JP2022089649A - Shaft sealing structure of oil-free screw compressor - Google Patents

Abstract

A shaft seal structure for an oil-free screw compressor capable of preventing lubricating oil from entering the rotor chamber side even when the rotation speed of the screw rotor is reduced is provided. A bearing (8) for supporting a rotor shaft (6) provided in a screw rotor (4) of an oil-free screw compressor (1) and a space between the outer peripheral surface of the rotor shaft (6) and the inner peripheral surface of a shaft hole (9) between the rotor chamber (3) and the rotor chamber (3). A shaft sealing device 10 is provided in which an air seal 11 and an oil seal 12 are combined, and an endless annular oil-proof partition wall 30 that rotates together with the shaft 6 is fitted on the rotor shaft 6 between the bearing 8 and the oil seal 12 . The outer diameter of the partition wall 30 is larger than the inner diameter of the oil seal 12. Preferably, the outer peripheral edge of the oil-proof partition wall 30 is aligned with the inner peripheral edge E1 of the outer ring 8b of the bearing 8 on the shaft sealing device 10 side and the oil seal. The flow of lubricating oil passing through the bearing 8 toward the oil seal side is cut off by setting it so as to be disposed on the outer peripheral side of the line L connecting the inner peripheral edge E2 of the bearing-side end surface 12a of the bearing 12 . [Selection drawing] Fig. 2

Description

The present invention relates to the shaft sealing structure of the oil-free screw compressor, and more specifically, the oil of the shaft sealing device provided on the rotor shaft between the bearing supporting the rotor shaft of the screw rotor and the rotor chamber accommodating the screw rotor. It relates to the shaft seal structure of the oil-free screw compressor, which can complement the sealing property of the seal.

As shown in FIG. 7, the oil-free screw compressor 100 rotates a pair of male and female screw rotors 104 and 105 in a rotor chamber 103 formed in the casing 102 in a non-contact state to obtain a gas to be compressed. The compressed gas is compressed without introducing lubricating oil for cooling, lubrication and sealing into the compression action space defined by the inner wall of the rotor chamber 103 and the screw rotors 104 and 105. It is configured to be able to.

Therefore, since the oil-free screw compressor 100 can obtain a compressed gas containing no oil, it is widely used in the medical field, paper making, chemistry, food manufacturing, and the like, which require a clean compressed gas.

The screw rotors 104 and 105 of the oil-free screw compressor 100 have rotor shafts 106, 106; 107 and 107 protruding from the suction side and the discharge side, respectively, and these rotor shafts 106, 106; 107, respectively. By supporting 107 by bearings 108, 108; 108, 108, respectively, the screw rotors 104, 105 are rotatably housed in the rotor chamber 103.

A shaft sealing device 110 is provided on each of the rotor shafts 106 and 107 between the bearing 108 and the rotor chamber 103, respectively, and the shaft sealing device 110 provides an outer peripheral surface of the rotor shaft 106 (107) and an inner peripheral surface of the shaft hole 109. The gap between them is sealed.

As shown in FIG. 8, the shaft sealing device 110 is formed by a combination of an air seal 111 arranged on the rotor chamber 103 side, which is a non-contact type seal, and an oil seal 112 arranged on the bearing 108 side. The air seal 111 prevents the gas from passing through the shaft hole 109, and the oil seal 112 prevents the lubricating oil from the bearing 108 from entering the rotor chamber 103 side, so that oil is mixed in the compressed gas. It is preventing that.

In FIG. 8, reference numeral 114 is a snap ring (C-shaped retaining ring), and by attaching the snap ring 114 to the annular groove 121 provided on the inner wall surface of the shaft hole 109, it is possible to attach the snap ring 114 to the bearing side of the oil seal 112. The position of the end face 112a is restricted so that the shaft sealing device 110 can be fixed in the shaft hole 109.

As the oil seal 112 provided in such a shaft sealing device 110, one that prevents the infiltration of lubricating oil by utilizing the fluid dynamic pressure generated by the rotation of the rotor shaft 106 (107) is used, which will be described later. In Patent Document 1, an oil seal known as a so-called "screw seal" is used.

In this screw seal, a spiral groove 112b that exerts a pumping action as the rotor shaft 106 (107) rotates is formed on the inner peripheral surface of the oil seal 112 configured as a cylindrical member. When the rotor shaft 106 (107) was rotated due to the formation, the bearing 108 was lubricated by pushing the lubricating oil that reached the gap Δ between the outer circumference of the rotor shaft 106 (107) and the inner circumference of the oil seal 112 back to the bearing 108 side. The lubricating oil is prevented from entering the rotor chamber 103 side.

In order to improve the sealing performance of the oil seal 112 configured as such a screw seal, in Patent Document 2 described later, as shown in FIG. 9, an annular shield is provided on the end face 112a of the oil seal 112 on the bearing side. It has been proposed that by attaching the plate 118, the opening area of the bearing side end of the spiral groove 112b formed on the inner peripheral surface of the oil seal 112 is narrowed, so that the lubricating oil is less likely to be introduced into the spiral groove 112b. There is.

Japanese Patent Application Laid-Open No. 2002-276574 Microfilm of Jitsugyo No. 60-61859 (Jitsukaisho No. 61-179460)

In the oil-free screw compressor 100, as described above, the compressed gas is compressed without introducing lubricating oil for lubrication, cooling, and sealing into the compression action space. Therefore, male and female screw rotors 104 and 105. A configuration is adopted in which the screw rotors 104 and 105 are rotated while maintaining a non-contact state between each other and between the male and female screw rotors 104 and 105 and the inner walls of the rotor chamber 103.

Due to the structure of the oil-free screw compressor 100, the oil-free screw compressor 100 has a higher pressure during compression than the oil-cooled screw compressor that compresses by introducing lubricating oil into the compression action space. The amount of compressed gas leaking from the compression action space on the low pressure side to the compression action space on the low pressure side increases.

Therefore, in the oil-free screw compressor 100, in order to compensate for this, the rotational driving force of a drive source (not shown) such as an engine or a motor is accelerated by, for example, a speed increasing gear (not shown) and then applied to the drive shaft. The screw rotors 104 and 105 are rotated at a higher speed than the oil-cooled screw compressor, such as transmission and operation.

In the oil-free screw compressor 100 that rotates the screw rotors 104 and 105 at high speed in this way, the bearing 108 that supports the rotor shafts 104 and 105 may have heat and seize. Therefore, both ends of the inner ring 108a as the bearing 108. An open type bearing that does not have a shield that closes the space between both ends of the outer ring 108b is used, and the lubricating oil injected from the lubrication nozzle 120 is supplied between the inner ring 108a and the outer ring 108b of this bearing 108. By refueling by a refueling method called "refueling", the bearing 108 is lubricated and cooled at the same time.

In this jet lubrication, a relatively large amount of lubricating oil is injected toward the bearing 108 at a relatively high pressure, so that a relatively large amount of lubricating oil maintains a certain momentum even after passing through the bearing 108. , Flows toward the oil seal 112 of the shaft sealing device 110.

Since the oil seal 112 is a non-contact type seal as described above, there is a gap Δ between the inner peripheral surface of the oil seal 112 and the outer peripheral surface of the rotor shaft 106 (107), and the rotor chamber 103. The bearing side end Δa of this gap Δ, which is the starting point of the infiltration of the lubricating oil to the side, is open toward the bearing 108 as shown in the enlarged view in FIG. 8, and therefore exceeds the processing capacity of the oil seal 112. If a large amount of lubricating oil flows vigorously from the bearing 108 side, the lubricating oil may infiltrate into the gap Δ between the inner peripheral surface of the oil seal 112 and the outer peripheral surface of the rotor shaft 106 (107).

Although the oil seal 112 is configured to generate a fluid dynamic pressure that pushes the lubricating oil back to the bearing 108 side to prevent such infiltration of lubricating oil, such fluid dynamic pressure is applied to the rotor shaft. Since it is generated with the rotation of 106 (107), when the rotation speed of the screw rotors 104 and 105 is changed due to capacity control or the like, the oil seal 112 when the rotation speed of the screw rotors 104 and 105 decreases. The ability to push the lubricating oil back to the bearing 108 side is reduced.

Therefore, when the screw rotors 104 and 105 rotate at low speed, the sealing capacity of the oil seal 112 is reduced, and when a large amount of lubricating oil that has passed through the bearing 108 flows vigorously toward the oil seal 112 side, the lubricating oil flows into the rotor chamber 103. The risk of invasion to the side will be further increased.

As described in Patent Document 2 described above, in a configuration in which an annular shielding plate 118 is attached to the end surface 112a on the bearing side of the oil seal 112 to narrow the opening area of the end on the bearing side of the spiral groove 112b, the bearing 108 The lubricating oil that has flowed from the side to the oil seal 112 side is difficult to enter into the spiral groove 112b.

However, although the opening area of the spiral groove 112b is narrowed, the inner peripheral surface of the oil seal 112 and the rotor shaft 106 (107) are between the inner peripheral surface of the shielding plate 118 and the outer peripheral surface of the rotor shaft 106 (107). ) A gap Δ'corresponding to the gap Δ between the outer peripheral surfaces is formed, and since this gap Δ'opens toward the bearing 108, any lubricating oil flowing in from the bearing 108 side is blocked. This gap Δ'can be reached without any problems.

It can be said that the opening area of the bearing side end of the spiral groove 112b is narrowed, and the oil seal 112 described in Patent Document 2 also utilizes the fluid dynamic pressure generated by the rotation of the rotor shaft 106 (107). As long as the lubricating oil is prevented from entering, when the rotation speed of the screw rotors 104 and 105 is reduced, the function of pushing the lubricating oil back to the bearing 108 side is still reduced, and the speed of the screw rotors 104 and 105 is low. If a relatively large amount of lubricating oil flows into the oil seal 112 side while maintaining the momentum during rotation, the risk of the lubricating oil infiltrating into the rotor chamber 103 side increases.

Therefore, the present invention has been made to eliminate the above-mentioned drawbacks in the prior art, and is an oil-free screw compressor that injects a relatively large amount of lubricating oil pressurized to the bearing by the above-mentioned jet lubrication to lubricate the bearing. Therefore, even when the rotation speed of the screw rotor is reduced, and therefore the sealing capacity of the oil seal is reduced, the lubricating oil from the bearing can be prevented from entering the rotor chamber side. The purpose is to provide the structure.

The means for solving the problem are described below together with the reference numerals used in the embodiment for carrying out the invention. This reference numeral is for clarifying the correspondence between the description of the scope of claims and the description of the form for carrying out the invention, and needless to say, it is used in a limited manner in the interpretation of the technical scope of the present invention. It is not something that can be done.

In order to achieve the above object, the shaft seal structure of the oil-free screw compressor 1 of the present invention is:
A pair of male and female screw rotors 4 (5) are provided between a bearing 8 for supporting a rotor shaft 6 (7) and a rotor chamber 3 for accommodating the screw rotor 4 (5). The outer peripheral surface of the rotor shaft 6 and the shaft into which the rotor shaft 6 is inserted by a non-contact shaft sealing device 10 including an air seal 11 arranged on the 3 side and an oil seal 12 arranged on the bearing 8 side. In the shaft sealing structure of the oil-free screw compressor 1 in which the space between the inner peripheral surfaces of the holes 9 is sealed,
An endless annular oil-proof partition wall 30 that rotates together with the rotor shaft 6 is fitted onto the rotor shaft 6 between the bearing 8 and the oil seal 12.
The outer diameter of the oil-proof partition wall 30 is made larger than the inner diameter of the oil seal 12 (see claims 1 and 2).

Preferably, the outer peripheral edge of the oil-proof partition wall 30 is outer peripheral than the line L connecting the inner peripheral edge E1 of the outer ring 8b of the bearing 8 on the shaft sealing device side and the inner peripheral edge E2 of the bearing-side end surface 12a of the oil seal 12. The outer diameter of the oil-proof partition wall 30 is set so as to be arranged on the side (claim 2).

More preferably, the outside of the oil-proof partition wall 30 is within a range in which a rotation allowable distance can be secured between the outer peripheral edge of the oil-proof partition wall 30 and the inner peripheral surface of the shaft hole 9 at the mounting position of the oil-proof partition wall 30. The diameter is made as close as possible to the inner diameter of the shaft hole 9 (claim 3).

Further, the outer diameter of the oil-proof partition 30 is larger than the inner diameter of the annular locking tool (snap ring in the illustrated example) 14 that regulates the end surface 12a of the oil seal 12 of the shaft sealing device 10 on the bearing side. As well as forming large
The shaft sealing device of the oil-proof partition 30 is within a range in which a rotation allowable distance can be secured between the side surface 32 of the oil-proof partition 30 on the shaft sealing device side and the side surface 14a of the locking tool 14 on the bearing side. The gap between the side surface 32 on the side and the side surface 14a on the bearing side of the locking tool 14 may be narrowed as much as possible (claim 4).

In the shaft sealing portion structure having the above configuration, an oil drainage flow path 40 that opens at the bottom of the shaft hole 9 may be further provided at a position below the oil-proof partition wall 30 (claim 5).

The side surface 31 on the bearing side of the oil-proof partition wall 30 may be an inclined surface that is inclined so that the outer peripheral side is away from the bearing 8 with respect to the inner peripheral side (see claims 6 and 3). ..

Alternatively, instead of the above configuration, the side surface 31 on the bearing side of the oil-proof partition wall 30 may be an inclined surface that is inclined so that the outer peripheral side approaches the bearing 8 with respect to the inner peripheral side (claim 7). , See Figure 4).

Further, ribs 34 extending in the radial direction of the oil-proof partition wall 30 may be provided on the side surface 31 of the oil-proof partition wall 30 on the bearing side at predetermined intervals in the circumferential direction (see claims 8 and 5). ..

An inclined portion 97 that gradually expands the inner diameter from the shaft sealing device 10 side toward the bearing 8 side is provided on the inner peripheral surface of the shaft hole 9 on the extension of the side surface 31 of the oil-proof partition wall 30 on the bearing side in the outer peripheral direction. It may be provided (see claim 9 and FIG. 6).

With the configuration of the present invention described above, the oil-free screw compressor 1 provided with the shaft sealing portion structure of the present invention was able to obtain the following remarkable effects.

An endless annular oil-proof partition wall 30 that rotates together with the rotor shaft 6 is fitted onto the rotor shaft 6 between the bearing 8 and the oil seal 12, and the outer diameter of the oil-proof partition wall 30 is larger than the inner diameter of the oil seal 12. By increasing the size, the space inside the shaft hole 9 is partitioned between the bearing 8 and the oil seal 12 by the oil-proof partition wall 30, and the inner peripheral surface of the oil seal 12 which is the starting point for the lubricating oil to enter the rotor chamber 3 side. The bearing side end portion Δa of the gap Δ between the outer peripheral surfaces of the rotor shaft 6 can be shielded by the oil-proof partition wall 30 when viewed from the bearing 8 side, and the flow of lubricating oil toward this portion is ensured by the oil-proof partition wall 30. I was able to shield it.

In particular, the outer peripheral edge of the oil-proof partition wall 30 is located on the outer peripheral side of the line L connecting the inner peripheral edge E1 of the outer ring 8b of the bearing 8 on the shaft sealing device side and the inner peripheral edge E2 of the bearing side end surface 12a of the oil seal 12. In the configuration in which the outer diameter of the oil-proof partition 30 is set so as to be arranged, the lubricating oil that passes through the bearing 8 and flies toward the oil seal 12 is transferred to the inner peripheral surface of the oil seal 12 and the rotor shaft 6. It was possible to reliably prevent the gap Δ between the outer peripheral surfaces from directly reaching the end portion Δa on the bearing side.

In the conventional shaft sealing structure, as shown in the enlarged view in FIG. 8, the bearing side end portion of the gap Δ between the inner peripheral surface of the oil seal 112 and the outer peripheral surface of the rotor shaft 106, which is the infiltration starting point of the lubricating oil. Δa opens toward the bearing 108 without any obstruction, and a large amount of lubricating oil supplied to the bearing by jet lubrication can reach this part while maintaining the momentum. The prevention of the infiltration of lubricating oil into the gap Δ between the inner peripheral surface of the seal 112 and the outer peripheral surface of the rotor shaft 106 has a structure that depends only on the fluid dynamic pressure generated by the oil seal 112.

On the other hand, in the configuration of the present invention, the flow of the lubricating oil toward the oil seal 12 side not only collides with the oil-proof partition wall 30 and its momentum is diminished, but also the oil-proof partition wall 30 causes the flow of the lubricating oil. By guiding toward the outer peripheral direction, the amount of lubricating oil reaching the oil seal 12 can be significantly reduced.

Even if the lubricating oil reaches the oil seal 12 side beyond the oil-proof partition wall 30, the rotor shaft 6 has a rotor shaft 6 because the initial momentum of the lubricating oil is diminished by the collision with the oil-proof partition wall 30. Even in the state of low-speed rotation, the lubricating oil can overcome the fluid dynamic pressure generated by the oil seal 12 and infiltrate into the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6. However, even when the rotor shaft 6 is rotating at a low speed, the oil seal 12 can prevent the lubricating oil from entering the rotor chamber 3 side.

Moreover, the oil-proof partition 30 is fitted onto the rotor shaft 6 and rotates together with the rotor shaft 6, so that the lubricating oil that collides with the rotating oil-proof partition 30 is blown in the outer peripheral direction by centrifugal force. The lubricating oil is guided in a direction away from the bearing side end Δa of the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6, which is the starting point for the lubricating oil to enter the rotor chamber 3 side. The structure is extremely difficult to reach the gap Δ.

The outer diameter of the oil-proof partition 30 is set to the extent that a rotation allowable interval can be secured between the outer peripheral edge of the oil-proof partition 30 and the inner peripheral surface of the shaft hole 9 at the mounting position of the oil-proof partition 30. In the configuration as close as possible to the inner diameter of the shaft hole 9, the gap between the inner wall of the shaft hole 9 and the outer peripheral edge of the oil-proof partition wall 30 becomes small, so that the lubricating oil flowing in from the bearing 8 side is in this gap. It was possible to make the structure more difficult for the lubricating oil to pass through the oil-proof partition wall 30 and reach the oil seal 12 side.

In particular, the outer diameter of the oil-proof partition 30 is formed larger than the inner diameter of the annular locking tool 14 such as a snap ring that locks the end face 12a on the bearing side of the oil seal 12, and the shaft of the oil-proof partition 30 is formed. In a configuration in which the gap between the side surface 32 on the sealing device side and the side surface 14a on the bearing side of the locking tool 14 is narrowed as much as possible within a range in which the allowable rotation interval can be secured, the lubricating oil from the bearing 8 is used. It is not possible to reach the oil seal 12 side without passing through this narrow gap, and the structure is such that the lubricating oil is difficult to reach the oil seal 12.

Further, in the configuration in which the oil drainage flow path 40 opened at the bottom of the shaft hole 9 is provided at a position below the oil barrier partition 30, the lubricating oil guided by the oil barrier 30 is guided downward. Is introduced into the oil drainage flow path 40 as it is, and the lubricating oil scattered in the outer peripheral direction due to the centrifugal force of the rotating oil-proof partition wall 30 is drained downward along the inner wall of the shaft hole 9. Most of the lubricating oil introduced into the flow path 40 and passing through the bearing 8 is smoothly discharged through the oil drainage flow path 40 without staying in the shaft hole 9 before reaching the oil seal 12. It is more difficult for the lubricating oil to flow into the oil seal 12 side.

Further, in a configuration in which the side surface 31 of the oil-proof partition wall 30 on the bearing side is inclined so that the outer peripheral side is away from the bearing 8 with respect to the inner peripheral side (see FIGS. 2 and 3), the oil flows in from the bearing 8 side. The lubricating oil that has been used is smoothly guided along this inclined surface toward the outer peripheral surface of the oil-proof partition wall 30 from the bearing side end portion Δa of the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6. It can be guided in the direction of separation.

On the contrary, in the configuration in which the side surface 31 of the oil-proof partition wall 30 on the bearing side is inclined so that the outer peripheral side approaches the bearing 8 with respect to the inner peripheral side (see FIG. 4), the oil-proof partition wall is used. The lubricating oil that collides with the side surface 31 on the bearing side of 30 and is guided in the outer peripheral direction is guided by this inclined surface and guided back to the bearing 8 side, so that the lubricating oil for the oil seal 12 side is supplied. It was possible to make it less likely to cause further infiltration.

Further, in a configuration in which ribs 34 extending in the radial direction of the oil-proof partition 30 are provided on the bearing-side side surface 31 of the oil-proof partition 30 at predetermined intervals in the circumferential direction, the bearing-side side surface 31 of the oil-proof partition 30 is provided. By guiding the lubricating oil that collided with the oil toward the outer peripheral side by the rib 34, the lubricating oil could be more efficiently guided in the outer peripheral direction of the oil-proof partition wall 30.

On the inner peripheral surface of the shaft hole 9 on the extension of the side surface 31 on the bearing side of the oil-proof partition wall 30, an inclined portion 97 that gradually expands the inner diameter from the shaft sealing device 10 side toward the bearing 8 side is provided. In the configuration, the lubricating oil scattered in the outer peripheral direction due to the centrifugal force accompanying the rotation of the oil-proof partition wall collides with the inclined portion 97, and is guided by the inclination of the inclined portion 97 and returned to the bearing 8 side. By being guided in this way, it was possible to more effectively prevent the infiltration of the lubricating oil into the oil seal 12 side.

FIG. 3 is a side sectional explanatory view of an oil-free screw compressor provided with the shaft sealing portion structure of the present invention. Enlarged view of the arrow II part (the part surrounded by the broken line) in FIG. FIG. 1A is a front view and FIG. 1B is a side sectional view of the oil-proof partition wall. A side sectional view of an oil-proof partition wall in a modified example. In yet another modification, (A) is a front view and (B) is a side sectional view of the oil-proof partition wall. The enlarged view which shows the modification of the arrow II part (the part surrounded by a broken line) of FIG. Planar cross-sectional view of an oil-free screw compressor with a conventional shaft seal structure. An enlarged explanatory view of a shaft sealing portion structure of a conventional oil-free screw compressor (Patent Document 1). An enlarged explanatory view of a shaft sealing portion structure of a conventional oil-free screw compressor (Patent Document 2).

Hereinafter, the configuration of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is an oil-free screw compressor provided with the shaft sealing portion structure of the present invention, and the casing 2 of the oil-free screw compressor 1 has a pair of male and female screw rotors 4 and 5 ( In FIG. 1, the female screw rotor 5 is hidden behind the male screw rotor 4), and a rotor chamber 3 is formed. In the rotor chamber 3, the male screw rotor 4 and the female screw rotor 4 are formed. 5 is configured to be able to compress the compressed gas by meshing and rotating in a non-contact state.

At both ends of the male and female screw rotors 4 and 5, the rotor shafts 6 and 7, which are the rotation shafts of the screw rotors 4 and 5, respectively (in FIG. 1, the rotor shaft 7 of the female screw rotor 5 is a male screw rotor 4). The rotor shafts 6 and 7 of the male screw rotor 4 and the female screw rotor 5 are located at both ends of the rotor chamber 3 in the longitudinal direction. Each of the shaft holes 9 to be inserted is formed, and the rotor shafts 6 and 7 are rotatably supported by the bearings 8 provided in the shaft holes 9.

The bearing 8 is composed of an open type bearing having no shield that closes the space between both end edges of the inner ring 8a and the outer ring 8b, and the lubrication nozzle 20 provided on the outer side of the machine with respect to the bearing 8. By injecting lubricating oil toward the distance between the inner ring 8a and the outer ring 8b of the bearing 8, the bearing 8 can be lubricated and cooled.

A shaft sealing device 10 for sealing the gap is attached to the gap between the outer peripheral surface of the rotor shaft 6 and the inner peripheral surface of the shaft hole 9 between the bearing 8 and the rotor chamber 3.

The shaft sealing device 10 is composed of a combination of an air seal 11 arranged on the rotor chamber 3 side and an oil seal 12 arranged on the bearing 8 side, both of which are non-contact type seals. As the oil seal 12, a screw seal having a spiral groove on the inner peripheral surface of the cylindrical member is used as in the oil seals described in Patent Documents 1 and 2 described above as the prior art.

The shaft hole 9 is provided with a small diameter portion 91 formed at the end on the rotor chamber 3 side with an inner diameter corresponding to the outer diameter of the rotor shaft, and the shaft on the bearing 8 side with respect to the small diameter portion 91. The hole 9 is formed with a shaft sealing device accommodating portion 92 having an inner diameter expanded with respect to the small diameter portion 91 described above, so that the shaft sealing device 10 can be accommodated in the shaft sealing device accommodating portion 92. It is configured.

To accommodate the shaft sealing device 10 in the shaft sealing device accommodating portion 92, the rotor shaft 6 is fitted into the rotor shaft 6 from the outside of the machine toward the rotor chamber 3 side with the rotor shaft 6 inserted into the shaft hole 9 from the rotor chamber 3 side. The shaft sealing device 10 is inserted into the shaft sealing device accommodating portion 92, and the end surface of the air seal 11 of the shaft sealing device 10 on the rotor chamber side is formed at the boundary portion between the shaft sealing device accommodating portion 92 and the small diameter portion 91. The locking tool ( The shaft sealing device 10 is fixed in the shaft sealing device accommodating portion 92 by restricting the position of the bearing side end surface 12a of the oil seal 12 of the shaft sealing device 10 by the snap ring) 14.

The locking tool 14 is not limited to the snap ring described above, and various known locking tools 14 are used as long as they have an annular portion that can regulate the position of the bearing side end surface 12a of the oil seal 12. It is possible.

The rotor shaft 6 between the shaft sealing device 10 and the bearing 8 is equipped with an endless annular disk-shaped oil-proof partition wall 30 having an opening 35 formed in the center corresponding to the outer diameter of the rotor shaft 6. By fitting the oil-proof partition wall 30 to the rotor shaft 6, the inside of the shaft hole 9 is partitioned between the bearing 8 and the oil seal 12.

The outer diameter of the oil-proof partition wall 30 is formed to be larger than the inner diameter of the oil seal 12, and as shown in an enlarged view in FIG. 2, the outer peripheral edge of the oil-proof partition wall 30 is the outer ring 8b of the bearing 8. It is preferable to form the oil seal 12 so as to be arranged on the outer peripheral side of the line L connecting the inner peripheral edge E1 on the shaft sealing device side and the inner peripheral edge E2 on the bearing side of the oil seal 12.

Preferably, the outside of the oil-proof partition wall 30 is within a range in which a rotation allowable interval can be secured in the gap between the outer peripheral edge of the oil-proof partition wall 30 and the inner peripheral surface of the shaft hole 9 at the mounting position of the oil-proof partition wall. The diameter shall be as close as possible to the inner diameter of the shaft hole 9.

More preferably, the outer diameter of the oil-proof partition 30 is formed to be larger than the inner diameter of the annular locking tool 14 such as a snap ring for fixing the bearing side end surface 12a of the oil seal 12, and the shaft of the oil-proof partition 30 is formed. A part of the side surface 32 on the sealing device side and a part of the side surface 14a on the bearing side of the locking tool 14 are configured to face each other, and the side surface 32 on the shaft sealing device side of the oil-proof partition wall 30 and the locking tool 14 The gap between the side surfaces 14a on the bearing side of the above is arranged as narrow as possible within the range where the allowable rotation interval can be secured.

In order to realize such an arrangement of the oil-proof partition wall 30, in the embodiment shown in FIG. 2, a boss 33 is provided on the side surface 31 of the oil-proof partition wall 30 on the bearing side so as to project from the peripheral edge of the central opening 35 toward the bearing side. The boss 33 is formed by sandwiching the portion of the boss 33 of the oil-proof partition wall 30 externally fitted to the rotor shaft 6 between the step portion 6a provided on the rotor shaft 6 and the inner ring 8a of the bearing 8. The side surface 32 on the shaft sealing device side is arranged at a position separated from the bearing 8 by the protruding length of the locking tool 14, and is arranged at a position close to the side surface 14a on the bearing side of the locking tool 14.

The side surface 31 on the bearing side of the oil-proof partition wall 30 may be formed as a plane in a direction orthogonal to the axis of the rotor shaft 6, but in the embodiment shown in FIG. 2, the side surface 31 on the bearing side of the oil-proof partition wall 30 may be formed. The side surface 31 is inclined so as to gradually separate from the bearing 8 from the inner peripheral side to the outer peripheral side.

Reference numeral 40 in FIG. 2 is an oil drainage flow path, and the oil drainage flow path 40 is inside the casing 2 so as to open to the bottom of the shaft hole 9 below the mounting position of the oil-proof partition wall 30. It is formed.

When the oil-free screw compressor 1 having the shaft sealing structure configured as described above is operated to start the rotation of the screw rotors 4 and 5, the rotor shafts 6 and 7 start to rotate and the lubrication nozzle is provided. 20 starts "jet lubrication" in which lubricating oil is injected to the bearing 8 toward the distance between the inner ring 8a and the outer ring 8b of the bearing 8.

Since the lubrication nozzle 20 injects a relatively large amount of lubricating oil at a relatively high pressure to supply oil to the bearing 8, the lubricating oil that has lubricated and cooled the bearing 8 is injected even after passing through the bearing 8. A large amount of oil flows out toward the oil seal 12 side while maintaining the momentum of the time to some extent.

However, as described above, the oil-proof partition wall 30 is externally fitted to the rotor shaft 6 between the bearing 8 and the oil seal 12, and the space in the shaft hole 9 between the bearing 8 and the oil seal 12 is the oil-proof partition wall 30. It is partitioned by.

The outer diameter of the oil-proof partition wall 30 is formed to be larger than the inner diameter of the oil seal 12, and the outer peripheral edge thereof is preferably the inner peripheral edge E1 on the shaft sealing device side of the outer ring 8b of the bearing 8. When the oil seal 12 is viewed from the bearing 8 side, the outer diameter is set so that it is arranged on the outer peripheral side of the line L connecting the inner peripheral edge E2 of the bearing side end of the oil seal 12. The bearing-side end Δa of the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6, which is the starting point when the lubricating oil infiltrates into the rotor chamber 3, is completely removed by the oil-proof partition wall 30. It will be placed in a position shielded by.

As a result, the flow of lubricating oil that passes through the bearing 8 and tends toward the bearing side end Δa of the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6 is surely this oil-proof partition wall. It will collide with 30 and prevent the lubricating oil that has passed through the bearing 8 from directly reaching the bearing side end portion Δa of the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6. There is.

In this way, the lubricating oil that has passed through the bearing 8 and collided with the oil-proof partition 30 is applied to the centrifugal force generated by the rotation of the oil-proof partition 30 together with the rotor shaft and the side surface 31 of the oil-proof partition 30 on the bearing side. The flow is changed in the outer peripheral direction by the guidance by the formed inclined surface.

As a result, the lubricating oil that has passed through the bearing 8 moves away from the bearing side end portion Δa of the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6, which is the starting point for the lubricating oil to enter the rotor chamber 3. A large amount of lubricating oil guided in the direction and passing through the bearing 8 cannot reach the bearing side end portion Δa of the above-mentioned gap Δ while maintaining the momentum.

Then, among the lubricating oils that collide with the oil-proof partition 30 and change their directions in this way, those guided downward in the outer peripheral direction are directly introduced into the oil drainage flow path 40 that opens at the bottom of the shaft hole 9. In addition, the other part is blown in the outer peripheral direction by centrifugal force, then falls along the inner wall of the shaft hole 9 and is introduced into the oil drainage flow path 40, so that the other part is smoothly discharged from the shaft hole 9. As a result, the amount of lubricating oil reaching the oil seal 12 is significantly reduced.

Further, in the shaft sealing portion structure of the present invention configured as described above, even if the oil-proof partition wall 30 is exceeded, the gap Δ between the inner peripheral surface of the oil seal 12 and the outer peripheral surface of the rotor shaft 6 is formed at the bearing side end portion Δa. Even if the lubricating oil that has reached is present, not only the amount of lubricating oil that can be reached is small as compared with the case where the oil-proof partition wall 30 is not provided, but also the reaching lubricating oil collides with the oil-proof partition wall. The momentum has been greatly diminished by.

As a result, even if the fluid dynamic pressure generated by the oil seal 12 is reduced due to the decrease in the rotation speed of the rotor shaft 6 and the function of pushing the lubricating oil back to the bearing 8 side is reduced, the amount of lubricating oil reached is reduced. Since the lubricating oil that has reached the oil seal 12 has lost its momentum as it has been reduced to less than the processing capacity of the oil seal 12, the inner peripheral surface of the oil seal 12 and the rotor shaft resist the fluid dynamic pressure generated by the oil seal 12. It cannot penetrate into the gap Δ between the outer peripheral surfaces of 6.

In particular, the gap between the outer peripheral edge of the oil-proof partition 30 and the inner peripheral surface of the shaft hole 9 is narrowed as much as possible within the range in which the allowable rotation interval can be secured, and the outer diameter of the oil-proof partition 30 is reduced. , The side surface 32 of the oil-proof partition wall 30 on the shaft sealing device side and the bearing side of the locking tool 14 are formed to have a diameter larger than the inner diameter of the annular locking tool 14 that locks the end surface 12a on the bearing side of the oil seal 12. In a configuration in which the gap between the side surfaces 14a is formed as narrow as possible within the range where the allowable rotation interval can be secured, the gap through which the lubricating oil must pass in order to reach the oil seal 12 becomes narrow, so that the oil The amount of lubricating oil that can reach the bearing side end Δa of the gap Δ between the inner peripheral surface of the seal 12 and the outer peripheral surface of the rotor shaft 6 can be further reduced, and the momentum of the lubricating oil can be reduced. It is possible to make it more difficult for the lubricating oil to infiltrate into the rotor chamber 3 side.

The oil-proof partition wall 30 provided in the shaft sealing structure of the oil-free screw compressor 1 described above with reference to FIGS. 2 and 3 has a side surface 31 on the bearing side bearing from the inner peripheral side to the outer peripheral side. It was formed as an inclined surface that is inclined in a direction that is more distant from each other.

On the other hand, the oil-proof partition wall 30 shown in FIG. 4 is formed with the side surface 31 on the bearing side as an inclined surface inclined so as to approach the bearing 8 from the inner peripheral side toward the outer peripheral side.

By forming in this way, the lubricating oil that has collided with the side surface 31 of the oil-proof partition wall 30 on the bearing side is guided in the inclined direction given to the side surface 31 from the inner peripheral side to the outer peripheral side of the oil-proof partition wall 30. By moving toward, the lubricating oil could be guided to return to the bearing 8 side, and as a result, the amount of the lubricating oil toward the oil seal 12 side could be further reduced.

Further, in the oil-proof partition wall 30 described with reference to FIGS. 2 to 4, the side surface 31 of the oil-proof partition wall 30 on the bearing side is inclined, but the surface thereof is formed flat.

On the other hand, in the embodiment shown in FIG. 5, ribs 34 (convex stripes) on the side surface 31 of the oil-proof partition wall 30 on the bearing side at predetermined intervals in the circumferential direction with the radial direction of the oil-proof partition wall 30 as the length direction. ) Is provided.

By providing the rib 34 on the side surface 31 on the bearing side of the oil-proof partition wall 30 in this way, the lubricating oil that has collided with the side surface 31 on the bearing side of the oil-proof partition wall 30 is guided by the rib 34 and efficiently outer peripheral. It can be moved in the direction, and the lubricating oil is more effectively prevented from flowing into the oil seal 12 side.

Further, in the embodiment shown in FIG. 2, a configuration example is shown in which the inner diameter of the shaft hole 9 from the shaft sealing device accommodating portion 92 to the bearing 8 is the same, but the space between the oil seal 12 and the bearing 8 is shown. As shown in FIG. 6, the inner diameter of the shaft hole 9 is at least on the inner peripheral surface of the shaft hole 9 on the extension of the bearing side side surface 31 of the oil-proof partition wall 30 from the shaft sealing device 10 side to the bearing 8 side. An inclined portion 97 that gradually widens the inner diameter may be provided.

In the configuration in which the inclined portion 97 is provided, as shown by an arrow in FIG. 6, the centrifugal force accompanying the rotation of the oil-proof partition wall 30 is transmitted along the side surface 31 of the oil-proof partition wall 30 on the bearing side and is scattered in the outer peripheral direction. The lubricated oil collides with the inclined portion 97 formed on the inner peripheral surface of the shaft hole 9, and is guided by the inclination of the inclined portion 97 so as to be returned to the bearing 8 side, whereby the oil seal 12 is used. It is possible to more reliably prevent the intrusion of lubricating oil to the side.

1 Oil-free screw compressor 2 Casing 3 Rotor chamber 4 Male screw rotor 5 Female screw rotor 6 Rotor shaft (male screw rotor)
7 Rotor shaft (of female screw rotor)
8 Bearing 8a Inner ring 8b Outer ring 9 Shaft hole 91 Small diameter part 92 Shaft sealing device accommodating part 93 Side of stepped part 97 Inclined part 10 Shaft sealing device 11 Air seal 12 Oil seal 12a Bearing side end face (of oil seal)
12b Spiral groove 14 Locking tool (snap ring)
14a Bearing side side surface (of locking tool)
20 Refueling nozzle 21 Circular groove 30 Oil-proof partition 31 Side surface on the bearing side (of oil-proof partition)
32 Side surface on the shaft sealing device side (of the oil-proof bulkhead)
33 Boss 34 Rib 35 Opening 40 Oil drainage channel 100 Oil-free screw compressor 102 Casing 103 Rotor chamber 104 Male screw rotor 105 Female screw rotor 106 Rotor shaft (of male screw rotor)
107 Rotor shaft (of female screw rotor)
108 Bearing 108a Inner ring 108b Outer ring 109 Shaft hole 110 Shaft sealing device 111 Air seal 112 Oil seal 112a Bearing side end face (of oil seal)
112b Spiral groove 114 Snap ring 118 Shielding plate 120 Refueling nozzle 121 Circular groove 140 Oil drainage flow path Δ Gap between the inner peripheral surface of the oil seal and the outer peripheral surface of the rotor shaft Δa Between the inner peripheral surface of the oil seal and the outer peripheral surface of the rotor shaft Bearing side end of the gap Δ'Gap between the inner peripheral surface of the shielding plate and the outer peripheral surface of the rotor shaft E1 Inner peripheral edge of the bearing outer ring on the shaft sealing device side E2 Inner peripheral edge of the oil seal on the bearing side

Claims (9)

A bearing that supports the rotor shaft provided in each pair of male and female screw rotors, an air seal that is provided between the rotor chambers that accommodate the screw rotor and is arranged on the rotor chamber side, and an air seal that is arranged on the bearing side. A shaft seal of an oil-free screw compressor that seals the gap between the outer peripheral surface of the rotor shaft and the inner peripheral surface of the shaft hole into which the rotor shaft is inserted by a non-contact shaft sealing device consisting of an oil seal. In the structure
An endless annular oil-proof partition wall that rotates with the rotor shaft is fitted onto the rotor shaft between the bearing and the oil seal.
A shaft sealing structure of an oil-free screw compressor, characterized in that the outer diameter of the oil-proof partition wall is made larger than the inner diameter of the oil seal. The oil-proof partition is arranged on the outer peripheral side of the line connecting the inner peripheral edge of the outer ring of the bearing on the shaft sealing device side and the inner peripheral edge of the bearing-side end face of the oil seal. The shaft sealing portion structure of the oil-free screw compressor according to claim 1, wherein the outer diameter of the partition wall is set. The outer diameter of the oil-proof partition is set to the inner diameter of the shaft hole within a range in which a rotation allowable interval can be secured between the outer peripheral edge of the oil-proof partition and the inner peripheral surface of the shaft hole at the mounting position of the oil-proof partition. The shaft sealing portion structure of the oil-free screw compressor according to claim 1 or 2, characterized in that the oil-free screw compressor is as close as possible to the above. The outer diameter of the oil-proof partition wall is formed to be larger than the inner diameter of the annular locking tool that regulates the end face of the oil seal on the bearing side.
The side surface of the oil-proof partition wall on the shaft sealing device side and the side surface of the oil-proof partition wall on the shaft sealing device side to the extent that a rotation allowable distance can be secured between the side surface of the oil-proof partition wall on the shaft sealing device side and the side surface of the locking tool on the bearing side. The shaft sealing portion structure of the oil-free screw compressor according to any one of claims 1 to 3, wherein the gap between the side surfaces of the locking tool on the bearing side is narrowed as much as possible. The shaft sealing portion structure of the oil-free screw compressor according to any one of claims 1 to 4, wherein an oil drainage flow path opened at the bottom of the shaft hole is provided at a position below the oil-proof partition wall. .. The oil-free screw according to any one of claims 1 to 5, wherein the side surface of the oil-proof partition wall on the bearing side is inclined so that the outer peripheral side is inclined away from the bearing with respect to the inner peripheral side. The shaft seal structure of the compressor. The oil-free screw according to any one of claims 1 to 5, wherein the side surface of the oil-proof partition wall on the bearing side is inclined so that the outer peripheral side approaches the bearing with respect to the inner peripheral side. The shaft seal structure of the compressor. The oil-free screw according to any one of claims 1 to 7, wherein ribs extending in the radial direction of the oil-proof partition wall are provided on the side surface of the oil-proof partition wall on the bearing side at predetermined intervals in the circumferential direction. The shaft seal structure of the compressor. The oil-proof partition is characterized in that an inclined portion that gradually expands the inner diameter from the shaft sealing device side toward the bearing side is provided on the inner peripheral surface of the shaft hole on the extension of the side surface of the bearing side of the oil-proof partition in the outer peripheral direction. The shaft sealing portion structure of the oil-free screw compressor according to any one of claims 1 to 8.

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