter for changing the frequency, wherein an outside air temperature sensor for detecting the outside air temperature is installed and when the outside air temperature is equal to or higher than a set temperature, A heat pump type air conditioner comprising a frequency changing means for lowering the inverter frequency.