JPH0518027B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air conditioner that controls the operating frequency during defrosting during heating operation of an air-cooled heat pump air conditioner.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 59-191851, conventional air conditioners have a defrosting operation control method in which a preparatory operation period for the end of defrosting is provided, the capacity of the compressor is reduced, and the compressor returns to heating operation. . However, no concrete measures are provided in the method for establishing the preparation period for the end of defrosting.
If the above-mentioned preparation period is provided after defrosting is completed, the defrosting operation time will be extended, resulting in a decrease in comfort. Also, if a certain period in the latter half of defrosting is set as the reference period, it will be necessary to provide the preparatory period before defrosting is completely completed. No consideration was given to the problem of returning to heating operation after a while.

[Problems to be Solved by the Invention] The above prior art reduces compressor capacity. If consideration is not given to the setting method for the preparation period for the end of defrosting, and if the compressor capacity is reduced for a certain period of time during the latter half of the defrosting operation described in this section, the defrosting operation time will be expanded. There was a problem that the cold air blowing time from the indoor heat exchanger became longer, resulting in a decrease in comfort, and a problem that the defrosting was completed incompletely due to a decrease in the defrosting ability during the preparation period for completing the defrosting.

The present invention was devised in view of the above-mentioned problems, and the progress of defrosting is detected by the temperature signal of the defrost detection sensor, and the progress of defrosting is detected by a control panel that sets the compressor operating frequency based on the detected temperature. By reducing the frequency in response to the sensor temperature, which increases as the temperature rises, defrosting performance is ensured and there is no preparation period for the end of defrosting, and the compressor capacity is reduced at the end of defrosting to allow heating operation. The purpose is to make it possible to return.

[Means for solving problems]

In order to achieve the above object, the air conditioner according to the present invention includes a compressor whose operating frequency can be changed by a control panel, a four-way valve, an outdoor exchanger, an expansion valve, and an indoor heat exchanger that are connected by piping. In an air conditioner in which a refrigeration cycle is formed by installing a solenoid valve on a bypass circuit from between the compressor and the four-way valve to between the expansion valve and the outdoor heat exchanger, the outdoor heat exchanger and the expansion valve A temperature detector is installed between the starts, and when the inlet temperature of the outdoor heat exchanger rises to a predetermined set temperature below the defrosting end set temperature, the operating frequency is lowered,
This configuration includes a control panel that reduces the temperature difference between the inlet temperature and outlet temperature of the outdoor heat exchanger.

[Effect]

Defrosting operation is performed by opening the solenoid valve of the bypass circuit from the compressor outlet to the outdoor heat exchanger inlet, and high-temperature, high-pressure gas refrigerant is sent from the compressor to the outdoor heat exchanger. A portion of the refrigerant is also sent to the indoor heat exchanger for heating operation.
In such a defrosting refrigeration cycle, the progress of defrosting is detected by a control panel from a temperature signal from a defrosting sensor installed on the piping between the expansion valve and the outdoor heat exchanger, and the temperature The compressor capacity is controlled during defrosting by a control panel that sets the operating frequency so that the compressor operates at high rotation speeds when the temperature is low and at low rotation speeds when the temperature is high. The defrosting operation progresses differently depending on the amount of defrost, but by changing the frequency it is possible to equalize the defrosting operation status, so defrosting is completed regardless of whether there is a large amount of frost or a small amount of frost. It becomes possible to shorten the defrosting time and shift to heating operation without performing preparatory operation.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a refrigeration cycle constructed by sequentially connecting a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an expansion valve 4, and an indoor heat exchanger 5 through piping. A solenoid valve 6 is disposed on a bypass circuit extending from the outdoor heat exchanger 3 to the four-way valve 4. Further, the operating frequency of the compressor 1 is variably controlled by a control panel 8. In the heating operation in this refrigeration cycle, the refrigerant gas compressed by the compressor 1 flows through the four-way valve 2 to the indoor heat exchanger 5, performs the heating operation, becomes liquid refrigerant, and is depressurized and expanded in the expansion valve 4. This is due to the fact that the outdoor heat exchanger 3 absorbs heat and evaporates, and the air is sucked into the compressor 1 again through the four-way valve 2, but the outside air temperature decreases and frost forms on the outdoor heat exchanger 3. A significant decrease in capacity occurs, and it becomes necessary to perform defrosting operation.

Defrosting operation is performed after a certain period of time when the temperature difference between the outside air detection temperature sensor (not shown) and the defrosting detection sensor 7 installed at the expansion valve outlet during heating operation is greater than or equal to the set temperature difference. be done. During defrosting operation, first, the operating frequency of the compressor 1 is set to the maximum value on the control panel 8, the solenoid valve 6 is opened, and the high-pressure high-pressure gas refrigerant is allowed to flow into the outdoor heat exchanger 3 through the bypass circuit. In addition, by flowing a part of the gas refrigerant to the internal heat exchanger 5, the indoor heat exchanger 5 performs heating operation, expands in the expansion valve 4, mixes with the refrigerant flowing from the bypass circuit, and heats the outdoor heat. It flows into the exchanger 3, is condensed in the outdoor heat exchanger 3, is defrosted, and is sucked into the compressor 1 again.

Figure 2 shows a time chart when the defrosting operation is always performed at the highest frequency. Since the compressor always operates at the maximum frequency during defrosting operation, the outdoor heat exchanger inlet temperature TEi, which is the mounting part of the defrosting detection sensor 7, increases as defrosting progresses. On the other hand, the outdoor heat exchanger outlet temperature TEo relatively follows TEi and rises when the frost condition is normal, but when the frost is heavy, it rises later than the rise of TEi. In addition, even when the defrosting end temperature TEiset was reached, the temperature TEo at the outlet of the outdoor heat exchanger 3 did not reach a level where the frost could be completely thawed, and heating was resumed. For this purpose, the defrosting sensor 7 detects the above TEi, and the control panel 8 sets the operating frequency of the compressor 1 in response to the detected temperature signal.
The set value is such that when TEi is low, the frequency is high, and as TEi increases with the progress of defrosting, the frequency is decreased, and when TEi is high, the frequency is decreased. Figure 3 shows a time chart of the above control. As the defrosting operation progresses, the heat exchanger inlet temperature TEi
rises and the set temperature is below the defrosting end set temperature.
When the temperature reaches TEi1, the control panel 8 lowers the operating frequency of the compressor 1, and the amount of refrigerant circulated in the refrigeration cycle decreases. Therefore, the suction pressure at the compressor inlet increases, and the outdoor exchanger outlet temperature TEo increases. on the other hand
The increase in TEi is temporarily suppressed due to the decrease in defrosting ability due to the decrease in the amount of circulation, and the temperature difference between TEi and TEo is reduced. As defrosting progresses further, TEi becomes TEi2.
When the temperature rises to this level, the frequency is lowered in the same manner as above, and the frequency is controlled to reduce the temperature difference between TEi and TEo while the temperature reaches TEiset, thereby uniformly defrosting the entire outdoor heat exchanger 3. becomes possible.

〔Effect of the invention〕

According to the present invention, since the operating frequency can be lowered without setting a defrosting end preparation period, there is no need to delay the time to return to heating from defrosting, and the defrosting time can be shortened and comfort can be improved. . When the temperature on the inlet side of the outdoor heat exchanger rises to a certain set temperature below the defrosting end pressure, the compressor operating frequency during defrosting is lowered and controlled by constantly running at high speed during defrosting. , frost can be removed uniformly from the entire outdoor heat exchanger. Furthermore, when defrosting is performed constantly at high speeds, oil in the compressor is likely to be released into the cycle system along with the amount of refrigerant being circulated, which inevitably reduces the retained amount. The reliability of the machine can be improved.

[Brief explanation of drawings]

FIG. 1 is a cycle system diagram of an embodiment of the present invention.
FIG. 2 is a time chart of the temperature at the inlet and outlet of the outdoor heat exchanger during constant high-speed operation during defrosting, and FIG. 3 is a time chart when the compressor is operated during defrosting. 1... Compressor, 2... Four-way valve, 3... Outdoor heat exchanger, 4... Four-way valve, 5... Indoor heat exchanger, 6...
...Solenoid valve, 7...Defrost detection sensor, 8...Control panel, ...Refrigerant flow during heating, ...Refrigerant flow during defrost, ...Signal flow, solid line...When frost formation is normal Time chart...One-dot chain line...Time chart when frost buildup is severe.

Claims (1)

[Claims] 1 A compressor whose operating frequency can be changed by a control panel, a four-way valve, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected by piping, and the expansion is connected between the compressor and the four-way valve. In an air conditioner in which a refrigeration cycle is formed by disposing a solenoid valve on a bypass circuit leading between the valve and the outdoor heat exchanger,
A temperature detector is provided between the outdoor heat exchanger and the expansion valve, and when the temperature difference between the temperature detection value of the temperature detector and the outside air temperature exceeds a set temperature difference, the operating frequency is set to a maximum value. At the same time, the solenoid valve is opened to start defrosting operation, and when the temperature on the inlet side of the outdoor heat exchanger rises to a predetermined set temperature that is equal to or lower than the frost end set temperature, the operating frequency is lowered, and the An air conditioner comprising the control panel that reduces the temperature difference between the inlet temperature and the outlet temperature of the outdoor exchanger.