JPS6349640Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to an air conditioner equipped with a heat pump type refrigeration cycle having a variable capacity compressor.

[Technical background of the invention and its problems]

Conventionally, as this type of air conditioner, there is one that performs control as shown in FIG. That is, the operating frequency of the compressor is variably controlled according to the difference between the indoor temperature setting and the indoor temperature. In particular, we have established a maximum and minimum operating frequency for the operating frequency.
The difference between the indoor temperature setting and the indoor temperature is a constant value (3deg)
In the above cases, the compressor is operated at the highest operating frequency.

By the way, the cooling/heating ratio of the air conditioning load in such an air conditioner, for example, a commercial air conditioner, is 1:1 to 1.
The ratio is approximately 1:1.5, and there is a strong demand for increased heating capacity, especially in cold regions. However, since the above-mentioned operation control is adopted not only for cooling operation and heating operation, that is, since the operating frequency is the same during cooling operation and heating operation, the cooling/heating ratio of the operation capacity is 1. : Only about 1.05,
The heating capacity is insufficient, and problems remain in terms of product quality and reliability.

Therefore, it may be possible to increase the maximum operating frequency of the compressor to obtain the necessary and sufficient heating capacity even in cold regions, but this would increase the amount of refrigerant circulating in the refrigeration cycle under conditions of high outdoor temperature. A new problem arises in that the durability of the valve is adversely affected. Moreover, the problem arises that the high pressure of the refrigeration cycle increases abnormally, causing the high pressure switch to operate and stop the operation.

[Purpose of invention]

This idea was devised in view of the above circumstances, and its purpose is to create a system that does not adversely affect the durability of the compressor valve or cause an abnormal increase in pressure on the high pressure side. The purpose of the present invention is to provide an air conditioner with excellent product quality and reliability that enables improved heating capacity.

[Summary of the idea]

This idea variably sets the maximum operating frequency of the compressor during heating operation according to the outdoor temperature.

[Example of idea]

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

As shown in FIG. 2, a variable capacity compressor 1, a muffler 2, a four-way valve 3, an outdoor heat exchanger 4, a pressure reducing device, such as a bridge between an expansion valve 5 and a check valve 6, 6, 6, 6, etc. The circuit, the dryer 7, the indoor heat exchanger 8, and the like are sequentially connected to form a heat pump type refrigeration cycle. Therefore, during cooling operation, the refrigerant flows in the direction of the solid line arrow shown in the figure, forming a cooling cycle, and during heating operation, the four-way valve 3 is switched and the refrigerant flows in the direction of the broken line arrow, forming the heating cycle. is formed. In addition, a high pressure switch 9 is installed in the high pressure side refrigerant pipe between the compressor 1 and the four-way valve 3.
will be provided. Further, an outdoor fan 10 is provided near the outdoor heat exchanger 4 , and an indoor fan 11 is provided near the indoor heat exchanger 8 .

FIG. 3 shows the control circuit. 20 is a three-phase AC power supply, and a rectifier circuit 2 is connected to the R, S, and T phases of this power supply 20.
1 and an inverter circuit 22, a compressor motor 1M is connected thereto. The inverter circuit 22 converts the direct current supplied from the rectifier circuit 21 into alternating current at a frequency according to a command from the outdoor controller 23, which will be described later, and supplies the alternating current to the compressor motor 1M. Further, the rotation speed of the compressor motor 1M changes depending on the frequency of the supplied alternating current.
Thus, an outdoor controller 23 is connected to the R and T phases of the power source 20, and an indoor controller 24 is connected to the power line of the outdoor controller 23. The outdoor controller 23 includes a four-way valve 3, a fan motor 1, and a fan motor 1.
0M, the outdoor heat exchanger temperature sensor 25, the outdoor temperature sensor 26, and the inverter circuit 22 are connected. On the other hand, a fan motor 11M, an indoor heat exchanger temperature sensor 27, an indoor temperature sensor 28, and a driving operation section 29 are connected to the indoor control section 24. Note that information is exchanged between the indoor side control section 24 and the outdoor side control section 23 by a serial transfer method using a power supply voltage.

Next, the operation of the above configuration will be explained with reference to FIG.

Now, use the operation unit 29 to set the heating operation, set the desired indoor temperature, and perform the operation start operation. Then, the compressor 1 starts operating and the four-way valve 3 switches, forming a heating cycle. In other words, heating operation is started. At this time, the outdoor controller 23 detects the indoor temperature using the sensor 28, and controls the output frequency of the inverter 22, that is, the operating frequency of the compressor 1, according to the difference between the indoor temperature setting and the indoor temperature. That is,
If the temperature difference is 3 degrees or less, the operating frequency of the compressor 1 changes in proportion to the temperature difference. and,
When the indoor temperature is very low and the temperature difference is 3 degrees or more, as at the start of operation, the operating frequency is at its highest value. However, at this time, the outdoor temperature is detected by the sensor 26, and if the outdoor temperature is 5° C. or higher, the maximum operating frequency is suppressed to 90 Hz. Also,
If the outdoor temperature is in the range of 0.5 to 4.5°C, the maximum operating frequency is set to 105Hz. Furthermore, if the outdoor temperature is below 0°C, the maximum operating frequency is set to 120Hz.

In this way, the maximum operating frequency can be variably set in advance according to the outdoor temperature, and in extremely low conditions such as when the outdoor temperature is below 0°C, the maximum operating frequency can be set up to 120Hz. Even in cold regions, sufficient heating capacity can be obtained. Moreover, in situations where the outdoor temperature is as high as 5°C or higher and the amount of circulation in the refrigeration cycle is large, the maximum operating frequency is suppressed to 90Hz, so the durability of the valve of the compressor 1 is not adversely affected. Further, the high pressure switch 9 will not be activated due to an abnormal increase in the pressure on the high pressure side. Then,
This not only improves product quality as an air conditioner, but also improves reliability.

In the above embodiment, the maximum operating frequency is variably set in three stages, but the number of stages is not limited, and may be set steplessly, for example. Further, as shown in FIG. 5, the maximum operating frequency may be set in both a stepwise setting and a stepless setting. Furthermore, in the above embodiment, the maximum operating frequency was set by directly detecting the outdoor temperature, but we focused on the fact that there is a characteristic between the outdoor temperature and the heating load as shown in Figure 6. However, we focused on the characteristic that the compressor motor current decreases when the load decreases (the outdoor temperature is high), and we installed a means to detect the compressor motor current. The maximum operating frequency may also be set.

[Effect of idea]

As described above, this invention has improved product quality and reliability, making it possible to improve heating capacity without adversely affecting the durability of the compressor valve or causing an abnormal increase in pressure on the high pressure side. We can provide air conditioners with excellent performance.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the operation of a conventional air conditioner, Figure 2 is a configuration diagram of a heat pump refrigeration cycle showing an embodiment of this invention, and Figure 3 is the configuration of a control circuit in the same embodiment. 4 is a diagram for explaining the operation of the same embodiment, FIG. 5 is a diagram for explaining a modification of the same embodiment, and FIG. 6 is a diagram for explaining another modification of the same embodiment. This is a diagram for 1... Variable capacity compressor, 4... Outdoor heat exchanger, 8... Indoor heat exchanger, 22... Inverter circuit, 23... Outdoor control section, 24... Indoor control control section, 26 ...Outdoor temperature sensor.

Claims (1)

[Scope of utility model registration request] An air conditioner equipped with a heat pump refrigeration cycle having a variable capacity compressor and variably controlling the operating frequency of the compressor according to the difference between an indoor set temperature and an indoor temperature during heating operation, the air conditioner having an outdoor temperature sensor. An air conditioner comprising means for variably setting the maximum operating frequency of the compressor during heating operation in advance in accordance with the temperature detected by the outdoor temperature sensor.