JPS5851294A - Shaft sealing apparatus for compressor - Google Patents

Abstract

PURPOSE:To seal the rotor shaft of a compressor in a most suited manner according to the operational conditions of the compressor, by sealing the rotor shaft by means of screw seal, forming an injection hole in the screw seal, and connecting a circuit capable of feeding oil or compressed air selectively to the injection hole. CONSTITUTION:In no-load operation of a compressor, airtightness at a suction port 3 of the compressor is maintained by injecting injecting oil into a non- contact type screw seal 18 through an injection hole 20 and thereby preventing intrusion of air into a bearing room 11 by this oil. In stopping operation of the compressor, on the other hand, compressed air is injected into the screw seal 18 to prevent backflow of oil from the screw seal 18. Further, in full load operation of the compressor, the injection hole 20 is closed so that the shaft is sealed by the sealing function of the screw seal 18 itself. Thus, the rotor shaft can be sealed in a most suited manner according to the operational conditions of the compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft sealing device for a compressor, and more specifically to an oil-cooled screw compressor in which the shaft sealing pressure changes from positive to negative depending on the operating state and reverse air pressure is applied when stopped. This invention relates to a shaft sealing device for an oil-cooled rotary compressor.

BACKGROUND ART Conventionally, an oil seal or a mechanical seal, which is a contact type seal, has been used in a shaft sealing device of this type of oil-cooled screw compressor or oil-cooled rotary compressor.

FIG. 1 shows a part of an oil-cooled screw compressor and a conventional shaft sealing device using an oil seal.

The compressor 1 shown in FIG. 1 includes a casing 2, a suction boat 3 formed on the end surface of the rotor, a rotor 5,
A shaft 6 provided on the axis of this, a bearing 7 held in the casing 2 via a bearing retainer 8 and a collar 9, a shaft sealing device, and a discharge boat (not shown in Figure 1)
The shaft seal device has an oil seal housing 10 attached to the casing 2, a bearing room 11 formed between the casing 2 and the oil seal housing 10, and a bearing room 11 that is shrink-fitted to the shaft 6. Oil seal bushing 1
2. An oil seal 13 interposed between the oil seal housing 10 and the oil seal bushing 12 and fixed by a snap ring 14; an oil supply hole 15 formed from the outside of the casing 2 toward the bearing room 11; Nozzle 1 provided at the end of the bearing room 11
In this conventional shaft sealing device, oil is supplied through the oil supply hole 15, is squeezed by the nozzle 16, and is supplied to the bearing room 11. When the compression device is fully loaded, oil becomes negative pressure on the suction port 3 side, and is sent to the bearing 7 to lubricate it and is sucked into the rotor 5, and the other part of the oil in the bearing room 11 is filled with oil. The oil is sent to the seal 13 for lubrication, and the oil seal 13 prevents this oil from leaking.

Incidentally, there has recently been a remarkable trend toward higher speeds and smaller size screw blocks for compressors, and those capable of rotating at high speeds of about 7000 rpm have entered the stage of practical use.

However, the oil seal of the conventional contact type shaft seal device has a problem with reliability at high speed rotation, and the mechanical seal has a problem with power loss at high speed rotation.

An object of the present invention is to provide a shaft sealing device for a compressor that can reduce power loss during high-speed rotation and improve reliability.

A feature of the present invention is that the shaft of the rotor is sealed with a threaded seal that is a non-contact type seal, and an injection hole is provided that penetrates into the threaded seal from the outside, and when the compressor is fully loaded, the injection hole is inserted into the injection hole. is closed, and connected to a circuit that can selectively supply oil during unloading and compressed air during stoppage. With this configuration, the above objective was reliably achieved.

Hereinafter, the present invention will be explained based on the drawings.

FIGS. 2 and 3 show an embodiment of an air compression device including a compressor and other members, and a shaft sealing device for a compressor according to the present invention.

The compressor 1 includes a casing 2, a suction port 3, a discharge boat 4, a rotor 5, a shaft 6 of the rotor 5, a bearing 7 housed in the casing 2 and fixed via a bearing retainer 8 and a collar 9, It has a shaft sealing device.

The shaft sealing device includes a vale cover 17 attached to the casing 2, a threaded seal 18 which is a non-contact type seal provided at a set position within the seal cover 17, and shrink-fitted to the shaft 6 of the rotor 5. Seal bush 19, an injection hole provided from the outside of the seal cover 17 to the inside of the threaded seal 18, or a circuit connected to the large injection side and selectively supplies oil and air to the large injection side. It is equipped with

The circuit of the embodiment shown in FIG. It has a pressure switch 40 that switches the three-way electromagnetic switching valve 38 according to the pressure, and an oil supply/air discharge pipe 39 that connects the large injection side and the opening of the three-way electromagnetic switching valve.

The air compressor shown in FIG. 3 includes the compressor 1, a suction unloader 21 provided on the suction port 3 side of the compressor 1, and a suction unloader 21 connected to the discharge boat 4 side of the compressor 1 via a check valve n. the oil separator 22, the aftercooler 241 connected to it, the pressure regulating valve 5 and the pressure switch 26 provided in the piping connecting the oil separator 22 and the aftercooler U, the oil storage chamber of the oil separator n and the compressor 1. Oil supply hole 15 formed in the casing 2,
15', an oil supply pipe 27 connecting to the oil separator 2
2 and the suction unloader 21, a discharge valve 29, a pressure reducing valve (equipment), and a pressure regulating valve 31 provided therein, and an electromagnetic switching valve 3 provided on the bypass of the discharge pipe.
4 and a pressure regulating valve 35.

The oil supply pipe 36 of the circuit that selectively supplies oil and compressed air to the large injection side is connected to the oil supply pipe 27 that connects the oil storage chamber of the oil separator 22 and the oil supply hole 15 of the compressor 1.
The air discharge pipe 37 is connected to the oil separator 22.
and the suction unloader 21.

In the shaft sealing device of the above embodiment, lubricating oil is supplied from the oil storage chamber of the oil separator 22 through the oil supply pipe 27 and the oil supply hole 15 formed in the casing 2 of the compressor 1, and the oil is supplied from the nozzle 16 to the bearing room. 11 is injected.

Table 1 Next, the operation of the control system will be explained according to the operation pattern shown in Table 1.

In the fully loaded state of pattern 1, the air release valve 29 of the oil separator 22 is on (closed), and the electromagnetic switching valve 34 in the unload pipe 33 is off (open). At this time, the three-way electromagnetic switching valve 38 is turned off (the discharge pipe 35 and the large injection side communicate), and the screw seal 18 is sealed.

Next, in the unloading state of pattern (3), the pressure in the oil separator 22 increases in accordance with the amount of decrease in the amount of air used, so the pressure regulating valve 3 in the average load piping 33 is closed.
The pulp of the suction unloader 21 is closed in response to the secondary air pressure generated at 5. Therefore, when the pressure inside the suction port 3 becomes a negative pressure below the set value, the pressure switch 40 provided on the suction boat 3 is activated and the three-way electromagnetic switching valve 38 is turned on (the oil supply pipe 27 and the large injection side communicate). Then, oil is injected to the threaded seal 18 through the oil supply/air discharge pipe 39 and the large injection side.

Next, in the air unloading state of pattern (1), the electromagnetic switching valve 34 in the unloading pipe 33 is turned on (closed). Therefore, when the amount of air used decreases, the pressure in the oil separator 22 and the aftercooler U increases, the pressure switch 26 is activated, and the air release valve 29 in the air air pipe path is turned off (opened). After the pressure inside the oil separator 22 is reduced by the pressure reducing valve 30, it acts on the suction unloader 21 to fully close the pulp of the suction unloader 21, and the remaining air is released into the suction filter 32. At this time, the three-way electromagnetic switching valve 38 is turned on by the operation of the pressure switch 4o provided on the suction boat 3 (the oil supply pipe 27 and the large injection side communicate), and the threaded seal 18 passes through the oil supply/discharge pipe 39 and the injection hole. – Oil is injected.

Next, in the stopped state of pattern H, the three-way electromagnetic switching valve 38
is turned off (the air discharge pipe 37 and the large injection side communicate), and the air release valve 29 is turned off (opened), and the reduced air pressure acts on the suction unloader 21 to completely remove the pulp from the suction unloader 2. At the same time, the remaining air passes through the Sakunyong filter 32 and the air release pipe 37, and is further emitted to the threaded seal 18 via the three-way cylinder; magnetic switching valve 38, oil supply air release pipe 39, and large injection side.

In the present invention, the circuit for closing the large injection side or selectively supplying oil and compressed air to the large injection side is not limited to the illustrated embodiment.

Furthermore, the present invention is applicable to both oil-cooled screw compressors and oil-cooled rotary compressors.

The present invention has the above-described configuration 3. According to the present invention, a threaded seal which is a non-contact type seal is used, and oil is injected through an injection hole in the threaded seal when the compressor is unloaded. This oil prevents air from entering the bearing room and maintains the airtightness of the compressor suction boat. Also, when the compressor is stopped, compressed air is injected, and this compressed air prevents oil from blowing out due to backflow from the screw seal. Furthermore, when the compressor is fully loaded, the injection hole is closed and the screw seal itself provides a seal, allowing for optimal sealing depending on the operating conditions of the compressor.
It can be applied to high-speed rotation, and has the effect of improving reliability and reducing power loss.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing the prior art, FIG. 2 is a vertical cross-sectional view of an embodiment of the shaft sealing device of the present invention, and FIG. 3 is a connection between an air compression device including a compressor and the shaft sealing device of the present invention. It is a piping system diagram showing an example. DESCRIPTION OF SYMBOLS 1...Compressor, 2...Casing, 3...Suction boat, 4...Discharge boat, 5...Rotor, 6...
Shaft, 7... Bearing, 11... Bearing room, 15... Oil supply hole for lubrication, 17... Seal cover, 18... Screw seal which is a non-contact seal, 19.
...Seal bushing, modification...injection hole, 36...oil supply piping to the injection hole, 37...air discharge piping, 38...three-way electromagnetic switching valve, 39...oil supply/air discharge piping. Representative Patent Attorney Tadashi Akimoto Actual Cause 1 Figure 2 Figure 3

Claims (1)

[Claims] The shaft of the rotor is sealed with a threaded seal that is a non-contact type seal, and an injection hole is provided that penetrates into the threaded seal from the outside, and the injection hole Z is closed when the compressor is fully loaded and unloaded. A shaft sealing device for a compressor, characterized in that a circuit is connected that can selectively supply oil at times and compressed air when stopped.