JP3653330B2 - Refrigeration cycle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration cycle of a refrigerator and an air conditioner.
[0002]
[Prior art]
As described in p19 of the “MYCOM Screw General Catalog” September 1990 edition, the conventional device generally returns the oil discharged from the shaft seal device to the suction side of the compressor.
[0003]
[Problems to be solved by the invention]
When the oil supplied to the shaft seal device is returned to the suction side of the compressor as in the above prior art, the compressor sucks oil in addition to the gas refrigerant, so the discharge amount is reduced and the refrigeration capacity is reduced. Will be invited. In addition, if the amount of oil returning to the suction side of the compressor is large, oil compression may occur, and if the suction pressure is ultra-vacuum, the intermediate pressure decreases and oil is supplied to the shaft seal device. Since the oil pressure also decreases, there is a drawback that it is necessary to always adjust the pressure in the shaft seal device so as not to be lower than the atmospheric pressure.
An object of the present invention is to obtain a refrigeration cycle capable of preventing a reduction in refrigeration capacity and oil compression in a refrigeration cycle including an open screw two-stage compressor having a shaft seal device.
[0004]
[Means for Solving the Problems]
To achieve the above object, the present invention provides an open-type screw two-stage compressor, an oil separator, an oil tank, an oil cooler, an oil having a suction side casing, an intermediate casing, and a shaft seal device provided on the suction side. In a refrigeration cycle including a strainer and a condenser, refrigerating machine oil from an oil separator provided in the refrigeration cycle is supplied to a shaft seal device provided on the suction side of the two-stage compressor through a throttle mechanism. The refrigerating machine oil supplied to the shaft seal device through a throttle mechanism and lubricated and cooled in the shaft seal device is discharged into the intermediate casing serving as an intermediate pressure portion of the two-stage compressor , The throttle mechanism adjusts the refrigerating machine oil from the oil separator to a pressure higher by 1 to ² kg / cm ² than the intermediate pressure in the intermediate casing, and supplies the oil to the shaft seal device. Also It is.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. The solid line arrow in the figure indicates the flow direction of the refrigerant, and the broken line arrow indicates the flow direction of the refrigerating machine oil. The refrigerant is compressed on the low-stage and high-stage sides of an open-type screw two-stage compressor (hereinafter referred to as a compressor) 1 and is discharged as a high-temperature and high-pressure gas together with the oil. Separated into gas and oil. The refrigerant gas is cooled by cooling water or liquid refrigerant in the condenser 6 to become a condensate, the liquid temperature is lowered in the supercooler 7, becomes a low-pressure wet gas by the action of the main expansion valve 8, and evaporates in the evaporator 9. Then, after cooling the object to be cooled, it is sucked into the compressor 1.
[0006]
On the other hand, the oil separated by the oil separator 5 is discharged to the oil tank 10. The oil that has entered the oil cooler 11 from the oil tank 10 and has been cooled by cooling water or liquid cooling is removed from the foreign matter in the oil by the oil strainer 12, and then each bearing portion that is an intermediate pressure portion between the hydraulic pressure and the compressor 1. Oil is supplied to the bearing portion of the compressor 1 and the shaft seal device 4 by a pressure difference from the pressure of the compressor.
[0007]
The oil supplied to the shaft seal device 4 lubricates and cools the shaft seal device 4, and is once discharged from the suction side casing 15 of the compressor 1 to the outside of the compressor, and between the suction side casing 15 and the intermediate casing 16. It passes through the connected external pipe 17 and is discharged into the intermediate casing 16. At this time, the hydraulic pressure in the shaft seal device 4 is 1 to ² kg / cm ² higher than the intermediate pressure at a throttle valve 13 provided in the middle of the oil supply pipe to the shaft seal device 4 and more than an appropriate amount of oil is supplied. It is adjusted not to flow into the shaft seal device 4.
[0008]
3 and 4, solid lines represent piping, and broken lines represent wiring. When the automatic flow control valve 18 is used for the throttle mechanism, the automatic flow control valve 18 detects the intermediate pressure, and adjusts the hydraulic pressure after passing through the automatic flow control valve 18 by automatically opening and closing the valve along with the change in the intermediate pressure, And adjust the amount of oil. Similarly, when the microcomputer 21 is controlled, the valve opening is adjusted from the microcomputer 20 to the microcomputer-controlled throttle valve 19 so that the intermediate pressure and the pressure in the shaft seal device 4 are detected by the sensor 20 and the optimum differential pressure is obtained. To stabilize the oil supply.
[0009]
【The invention's effect】
According to the present invention, the shaft seal device provided on the suction side of the open-type screw two-stage compressor is supplied with refrigerating machine oil from the oil separator provided in the refrigeration cycle through the throttle mechanism, and this shaft. The refrigerating machine oil supplied to the sealing device through the throttle mechanism and lubricated and cooled by the shaft sealing device is discharged into an intermediate casing that serves as an intermediate pressure part of the two-stage compressor , and the throttle mechanism Since the refrigerating machine oil from the oil separator is adjusted to a pressure higher by 1 to ² kg / cm ² than the intermediate pressure in the intermediate casing and supplied to the shaft seal device, an appropriate amount of refrigerating machine oil is used as a shaft. The refrigerating machine oil can be returned to the refrigerating cycle from the intermediate casing of the screw two-stage compressor. Or a result, since it is possible to prevent the said shaft sealing device refrigerating machine oil discharged from is sucked into the compressor along with gas refrigerant from the suction side of the two-stage compressor, reduces the refrigeration capacity discharge amount decreases The effect which can prevent that oil compression arises is acquired.
[0010]
In addition, when an automatic flow control valve, a microcomputer-controlled throttle valve, or the like is used as the throttle valve 13, work such as opening adjustment of the throttle valve 13 can be omitted even when there is a sudden pressure fluctuation. Saves maintenance. And by adopting the external piping, it is possible to check whether the refrigeration oil is always flowing by the surface temperature of the piping, the flow noise in the piping, etc., and it becomes difficult for the oil to flow when poor oil supply occurs. Therefore, since the pipe surface temperature falls, it can be noticed quickly.
[0011]
Furthermore, the supply and discharge oil to the shaft sealing apparatus 4, and the oil supply from the upper shaft sealing apparatus 4, if the structure to discharge upwardly, always possible to fill the shaft seal device 4 with oil, the shaft sealing device 4 It is possible to prevent the oil from running out , and to improve the reliability of the shaft seal device 4.
[Brief description of the drawings]
FIG. 1 is a refrigeration cycle system diagram of one embodiment of the present invention.
FIG. 2 is a compressor cross-sectional view showing a flow path of supply and discharge oil of a shaft seal device according to the present invention.
FIG. 3 is a diagram of an oil supply system when an automatic flow control valve is used for the throttle mechanism.
FIG. 4 is a diagram of an oil supply system when a microcomputer-controlled throttle valve is used for the throttle mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 4 ... Shaft seal device, 13 ... Throttle valve, 14 ... Seal cover, 15 ... Suction side casing, 16 ... Intermediate casing, 17 ... Oil return piping

Claims (1)

In a refrigeration cycle including a suction side casing, an intermediate casing and an open screw two-stage compressor having a shaft seal device provided on the suction side, an oil separator, an oil tank, an oil cooler, an oil strainer and a condenser ,
While supplying the refrigerating machine oil from the oil separator provided in the refrigeration cycle to the shaft seal device provided on the suction side of the two-stage compressor through the throttle mechanism,
The refrigerating machine oil, which is supplied to the shaft seal device through a throttle mechanism and lubricated and cooled, is configured to be discharged into the intermediate casing serving as an intermediate pressure portion of the two-stage compressor , and The squeezing mechanism adjusts the refrigeration oil from the oil separator to a pressure higher by 1 to ² kg / cm ² than the intermediate pressure in the intermediate casing, and supplies the oil to the shaft seal device. cycle.

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