JP2012127314A - Water injection type screw fluid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water injection type screw fluid machine provided with adequate sealing properties, and a shaft sealing device with a long life.SOLUTION: In a screw fluid machine 1, a shaft sleeve 15 fit together onto an outer periphery of a rotor shaft 7, and an outer sleeve 16 fixed to a casing 2, have at least five adjacent portions 29, 30, 31, 32, 33 adjoining each other in an axial direction, and form at least six spaces of an outflow space 35, a rotor side interference space 36, a pressurizing space 37, a seal side interference space 38, an open space 39 and seal space 41, and the casing 2 is provided with a low-pressure communication passage 26 that communicates with the outflow space 35 with a compression halfway space of a rotor chamber 3 or a suction flow passage to a rotor chamber 3, a high-pressure communication passage 27 for introducing a target gas discharged to the pressurizing space 37 from the rotor chamber, and an open communication passage 28 that communicates with the pressurizing space 37 to an outside space of the casing 2.

Description

  The present invention relates to a water jet screw fluid machine.

  In a screw fluid machine such as a screw compressor that compresses the target gas with a male and female screw rotor housed in the rotor chamber, and a screw expander that rotates the screw rotor that expands and gasifies the target gas in the rotor chamber, A shaft seal structure is provided between the screw rotor of the rotor shaft and the bearing in order to seal the target gas in the system or prevent external air from being mixed into the target gas.

  As described in Patent Document 1, in the conventional screw compressor, a lip seal is used as a suction side shaft seal device, and a mechanical seal is used as a discharge side shaft seal device.

The lip seal is an inexpensive and space-saving shaft seal device, but generally the maximum pressure that can be sealed is about 0.3 kgf / cm ² . For this reason, the lip seal can be used only for the shaft seal on the low pressure side because the shaft seal may be insufficient on the high pressure side or the durability may be significantly reduced. On the other hand, the mechanical seal is capable of high-pressure shaft sealing, but has a problem that it is very expensive and requires a large space for installation.

  In Patent Document 2, a lip seal is further provided on the bearing side of the mechanical seal to ensure the shaft seal. However, a space between the mechanical seal and the lip seal is provided so that excessive pressure is not applied to the lip seal. The rotor chamber communicates with the suction side.

  Further, some screw fluid machines include a water injection type in which water is injected into a rotor chamber to perform lubrication and cooling. In a water jet screw fluid machine equipped with a lip seal in a shaft seal device, when water leaked from the rotor chamber enters a space sealed by the lip seal, the lip seal must seal the water. Unlike oil, since water has low lubricity, wear of the lip seal increases when water is sealed with a lip seal. Therefore, the water jet screw fluid machine has a problem that the life of the lip seal is short and frequent maintenance is required.

JP 2000-45948 A JP 2007-132243 A

  In view of the above problems, an object of the present invention is to provide a water-lubricated screw fluid machine that has sufficient sealing performance and has a long life of a shaft seal device.

  In order to solve the above-mentioned problems, a water jet screw fluid machine according to the present invention compresses a target gas with a male and female screw rotor housed in a rotor chamber formed in a casing or uses an expansion force of the target gas as a rotational force. In the screw fluid machine for conversion, a lip seal that prevents the lubricating oil of the bearing from leaking to the rotor chamber side between the screw rotor and the bearing on the high-pressure side of the rotor shaft of the screw rotor, and the rotor A shaft sleeve fitted on the outer periphery of the shaft and rotating together with the rotor shaft; and an outer sleeve positioned outside the shaft sleeve and fixed to the casing. The shaft sleeve and the outer sleeve are: It has at least five proximity parts that are close to each other in the radial direction, and a space between them is defined by the proximity part Thus, in order from the rotor chamber side, at least six spaces of an outflow space, a rotor side interference space, a pressurizing space, a seal side interference space, an open space and a seal space are formed, and the casing defines the outflow space. A low-pressure communication path communicating with a low-pressure space in the middle of compression of the rotor chamber or a suction flow path to the rotor chamber; a high-pressure communication path for introducing a target gas discharged from the rotor chamber into the pressurization space; An open communication path that communicates the open space with an external space of the casing.

  According to this configuration, by reducing the outflow space by connecting to the rotor chamber or the suction flow path lower than the discharge pressure through the low-pressure communication path, and introducing the high-pressure target gas through the high-pressure communication path. Since the pressurized space is pressurized, the water leaked from the rotor chamber to the outflow space due to the pressure difference is circulated to the rotor chamber through the low-pressure communication path and does not enter the pressurized space. For this reason, water does not enter the seal space and the lip seal is not damaged, and leakage of the lubricating oil for the bearing can be prevented. Further, since the high-pressure target gas introduced into the pressurizing space is discharged to the outside from the open space via the open communication path, the pressure in the seal space is not increased, and excessive pressure is not applied to the lip seal.

  Further, the screw fluid machine of the present invention is such that, further on the rotor chamber side of the outflow space, an inner diameter is slightly larger than an outer diameter of the rotor shaft and the outer diameter is between the rotor shaft and the casing. A seal ring slightly smaller than the inner diameter of the casing may be arranged.

  According to this configuration, since the amount of the target gas and water leaking from the rotor chamber to the outflow space is reduced by the seal ring, it is possible to more reliably prevent water from entering the bearing and also reduce the pressure loss of the target gas. .

  Further, in the screw fluid machine according to the present invention, the shaft sleeve includes a disk part that continuously protrudes outward in the outflow space, and a radial part that protrudes radially on the rotor chamber side of the disk part. May be provided.

  According to this configuration, the disk portion and the radial portion move the water that has leaked from the rotor chamber and entered the outflow space to the outside in the radial direction. Accordingly, it is possible to prevent the water from easily reaching the proximity portion by moving straight along the shaft sleeve in the axial direction, and to further reduce the possibility of water entering the rotor side interference space.

  Further, in the screw fluid machine of the present invention, the diameter of the adjacent portion of the proximity portion between the outflow space and the rotor side interference space is equal to the proximity between the rotor side interference space and the pressurization space. It may be larger than the diameter of adjacent parts. Further, the diameter of the adjacent portion of the proximity portion between the pressurizing space and the seal-side interference space is equal to that of the adjacent portion of the proximity portion between the seal-side interference space and the open space. It may be larger than the diameter.

  According to this configuration, the water that has passed through the proximity portion is blown outward in the radial direction by centrifugal force. Therefore, if the water does not travel along the protrusion of the outer sleeve radially inward, it will reach the next proximity portion. I can't.

  Further, in the screw fluid machine of the present invention, a diameter of the adjacent portion of the proximity portion between the rotor side interference space and the pressurization space is between the pressurization space and the seal side interference space. It may be different from the diameter of the adjacent portion of the proximity portion.

  According to this configuration, since the shaft sleeve and the outer sleeve are stepped, it is not possible to reach the seal-side interference space only by moving water along the surface of the shaft sleeve or the outer sleeve in the axial direction.

It is a simplified sectional view of the screw compressor of a 1st embodiment of the present invention. It is a detailed sectional view of the shaft seal part of the screw compressor of FIG.

  In FIG. 1, the screw compressor 1 which is one embodiment of the water-injection-type screw fluid machine which concerns on this invention is simplified and shown. The screw compressor 1 compresses and discharges a target gas (for example, air) with a pair of screw rotors 4 engaged in male and female, housed in a rotor chamber 3 formed in a casing 2. Water is introduced for cooling, sealing and lubrication.

  The casing 2 includes a suction flow path 5 that supplies a target gas to be compressed to the rotor chamber 3, a discharge flow path 6 that discharges the target gas compressed by the screw rotor 4 in the rotor chamber 3, and the screw rotor 4. Bearing shaft sealing spaces 8 and 9 are provided for installing a structure for supporting and shaft sealing the rotor shaft 7 on the suction side and the discharge side, respectively.

  The rotor shaft 7 is rotatably supported by a roller bearing 10 installed in the suction-side bearing shaft sealing space 8 and two ball bearings 11 installed in the discharge-side bearing shaft sealing space 9, The bearing shaft sealing space 9 on the side is extended and connected to a motor (not shown).

  A lip seal 12 is installed on the motor side of the roller bearing 10 to prevent foreign substances (such as grease on the roller bearing 10) from entering the motor side. On the screw rotor 4 side of the roller bearing 10, grease on the roller bearing 10 is installed. A lip seal 13 is provided for sealing so as not to flow out to the screw rotor 4 side, and a lip seal 14 for sealing the target gas or lubricating fluid from entering the roller bearing 10 side from the suction flow path 5. .

  Between the ball bearing 11 and the rotor chamber 3, the rotor shaft 7 is fitted in an airtight manner, the shaft sleeve 15 that rotates together with the rotor shaft 7, the shaft sleeve 15 is positioned outside, and the airtightly fixed to the casing 3. An outer sleeve 16 is disposed. The shaft sleeve 15 is divided into three parts, ie, a first rotating sleeve 17, a second rotating sleeve 18 and a third rotating sleeve 19 from the rotor chamber 3 side. The outer sleeve 16 is divided into three parts, ie, a first fixed sleeve 20, a second fixed sleeve 21, and a third fixed sleeve 22 from the rotor chamber 3 side.

  The third fixed sleeve 22 is in slidable contact with the third fixed sleeve 19 and divides the bearing shaft sealing space 9 to seal the ball bearing 11 so that the lubricating oil does not leak to the rotor chamber 3 side. 23 is held.

  Further, a seal ring 24 is disposed in the bearing shaft sealing space 9 on the rotor chamber 3 side further than the first sleeve 17 and the first fixed sleeve 20. The seal ring 24 has an inner diameter slightly larger (for example, about 0.05 mm) than the outer diameter of the corresponding position of the rotor shaft 7 and an outer diameter that is slightly smaller (for example, about 0.05 mm) than the inner diameter of the corresponding position of the casing 2. And have.

  In the casing 2, a seal communication path 25 that communicates the space between the lip seal 13 and the lip seal 14 to the outside, and a low-pressure communication path 26 that communicates with the suction flow path 5 and opens to the outside of the first fixed sleeve 20. A high-pressure communication path 27 that communicates with the discharge flow path 6 and opens to the outside of the second fixed sleeve 21; and an open communication path that communicates with the outside (outside air) of the casing 2 and opens to the outside of the third fixed sleeve 22 28 are formed.

  FIG. 2 shows the shaft sleeve 15 and the outer sleeve 16 in detail. The shaft sleeve 15 and the outer sleeve 16 have six adjacent portions 29, 30, 31, 32, 33, 34, at least one of which partially protrudes toward the other and is close to the other.

  The space (bearing shaft sealing space 9) between the shaft sleeve 15 and the outer sleeve 16 flows out in order from the rotor chamber 3 side by the proximity portions 29, 30, 31, 32, 33, 34 and the lip seal 23. The space 35 is divided into a rotor side interference space 36, a pressurizing space 37, a seal side interference space 38, an open space 39, a spare space 40, a seal space 41, and a bearing space 42.

  The outflow space 35 communicates with the space where the seal ring 24 is disposed on the rotor chamber 3 side, and the lip seal 23 side is separated from the rotor side interference space 36 by the proximity portion 29 closest to the rotor chamber 4 side. The first fixed sleeve 20 is formed with a through hole 43 that allows the outflow space 35 to communicate with the low pressure communication path 26. In addition, the first rotating sleeve 17 is formed with a disk portion 44 that protrudes outward from the disk at a position near the rotor chamber 3 in the outflow space 35, and is formed on the surface of the disk portion 44 on the rotor chamber 4 side. Includes a plate-like or rib-like radial portion 45 projecting radially. Further, a locking portion 46 protruding inward is provided at the end of the first rotating sleeve 17 on the rotor chamber 4 side so as to lock the seal ring 24 so as not to move to the lip seal 23 side.

  The second fixed sleeve 21 is formed with a through hole 47 that allows the pressurizing space 37 to communicate with the high pressure communication path 27, and the third fixed sleeve 22 is a through hole that allows the open space 39 to communicate with the open communication path 28. 48 is formed.

  The diameter of the adjacent portion of the proximity portion 29 between the outflow space 35 and the rotor side interference space 36 is larger than the diameter of the adjacent portion of the proximity portion 30 between the rotor side interference space 36 and the pressurizing space 37. Is also getting bigger. Also, the diameter of the adjacent portion of the proximity portion 30 between the rotor side interference space 36 and the pressurizing space 37 is the close portion of the proximity portion 31 between the pressurization space 37 and the shaft side interference space 38. It is smaller than the diameter. Furthermore, the diameter of the proximity portion 31 of the proximity portion 31 between the pressurizing space 37 and the shaft side interference space 38 is equal to that of the proximity portion 32 of the proximity portion 32 between the seal side interference space 38 and the open space 39. It is larger than the diameter. Further, the adjacent portions 33 and 34 on both sides of the spare space 40 have mutually different diameters.

  Further, a protruding portion 49 that protrudes in a flange shape outwardly in the radial direction is formed at the end of the third rotating sleeve 19 on the rotor chamber 3 side.

  In the screw compressor 1 of the present embodiment, since the outflow space 35 has a lower pressure than the discharge side space of the rotor chamber 3, water for lubrication and cooling is supplied from the rotor chamber 3 to the outflow space 35 together with the target gas. Can be spilled. Here, since the seal ring 24 forms a narrow gap between the casing 2 and the rotor shaft 7, a pressure loss is caused when water passes through the narrow gap, and the flow from the rotor chamber 3 to the outflow space 35 occurs. It functions as a shaft seal device that reduces the amount of target gas and water flowing out.

  The water leaked from the rotor chamber 3 through the gap between the seal ring 24 and the rotor shaft 7 and the casing 2 to the outflow space 35 due to the pressure of the target gas passes through the low pressure communication passage 26 and is sucked in at a lower pressure than the outflow space 35. It circulates to the flow path 5 and is sucked into the rotor chamber 3 again. At this time, the water that has traveled to the lip seal 23 side along the outer surface of the first rotating sleeve 17 is moved radially outward by the disk portion 44. At this time, the radial portion 45 rotates the water together with the first rotating sleeve 17 to apply centrifugal force to move the water toward the outer periphery of the disk portion 44, and further toward the first fixed sleeve 20. Scatter. Thereby, the water that has entered the outflow space 35 is efficiently guided to the through hole 43 formed in the first fixed sleeve 20. The low pressure communication passage 26 may communicate with the low pressure space in the middle of compression of the rotor chamber 3.

  Thus, the water leaked into the outflow space 35 is circulated from the outflow space 35 to the rotor chamber 3 through the low-pressure communication path 26. Even if water leaks into the space 36, the leaked water is blown outward by the centrifugal force associated with the rotation of the protrusion that constitutes the proximity portion 29 of the first rotating sleeve 17. Therefore, the water leaked into the rotor side interference space 36 must travel from the first fixed sleeve 20 to the protrusion of the second fixed sleeve 21 that forms the proximity portion 30 between the rotor side interference space 36 and the pressurizing space 37. In this case, it is not possible to enter the pressurizing space 37 through the proximity portion 30.

  Further, since the high pressure target gas is introduced from the discharge flow path 6 into the pressurization space 37 via the high pressure communication path 27, the internal pressure of the pressurization space 37 communicates with the suction flow path 35 via the low pressure communication path 26. Higher than the internal pressure of the rotor side interference space 36 and the seal side interference space 38 between the open space 39 opened to the atmosphere via the outflow space 35 and the open communication passage 28, and the pressure space 37. Become. Accordingly, the target gas flows from the pressurized space 37 to the outflow space 35 via the rotor side interference space 36 and from the pressurized space 37 to the open space 39 via the seal side interference space 38.

  The flow of the target gas from the pressurized space 37 to the rotor side interference space 36 through the proximity portion 30 causes water to flow from the outflow space 35 to the rotor side interference space 36 and from the rotor side interference space 36 to the pressure space 37. Prevent inflow. Even if water enters the rotor side interference space 36, the flow of the target gas pushes the entered water back into the outflow space 35. Thus, in addition to the shapes of the shaft sleeve 15 and the outer sleeve 16, the water leaked from the rotor chamber 3 to the outflow space 35 is prevented from moving to the lip seal 23 side due to the flow of the target gas. The contact of water with the seal 23 does not promote wear.

  Further, in the present embodiment, the diameter of the proximity portion 30 between the rotor side interference space 36 and the pressurization space 37 is smaller than the diameter of the proximity portion 31 between the pressurization space 37 and the seal side interference space 38. Therefore, even if water enters the pressurizing space 37, the water cannot pass through the proximity portion 32 and enter the seal-side interference space 38 unless it reaches the radial wall.

  Furthermore, since the diameter of the proximity portion 31 between the pressurizing space 37 and the seal side interference space 38 is larger than the diameter of the proximity portion 32 between the seal side interference space 38 and the open space 39, the seal side The water that has entered the interference space 38 cannot pass through the proximity portion 32 and enter the open space 39 unless it travels along the protrusions that constitute the proximity portion 32 of the third fixed sleeve. For this reason, the water that has entered the seal-side interference space 38 stays in the seal-side interference space 38 for a while, but is introduced into the pressurized space 37 and the target gas flowing into the open space 39 blows through the bearing interference space 38. Therefore, the flow of the target gas evaporates water and releases water vapor from the open communication path 28 to the atmosphere via the open space 39.

  Further, in the present embodiment, since the spare space 40 is formed further on the lip seal 23 side of the open space 39, even if water enters the open space 39 and the spare space 40 due to an unexpected situation, the spare space 40 is provided. The space 40 traps water. Furthermore, even if water enters the spare space 40 and the water enters the bearing space 42 only slightly, the protruding portion 49 is formed on the third rotating sleeve 19. The water that travels is pushed down by the protrusion 49. For this reason, water cannot reach the lip seal 23 and the lip seal 23 is not damaged.

1 ... Screw compressor (water jet type screw fluid machine)
DESCRIPTION OF SYMBOLS 2 ... Casing 3 ... Rotor chamber 4 ... Screw rotor 5 ... Suction flow path 6 ... Discharge flow path 7 ... Screw shaft 9 ... Bearing shaft sealing space 11 ... Ball bearing 15 ... Shaft sleeve 16 ... Outer sleeve 17 ... 1st rotation sleeve 18 2nd rotating sleeve 19 ... 3rd rotating sleeve 20 ... 1st fixed sleeve 21 ... 2nd fixed sleeve 22 ... 3rd fixed sleeve 23 ... Lip seal 24 ... Seal ring 26 ... Low pressure communication path 27 ... High pressure communication path 28 ... Open Communication path 29, 30, 31, 32, 33, 34 ... Proximity part 35 ... Outflow space 36 ... Rotor side interference space 37 ... Pressurization space 38 ... Seal side interference space 39 ... Open space 40 ... Preliminary space 41 ... Seal space 42 ... Bearing space 43, 47, 48 ... Through hole 44 ... Disk part 45 ... Radial part 46 ... Locking part

Claims (6)

In a screw fluid machine that compresses a target gas by a male and female screw rotor housed in a rotor chamber formed in a casing or converts an expansion force of the target gas into a rotational force,
Between the screw rotor and the bearing on the high-pressure side of the rotor shaft of the screw rotor,
A lip seal that prevents the lubricating oil of the bearing from leaking to the rotor chamber side;
A shaft sleeve fitted around the rotor shaft and rotating together with the rotor shaft;
An outer sleeve positioned outside the shaft sleeve and fixed to the casing;
The shaft sleeve and the outer sleeve have at least five proximity portions that are close to each other in the radial direction, and the space between them is divided by the proximity portion, so that the outflow space is sequentially arranged from the rotor chamber side. , Forming at least six spaces of rotor side interference space, pressure space, seal side interference space, open space and seal space,
The casing has a low-pressure communication path that communicates the outflow space with a low-pressure space in the middle of compression of the rotor chamber or a suction flow path to the rotor chamber;
A high-pressure communication path for introducing the target gas discharged from the rotor chamber into the pressurized space;
A screw fluid machine comprising: an open communication path that communicates the open space with an external space of the casing.   Further on the rotor chamber side of the outflow space, between the rotor shaft and the casing, a seal ring whose inner diameter is slightly larger than the outer diameter of the rotor shaft and whose outer diameter is slightly smaller than the inner diameter of the casing. A screw fluid machine characterized by comprising:   2. The shaft sleeve includes a disk portion that continuously protrudes outward in the outflow space, and a radial portion that protrudes radially on the rotor chamber side of the disk portion. Or the screw fluid machine of 2.   The diameter of the adjacent portion of the proximity portion between the outflow space and the rotor side interference space is larger than the diameter of the adjacent portion of the proximity portion between the rotor side interference space and the pressurization space. The screw fluid machine according to any one of claims 1 to 3, wherein the screw fluid machine is also larger.   The diameter of the adjacent portion of the proximity portion between the rotor side interference space and the pressure space is the diameter of the proximity portion of the proximity portion between the pressure space and the seal side interference space. The screw fluid machine according to claim 1, wherein the screw fluid machine is different from the screw fluid machine according to claim 1.   The diameter of the adjacent portion of the proximity portion between the pressurizing space and the seal side interference space is larger than the diameter of the adjacent portion of the proximity portion between the seal side interference space and the open space. The screw fluid machine according to claim 1, wherein the screw fluid machine is also larger.

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