JPH04159479A - Refrigerating and air conditioning device - Google Patents

Abstract

PURPOSE:To prevent a seizure trouble due to improper lubrication by connecting a lubricating oil reservoir to a compressor suction side pipe through a pipe, on the halfway of which an opening/closing control valve and a pressure reducer are interposed, and introducing lubricating oil to a compressor suction side as necessary. CONSTITUTION:In addition to a main cycle constituted of a condenser 14, pressure reducer 15, evaporator 16 and a scroll compressor 13, a pipe is connected to a liquid refrigerant introducing pipe, connected to a compression chamber of the compressor 13 through a pressure reducing pipe from an outlet of the condenser 14, and to a suction side pipe of the compressor 13 from an oil reservoir part in the compressor 13, to connect a pressure reducing pipe 17 and an electromagnetic valve 18 between these pipes. The electromagnetic valve 18 is controlled so as to open only during operation of the compressor 13, so that oil is prevented from accumulating in the compression chamber during stopping. Based on the above-mentioned control, oil is introduced only at the time of introducing overheat operation-preventing high pressure liquid refrigerant. Further in the case of considering oil introduced only at the time of liquid return operation, suction gas temperature, pressure, etc., are detected to introduce oil in the case of, for instance, an overheat degree of 5deg deg.C or less.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a refrigeration and air conditioning system using a fluorocarbon refrigerant, and relates to a method for lubricating a compressor installed in the system.

[Conventional technology]

In conventional refrigeration and air conditioning systems, high-pressure liquid refrigerant is introduced into a closed space during compression in order to prevent overheating of the compressor, as described in Tokuhara No. 63-95606.

In addition, as described in Japanese Patent Application Laid-Open No. 63-186991, in order to prevent lubrication failure accidents due to insufficient oil amount in the oil reservoir in the compressor closed container, the amount of oil coming up is reduced and the oil reservoir is lubricated. The amount of oil was secured.

[Problem to be solved by the invention]

Reducing oil spillage using the above conventional technology is a very important item in order to secure the lubricating oil that is essential for compressor operation, but at the same time, the small amount of oil spilling into the refrigeration cycle means that the compressor This indicates that the amount of oil returned is small. In a compressor that has a structure in which suction gas is sucked directly into the compression mechanism from the suction pipe of the compressor, if liquid refrigerant returns from the evaporator side,
Since it is directly sucked into the compression mechanism, the liquid refrigerant may reduce the lubricating effect of the lubricating oil, and if the amount of oil returned from the refrigeration cycle is small, this effect will be noticeable.
In the worst case, poor lubrication may result in metal-to-metal contact and seizure. Further, if high-pressure liquid refrigerant for preventing overheating operation is introduced in a state where the amount of oil returned is small at the other end, the lubricating effect of the sliding portion may be reduced.

The present invention aims to prevent deterioration of lubrication performance due to liquid refrigerant by utilizing conventional techniques for preventing oil run-up and overheating.

[Effect]

During operation, the pressure in the oil reservoir in the compressor's closed container is high, while the pressure in the suction pipe that introduces oil is low. When the pipe connecting the two is opened by valve control, the pressure difference causes the oil to The lubricating oil in the reservoir flows into the suction side piping.

The piping should be decompression piping with a certain resistance, or
A flow rate adjustment valve is installed, and the amount of oil introduced is controlled by controlling the opening and closing of the valve in the former case, and by controlling the valve opening degree in the latter case.

The lubricating oil introduced into the suction pipe is sucked into the compression space of the compressor and assists in lubricating the sliding parts.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a scroll compressor used in this example.

The structure of this compressor is that a fixed spiral portion 2. Rotating whirlpool 3. Anti-rotation device 4. The compression mechanism section consisting of the frame 5, the electric motor 6 and the compression mechanism section are connected 2M! It is equipped with a compression device constituted by a moving drive shaft 7, and the bottom of the closed container serves as an oil reservoir 8 for lubrication. The suction gas from the refrigeration cycle is sucked through the suction pipe 9, and is passed through the compression chamber 10.
It is compressed and discharged from the discharge boat 11 into a closed container. Thereafter, after oil separation and motor cooling, the oil is discharged from the discharge plumber 2. The separated oil will collect at the bottom of the sealed container.

During overheating operation, liquid refrigerant is introduced from the liquid refrigerant introduction pipe 19.

FIG. 2 shows an explanatory diagram of the refrigeration cycle. Condenser 14, pressure reducing device 15. In addition to the main cycle consisting of the evaporator 16 and the scroll compressor 13, the liquid refrigerant introduction pipe connected to the compressor compression chamber from the condenser outlet via the decompression pipe 20, and the compressor from the oil reservoir inside the compressor, Connect the piping to the suction side piping of the machine, and in between, connect the depressurization piping 17. Connect the solenoid valve 18.

The solenoid valve 18 is controlled to open only when the compressor is in operation, to prevent oil from accumulating in the compression chamber while the compressor is stopped.

Based on the above control, it is also possible to introduce oil only when high-pressure liquid refrigerant is introduced to prevent overheating.

In addition, when considering introducing oil only during liquid return operation, it is possible to detect either or both of the suction gas temperature and pressure, or the discharge gas temperature and pressure, and for example, when the degree of superheat is 5 deg C or less. It is possible to introduce oil.

The opening/closing control using a solenoid valve and pressure reducing piping has been shown above, but instead, a flow rate adjustment valve is used to detect the degree of superheating of the suction or discharged gas, adjust the opening degree of the flow rate adjustment valve, and change the amount of oil returned. The required amount of oil can be returned according to the liquid return condition.

Furthermore, by arranging the return position of the oil within the closed space of the compression chamber of the compressor, it is possible to reduce the decrease in the amount of refrigerant circulation, that is, the decrease in the refrigerating capacity, due to the thermal influence of the returned oil.

〔Effect of the invention〕

According to the present invention, while reducing oil drainage, which has been considered important in the past, it is possible to prevent lubricating oil shortage even if liquid returns due to transient operation or improper adjustment of the expansion valve, etc. It becomes possible to prevent seizure accidents.

In this case, by detecting the degree of superheat when introducing high-pressure liquid refrigerant, oil can be introduced only when necessary. Furthermore, when a flow rate adjustment valve is used, it is possible to prevent the amount of oil introduced from being too large or too small depending on the operating conditions, thereby enabling highly efficient operation.

When the oil is returned to the space after confinement in the compression chamber of the compressor, compared to when it is returned to the suction side piping, there are problems such as overheating of the suction gas due to high-temperature, high-pressure oil, release of refrigerant mixed in the oil, and Performance deterioration due to a decrease in gas refrigerant circulation amount due to volume is reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the structure of a scroll compressor according to an embodiment of the present invention, and FIG. 2 is a diagram showing the structure of a refrigeration cycle using the scroll compressor. DESCRIPTION OF SYMBOLS 1... Airtight container, 2... Fixed whirlpool part, 3... Rotating whirlpool part, 5... Frame, 8... Oil pool part, 9...
... Suction pipe, 12... Discharge pipe, 13... Scroll compressor, 14... Condenser, 15... Pressure reducing device,
16... Evaporator, 17... Piping for pressure reduction, 18...
Solenoid valve, 19...liquid refrigerant introduction pipe.

Claims (3)

[Claims] 1. The compressor is equipped with a structure in which a compression mechanism, a motor that drives it, and a lubricating oil reservoir are housed in a high-pressure sealed container, and suction gas is sucked directly into the compression chamber from the suction piping of the sealed container. , in a refrigeration and air conditioning system for fluorocarbon refrigerant that introduces high-pressure liquid refrigerant into the closed space of the compression chamber of the compressor as necessary to cool the motor and discharged gas, between the lubricating oil reservoir and the compressor suction side piping. are connected by piping via an on-off control valve and a pressure reducing device in the middle, and lubricating oil is continuously or temporarily introduced into the compressor suction side as necessary,
A refrigeration and air conditioning system characterized by increasing the amount of oil supplied to sliding parts in a compression chamber space. 2. The refrigeration and air conditioning system according to claim 1, wherein lubricating oil is introduced into the compressor suction pipe during the high-pressure liquid refrigerant introduction operation for preventing overheating to increase the amount of oil supplied to the compression chamber space. 3. To control the on-off control valve for introducing lubricating oil, the pressure and temperature inside the suction pipe are detected, and when the degree of superheat of the suction gas calculated from this becomes less than the set value, the on-off control valve controls the compressor suction. The refrigeration and air conditioning system according to claim 1, wherein lubricating oil is introduced to the side.