JPS6373053A - Air conditioner - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an air conditioner using an electric expansion valve as a pressure reducer.

Conventional technology In recent years, air conditioners have become mainstream with the aim of improving comfort and energy saving, and are equipped with electronic control devices such as microcomputers, and are variable in capacity using frequency variable devices. There is.

Hereinafter, the above-mentioned air conditioner will be explained with reference to FIG.

In other words, the main parts of the refrigerator are compressor 1 and condenser 2.
．． Electric expansion valve 3. Secondary pressure reducer4. Evaporator 5, liquid tank 6
, is equipped with a suction accumulator 7, and has refrigerant piping 8~
11 to connect each of the above-mentioned parts to form a refrigeration cycle.

Next, the operation of the air conditioner configured as described above will be explained. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the refrigerant pipe 8 and enters the condenser 2, where it exchanges heat with outdoor air and is liquefied.

The liquefied refrigerant passes through the refrigerant pipe 9 and is depressurized by the electric expansion valve 3 which is a secondary pressure reducer, passes through the refrigerant pipe 12 while being partially vaporized, and is further depressurized by the secondary pressure reducer 4.

At this time, surplus refrigerant in the cooling cycle remains in the liquid tank 6. The refrigerant, whose pressure has been reduced and whose temperature has been reduced, enters the evaporator 5, where it exchanges heat with indoor air and performs an indoor cooling action. The refrigerant vaporized in the evaporator 6 passes through the refrigerant pipe 11,
The liquid enters the succinic accumulator 7 and is separated into gas and liquid, and then returns to the compressor 1.

In this series of operations, the electric expansion valve 3 acts as a pressure reducer as described above, and also controls the refrigerant flow rate.Air conditioners equipped with variable capacity compressors have become mainstream. In recent years, they have been widely used in air conditioners instead of conventional capillary tube pressure reducers because of the advantages of having a wide range of variable refrigerant flow rate and the ability to easily and accurately control the refrigerant flow rate using a microcomputer.

Problems to be Solved by the Invention In such a conventional configuration, the pressure within the refrigeration cycle during operation of the air conditioner is distributed from the compressor 1 to the condenser 2. The high pressure side up to the electric expansion valve 3, and the high pressure side from the electric expansion valve 3 to the evaporator 5.
Although it is largely divided into a low pressure side up to the suction of the compressor 1, when the air conditioner is stopped, the liquid refrigerant on the high pressure side flows into the low pressure side, and the pressure within the refrigeration cycle becomes the same after a short time.

However, since the air conditioner is stopped, the low-temperature liquid refrigerant flowing into the evaporator 5 absorbs the heat of the indoor air and flows toward the compressor 1 while maintaining its liquid state without being evaporated. Therefore, when the air conditioner is operated again, the liquid refrigerant suddenly flows into the compressor 1, causing liquid compression and causing damage to the compressor 1.

The present invention solves the above problem, and when the operation of the air conditioner is stopped, the electric expansion valve is closed to prevent the liquid refrigerant from flowing from the high pressure side to the low pressure side, and the gas refrigerant is transferred from the high pressure side. The purpose of this is to operate the electric expansion valve 3 to open the electric expansion valve 3 after injecting the refrigerant and equalizing the pressure, thereby preventing liquid refrigerant from being sucked into the compressor, causing liquid compression, and causing damage.

Means for Solving the Problem In order to solve this problem, the air conditioner of the present invention includes a compressor, a condenser, an electric expansion valve, and a secondary pressure reducer.

A main circuit of a refrigeration cycle is formed by refrigerant piping that connects these parts, including an evaporator and a suction accumulator, and a refrigerant piping that connects the condenser and the electric expansion valve, and the evaporator and the suction accumulator. In addition to providing a bypass capillary tube that connects the compressor with the compressor and passing the refrigerant therethrough, the electric expansion valve control means fully closes the electric expansion valve at the same time as the compressor stops, and fully opens the electric expansion valve after a certain period of time. .

With this configuration, when the operation of the air conditioner is stopped, the flow of liquid refrigerant from the high pressure side to the low pressure side is blocked by the electric expansion valve being fully closed by the control signal from the electric expansion valve control means. In addition, the pressure on the high-pressure side and the low-pressure side is balanced by supplying gaseous refrigerant through a bypass capillary tube that connects the refrigerant pipe between the condenser and the electric expansion valve and the refrigerant pipe between the evaporator and the suction accumulator. The pressure is nine.

Thereafter, the electric expansion valve opens again in response to a control signal from the electric expansion valve control means to prepare for the next operation. Therefore, even if the compressor is restarted after being stopped, it will not suck in liquid refrigerant and liquid compression will be prevented.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, a compressor 12. Condenser 13. Electric expansion valve 14, secondary pressure reducer 15. Evaporator 16. Liquid tank 17. There is a suction accumulator 18, and refrigerant piping 19~
The refrigerant pipe 21 between the liquid tank 17 and the electric expansion valve 14 and the refrigerant pipe 23 between the evaporator 16 and the suction accumulator 18 are bypass capillary tubes that connect each component through 23 to form the main circuit of the refrigeration cycle. 24. This bypass capillary tube 24 reduces the pressure of the high-pressure liquid refrigerant to make it into a low-pressure, low-temperature liquid refrigerant and then converts it into a gas, so the refrigerant pipe 19 on the high-pressure side
, 20 are fixed in contact with each other.

The electric expansion valve control means 26 is composed of an electronic control device equipped with a microcomputer, and controls the electric overexpansion valve 14 to control pressure reduction and refrigeration capacity, as well as fully close operation at the same time as the air conditioner stops, and fully open after a certain period of time. Make the action take place.

The operation of the air conditioner configured as described above will be explained next. When the air conditioner is operated, the high temperature, high pressure gas refrigerant discharged from the compressor 12 passes through the refrigerant pipe 19 and enters the condenser 13, where it exchanges heat with outdoor air and is cooled and liquefied. The liquefied refrigerant passes through the refrigerant pipe 20 , and a small amount of the refrigerant flows into the bypass capillary tube 24 from the refrigerant pipe 21 via the liquid tank 17 . The liquid refrigerant, which has been reduced in pressure to a low pressure and low temperature, is in contact with and fixed to the high pressure side refrigerant pipes 19 and 20, absorbs heat, becomes a gas, and is sucked into the suction accumulator 18. On the other hand, high pressure side refrigerant pipe 19
, 20 emit heat and are cooled.

Most of the other refrigerants are depressurized by the electric expansion valve 14, which is a primary pressure reducer, and the secondary pressure reducer 15, and a part of the liquid refrigerant is vaporized to a low temperature, and then passes through the refrigerant pipe 22 to the evaporator 16. The liquid refrigerant evaporates by exchanging heat with the indoor air, and the air that exchanged heat is cooled to provide air conditioning. The low-pressure gas refrigerant that has exited the evaporator 16 passes through the refrigerant pipe 23 and joins with the refrigerant flowing out of the bypass capillary tube 24, and is then sucked into the compressor 12 via the suction accumulator 18 and circulated.

While the air conditioner is in operation, the electric expansion valve 14 performs capacity control adapted to the indoor load and adjusts its opening according to a control signal from the electric expansion valve control manual 5 so that the temperature and refrigerant pressure in the refrigeration cycle are appropriate.

Next, the operation of the electric expansion valve 14 when the air conditioner is stopped will be explained based on the time chart shown in FIG.

When the air conditioner is stopped, the electric expansion valve control means 26 receives the signal to stop the compressor 12, and outputs a control signal to immediately fully close the electric expansion valve 14, and maintains the fully closed state for t seconds.

is maintained for seconds, the gas refrigerant flowing from the high pressure side to the low pressure side through the bypass capillary tube 24 causes
The pressure on the high pressure side decreases, and the pressure on the low pressure side increases to equalize the pressure. The bypass capillary tube 24 is arranged to absorb heat from the high pressure side so that the liquid refrigerant that flows in from the high pressure side and is depressurized and cooled is vaporized, so it also has the function of promoting pressure reduction on the high pressure side.

After seconds have elapsed, the electric expansion valve 14 is fully opened in response to a control signal from the electric expansion valve control means 25 in order to prevent a sudden pressure rise due to insufficient opening at the time of starting the compressor.

Because of the configuration that operates as described above, the compressor 12 sucks liquid refrigerant and does not cause liquid compression.

Note that in this embodiment, the high-pressure side connection portion of the bypass capillary tube 24 is connected to the refrigerant pipe 21, but there is no difference in operation and effect even if it is connected close to the liquid tank 17 side of the refrigerant pipe 2o.

Effects of the Invention As described above, according to the present invention, while the air conditioner is operating, the refrigeration cycle operates stably with appropriate refrigerant pressure and suction temperature, and the cooling capacity is controlled according to the indoor load. The expansion valve is fully closed at the same time as the equipment is stopped, and while it is maintained fully closed, vaporized refrigerant flows from the high pressure side to the low pressure side via the bypass capillary tube and equalizes the pressure, so the evaporator is There is no inflow of liquid refrigerant, so when restarting, a large amount of liquid refrigerant suddenly returns through the suction accumulator and is sucked into the compressor, preventing liquid compression from occurring, preventing compressor failure and improving reliability. This effect can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a refrigeration cycle diagram of an air conditioner according to an embodiment of the present invention, Fig. 2 is a time chart showing the opening/closing operation of the electric expansion valve from the time the air conditioner is stopped until a certain period of time has elapsed, and Fig. 3 is a It is a refrigeration cycle diagram of a conventional air conditioner. 12... Compressor, 13... Condenser, 14
...Electric expansion valve, 15...Secondary pressure reducer,
16... Evaporator, 18... Suction accumulator, 19-23... Refrigerant piping,
24... Bypass capillary tube, 25.
...Electric expansion valve control means. Name of agent: Patent attorney Toshio Nakao and 1 other person
H.

Claims (1)

[Claims] The main circuit of the refrigeration cycle includes a compressor, a condenser, an electric expansion valve, a secondary pressure reducer, an evaporator, and a suction accumulator. A bypass capillary tube is provided that connects the refrigerant pipe connecting the expansion valve to the refrigerant pipe that connects the evaporator and the suction accumulator and allows the refrigerant to pass therethrough, and the electric expansion valve is fully closed at the same time as the compressor is stopped. An air conditioner equipped with an electric expansion valve control means that opens the valve fully after a certain period of time.