JP2000314385A - Lubricating screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently recover drain oil on a delivery side bearing, reduce abrasion loss power of a suction side bearing, and improve efficiency of a compressor by connecting a delivery side bearing chamber and a suction side bearing oiling hole to each other through a passage, and supplying drain oil of high temperature to the suction side bearing. SOLUTION: In a compression main body 1, oil is supplied from a piping 10a to a rotor chamber 29 via a rotor oiling hole 21, oil is supplied from a piping 10b to delivery side bearings 16a, 17a via a bearing oiling hole 25a, and oil is supplied from a piping 10c to a mechanical seal 20 via a bearing oiling hole 27. Oil is supplied to the delivery side bearings 16a, 17a serving as shaft sealing on a delivery side, and oil is discharged into a D-cover 18, after passing the delivery side bearings 16a, 17a. The oil is guided to an suction side bearing oiling hole passing a return pipe 31 and is recovered to a rotor chamber 29 of a suction stroke after passing the suction side bearing 15a. The temperature of oil supplied to the suction side bearing 15a is higher than the temperature of oil supplied to the delivery side bearings 16a, 17a, effects are exerted on a rotor temperature, and the temperatures of the delivery and suction side bearings 16a, 17a, 15a are set to a nearly equal level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oil supply type screw compressor for injecting oil into a rotor chamber.

[0002]

2. Description of the Related Art A conventional oil-filled screw compressor is actually open.
As described in JP-A-60-118390, a pair of male and female screw rotors are housed in a casing, and oil cooled by an oil cooler is supplied to a rotor chamber and a bearing.

[0003] Oil supply to the rotor chamber cools the gas during compression,
The oil is separated from the compressor and the high-pressure gas by an oil separator, and the separated oil is recirculated to the compressor body. The separation oil is circulated by the pressure difference between the receiver tank having the oil reservoir, the rotor chamber and the bearing position, and the oil discharged from the bearing is recovered to the rotor chamber near the suction completion position on both the suction side and the discharge side.

[0004] The oil to the rotor chamber and the bearings in the oil supply type compressor is branched at the oil cooler outlet, and is supplied at a constant temperature. In order to maintain the performance of the compressor, the refueling temperature should be 6
It is about 0 ° C.

[0005]

In an air compressor having a pressure ratio of 8, the oil supply temperature to the compression body is about 60 ° C., the weight ratio of oil to air per unit time is about 10: 1, and the discharge is The temperature will be about 75 ° C. At this time, the bearing temperature is about 70 ° C. on the discharge side and about 60 ° C. on the suction side, and the bearing temperature is affected by the rotor having a large heat capacity. During operation, the suction-side rotor temperature is about the atmospheric temperature (≒ 20 ° C.), which is the suction temperature, and the discharge-side rotor temperature is about the discharge temperature (≒ 75 ° C.). This rotor temperature is affected by the bearing temperature. Usually, the upper limit of the bearing temperature is suppressed as a measure of the reliability of the bearing, and there is room for the suction-side bearing temperature.

[0006] In order to improve the efficiency of the compressor, it is necessary to reduce the mechanical loss. For that purpose, it is necessary to reduce the friction loss power of the bearing. The friction loss power of the bearing affects the oil viscosity in the bearing, and the lower the viscosity, the smaller the friction loss power of the bearing. However, in the prior art, since the oil is supplied at a constant temperature to both the discharge side and the suction side bearing, the temperature of the suction side bearing is lower than that of the discharge side bearing, and the friction loss power of the suction side bearing is high.

An object of the present invention is to solve the above-mentioned problems of the prior art.

[0008]

According to the present invention, in order to make the temperature of the suction side bearing and the temperature of the discharge side bearing substantially the same, the discharge side bearing chamber and the suction side bearing lubrication hole are connected by piping or the like, and the temperature of the discharge side bearing is increased. Is supplied to the suction-side bearing.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the overall structure of a refueling screw compressor according to the present invention. The discharge side of the compressor body 1 is connected to a receiver tank 3 by a pipe 2, and an oil separator 4, an aftercooler 5
In this order by pipes 6 and 7. The lower part of the receiver tank 3 is an oil reservoir, and is connected to the compressor body 1 via an oil cooler 8. The connection is through pipes 9 and 10. The casing of the compressor body 1 is composed of an M casing 11 and a D casing 12, and a male rotor 13 and a female rotor 14 are fitted in the M casing 11 and fitted therein. Both ends of the male and female rotors 13 and 14 have suction side radial bearings 15a and 15b and discharge side radial bearings 1 respectively.
Thrust bearings 17a and 17b supported by 6a and 16b and receiving a thrust load are provided on the discharge side. The discharge side bearings 16a, 16b, 17a, and 17b are D covers 18,
The suction-side bearings 15a and 15b are covered with an S cover 19, and a mechanical seal 20 is provided on the shaft of the suction-side male rotor 13 to shut off the outside.

The M casing 11 has a rotor oil supply hole 21,
The suction-side bearing oil supply hole 22, the oil drain hole 23, and the suction port 24,
In the D casing 12, the discharge side bearing oil supply holes 25a, 25
b, a discharge port 26 is formed, a mechanical seal oil supply hole 27 is formed in the S cover 19, and an oil discharge hole 28 is formed in the D cover 18.

Next, the operation of the oil-filled screw compressor having the above-described structure will be described. When the male rotor 13 is driven by a motor or the like, the female rotor 14 meshing with the male rotor 13 also rotates.

As a result, air is sucked in from the suction port 24 and further compressed. During compression, oil is injected from the oil supply hole 21 to bring the compression process closer to isothermal compression. The air discharged from the compressor 1 contains a large amount of oil, and the receiver tank 3 performs primary separation of the air and the oil. Further, the oil separator 4 performs a secondary separation of air and oil, and the aftercooler 5
It cools high-pressure air and is used as clean high-pressure air without oil.

The oil separated by primary separation of air and oil in the receiver tank 3 falls by gravity. The lower part of the receiver tank 3 is an oil reservoir, and is supplied to the compressor body 1 by a pressure difference between the receiver tank pressure and the compressor body refueling position. In an air compressor with a pressure ratio = 8, the oil supply temperature is about 60 ° C., and the weight ratio of oil and air per unit time is 10:
At about 1, the discharge temperature is about 75 ° C. The oil temperature of the oil reservoir in the receiver tank 3 is about 75 ° C. of the discharge temperature, and the oil temperature after passing through the oil cooler 8 is about 60 ° C.

Oil is supplied to the compression main body 1 from the pipe 10a to the rotor chamber 29 via the rotor oil hole 21 and from the pipe 10b to the discharge-side bearings 16, via the bearing oil hole 25.
17 and oil supply from the pipe 10 c to the mechanical seal 20 via the oil supply hole 27. Discharge side bearing 1
The oil supply to the cylinders 6 and 17 also serves as the shaft seals 30a and 30b on the discharge side, and is discharged into the D cover 18 after passing through the bearings 16 and 17. This oil is guided to the suction-side bearing oil supply hole 22 through the return pipe 31, and is recovered to the rotor chamber 29 in the suction stroke after passing through the suction-side bearing 15.

As described above, the oil supply temperature to the suction-side bearing 15 is higher than the oil supply temperature to the discharge-side bearings 16 and 17, but is affected by the rotor temperature (high on the discharge side and low on the suction side). The temperatures of the bearings 16 and 17 and the suction-side bearing 15 are substantially the same. Therefore, the oil viscosity in the suction side bearing 15 can be increased as compared with the conventional oil supply system, and the friction loss power of the suction side bearing 15 can be reduced.

[0017]

According to the present invention, it is possible to sufficiently recover the drain oil of the discharge side bearing, to increase the oil viscosity in the suction side bearing without deteriorating the reliability of the bearing, and to reduce the friction loss of the suction side bearing. Power can be reduced, and compressor efficiency can be increased.

[Brief description of the drawings]

FIG. 1 shows a longitudinal sectional view and an overall configuration of a refueling screw compressor according to the present invention.

FIG. 2 is a cross-sectional view of the oil supply type screw compressor of the present invention.

[Explanation of symbols]

15: suction side radial bearing, 16: discharge side radial bearing, 17: discharge side thrust bearing, 21: rotor oil supply hole,
22 ... suction side bearing oil supply holes, 23, 28 ... oil drain holes, 25 ...
Discharge side bearing lubrication hole, 31 ... return pipe.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuka Aoki 390 Muramatsu, Shimizu-shi, Shizuoka F-term in the Industrial Equipment Group, Hitachi, Ltd. 3H029 AA03 AA15 AA21 AB02 BB12 BB35 BB42 CC17 CC22 CC33 CC44

Claims (1)

[Claims] An oil-filled screw compressor in which a pair of male and female screw rotors are housed in a casing, an inlet is formed in one of the casings, and a discharge port is formed in the other, and both ends of the screw rotor are supported by bearings. A refueling screw compressor characterized in that a chamber and a suction-side bearing lubrication hole are connected by a passage.