JPH109179A - Oil recovery mechanism of oil-cooled screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a difference in temperature between the recovered oil and suction air, and prevent a drop in performance of an oil recovery mechanism for an oil-cooled screw compressor by providing a recovery pipeline communicating with the suction confined space of the compressor for recovering oil into the suction confined space after cooling the oil by way of a cooler. SOLUTION: The oil reserved in an oil separator 6 circulates due to the differential pressure between the oil separator 6 and the oil filler port of a compressor body 1 through a pressure regulating valve 7 to an oil cooler 8 to be cooled there, and through a filter 9 into the compressor body 1, bearings 10 to 13 and a mechanical seal 14 for lubrication. The oil fed to the bearings 10 to 13 and the mechanical seal 14 in the compressor body 1 is recovered along a recovery pipeline 16 through an oil cooler 17 to be cooled there and into a suction confined space 18 in the compressor body 1. The returning of hot oil recovered from the bearings 10 to 13 and the mechanical seal 14 into the suction confined space 18 between the rotors in the compressor 1 prevents a drop is quantity of suction air caused by the expansion of suction air in the suction port before its confinement due to the heating by the recovered oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oil recovery mechanism for an oil-cooled screw compressor.

[0002]

2. Description of the Related Art A known example closest to the present invention is disclosed in
Japanese Patent Application Laid-Open No. 5-60082 discloses an "oil recovery mechanism for a screw compressor". In this known example, a recovery path communicating with the compression chamber after the suction cutoff of the compressor and a recovery path communicating with the suction side are provided as an oil recovery path of the oil supply unit, and the oil recovery is performed by a differential pressure valve operated by a high-low differential pressure. This is a mechanism that switches the path to prevent performance deterioration due to insufficient oil supply at low differential pressure and oil collection to the suction side at high differential pressure. The problem with this known example is that performance degradation caused by the temperature difference between the recovered oil temperature and the suction fluid cannot be prevented.

[0003]

When the oil supplied to the bearings and shaft seals is recovered to the suction side during operation, the temperature of the recovered oil is higher than the intake air temperature. However, the present invention has a problem that heat expansion occurs, and the amount of intake air decreases, leading to a decrease in performance. An object of the present invention is to solve this problem.

[0004]

Means for Solving the Problems As means for recovering oil supplied to the bearing and the shaft seal portion, the oil is recovered through a recovery pipe communicating with a space after the suction of the compressor is closed, and a cooler is provided in the recovery pipe. The recovered oil is cooled to reduce the temperature difference between the recovered oil and the intake air.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. This figure shows a sectional view of a compressor main body 1 of an oil-cooled screw air compressor, and shows a system of an oil supply system and an oil recovery path. The compressor body 1 has a pair of a male rotor 2 and a female rotor 3. The air sucked from the suction port 4 with the rotation of each rotor is compressed in the rotor and then passes through the discharge pipe 5 to the oil separator 6. Discharged after separating oil inside the entrance. The oil collected in the oil separator 6 circulates due to the differential pressure between the oil supply port of the compressor body 1 and the oil cooler 8 through the temperature control valve 7.
Is cooled in the compressor body through the filter 9 and each bearing 1
Oil is supplied to the mechanical seals 14 and 13.

The function of the temperature control valve 7 is to control the refueling temperature in order to prevent the discharge temperature of the compressor from dropping too much at the time of light load operation and start-up, and to prevent drainage. Hot oil is supplied into the compressor body through the bypass pipe 15 without passing through the oil cooler 8.

The oil supplied to the bearings 10 to 13 and the mechanical seal 14 in the compressor body is recovered through a recovery pipe 16 shown by a dotted line, cooled by an oil cooler 17, and then cooled into a suction closed space 18 of the compressor body 1. Collect inside.

[0008]

The effects of the present invention include the following.

1) By returning the high temperature recovered oil of the bearing and the mechanical seal into the suction closed space between the rotors of the compressor,
It is possible to prevent a decrease in the amount of intake air caused by the heating expansion of the intake air in the intake port before closing by the recovered oil.

2) By further cooling the recovered oil, it is possible to prevent a rise in pressure caused by heating of the intake air by the recovered oil in the confined space and a decrease in performance due to air leakage between the rotors.

Particularly when the ambient temperature is low, the temperature difference between the oil supply temperature to the compressor body and the intake air temperature increases due to the oil temperature control operation of the temperature control valve, and the influence of the heating of the intake air by the recovered oil. However, according to the present invention, when the ambient temperature is 0 ° C. and the recovered oil temperature is cooled from 80 ° C. to 60 ° C., about 6%
Is expected to improve performance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a compressor main body, an oil supply system, and an oil recovery system of an oil-cooled screw air compressor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor main body, 2 ... Male rotor, 3 ... Female rotor, 4 ... Suction port, 5 ... Discharge piping, 6 ... Oil separator, 7 ...
Temperature control valve, 8, 17 ... oil cooler, 9: filter, 10
-13: bearing, 14: mechanical seal, 15: bypass piping, 16: recovery piping, 18: suction closed space.

Claims (1)

[Claims] An oil recovery mechanism for constantly recovering oil supplied to an oil supply section of an oil-cooled screw compressor, wherein a recovery pipe communicating with a suction closed space of the compressor is provided, and the recovered oil is passed through a cooler. An oil recovery mechanism for an oil-cooled screw compressor, wherein the oil is recovered in a closed space of the compressor after cooling.