JPH023103B2 - - Google Patents

Description

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

Generally, the lower the outside air temperature is, the greater the required indoor heating capacity is, and the higher the outside air temperature is, the smaller the required indoor heating capacity is. On the other hand, in the case of an air conditioner equipped with a heat pump type refrigeration cycle, during heating operation, the heating capacity changes significantly depending on the outside temperature and indoor temperature. For example, when the outside temperature is 10°C and the indoor temperature is 21°C. ℃ heating capacity is approximately 1.5 times the heating capacity when the outside temperature is 0℃ and the indoor temperature is 21℃. In other words, when the outside temperature is high, the air conditioner's heating capacity increases even though the required heating capacity is small.If the indoor temperature is also particularly high, the air conditioner's compressor operates overload (the compressor motor is underpowered). It becomes a breakdown) and becomes a breakdown. However, in the case of a variable capacity air conditioner that has a heat pump refrigeration cycle equipped with a release circuit, the amount of load placed on the compressor during heating is detected, and when the amount of load exceeds the standard value. By reducing the heating capacity when the weather gets hot, it is possible to prevent the compressor from operating under overload as described above.

However, in such an air conditioner, when a low-output compressor motor is used for the purpose of improving energy efficiency, the following problems occur. In other words, the capacity of the compressor is approximately proportional to the power frequency, and the ratio of capacity at 50Hz and 60Hz is 5:6. Therefore, when the power frequency is 60Hz, the load on the compressor (compressor motor) is 20% larger than when the power frequency is 50Hz, and as mentioned above, In a system in which capacity is switched based on a reference value, it is difficult to achieve optimal operation according to the situation.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide an excellent air conditioner that can operate optimally depending on the situation, despite the use of a low-output compressor motor. It is about providing.

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

In FIG. 1, a compressor 1 having a variable capacity port, a four-way valve 2, an outdoor heat exchanger 3, a first capillary tube 4, a second capillary tube 5, and an indoor heat exchanger 6 are connected in order. A heat pump refrigeration cycle is formed. A check valve 7 is connected to the second capillary tube 5 in parallel in the direction shown. Furthermore, the first
The communication connection part of the second capillary tubes 4 and 5 is
It communicates with the variable capacity port of the compressor 1, that is, the compression chamber, via the compressor cooling circuit 8. Further, a release circuit 9 is communicated between the variable capacity port of the compressor 1 and the suction side, and a two-way valve 10 is provided in the release circuit 9. In this way, when the cooling operation is set, the refrigerant flows in the direction of the solid line arrow in the figure, and when the heating operation is set, the refrigerant flows in the direction of the broken line arrow in the figure. Furthermore, when the two-way valve 10 opens, the refrigerant that should flow from the cooling circuit 8 into the compression chamber of the compressor 1 passes through the release circuit 9 to the compressor 1.
The refrigeration cycle is bypassed to the suction side of the refrigeration cycle from a high-capacity operating state to a low-capacity operating state. Note that an outdoor blower 11 is provided near the outdoor heat exchanger 3, and an indoor blower 12 is provided near the indoor heat exchanger 6.

FIG. 2 shows the control circuit. Reference numeral 20 denotes a temperature sensor, such as a positive temperature coefficient thermistor, which detects the temperature of the indoor heat exchanger 6, and a DC voltage V is applied to this thermistor 20 via a resistor 21. In this case, the temperature of the indoor heat exchanger 6 detected by the thermistor 20 approximately corresponds to the refrigerant discharge pressure of the compressor 1 when the indoor heat exchanger 6 acts as a condenser (during heating operation). be. That is, the positive characteristic thermistor 20 is used as a detection means for detecting the refrigerant discharge pressure of the compressor 1. Here, the refrigerant discharge pressure of the compressor 1 has a strong correlation with the magnitude of the load applied to the compressor 1, and by detecting the refrigerant discharge pressure, the magnitude of the load applied to the compressor 1 can be detected. It will be possible. In short, the magnitude of the load applied to the compressor 1 can be detected by the thermistor 20.
The voltage obtained at the connection point a between the resistor 21 and the resistor 21 represents the magnitude of the load applied to the compressor 1. Then, the output voltage of this thermistor 20 is determined by the comparator 3.
0 non-inverting input terminal (+). On the other hand, 2
2 is the load reference value setting circuit for 50Hz, resistors 23, 2
It consists of four series circuits, and a DC voltage V is applied to this series circuit. In this way, the voltage obtained at the connection point b between the resistors 23 and 24 represents the load reference value when the commercial AC power source is 50 Hz. Also, 25 is
This is a load reference value setting circuit for 60Hz, consisting of a series circuit of resistors 26 and 27, and this series circuit has a DC voltage V.
is applied. In this way, the voltage obtained at the connection point C between the resistors 26 and 27 represents the load reference value when the commercial AC power source is 60 Hz. In this case, the output voltage of the 60Hz load reference value setting circuit 25 is set smaller than the output voltage of the 50Hz load reference value setting circuit 22. In other words, the load reference value when the power supply frequency is 60Hz is set smaller than the load reference value when the power supply frequency is 50Hz. Therefore, the output voltage of these load reference value setting circuits 22 and 25 is determined by the frequency designation switch 4.
0 and is supplied to the inverting input (-) of the comparator 30. This comparative example 30 outputs a logic "1" signal when the output voltage of the thermistor 20 becomes higher than the selection voltage of the switch 40, and the output is supplied to the arithmetic processing section 50. The arithmetic processing unit 50 excites the relay 51 by being supplied with a logic “1” signal from the comparator 30, and maintains this state for a certain period of time (time safe) regardless of the change in the output of the comparator 30. It's getting old.

On the other hand, 60 is a commercial AC power supply, and this power supply 60 is connected to a blower motor 12M via a relay contact 61.
The blower motor 11M is connected through the relay contact 62, the electromagnetic coil 2L of the four-way valve 2 is connected through the relay contact 63, and the compressor motor 1M is connected through the relay contact 64.
are connected to each other. Here, relay contact 6
1, 62, 63, and 64 are operation control units (not shown) mainly composed of microcomputers, etc.
The controller is adapted to operate in response to commands such as, for example, the operating state of a driving operation unit (not shown) or changes in indoor temperature. Furthermore, the power supply 60 has a contact 51a of the relay 51.
The electromagnetic coil 10L of the two-way valve 10 is connected through the two-way valve 10.

In this way, the comparator 30, the arithmetic processing section 50, the relay 51, the two-way valve 10, etc. are used as main components, and the positive characteristic is a means for setting the refrigeration cycle to a high capacity operating state when the detection result of the positive characteristic thermistor 20 is below the reference value. means for setting the refrigeration cycle to a low capacity operating state when the detection result of the thermistor 20 is equal to or higher than a reference value; It constitutes a means for maintaining the temperature for a certain period of time.

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

First, when the frequency of the power supply 60 is 50Hz, the switch 40 is switched to the 50Hz load reference value setting circuit 22 side. However, now, relay contacts 61, 6
2, 63, and 64 are closed, the operation of the compressor 1, outdoor blower 11, and indoor blower 12 is started, and the four-way valve 2 is switched to start heating operation. At this time, if an overload condition occurs where the total temperature of the outside air temperature and indoor temperature exceeds 30℃, the third
As shown in the figure, although the required heating capacity (broken line in the figure) is small, the heating capacity (solid line in the figure) becomes large, and as a result, the compressor 1 becomes overloaded. At this time, if the output voltage of the thermistor 20 exceeds the output voltage of the 50Hz load reference value setting circuit 22, that is, if the load applied to the compressor 1 exceeds the 50Hz load reference value, the comparator 30 outputs a logic "1" signal, which causes the two-way valve 10 to open. Then, as shown by the dashed line in Fig. 3, the heating capacity decreases and the compressor 1
overload operation is prevented. In this case, as the condensing temperature in the indoor heat exchanger 12 decreases as the capacity decreases, the output of the comparator 30 returns to the logic "0" signal, and this output change is repeated. By maintaining the excitation state of the relay 51 for a certain period of time by the time safe function of the relay 50, stable operation is performed.

By the way, in the national situation of Japan, areas where commercial AC power has a frequency of 50Hz include cold regions.
Heating capacity tends to be insufficient in such cold regions. Therefore, if the capacity is reduced just to prevent overload operation of the compressor 1 as described above, comfortable heating in cold regions will become impossible. Therefore, 50Hz load standard setting circuit 2
The load reference value based on No. 2 is set to be larger than the actually required value to some extent to allow overload operation of the compressor 1 to the extent that breakdown does not occur.

On the other hand, when the frequency of the power supply 60 is 60Hz, the switch 40 is switched to the 60Hz load reference value setting circuit 25 side. However, during heating operation, thermistor 2
When the output voltage of 0 exceeds the output voltage of the 60Hz load reference value setting circuit 25, that is, when the load applied to the compressor 1 exceeds the load reference value for 60Hz (lower than that for 50Hz), the comparator The output of 30 becomes a logic "1" signal and the two-way valve 10 opens. In this way, heating capacity is reduced and overload operation of the compressor 1 is prevented.

Therefore, we have prepared a load reference value for a power supply frequency of 50Hz and a load reference value for a smaller 60Hz power supply frequency, and these load reference values can be switched appropriately according to the power supply frequency, thereby improving energy efficiency. Even if a low-output compressor motor is used for the purpose,
Overload operation can be prevented, and breakdown of the compressor motor and accompanying burnout of the compressor motor can be prevented. In addition, while preventing overload operation, the maximum capacity variable range is ensured for each power supply frequency, and efficient operation is possible without waste.

In the above embodiment, the load reference value is changed by operating the switch 40, but for example, a discrimination circuit for discriminating the power supply frequency is provided, and the load reference value is automatically changed based on the output of this discrimination circuit. It is also possible to switch. In addition, this invention is not limited to the above embodiments,
Of course, various modifications can be made without changing the gist.

As described above, according to the present invention, there is provided a detection means for detecting the refrigerant discharge pressure of the compressor of the refrigeration cycle during heating operation, and a detection means for detecting the refrigerant discharge pressure of the compressor of the refrigeration cycle, and when the detection result of the detection means is below a reference value, the refrigeration cycle is The apparatus includes means for setting the refrigeration cycle to an operating state, means for setting the refrigeration cycle to a low capacity operating state when the detection result of the detecting means is equal to or higher than a reference value, and means for switching the reference value according to the power supply frequency. Although the compressor motor has a low output, it is possible to provide an excellent air conditioner that enables optimal operation depending on the situation.

[Brief explanation of drawings]

The drawings show one embodiment of the invention.
The figure is an overall schematic configuration diagram, FIG. 2 is a configuration diagram of a control circuit, and FIG. 3 is a characteristic diagram of temperature and heating capacity. 1...Compressor, 9...Release circuit, 10...
Two-way valve, 20...Temperature sensor (positive characteristic thermistor), 22...Load reference value setting circuit for 50Hz, 25
...Load reference value setting circuit for 60Hz, 30...Comparator, 40...Frequency specification switch.

Claims (1)

[Claims] 1. In an air conditioner equipped with a heat pump type refrigeration cycle having a variable capacity function, a detection means for detecting the refrigerant discharge pressure of the compressor of the refrigeration cycle during heating operation, and a detection means for detecting the refrigerant discharge pressure of the compressor of the refrigeration cycle when the detection result of the detection means is below a reference value. means for setting the refrigeration cycle to a high capacity operation state when the detection result of the detection means is equal to or higher than a reference value; An air conditioner characterized by comprising a switching means.