JP4908953B2 - Screw compressor - Google Patents

Description

  The present invention relates to an improvement in a screw compressor, and more particularly to a screw compressor used in a refrigeration apparatus that handles a refrigerant such as corrosive ammonia with respect to a drive motor that drives a compressor body. .

  Today, there are many global environmental problems that require international efforts and urgent solutions. Among them, problems related to ozone layer destruction and global warming are related to refrigeration equipment. And there is an international agreement for these problems, and R22 of HCFC refrigerant, which has been widely used for a long time, has been regulated as destroying the ozone layer.

  Therefore, at present, HFC refrigerants such as R407C and R404A, which have little influence on the ozone layer and have zero ozone depletion coefficient, are replacing HCFC refrigerants. However, HFC refrigerants have a large global warming potential and are problematic in terms of preventing global warming, and they are prohibited from being discharged into the atmosphere together with HCFC refrigerants.

  Therefore, it is not an artificially created refrigerant such as an HCFC refrigerant or an HFC refrigerant, but a natural refrigerant that has the properties of a refrigerant that has a low ozone depletion coefficient, a low global warming coefficient, and exists naturally in nature. Has been reviewed. As such a natural refrigerant, there is ammonia, which is corrosive to copper, and also has toxicity and flammability. Therefore, in order to employ a screw compressor in a refrigeration apparatus using ammonia as a refrigerant, it is necessary to take measures against ammonia for the screw compressor.

  As a conventional screw compressor with such countermeasures, for example, the winding of the stator of the drive motor is made of an aluminum enamel wire, and the ammonia refrigerant and the stator can be contacted by coating with ammonia resistance. (See Patent Document 1). However, in the case of such a conventional screw compressor, there is a problem that the cost is greatly increased and the performance is inferior to other drive motors of the same specification.

  Next, an outline of a screw compressor according to another conventional example used in a refrigeration apparatus using ammonia as a refrigerant will be described below with reference to FIGS. 6 and 7. FIG. 6 is a partially broken front view showing an embodiment of a compressor according to a conventional example, and FIG. 7 is a cross-sectional view of a conventional example in which a two-stage screw compressor is modified to be compatible with an ammonia refrigerant.

  The compressor for a refrigerator according to the conventional example shown in FIG. 6 is provided with a cylindrical cover 34 that surrounds the rotating shaft 32 a of the motor 32 and the rotor shaft 31 b of the compressor 31 between the motor 32 and the compressor 31. An exhaust pipe 35 is connected to a part of the cover 34, and a leaked refrigerant gas remover 37 from the compressor 31 is connected to the exhaust pipe 35 (see Patent Document 2). However, since the compressor 31 for a refrigerator according to this conventional example is provided with a cylindrical cover 34 between the motor 32 and the compressor 31, it has a long configuration in the axial direction and is accompanied by an increase in installation space. Have

  Further, the two-stage screw compressor according to another conventional example shown in FIG. 7 forms a rotor chamber that opens on the first suction port 46 on the one hand and a first discharge port (not shown) on the other hand, The first-stage compressor body 41 having a first casing 47 that rotatably accommodates a pair of male and female low-pressure stage side screw rotors 48, 49, and the screw rotors 48, 49 of the low-pressure stage side compressor body 41. A motor 42a is provided for driving, in which the lubricating oil flows into the bearing portion 63a and from which the lubricating oil flows out.

  At the same time, the two-stage screw compressor has a rotating shaft of the motor 42a and the pair of screw rotors 48, 49 by a coupling 53 positioned in a coupling casing 44 that is detachably attached to the first casing 47. A coupling portion 43 that is coupled to one of the rotor shafts so as to be integrally rotatable and a pair of male and female high-pressure stage side screw rotors 60 and 61 that mesh with each other are rotatably accommodated.

  At the same time, the two-stage screw compressor has a second casing attached to the non-motor side of the low-pressure stage compressor body 41, and one rotor of the pair of high-pressure stage screw rotors 60 and 61. A suction port that has a coupling that couples the shaft and one of the pair of low-pressure stage side screw rotors 48 and 49 so as to be integrally rotatable, and communicates with the discharge port of the low-pressure stage side compressor body 41 And a high-pressure stage compressor body 45 having 58.

Further, the two-stage screw compressor includes a mechanical seal arrangement space 50 around the penetrating portion of the rotor shaft that passes through the partition wall facing the coupling portion 43 of the first casing 47. A mechanical seal 61 is arranged in the mechanical seal arrangement space 50. Furthermore, at the lower part of the coupling part 43, a first through hole 54 that can communicate with the internal space and the suction port 46 of the first stage compressor body 41, and that can be sealed with the plug 62, In the lower part of the motor 42a, the oil drainage through hole 51 for communicating the space inside the motor 42a with the outside, and the third penetration for communicating the inside and outside of the coupling part 43 at the bottom of the coupling part 43. The third through hole 56 is closed by a plug body that is provided with a hole 56 and is removable (see Patent Document 3).
Japanese Patent Laid-Open No. 10-141226 JP-A-7-71380 Japanese Utility Model Publication No. 7-38683

  However, the two-stage screw compressor according to the above conventional example connects the motor-side drive shaft and the screw rotor-side rotor shaft in the same manner as the refrigerator compressor according to the conventional example described with reference to FIG. In order to have the coupling (joint) for doing, it has the fault that it becomes a structure long in the direction of an axis, and an increase in installation space accompanies. In addition, since there is such a coupling portion, there is a problem in that the troublesome work described below is required for exchanging the mechanical seal, which is a consumable item. This mechanical seal is a member for sealing so that refrigerant gas does not leak to the motor side from the shaft penetration part of the screw compressor.

An operation procedure for exchanging such a mechanical seal will be described below with reference to FIG.
(1) First, a bolt (not shown) for fastening the first casing 47 and the coupling casing 44 constituting the first stage compressor main body 41 is removed, and the motor 42a and the coupling casing 44 are integrally illustrated. Move to the upper right. At this time, since the coupling 53 is only fitted in the axial direction, it can be removed leaving the hub on the first stage compressor body 41 side.

(2) The remaining hub of the coupling 53 on the rotor shaft side of the first stage compressor body 41 is extracted from the rotor shaft on the first stage compressor body 41 side.
(3) Next, the bolt that attaches the flange of the mechanical seal 61 to the first casing 47 is removed, and the mechanical seal 61 is removed.
(4) A replacement mechanical seal is mounted in the mechanical seal arrangement space 50.
(5) The rotor shaft on the first stage compressor main body 41 side and the rotation shaft on the motor 42a side are centered, and the hub of the coupling 53 on the first stage compressor main body 41 side is attached.

(6) The motor 42a and the coupling casing 44 are integrally moved to the left in the drawing, and the hub of the coupling 53 on the rotating shaft side of the motor 42a is moved to the rotor shaft side of the first stage compressor body 41. Insert into the hub.
(7) A bolt for fastening the first casing 47 and the coupling casing 44 is tightened.

  Accordingly, an object of the present invention is to provide a screw compressor for a refrigeration apparatus that handles a refrigerant such as ammonia, which has a simple structure, requires less installation space, and allows easy replacement of a mechanical seal. is there.

The means employed by the screw compressor according to claim 1 of the present invention in order to solve the above-mentioned problem is
A compression chamber in which a drive screw rotor driven by a rotor drive shaft of a drive motor provided outside the compressor casing and a driven screw rotor meshing with the drive screw rotor are accommodated in a compression chamber of the compressor casing. Screw compression comprising a machine main body, wherein a first seal means for shutting off the interior of the motor casing of the drive motor and the compression chamber of the compressor casing is provided in a shaft penetrating portion of the rotor drive shaft of the compressor casing. Related to the machine.

And this screw compressor has the shaft through-hole of the said rotor drive shaft in the position adjacent to the said 1st sealing means along the direction of the said rotor drive shaft between the said motor casing and the said compressor casing. A partition plate is interposed, and between the compressor casing and the partition plate, the wall surface on the partition plate side facing the compressor casing, or the wall surface on the compressor casing side facing the partition plate And a gas exhaust passage that communicates the shaft through portion of the rotor drive shaft with the outside of the machine is formed.

  The screw compressor according to claim 2 of the present invention employs the screw compressor according to claim 1, wherein the shaft through hole of the partition plate has a shaft through portion of the motor casing and the rotor drive shaft. The second sealing means is provided to block the above.

The screw compressor according to claim 3 of the present invention is the screw compressor according to claim 1 or 2, wherein one end of the screw compressor is connected to the gas discharge channel outside the screw compressor. A gas discharge hose, a gas discharge pump interposed in the gas discharge hose, and a water tank in which water is immersed in the other end of the gas discharge hose, and is discharged from the gas discharge flow path. An ammonia recovery means for recovering ammonia contained in the gas is provided.

The screw compressor according to claim 4 of the present invention is the screw compressor according to any one of claims 1 to 3, wherein the screw compressor is provided between the compressor casing and the partition plate. An air supply passage communicating with the gas discharge passage, and an air supply hose provided in the air supply passage outside the compressor, and an air supply pump interposed in the air supply hose; It is characterized by the fact that the air supply means constituted by is connected.
Further, the means adopted by the screw compressor according to claim 5 of the present invention is the screw compressor according to claim 3 , wherein the gas discharge passage is communicated between the compressor casing and the partition plate. An air supply passage configured to include an air supply hose and an air supply pump provided in the air supply hose and provided outside the compressor. On the other hand, a flow rate adjusting valve is interposed in each of the air supply hose and the gas exhaust hose, and air is supplied to the air supply flow path by the flow rate adjusting valve interposed in the air supply pump and the air supply hose. The flow rate of the gas to be discharged, and the exhaust flow rate discharged by the flow rate adjusting valve interposed in the gas discharge pump and the gas discharge hose is set to the flow rate of the gas supplied to the air supply flow path and the first flow rate. Leakage from one sealing means The pressure in the shaft penetrating portion of the rotor drive shaft can be adjusted to be more negative than the pressure in the motor casing by adjusting so as to be larger than the sum of the flow rates of the compressed gas. It is what.

According to the screw compressor according to claim 1 of the present invention, a partition plate having a shaft through hole of the rotor drive shaft is interposed between the motor casing and the compressor casing, and the compressor casing and the compressor Between the partition plate, a groove is formed in the wall surface on the partition plate side facing the compressor casing, or on the wall surface on the compressor casing side facing the partition plate. Since the gas discharge passage communicating with the outside is formed, the gas discharge passage formed with a simple structure ensures that the refrigerant such as ammonia leaking from the compressor body side to the drive motor side can be reliably It can be discharged outside the machine.

In addition, a partition plate having a shaft through hole of the rotor drive shaft is interposed between the motor casing and the compressor casing at a position adjacent to the first seal means along the direction of the rotor drive shaft. Therefore, if the motor casing and the partition plate are separated from the compressor casing, the first seal means provided in the shaft penetrating portion of the rotor drive shaft of the compressor casing is exposed, and the first seal Means maintenance and parts replacement became easy.

  Further, since the gas discharge passage is formed between the compressor casing and the partition plate, the gas discharge passage is formed when the motor casing and the partition plate are separated from the compressor casing. The wall surface is also exposed, and maintenance such as cleaning of the gas discharge channel is easy. Furthermore, in forming the gas discharge channel, it is only necessary to groove the wall surface on the partition plate side facing the compressor casing or the wall surface on the compressor casing side facing the partition plate. The flow path is inexpensive and can be easily formed.

  According to the screw compressor according to claim 2 of the present invention, the second seal means for blocking the inside of the motor casing and the shaft through portion of the rotor drive shaft is provided in the shaft through hole of the partition plate. The second sealing means can more reliably prevent refrigerant such as ammonia leaking from the compressor body side from flowing into the drive motor side.

  According to the screw compressor according to claim 3 of the present invention, ammonia recovery means for recovering ammonia contained in the gas discharged from the gas discharge flow path is provided outside the screw compressor. Therefore, ammonia is recovered by the ammonia recovery means, and ammonia that may adversely affect the human body is not released to the atmosphere, so that deterioration of the working environment around the screw compressor can be prevented.

According to the screw compressor according to claim 4 of the present invention, an air supply passage communicating with the gas discharge passage is provided between the compressor casing and the partition plate, and the air supply passage includes the air supply passage. Since the air supply means provided outside the compressor is connected, a gas such as air can be supplied to the gas discharge flow path via the air supply flow path by the air supply means. A refrigerant such as ammonia leaking from the sealing means can be effectively discharged outside the apparatus.
And according to the screw compressor which concerns on Claim 5 of this invention, the flow volume of the gas supplied to the said air supply flow path is adjusted with the flow control valve interposed by the said air supply pump and the said air supply hose. In addition, the exhaust flow rate discharged by the flow rate adjusting valve interposed between the gas discharge pump and the gas discharge hose leaked from the flow rate of the gas supplied to the air supply flow path and the first sealing means. Since the pressure in the shaft penetrating portion of the rotor drive shaft can be adjusted to be more negative than the pressure in the motor casing by adjusting to be greater than the sum of the flow rates of the compressed gas, the first Compressed gas leaking from one sealing means does not flow into the motor casing.

  First, a refrigeration apparatus provided with a screw compressor according to an embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic circuit diagram of a refrigeration apparatus provided with a screw compressor according to Embodiment 1 of the present invention.

  The code | symbol 21 shown in FIG. 1 is the freezing apparatus which uses ammonia as a refrigerant | coolant. The refrigeration apparatus 21 includes the screw compressor 1 according to any one of Embodiments 1 to 3 described later. The discharge port 1о and the suction port 1i of the screw compressor 1 are devices described later. It communicates via the provided refrigerant circulation line 22. In the refrigerant circulation line 22, an oil separator / recoverer 22a, a condenser 22b, an expansion valve 22c, and an evaporator 22d are arranged in this order from the discharge port 1о to the suction port 1i.

  Also, oil discharged from the screw compressor 1 from the bottom of the oil separator / recoverer 22a, separated from the discharge gas containing refrigerant and oil, and collected in an oil reservoir below the oil separator / recoverer 22a. Is connected to the screw compressor 1 through an oil supply line 23 that supplies the shaft for lubrication of the bearing, cooling of the screw rotor, and shaft sealing. The oil supply line 23 is provided with an oil cooler 23a.

  Next, the screw compressor 1 according to Embodiment 1 of the present invention used in the refrigeration apparatus 21 configured as described above will be described with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional configuration explanatory view of the screw compressor according to Embodiment 1 of the present invention, and FIG. 3 is a partial detailed cross-sectional view showing an enlarged portion A of FIG.

  The screw compressor 1 includes a first-stage compressor casing 2 having a suction port 1i, and a second-stage compressor casing fixed to the first-stage compressor casing 2 via an intermediate casing 3 and having a discharge port 1о. 4 is provided. A motor casing 9a, a stator 9b provided in the motor casing 9a, and the stator are provided on the opposite side (left side in the figure) of the first stage compressor casing 2 to the second stage compressor casing 4. A drive motor 9 comprising a rotor 9c disposed inside 9b and rotating is fixed.

  The first stage compression chamber 2a of the first stage compressor casing 2 includes a first stage drive screw rotor 5 driven by a rotor drive shaft 10 rotated by the rotor 9c, and the first stage drive screw rotor. The first-stage driven screw rotor 6 that meshes with 5 is accommodated. A first sealing means for preventing leakage of compressed gas from the first-stage compression chamber 2a to the drive motor 9 side in the shaft penetration portion 2b of the rotor drive shaft 10 of the first-stage compressor casing 2 2c is provided. As the first sealing means 2c, a mechanical seal or a gland packing is used, but the mechanical seal is preferable from the viewpoint of sealing performance.

  The second stage compression chamber 4a of the second stage compressor casing 4 is provided on the side opposite to the rotor drive shaft 10 of the first stage drive screw rotor 5, and the intermediate casing 3 is connected via a bearing device 3a. A second-stage drive screw rotor 7 driven by the intermediate rotor drive shaft 11 passing therethrough and a second-stage driven screw rotor 8 meshing with the second-stage drive screw rotor 7 are accommodated.

  In the second-stage compression chamber 4a, the first-stage compressed gas compressed in the second stage by the second-stage drive screw rotor 7 and the second-stage driven screw rotor 8 is provided in the first-stage compressor casing 2. Outflowing from the first-stage compressed gas discharge port 2о, via the first-stage compressed gas flow passage 3b provided in the intermediate casing 3 and outside the bearing chamber that houses the bearing device 3a, The second stage compressor casing 4 is configured to flow into the second stage compression chamber 4a from a first stage compressed gas inlet 4i provided in the second stage compressor casing 4.

  As is well understood from the above description, the configuration of the screw compressor 1 is a screw compressor in which the compressor body is a normal two-stage compression type. In the case of the screw compressor 1 according to Embodiment 1 of the present invention, a partition having a shaft through hole 17a of the rotor drive shaft 10 between the motor casing 9a and the first stage compressor casing 2. A gas exhaust is provided in which a plate 17 is interposed and a wall surface of the partition plate 17 facing the first stage compressor casing 2 communicates the shaft penetrating portion 2b of the rotor drive shaft 10 with the outside of the machine. The flow path 14 is formed by grooving in the radial direction.

  Further, in the gas discharge flow path 14, the ammonia recovery is performed in order to recover the ammonia leaked from the first stage compression chamber 2 a to the shaft penetrating portion 2 b of the rotor drive shaft 10 through the first sealing means 2 c. Means 14d are provided. The ammonia recovery means 14d has a gas discharge hose 14a having one end connected to the gas discharge flow path 14, a gas discharge pump 14c interposed in the gas discharge hose 14a, and the gas discharge hose 14a. The other end of the water tank 14b is composed of a water tank 14b in which water is stored.

  As described above, the gas discharged from the gas discharge channel 14 is blown into the water in the water tank 14b because the ammonia contained in the discharged gas is water-soluble and dissolved in water. This is because, by collecting ammonia as ammonia water, which may adversely affect the human body, it is possible to eliminate release into the atmosphere and prevent contamination of the work environment. It is desirable that the capacity of the water tank 14b is sufficiently large so that ammonia is completely dissolved in the water in the water tank 14b. It is also preferable that the water tank 14b be sealed.

  On the other hand, the inner diameter of the shaft through hole 17a provided in the partition plate 17 is set so that a gap t formed between the shaft through hole 17a and the rotor drive shaft 10 is reduced. More specifically, when the gas present in the shaft penetrating portion 2b space of the rotor drive shaft 10 is sucked by driving the gas discharge pump 14c, the inner space of the shaft penetrating portion 2b becomes the inner space of the motor casing 9a. On the other hand, the gas present in the motor casing 9a with a negative pressure is set so as to flow through the gap t and flow into the shaft penetrating portion 2b.

  Therefore, even if ammonia leaks from the mechanical seal 2c, it does not enter the drive motor 9 side. Incidentally, it is preferable that the gap t is set to such an extent that the shaft through hole 17a and the rotor drive shaft 10 do not come into contact with each other by the rotation of the rotor drive shaft 10, that is, about 0.1 to 0.2 mm.

  Further, the shaft through hole 17a provided in the partition plate 17 has a second seal for blocking the flow of gas between the motor casing 9a and the space of the shaft through portion 2b of the rotor drive shaft 10. Means 17b are provided. As the second sealing means, it is preferable to use a labyrinth seal 17b as shown in FIG. 3 from the following points. That is, the labyrinth seal 17b having a concavo-convex shape perpendicular to the axis of the rotor drive shaft 10 is coupled with the gap t formed between the shaft through hole 17a and the rotor drive shaft 10. This is because the rotating rotor drive shaft 10 can be non-contact sealed.

  Hereinafter, the operation mode of the screw compressor 1 according to the first embodiment of the present invention will be described. That is, by making the configuration as described above, even if the compressed gas compressed by the compressor main body leaks from the mechanical seal 2c of the compressor main body, the above described provided in the shaft through hole 17a of the partition plate 17 The leaked compressed gas is prevented from flowing into the motor casing 9a by the second sealing means 17b, and is recovered by the ammonia recovery means 14d through the gas discharge passage 14 provided in the partition plate 17. Therefore, there is no contact with the stator 9b of the drive motor 9.

  Therefore, even if the compressed gas is ammonia, as in the conventional example, there is no need to use an expensive ammonia screw compressor having a stator wound with an aluminum enamel wire, The drive motor 9 provided with the stator 9b in which the winding having excellent performance is made of copper wire can be used as a screw compressor for ammonia. In the above description, ammonia is dissolved and recovered by the water in the water tank 14b. However, the ammonia may be discharged to the outside without affecting the human body.

  As described above, the screw compressor 1 according to the first embodiment of the present invention includes the partition plate 17 having the shaft through hole 17a of the rotor drive shaft 10 between the motor casing 9a and the first stage compressor casing 2. And a gas discharge passage 14 in which the shaft penetrating portion 2b of the rotor drive shaft 10 and the outside of the rotor are communicated with the wall surface of the partition plate 17 on the side facing the first compressor casing 2. Since the gas is formed by groove processing, the refrigerant such as ammonia leaking from the first stage compression chamber 2a to the drive motor 9 side is surely functioned by the gas discharge passage 14 formed with a simple structure. It can be discharged outside.

  Further, since the partition plate 17 is interposed between the motor casing 9 a and the first stage compressor casing 2, if the motor casing 9 a and the partition plate 17 are separated from the first stage compressor casing 2. The first seal means 2c provided in the shaft penetrating portion 2b of the rotor drive shaft 10 of the first stage compressor casing 2 is exposed, and maintenance and replacement of parts of the first seal means 2c are facilitated. It was.

  Further, since the gas discharge passage 14 is formed between the first stage compressor casing and the partition plate 17, the motor casing 9a and the partition plate 17 are separated from the first stage compressor casing 2. Then, the wall surface forming the gas discharge channel 14 is also exposed, and maintenance such as cleaning of the gas discharge channel 14 is easy. Furthermore, in forming the gas discharge channel 14, the gas discharge channel 14 can be formed inexpensively and easily because a groove is formed in the wall surface on the side of the partition plate 17 facing the first stage compressor casing 2. It can be formed.

  Next, a screw compressor 1 according to Embodiment 2 of the present invention will be described with reference to FIG. However, the difference between the second embodiment of the present invention and the first embodiment is that there is a difference in the configuration of the gas discharge flow path 14, and the other configuration is exactly the same as in the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and different points will be described below.

  In the screw compressor 1 according to Embodiment 2 of the present invention, a partition plate 17 having a shaft through hole 17a of the rotor drive shaft 10 is interposed between the motor casing 9a and the first stage compressor casing 2. In addition, the gas discharge passage 14 communicates with the wall surface on the first stage compressor casing 2 side facing the partition plate 17 so that the shaft penetrating portion 2b of the rotor drive shaft 10 communicates with the outside of the machine. It is formed by grooving in the direction.

  Therefore, according to the screw compressor 1 according to the second embodiment of the present invention, the above-described present invention is provided by the gas discharge channel 14 formed in a simple structure on the wall surface on the first stage compressor casing 2 side. As in the first embodiment, the refrigerant such as ammonia leaking from the first stage compression chamber 2a to the drive motor 9 side can be reliably discharged out of the machine.

  Next, a screw compressor 1 according to Embodiment 3 of the present invention will be described with reference to FIG. However, the third embodiment of the present invention differs from the first embodiment in that the gas existing in the space of the shaft penetrating portion 2b of the rotor drive shaft 10 is actively sent to the gas discharge passage 14. Since there is a difference in the configuration to be noticed and the configuration other than this is exactly the same as in the first embodiment, the same reference numerals are given to the same components as those in the first embodiment, and the differences are hereinafter described. Will be described.

  In the screw compressor 1 according to Embodiment 3 of the present invention, the wall surface of the partition plate 17 on the side facing the first-stage compressor casing 2 is located at a position different from the gas discharge flow path 14 on the circumference. In addition, an air supply flow path 12 that connects the shaft penetrating portion 2b of the rotor drive shaft 10 to the outside of the machine is formed by groove processing in the radial direction. And the said gas exhaust flow path 14 and this air supply flow path 12 are comprised so that it may communicate in the said shaft penetration part 2b space. The water tank 14b has a substantially sealed structure. The water tank 14b is provided with a discharge pipe 14e that communicates the inside and the outside, and is configured to be able to discharge excess ammonia that cannot be dissolved in the water of the water tank 14b without affecting the human body. .

  A suction filter and an air supply means 12 c (not shown) are connected to the air supply flow path 12. The air supply means 12c comprises an air supply hose 12a and an air supply pump 12b interposed in the air supply hose 12a. Then, dry air (gas) is supplied from the air supply hose 12 a to the shaft penetrating portion 2 b of the rotor drive shaft 10 via the air supply flow path 12. It is preferable to use a small air pump or a fan as the air pump 12b. The reason why the air blown into the motor casing 9a is dried is that moisture in the air reduces the insulating properties of the stator 9b and the rotor 9c.

  In this case, the dry air blown into the shaft penetrating portion 2b from the air supply passage 12 and the gas flowing into the shaft penetrating portion 2b through the gap t are discharged together with the compressed gas leaking from the mechanical seal 2c. It is discharged from the flow path 14. In this case, as described above, the dry air (gas) blown from the air supply passage 12 and the compressed gas leaked from the mechanical seal 2c do not stay in the motor casing 9a or flow backward. It is desirable that each pressure is appropriately adjusted so that the gas flows smoothly and is finally discharged from the gas discharge channel 14.

  That is, the air supply hose 12a is provided with a flow rate adjusting valve, and the pressure in the shaft penetrating portion 2b of the rotor drive shaft 10 is appropriately adjusted by adjusting the flow rate of the dry air (gas) supplied. However, it is important that the compressed gas leaking from the mechanical seal 2c does not flow into the motor casing 9a.

  For this reason, the gas exhaust hose 14a is also provided with a gas exhaust pump and a flow rate control valve, and the exhaust flow rate exhausted by the gas exhaust pump is supplied to the air supply passage 12 as dry air (gas). So that the pressure in the shaft penetrating portion 2b of the rotor drive shaft 10 is slightly higher than the pressure in the motor casing 9a. However, the negative pressure is preferably adjusted.

  As mentioned above, according to the screw compressor 1 which concerns on Embodiment 3 of this invention, the dry air supplied from the air supply hose 12a is blown in in the shaft penetration part 2b of the said rotor drive shaft 10 through the air supply flow path 12. . And since the dry air which flowed into this shaft penetration part 2b is discharged | emitted from the gas discharge flow path 14 with the compressed gas which flows out out of the mechanical seal 2c, from the said Embodiment 1 or Embodiment 2, the said The compressed air containing the refrigerant such as ammonia leaking from the mechanical seal 2c to the shaft penetrating portion 2b of the rotor drive shaft 10 can be discharged more effectively.

  In the first to third embodiments, the case where the screw compressor 1 is a two-stage compression type has been described as an example. However, the present invention is not limited to these configurations, and the technical idea of the present invention can be applied to, for example, the single-stage screw compressor 1, so that the configuration of the screw compressor according to the first to third embodiments is applied. It is not limited.

  Moreover, in the above forms 1 to 3, the thing of the very simple structure which consists of the water tank 14b etc. as an ammonia collection | recovery means was shown. However, the present invention is not limited to the water tank as described above. For example, the ammonia recovery means may be based on a chemical method using an acidic solution such as hypochlorous acid, or based on a physicochemical method using zeolite or activated carbon.

It is a typical circuit diagram of the freezing apparatus provided with the screw compressor which concerns on embodiment of this invention. It is a section composition explanatory view of the screw compressor concerning Embodiment 1 of the present invention. FIG. 3 is a partial detailed cross-sectional view showing an enlarged portion A of FIG. 2. It is sectional structure explanatory drawing of the screw compressor which concerns on Embodiment 2 of this invention. It is sectional structure explanatory drawing of the screw compressor which concerns on Embodiment 3 of this invention. It is a partially broken front view which shows the Example of the compressor which concerns on a prior art example. It is sectional drawing of the thing which concerns on the prior art example remodeled so that it could respond | correspond to an ammonia refrigerant.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Screw compressor, 1i ... Suction port, 1о ... Discharge port 2 ... 1st stage compressor casing, 2a ... 1st stage compression chamber, 2b ... Shaft penetration part,
2c: 1st sealing means (mechanical seal), 2о: 1st stage compressed gas discharge port 3 ... Intermediate casing, 3a ... Bearing device, 3b ... 1st stage compressed gas flow passage 4 ... 2nd stage compressor casing, 4a ... 2nd stage compression chamber, 4i ... 1st stage compressed gas inlet 5 ... 1st stage drive screw rotor 6 ... 1st stage driven screw rotor 7 ... 2nd stage drive screw rotor 8 ... 2nd stage driven screw rotor 9 ... Drive Motor, 9a ... Motor casing, 9b ... Stator, 9c ... Rotor 10 ... Rotor drive shaft 11 ... Intermediate rotor drive shaft 12 ... Air supply flow path, 12a ... Air supply hose, 12b ... Air supply pump, 12c ... Air supply means 14 ... Gas exhaust passage, 14a ... Gas exhaust hose, 14b ... Water tank,
14c ... Gas discharge pump, 14d ... Ammonia recovery means, 14b ... Discharge pipe 17 ... Partition plate, 17a ... Shaft through hole, 17b ... Second seal means (labyrinth seal)
21 ... Refrigeration equipment, 22 ... Refrigerant circulation line, 22a ... Oil separation and recovery device, 22b ... Condenser,
22c ... Expansion valve, 22d ... Evaporator, 23 ... Oil supply line, 23a ... Oil cooler t ... Gap between shaft through hole and rotor drive shaft

Claims (5)

A compression chamber in which a drive screw rotor driven by a rotor drive shaft of a drive motor provided outside the compressor casing and a driven screw rotor meshing with the drive screw rotor are accommodated in a compression chamber of the compressor casing. Equipped with the machine body,
In the screw compressor, in which the first seal means for shutting off the inside of the motor casing of the drive motor and the compression chamber of the compressor casing is provided in the shaft penetrating portion of the rotor drive shaft of the compressor casing.
A partition plate having a shaft through hole of the rotor drive shaft is interposed between the motor casing and the compressor casing at a position adjacent to the first seal means along the direction of the rotor drive shaft. ,
The rotor drive shaft is grooved between the compressor casing and the partition plate on the wall surface on the partition plate side facing the compressor casing or on the wall surface on the compressor casing side facing the partition plate. A screw compressor characterized in that a gas discharge passage is formed to communicate between the shaft penetrating part and the outside of the machine.   The screw compressor according to claim 1, wherein a second seal means for blocking the inside of the motor casing and the shaft through portion of the rotor drive shaft is provided in the shaft through hole of the partition plate. Outside the screw compressor,
From a gas discharge hose having one end connected to the gas discharge flow path, a gas discharge pump interposed in the gas discharge hose, and a water tank in which water into which the other end of the gas discharge hose is immersed is stored Configured,
The screw compressor according to claim 1 or 2, wherein ammonia recovery means for recovering ammonia contained in the gas discharged from the gas discharge channel is provided.   An air supply passage communicating with the gas discharge passage is provided between the compressor casing and the partition plate. The air supply passage is provided outside the compressor, and the air supply hose and the air supply passage are provided. The screw compressor according to any one of claims 1 to 3, wherein an air supply means including an air supply pump interposed in the air hose is connected. An air supply passage communicating with the gas discharge passage is provided between the compressor casing and the partition plate. The air supply passage is provided outside the compressor, and the air supply hose and the air supply passage are provided. While an air supply means composed of an air supply pump interposed in an air hose is connected,
A flow control valve is interposed in each of the air supply hose and the gas discharge hose,
While adjusting the flow rate of the gas supplied to the air supply flow path by the flow rate adjustment valve interposed in the air supply pump and the air supply hose,
The exhaust flow rate discharged by the flow rate adjusting valve interposed between the gas discharge pump and the gas discharge hose is the same as the flow rate of the gas supplied to the air supply channel and the compressed gas leaked from the first sealing means. Adjust it to be more than the sum of the flow rates,
The screw compressor according to claim 3 , wherein the pressure in the shaft penetrating portion of the rotor drive shaft is adjustable so as to be a negative pressure from the pressure in the motor casing.

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