JP2558968Y2 - Screw compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an oil-cooled screw compressor.

(Prior Art) Conventionally, an oil-cooled screw compressor shown in FIG. 5 is known, and a pair of male and female screw rotors meshing with each other in a casing 42 having a suction port 41 formed on one side and a discharge port 42 formed on the other side. 44,45 are stored. Each of the rotors 44, 45 is rotatably supported by bearings 46, 47, 48, 49 on both rotor shafts, and one of the rotor shafts of the male rotor 45 is connected to the casing 43 via a shaft seal 50. An input shaft 52 penetrates a lid 51 attached to the end of the input shaft 52 and projects outward. That is, for example, a V-pulley is attached to the input shaft 52, and a V-belt is wound around the V-pulley to drive the male rotor 45. Here, the shaft sealing portion 50 includes a mechanical seal fixed ring 53 attached to the lid body 51 side and a rotating ring 54 as a mechanical seal that rotates together with the input shaft 52.

Further, lubricating oil is supplied to the bearings, shaft seals, and tooth grooves of the rotors through oil passages (not shown). After the lubricating oil is supplied, the lubricating oil is recovered and used for circulation.

A screw compressor having the same structure as described above is also disclosed in Japanese Utility Model Laid-Open No. 60-143184.

(Problem to be Solved by the Invention) In the above-described conventional device, the input shaft 52 includes the rotating ring 54 and the fixed ring 53.
Through the cover 51 constituting a part of the casing 43, and protrudes to the outside.

Since a gap is always formed between the input shaft 52 and the shaft penetrating portion of the lid 51, a fixed ring is used to prevent the oil supplied to the bearing 48 and the shaft sealing portion 50 from spilling out of the gap. 53
Is provided.

However, the fixed ring 53 and the rotating ring 54 are in contact with each other at their end faces, and when the surface roughness or parallelism of any of these end faces becomes poor and oil runs out, There is a problem that when dust or the like enters between, oil may squirt to the outside, and such a situation occurs very frequently.

In addition, the mechanical seal is expensive in itself, has many problems, such as not only taking a lot of time to assemble the mechanical seal, but also increasing the accuracy of parts around the mechanical seal.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has as its object to provide a screw compressor that has a simple configuration and is capable of preventing oil leakage to the outside of a casing and prevention of oil ejection. .

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a compressor casing of an input shaft of a screw rotor which is disposed on a side opposite to a rotor with respect to a bearing portion supporting an input shaft of the screw rotor. When the compressor is stopped, while the pressure at the suction port is higher than the atmospheric pressure, the gas after oil separation from the oil separation and recovery device installed in the discharge flow path following the discharge port is supplied to the shaft seal that shuts the inside and outside. It was formed by providing a guiding channel.

(Operation) With the configuration described above, a high-pressure gas barrier is formed in the shaft sealing portion of the input shaft, and oil is prevented from leaking to the outside.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a screw compressor according to the present invention, in which a casing 3 having a suction port 1 formed on one side and a discharge port 2 formed on the other side.
The male rotor 4 of a pair of male and female screw rotors meshing with each other housed therein is shown.

The suction port 1 communicates with a suction channel 7 having a filter 5 and an intake control valve 6, and the discharge port 2 communicates with a discharge channel 10 having an oil separation / recovery device 8 and a check valve 9 for holding pressure. . Oil separation and recovery unit 8
Has a demister 11 for gas-liquid separation inside, and the lower part is an oil reservoir 12, from which an oil cooler
13, an oil flow path 17 which communicates with the male rotor 4 and the tooth grooves of the female rotor (not shown) and the bearings 15 and 16 via an oil filter 14.
Are formed so as to supply oil to these portions. Further, an air introduction passage provided with a throttle valve 18 and an electromagnetic on-off valve (hereinafter, referred to as an electromagnetic valve) 19 at the outlet side of the check valve 9 in the discharge passage 10 extending from above the oil separation and recovery device 8. 20 are provided. Further, a blow-off valve is provided above the oil separation and recovery unit 8.
An air discharge channel 22 provided with 21 is provided.

On the other hand, the male rotor 4 has bearings on both rotor shafts.
The rotor shaft is rotatably supported by 15, 16 and one end of the rotor shaft penetrates through a screw seal 24 through a lid 23 which forms a part of the casing 3 which also serves as a bearing presser at its end. The input shaft 25 protrudes from the input shaft 25. A space A is formed around the input shaft 25 between the bearing 15 and the screw seal 24, and a slinger ring 26 having a flange for oil drainage is fitted in the space A of the input shaft 25. To rotate integrally with the shaft. Here, the screw seal 24 is formed by forming a screw on the inner peripheral surface which advances toward the rotor when the input shaft 25 rotates in the rotation direction. In addition, the partition wall between the suction port 1 and the space A is made to communicate with each other, and the through-holes 27 for equalizing pressure are formed.
And the input shaft in the middle of the screw seal 24
An annular space B is formed around the space 25, and the air introduction flow path 20 is led into the space B through a through hole 20a formed in the casing 3 so as to open to the space B.

Then, the air sucked from the suction port 1 through the filter 5 and the intake control valve 6 is compressed by the female rotor and the male rotor 4 and is cooled by the oil injected from the oil flow path 17, and is discharged together with the oil into the discharge port 2. The oil is further discharged to the oil separation / recovery unit 8 in the discharge passage 10. In the oil separation / recovery unit 8, gas-liquid separation is performed by a demister 11, the oil drops into the lower oil reservoir 12, and the air from which the oil has been removed is sent out from the upper part of the oil separation and recovery unit 7 through the check valve 9. . Further, when the pressure in the oil separation and recovery unit 8 becomes equal to or higher than a predetermined pressure, the blow-off valve 21 is opened, and air is released from the blow-off channel 22 to ensure safety.

On the other hand, the oil in the oil reservoir 12 is cooled from the oil flow path 17 through the oil cooler 13 and further passes through the oil filter 14, and then the female rotor,
After being supplied to the tooth grooves of the male rotor 4 and the bearings 15 and 16 and discharged together with the air from the discharge port 2 and collected by the oil separating and collecting device 7 in the oil reservoir 12, it is circulated in the same flow path as described above. Served for use.

Furthermore, the solenoid valve 19 is opened at the same time when the compressor is stopped,
The high-pressure air after oil separation in the discharge passage 10 is adjusted to an appropriate flow rate by the throttle valve 18 and guided to the space B of the screw seal 24 so that the oil of the bearing 15 does not leak out of the machine. It is. That is, as shown by the pressure change curves of the suction port 1 and the A chamber in FIG. 2, the moment the compressor stops, the high-pressure air returns to the suction port 1 side. The pressure in the suction port 1 and the chamber A becomes higher than the atmospheric pressure for t seconds. At this time, oil tends to leak from the chamber A to the outside of the machine under the atmospheric pressure through the portion of the screw seal 24.
With the valve appropriately opened, the solenoid valve 19 is opened for T (T> t) seconds longer than t seconds to guide the discharge air at a higher pressure than the chamber A to the chamber B, thereby forming a high-pressure air barrier here. It is designed to prevent oil from leaking out of the machine from room A. In FIG. 2, a represents the time when the compressor is stopped, b represents the time when the compressor is started, c is the time when the intake control valve is turned on and off while the compressor is operating,
"d" indicates a stop time after the compressor is once operated.

Also, by the slinger ring 26, the oil that has flowed backward from the bearing 15 to the screw seal 24 side is scattered outward by centrifugal force, preventing the oil from flowing directly into the screw seal 24,
The oil itself reaching the screw seal 24 is reduced.

However, in the present invention, the slinger ring 26 and the throttle valve 18 are not always necessary, and the screw seal 24 may be replaced with a simple shaft sealing means without a screw, and the starting point of the air introduction passage 20 is reversed. The stop valve 9 may be on the inlet side instead of the outlet side.

FIG. 3 is an example of a circuit diagram for detecting the stop of the compressor. PB-ON is a start button, PB-OFF is a stop button, M
Denotes an auxiliary relay and V19 denotes a solenoid valve relay for opening and closing the solenoid valve 19. When the stop button PB-OFF is pressed to stop the compressor, the auxiliary relay M is demagnetized, and the solenoid valve relay V19 is also demagnetized accordingly,
As a result, the solenoid valve 19 is opened. That is, the stop of the compressor is detected by this circuit, and a control signal is sent to the solenoid valve 19.

Further, the present invention is not limited to the above-described embodiment. In addition, in consideration of a time delay until the high pressure discharge air is filled in the chamber B after the solenoid valve 19 is opened, for example, immediately before the stop of the compressor, The solenoid valve 19 may be opened to ensure that the chamber B is filled with high-pressure discharge air when the pressure in the chamber A rises. Also, as shown by a two-dot chain line in FIG. 1, a bypass passage 30 is provided through the on-off valve 28 and the orifice 29 to allow the inlet and the outlet of the solenoid valve 19 to pass therethrough. High-pressure discharge air may be guided to the chamber B to prevent oil from leaking out of the machine at the screw seal 24 portion.

4 is an enlarged view of a portion of the screw seal 24 shown in FIG.
As shown in the figure, since there is always a gap between the screw seal 24 and the input shaft 25, when the suction throttle operation by the intake control valve 6 is performed during the operation of the compressor, the screw seal 24 When the suction pressure does not drop to a predetermined pressure due to too much air inflow, the floating seal 31 is provided on the side opposite to the rotor of the screw seal 24, and the push plate 32 for pressing the floating seal 31 against the screw seal 24 is provided. The gap around 25 may be reduced, thereby reducing the leakage of air from the room B to the outside and effectively maintaining the high pressure state in the room B. Here, the floating seal 31 is formed by interposing a spring 34 between two seal rings 33.

Further, in the above embodiment, the input shaft 25 is provided on the suction side of the compressor.
However, the present invention also includes a case in which an input shaft is provided on the discharge side. In this case, an air introduction flow path branched from the discharge flow path 10 is provided in a shaft sealing portion on the discharge side.

(Effects of the Invention) As is apparent from the above description, according to the present invention, the input shaft of the screw rotor is arranged on the side opposite to the rotor with respect to the bearing portion supporting the input shaft of the screw rotor, and the inside and outside of the compressor casing of the input shaft of the screw rotor. When the compressor is stopped, the gas after oil separation is guided from the oil separation and recovery device provided in the discharge flow path following the discharge port to the shaft seal portion that shuts off the pressure while the compressor is stopped. It is formed by providing a flow path.

For this reason, a high pressure gas barrier is formed in the shaft sealing portion of the bearing portion on the side opposite to the rotor, so that oil injection and oil leakage from the input shaft portion can be prevented. Thus, it is possible to eliminate the occurrence of various troubles caused by contact with the device.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of the screw compressor according to the present invention, FIG. 2 is a diagram showing an example of a temporal change in pressure on the compressor suction side, and FIG. 3 is a circuit for detecting a stop of the compressor. FIG. 4 is a partially enlarged cross-sectional view showing another modified example of the apparatus shown in FIG. 1 in place of the shaft sealing portion, and FIG. 5 is a cross-sectional view of a conventional screw compressor. 2 ... Discharge port, 4 ... Male rotor, 8 ... Oil separator / collector,
10 ... discharge passage, 19 ... solenoid valve, 20 ... air introduction passage,
24: Screw seal, 25: Input shaft.

Claims (1)

(57) [Scope of request for utility model registration] A suction shaft is provided at a shaft sealing portion which is disposed on a side opposite to a rotor with respect to a bearing portion supporting an input shaft of a screw rotor and which blocks the inside and outside of a compressor casing of the input shaft of the screw rotor. A screw compressor characterized in that a passage for guiding gas after oil separation from an oil separation and recovery device provided in a discharge passage following the discharge opening is provided while the pressure of the mouth portion is higher than the atmospheric pressure. .