JP2011256828A - Oilless screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oilless screw compressor capable of enhancing cleanness of discharged compressed air.SOLUTION: The oilless screw compressor has a mail rotor 1 and a female rotor 2, a compressor casing 8 housing both rotors, a suction side bearing and a discharge side bearing 6b supporting rotor shafts 1a, 2a of both rotors, respectively, a timing gears for non-contact rotation of both rotors, and a non-contact shaft seal device 7b arranged in the rotor shafts for preventing leakage of compressed air. The shaft seal device has an air seal 9a for sealing gas, an oil cut seal 11a for sealing oil from the bearings, and a seal box 10a arranged between the air seal and the oil cut seal, the seal box is connected to an air opening hole 12 in communication with the air, O rings 14A, 14B are arranged in both an outer periphery of the oil cut seal and an outer periphery of the air seal.

Description

  The present invention relates to an oil-free screw compressor, and more particularly to a shaft seal device in an oil-free screw compressor.

  An oil-free (oil-free) screw compressor that compresses air with a pair of male and female screw rotors that can rotate without contact and without oil is known. This oil-free screw compressor is usually configured as a compressor unit by providing a screw compressor (compressor body) for compressing air in a housing. Since the compressed air discharged from the screw compressor is hot, a cooling device for cooling the compressed air is also provided in the compressor unit, and the compressed air discharged from the screw compressor is supplied to the cooling device. After cooling, it is configured to be discharged out of the compressor unit via a pipe in the compressor unit.

In the oilless screw compressor, the compressed air from the compression chamber formed by the screw rotor is transmitted to the outside through the rotor shaft (rotary shaft), or the gear that drives the shaft and the bearing that supports the shaft A shaft seal device is provided to prevent the lubricating oil supplied to the oil from entering the compression chamber.
As this kind of prior art, there is one described in Patent Document 1 (Japanese Patent Laid-Open No. 6-66276).

JP-A-6-66276

  The oil-free screw compressor does not inject lubricating oil for sealing between the rotors like the oil-type screw compressor, so the efficiency of the compressor is formed around the compression chamber, such as the gap between the rotors. It is greatly influenced by compressed air leakage from the gap. In general, in an oil-free screw compressor, in order to overcome the leakage of the compressed air and obtain a certain efficiency, it is used at a rotor peripheral speed of 50 m / s or more, and the rotor is driven at a high speed of about 10,000 to 20,000 revolutions per minute. The

  As described above, the oil-free screw compressor does not use a lubricating oil for sealing between the rotors, so that the compression performance of the compression chamber in the compression process is low, and compressed air leaks frequently. In particular, the magnitude of leakage of compressed air from the compressor suction side and discharge side end faces to the rotor shaft side greatly affects the performance of the compressor. Conventionally, in order to prevent leakage of the compressed air, an air seal such as a fixed non-contact metal seal or a floating carbon seal has been used as a shaft seal device provided on the rotor shaft.

  In an oil-free screw compressor, lubricating oil is used for bearings that support the rotor shaft and gears (pinion gear, timing gear, etc.) for transmitting rotation to the rotor shaft. For this reason, a shaft seal device different from the air seal is provided so that the lubricating oil supplied to the bearings and gears does not enter the compression chamber. As this shaft seal device, an oil draining seal such as a Bisco seal or a labyrinth seal, which is a non-contact seal, is usually used, and lubricating oil supplied to the bearing and gear enters the compression chamber. I try to prevent it.

  The air seal or Bisco seal seals the gap between the inner circumference of the seal and the rotor shaft, and has no sealing effect against oil that enters from the gap between the outer circumference of the seal and the compressor casing. However, it has been elucidated by the present inventors that oil may enter from the gap between the outer periphery of the seal and the casing when the compressor is stopped, thereby reducing the cleanliness of the discharged compressed air. In recent years, the demand for cleanliness of the compressed air discharged from an oil-free screw compressor has become strict, and the demand for oil content has become particularly strict, as seen in the revision of the international standard ISO8573. For this reason, it is required to further improve the cleanliness of the compressed air discharged from the compressor.

  An object of the present invention is to obtain an oil-free screw compressor capable of improving the cleanliness of discharged compressed air.

  In order to achieve the above object, the present invention comprises a male rotor and a female rotor that mesh with each other, a compressor casing that houses both rotors, and a suction side and a discharge side bearing that support the rotor shafts of both rotors. An oil-free screw compressor comprising: a timing gear for rotating both the rotors in a non-contact manner; and a non-contact type shaft seal device provided on the rotor shaft for preventing leakage of compressed air. The sealing device includes an air seal portion that seals gas, an oil drain seal portion that seals oil from the bearing, and a seal box portion provided between the air seal portion and the oil drain seal portion. The box portion is connected to an air opening hole communicating with the atmosphere, and an O-ring is provided on both the outer peripheral surface of the oil drain seal portion and the outer peripheral surface of the air seal portion. And butterflies.

In the above, it is preferable that the shaft seal device includes an air seal portion, a seal box portion, and an oil drain seal portion integrally formed.
In addition, a sliding material is provided on the inner diameter portion of the air seal portion that is integrally formed with the oil drain seal portion and the seal box portion, which has good slidability and does not easily ignite or burn out even if it contacts the rotor shaft. More preferably, it is configured. The sliding material is preferably carbon or fluororesin having high slidability, and the sliding material is an epoxy resin-based adhesive that has high heat resistance and does not contain an organic solvent in the inner diameter portion of the air seal. It is good to adhere.

A visco seal or labyrinth seal may be used as the oil draining seal.
In addition, O-rings provided on both the shaft seal device, the air release hole, and the outer peripheral surface of the oil drain seal portion and the outer peripheral surface of the air seal portion are provided on both the suction side and the discharge side of the rotor shaft. It is preferable that

  According to the present invention, it is possible to obtain an oil-free screw compressor that can improve the cleanliness of discharged compressed air.

The principal part expanded sectional view of the shaft seal device vicinity which shows Example 1 of the oilless type screw compressor of this invention. 1 is a longitudinal sectional view of an oil-free screw compressor applied to Example 1. FIG. The principal part expanded sectional view which shows the general example of the shaft seal apparatus of the discharge side in the oil-free type screw compressor shown in FIG. The principal part expanded sectional view which shows the general example of the shaft-seal apparatus of the suction side in the oil-free type screw compressor shown in FIG. The principal part expanded sectional view which shows the other example of the shaft seal apparatus shown in FIG. The figure explaining the oil penetration | invasion path | route in the shaft seal apparatus shown in FIG. The figure explaining the oil penetration | invasion path | route in the shaft seal apparatus shown in FIG.

  Embodiments of the oil-free screw compressor of the present invention will be described below with reference to the drawings.

The case where the first embodiment of the present invention is applied to an oil-free screw compressor that compresses air by a pair of male and female screw rotors will be described.
First, the whole structure of the oil-free screw compressor applied to Example 1 of this invention is demonstrated with reference to FIG.

  An oil-free screw compressor shown in FIG. 2 includes a male rotor 1, a female rotor 2 meshed with the male rotor 1, a main casing 8a housing the male and female rotors 1 and 2, and the main casing 8a. S casing 8b attached to the suction side, D casing 8c attached to the discharge side of the main casing 3, cooling jacket 25 formed in the main casing 8a, suction side and discharge side ends of the male rotor 1 A rotor shaft 1a provided integrally with the rotor, a rotor shaft 2a provided integrally with the suction side and discharge side end of the female rotor 2, and a suction side end of the rotor shaft 1a of the male rotor 1; A pinion gear (compressor driving gear) 3 meshed with a bull gear (not shown) on the motor side, and a male and female rod provided in an S casing 8b. The rotors of the male and female rotors 1 and 2 are provided at the suction side bearing (roller bearing) 6a for supporting the suction side ends of the rotor shafts 1a and 2a of the rotors 1 and 2 and the discharge side end of the main casing 8a. Discharge side bearings 6b (roller bearings) and bearings 6c (combination angular bearings) for supporting the discharge side ends of the shafts 1a and 2a, and the male and female rotors 1 and 2 near the suction side bearing 6a. A shaft seal device 7a, a shaft seal device 7b provided closer to the male and female rotors 1 and 2 side of the discharge side bearing 6b, and the discharge side ends of the rotor shafts 1a and 2a of the male and female rotors 1 and 2 are provided. Timing gears 4 and 5 which are attached and meshed with each other, and a lubricating oil system (not shown) for lubricating the bearings 6a to 6c and the timing gears 4 and 5 are provided.

  The main casing 8a, the S casing 8b, and the D casing 8c constitute a compressor casing 8, and the compressor casing is provided with an air suction port and a discharge port (all not shown).

  The rotational force of a motor (not shown) is transmitted from the bull gear to the male rotor 1 via the pinion gear 3. The rotational force transmitted to the male rotor 1 is also transmitted to the female rotor 2 through the timing gears 4 and 5, and the male rotor 1 and the female rotor 2 mesh with each other in a non-contact state and rotate, whereby the suction port The air sucked between the rotors 1 and 2 is compressed to a predetermined pressure and discharged to the outside from the discharge port.

  The shaft seal devices 7a and 7b provided on the suction side and the discharge side are provided on gears and bearings 6 such as an air seal 9, a pinion gear 3, and timing gears 4 and 5 for preventing leakage of compressed air from the compression chamber. A non-contact type visco seal (oil drain seal) 11 that prevents the supplied lubricating oil from entering the compression chamber, and a seal box 10 provided between the air seal 9 and the visco seal 11 are provided. .

  The detailed structure of the shaft seal devices 7a and 7b will be described with reference to FIGS. FIG. 3 is an enlarged cross-sectional view of the main part showing a general example of the shaft seal device 7b on the discharge side, and FIG. 4 is an enlarged cross-sectional view of the main part showing a general example of the shaft seal device 7a on the suction side.

  3 and 4, reference numeral 12 denotes an air release hole provided in the compressor casing so as to communicate the seal box 10 and the atmosphere side. The air release hole 12 is used for generating pressure and compression of the Bisco seal 11. It is provided so that the pressure in the seal box 10 does not become negative depending on the operation state of the machine.

  The visco seal 11 generates a shaft sealing pressure by the rotation of the rotor shafts 1a and 2a, so that the lubricating oil is transmitted through the rotor shafts 1a and 2a and enters the male and female rotors 1 and 2 (compression chamber side). Is a shaft seal component that pushes back the gears 3-5 and the bearings 6a-6c.

However, the intrusion path of the lubricating oil to the compression chamber side enters not only from the gap between the rotor shafts 1a, 2a and the shaft seal devices 7a, 7b but also from the outer peripheral side of the shaft seal devices 7a, 7b. This will be described with reference to FIGS. 6 is a view for explaining an oil intrusion route in the shaft seal device shown in FIG. 3, and FIG. 7 is a view for explaining an oil intrusion route in the shaft seal device shown in FIG. 6 and 7, an arrow 15 indicates an oil intrusion path from the outer peripheral surface side of the shaft seal device, and an arrow 16 indicates between seal parts of the shaft seal devices 7a and 7b (between the air seal 9 and the seal box 10, and The oil intrusion path from the visco seal 11 and the seal box 10) is shown.
When the bearing and gear side of the air opening hole 12 is the primary side and the compression chamber side is the secondary side, the visco seal 11 is disposed on the primary side, and the air seal 9 is disposed on the secondary side.

  Conventionally, as shown in Patent Document 1, by providing an O-ring 14A on the outer peripheral surface of the visco seal 11 provided on the primary side, lubricating oil from a bearing or the like is provided between the visco seal 11 and the compressor casing. 6 and 7, as shown by an arrow 15, entry into the secondary side was prevented.

However, since these sealing parts and the compressor casing 8 are configured by clearance fitting in assembly, the sealing performance of the O-ring 14A provided on the primary side is lowered due to the processing accuracy of the casing and the shaft sealing part. There may be.
Further, the portion of the seal box 10 is opened to the atmosphere by the atmosphere opening hole 12 so that the inside of the seal box 10 does not become a negative pressure by the seal generation pressure indicated by the arrow 21 (see FIGS. 3 and 4). However, the minute gap between the outer periphery of the shaft seal device and the compressor casing, which is not affected by the pressure generated by the seal indicated by the arrow 21, may be negative with respect to the bearing side. The pressure acts in the direction of being drawn into the compression chamber as indicated by the arrow 17.

  Further, as shown in FIGS. 3 and 4, the air flow in the air seal 9 and the atmosphere opening hole 12 during operation of the compressor facilitates the infiltration of oil from the outer peripheral portion of the shaft seal device to the compression chamber side.

  Also, when the compressor is stopped, oil from the bearing side enters and accumulates on the back surface (outer peripheral surface) of the air seal 9 or between the air seal 9 and the seal box 10, and the air flows as the compressor starts operating. For example, it has been found that oil accumulated between the back surface of the air seal 9 and the air seal 9 and the seal box 10 may enter the compression chamber side.

  Therefore, in this embodiment, in order to prevent the oil that has passed through the primary side O-ring 14A and the like and entered the back surface of the air seal 9 from entering the compression chamber side, as shown in FIG. An O-ring 14 </ b> B is also provided on the outer peripheral surface of the provided air seal 9. As a result, oil that has entered the back surface of the air seal 9 can be prevented from flowing into the compression chamber side through the back surface of the air seal 9 (that is, the oil indicated by the arrow 15 in FIGS. 6 and 7). It is possible to block the intrusion path), and to prevent oil from entering the compressed air.

  Further, in this embodiment, the air seal 9, the seal box 10 and the visco seal 11 shown in FIGS. 3 and 4 are integrated, and the air seal portion 9a, the seal box portion 10a and the visco seal portion 11a are integrated as shown in FIG. A shaft seal device 7b (suction-side shaft seal device 7a has the same configuration, but the description thereof is omitted). By integrating the shaft seal components constituting the shaft seal device, the oil intrusion path indicated by the arrow 16 in FIGS. 6 and 7 can be blocked. Thus, by using the shaft seal device 7b having the integrated air seal portion 9a, seal box portion 10a and visco seal portion 11a, there is a conventional problem between the seal box portion 10a and the air seal portion 9a or the visco seal portion 11a. Since the oil intrusion paths 15 and 16 are eliminated, there is an effect that oil intrusion to the compression chamber side can be suppressed. Further, the number of shaft seal parts constituting the shaft seal device can be reduced, and the cost and assembly man-hours can be reduced.

  In addition, when integrating the air seal part 9a, the seal box part 10a, and the Bisco seal part 11a, it manufactures integrally with metal materials, such as a gun metal. In this case, in order to prevent metal contact with the rotor shafts 1a and 2a, the clearance between the inner diameter portion of the air seal portion 13a and the rotor shafts 1a and 2a needs to be sized in consideration of safety.

  FIG. 5 is a diagram for explaining another example of the shaft seal device 7b in which the air seal portion 9a, the seal box portion 10a, and the Bisco seal portion 11a shown in FIG. 1 are integrated. In this example, the sliding member 13 having a high slidability such as carbon or fluororesin (PTFE) at the inner diameter portion of the air seal portion 9a of the shaft seal device 7b has no risk of ignition or burning even when it comes into contact with the rotor shaft. Are attached by bonding or the like. By providing a sliding material having an advantage in terms of safety in the inner diameter portion of the air seal portion 9a as described above, the gap between the inner diameter portion of the air seal portion 9a and the rotor shafts 1a and 1b can be reduced. The leakage of compressed air from the chamber can be reduced.

  Adhesion between the air seal portion 9a (metal) and the sliding member 13 (carbon, fluororesin, etc.) is desirably made of an epoxy resin adhesive having high heat resistance. As the epoxy resin-based adhesive, there are high heat resistance and organic solvent-free (no organic solvent is included), and by using such an adhesive, the discharge in the international standard ISO8573-5 A high degree of cleanliness can be secured even with respect to the content of the organic solvent in the compressed air.

  In the embodiment shown in FIGS. 1 and 5, the discharge-side shaft seal device 7b has been described, but the suction-side shaft seal device 7a can also be configured in the same manner as in FIGS. That is, in the case of the shaft seal device 7a on the suction side, the air seal 9, seal box 10 and visco seal 11 shown in FIG. 4 may be integrated as shown in FIG. 1 and FIG. good.

  As described above, according to the present embodiment, it is possible to reduce the intrusion of oil from the space between the outer periphery of the shaft seal device and the compressor casing to the compression chamber side, and the shaft seal is highly reliable against oil intrusion. An oil-free screw compressor having the device can be obtained. As a result, the cleanliness of the compressed air discharged from the oil-free screw compressor can be increased, and the effect of supplying compressed air with a high cleanness with a low oil content can be obtained.

1 ... male rotor (1a: rotor shaft)
2 ... Female rotor (2a: rotor shaft)
3. Pinion gears 4, 5 ... Timing gears 6a, 6b, 6c ... Bearings 7a, 7b ... Shaft seal devices (9: air seal, 10: seal box, 11: bisco seal (oil drain seal), 9a: air seal part, 10a: (Seal box part, 11a: Bisco seal part, 13: Sliding material)
8: Compressor casing (8a: main casing, 8b: S casing, 8c: D casing)
12 ... Air release holes 14A, 14B ... O-rings.

Claims (7)

The male and female rotors that mesh with each other, the compressor casing that houses the rotors, the bearings on the suction and discharge sides that support the rotor shafts of the rotors, and the timing for rotating the rotors in a non-contact manner. In an oil-free squeeze compressor comprising a gear and a non-contact type shaft seal device provided on the rotor shaft to prevent leakage of compressed air,
The shaft seal device has an air seal part that seals gas, an oil drain seal part that seals oil from the bearing, and a seal box part provided between the air seal part and the oil drain seal part,
The seal box portion is connected to an air opening hole communicating with the atmosphere, and an O-ring is provided on both the outer peripheral surface of the oil drain seal portion and the outer peripheral surface of the air seal portion. Screw compressor.   2. The oilless screw compressor according to claim 1, wherein the shaft seal device includes an air seal portion, a seal box portion, and an oil drain seal portion which are integrally formed. .   3. The oil-free screw compressor according to claim 2, wherein an inner diameter portion of the air seal portion formed integrally with the oil drain seal portion and a seal box portion has good slidability and is in contact with the rotor shaft. An oil-free screw compressor characterized by being provided with a sliding material that is unlikely to ignite or burn.   4. The oil-free screw compressor according to claim 3, wherein the sliding material is carbon or fluororesin having high slidability.   5. The oilless screw compressor according to claim 3, wherein the sliding member is bonded to an inner diameter portion of the air seal with an epoxy resin adhesive that has high heat resistance and does not contain an organic solvent. Oil-free screw compressor characterized by   The oilless screw compressor according to any one of claims 1 to 5, wherein the oil draining seal is a visco seal or a labyrinth seal.   The oil-free screw compressor according to any one of claims 1 to 6, wherein the shaft seal device, the air release hole, and the outer surface of the oil drain seal portion and the outer surface of the air seal portion are provided. An oil-free screw compressor, wherein the O-ring is provided on both the suction side and the discharge side of the rotor shaft.

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