JP2009162129A - Screw compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw compressor wherein the life of a lip seal is not shortened by dirt. <P>SOLUTION: The screw compressor 1 is arranged with the lip seals 13, 14 between a suction flow passage 5 sucking target gas into a rotor chamber 3 storing a screw rotor 4 fitting female and male threads, and a bearing 11 supporting a rotor shaft 7 on the suction side of the screw rotor 4. A clearance between a partitioning wall 10 between the suction flow passage 5 and the lip seal 15, and the rotor shaft 7 is 0.5 to 1.5 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a screw compressor.

  For example, Patent Document 1 describes a screw compressor in which a lip seal is provided in a bearing chamber so that lubricating oil in a suction-side bearing does not flow out into a suction passage in a water-cooled screw compressor. In such a screw compressor, the gap between the partition wall separating the suction flow path and the bearing chamber and the rotor shaft causes the bearing lubricating oil to immediately flow out into the suction flow path even if the lip seal is broken, and the bearing immediately It is set as small as possible so as not to break.

  Normally, the suction flow path becomes negative pressure (negative pressure) with respect to the bearing chamber, but the pressure of the suction flow path becomes higher than the bearing chamber at the moment when operation is stopped, and the target gas may flow into the bearing chamber. . At this time, the target gas may be accompanied by dust, and dust may enter between the lip seal and the partition wall. Since the gap between the partition wall and the rotor shaft is small, dust that has entered once stays as it is, damages the lip seal, and shortens the life of the lip seal.

In addition, when the screw compressor is assembled, dust may be mixed between the lip seal and the partition wall that separates the suction flow path and the bearing chamber, thereby shortening the life of the lip seal.
JP 2007-132243 A

  In view of the above problems, an object of the present invention is to provide a screw compressor in which the life of a lip seal is not shortened by dust.

  In order to solve the above-mentioned problems, a first aspect of the screw compressor according to the present invention includes a suction flow path for sucking a target gas into a rotor chamber that houses a male and female screw rotor, and a suction side of the screw rotor. In a screw compressor in which a lip seal is disposed between a bearing that supports a rotor shaft, a gap between the suction passage and the lip seal and the rotor shaft is 0.5 mm or more.

  According to this configuration, dust that has entered the space on the rotor side of the lip seal is discharged from the gap between the partition wall and the rotor shaft, so that the lip seal is not damaged.

  In the screw compressor according to the first aspect of the present invention, the gap between the partition wall and the rotor shaft may be 1.5 mm or less.

  Even if the gap between the partition wall and the rotor shaft is larger than 1.5 mm, there is no difference in the action of discharging dust. In addition, it is preferable to reduce the gap between the partition wall and the rotor shaft when the lip seal is broken.

  A second aspect of the screw compressor according to the present invention includes a suction flow path for sucking a target gas into a rotor chamber that houses a screw rotor that engages a male and female, and a bearing that supports a rotor shaft on the suction side of the screw rotor. In the screw compressor in which the lip seal is disposed between the suction passage and the lip seal, the gap between the suction passage and the rotor shaft is set to be 1/10 or more of the height of the lip seal. To do.

  According to this configuration, dust that has entered the space on the rotor side of the lip seal is discharged from the gap between the partition wall and the rotor shaft, so that the lip seal is not damaged.

  Moreover, the screw compressor of the 2nd aspect of this invention WHEREIN: It is good also considering the clearance gap between the said partition and the said rotor shaft as 3/10 or less of the height of the said lip seal.

  Even if the gap between the partition wall and the rotor shaft is larger than 3/10 of the height of the lip seal, there is no difference in the action of discharging dust. In addition, it is preferable to reduce the gap between the partition wall and the rotor shaft when the lip seal is broken.

  Further, in the screw compressor according to the first and second aspects of the present invention, a lubricating space for introducing a lubricating fluid is formed between the lip seal and the partition wall, and the lubricating fluid is introduced into the lubricating space. A lubricating flow path may be provided.

  According to this configuration, the lubricating fluid prevents dust from entering the lubrication space from the suction flow path, and even if dust enters the lubrication space, the lubricating fluid discharges the dust to the suction flow path. Dust does not damage the lip seal.

  The present invention can prevent the shortening of the life of the lip seal that prevents the bearing lubricating oil from flowing out, particularly in a water-cooled screw compressor that lubricates the bearing with lubricating oil and lubricates the rotor chamber with water.

  According to the present invention, even if dust enters the periphery of the lip seal that isolates the bearing from the suction flow path, it can be discharged to the suction flow path, so that the life of the lip seal is not shortened.

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows a screw compressor 1 according to a first embodiment of the present invention. The screw compressor 1 is an oil-free screw compressor that compresses a target gas (for example, air or a refrigerant) by a pair of male and female screw rotors 4 housed in a rotor chamber 3 of a housing 2.

  The housing 2 includes a suction flow path 5 for supplying a target gas to be compressed to the rotor chamber 3, a discharge flow path 6 for discharging the target gas compressed by the screw rotor 4 in the rotor chamber 3, and the screw rotor 4. Bearing shaft sealing chambers 8 and 9 are provided for installing a structure for supporting and sealing the rotor shaft 7 on the suction side and the discharge side, respectively. The suction flow path 5 and the suction-side bearing shaft sealing chamber 8 are divided by a partition wall 10 in which an opening through which the rotor shaft 7 passes is formed.

  The screw compressor 1 is configured so that cooling water is supplied to the rotor chamber 3 together with the target gas from a water supply passage (not shown) via a suction passage 5 for lubrication and cooling in the rotor chamber 3. This is a water-cooled compressor.

  The rotor shaft 7 is rotatably supported by a roller bearing 11 installed in the bearing shaft sealing chamber 8 on the suction side and two ball bearings 12 installed in the bearing shaft sealing chamber 9 on the discharge side. The bearing shaft sealing chamber 9 on the side is further extended to the outside of the housing 2 and connected to a motor (not shown).

  A lip seal 13 is installed on the motor side of the roller bearing 11 to prevent foreign matter (lubricating oil or grease from the roller bearing 11) from entering the motor side. The roller bearing 11 has a roller bearing 11 on the screw rotor 4 side. A lip seal 14 that seals the lubricating oil from flowing out to the screw rotor 4 side and a lip seal 15 that seals cooling water from entering the roller bearing 11 side from the suction flow path 5 are provided. .

  In the bearing shaft sealing chamber 9 on the discharge side between the screw rotor 4 and the ball bearing 12, a mechanical seal 16 and lip seals 17 and 18 are provided in this order from the screw rotor 4 side. The mechanical seal 16 includes a stator that is fitted and fixed to the inner wall of the bearing shaft sealing chamber 9, and a known rotor that is fitted to the rotor shaft 7 and rotates together with the rotor shaft 7 so as to be in airtight contact with the stator. It is a sealing device. The lip seal 17 is installed in a direction that seals intrusion of cooling water from the mechanical seal 16 side, and the lip seal 18 is installed in a direction that prevents outflow of lubricating oil or grease from the ball bearing 12. .

  Further, in the housing 2, an open channel 19 for communicating the bearing shaft sealing chamber 8 between the lip seal 14 and the lip seal 15 to the outside, and a bearing shaft sealing chamber 9 between the mechanical seal 16 and the lip seal 17 are provided. And a decompression flow path 20 for communicating with the suction flow path 5.

  FIG. 2 shows a relationship between the clearance δ between the rotor shaft 7 and the partition wall 10 in the screw compressor 1 and the amount of wear of the lip seal 15 after 5000 hours of operation, which is the nominal life of the lip seal. When the gap δ between the rotor shaft 7 and the partition wall 10 was made smaller than 0.5 mm, the lip seal 15 was broken before 5000 hours passed.

  As shown in the figure, the required life of the lip seal 15 can be ensured by setting the gap δ between the rotor shaft 7 and the partition wall 10 to 0.5 mm or more. This is because by increasing the gap δ between the rotor shaft 7 and the partition wall 10, dust that has entered the bearing shaft sealing chamber 8 from the gap δ is discharged from the gap δ into the suction flow path 5 and is difficult to damage the lip seal 15. By becoming. In this experiment, the height of the lip seal 15 is 5 mm, and the gap δ between the rotor shaft 7 and the partition wall 10 is 1/10 or more of the height of the lip seal 15 based on the height of the lip seal 15. It is necessary to.

  Further, when the gap δ between the rotor shaft 7 and the partition wall 10 is increased, the wear of the lip seal 15 due to dust is further reduced. Considering the safety factor, the gap δ between the rotor shaft 7 and the partition wall 10 is desirably 1.0 mm (2/10 of the height of the lip seal 15) or more.

  However, if the gap δ exceeds 1.5 mm (3/10 of the height of the lip seal 15), there is no difference in the effect of reducing wear. Even if the lip seals 13 and 14 are broken, the gap δ between the rotor shaft 7 and the partition wall 10 should be as small as possible in order to reduce the outflow of lubricating oil from the roller bearing 11. , 1.5 mm (3/10 of the height of the lip seal 15) or less.

  FIG. 3 shows a screw compressor 1a according to the second embodiment of the present invention. In the following description, the same components as those described above are denoted by the same reference numerals, and redundant descriptions are omitted. The screw compressor 1a is a water-cooled screw compressor that lubricates and cools the rotor chamber 3 with cooling water, similarly to the screw compressor 1 of the first embodiment.

  In the screw compressor 1a, a lubricating space 21 is formed between the lip seal 15 and the partition wall 10 on the rotor chamber 3 side. Furthermore, a lubrication flow path 22 for supplying cooling water (lubricating fluid) to the lubrication space 21 is formed in the housing 2. The bearing shaft sealing chamber 9 on the discharge side of the screw compressor 1a is provided with a non-contact labyrinth seal 16a that seals the gap between the rotor and the stator with cooling water.

  The screw compressor 1a introduces the compressed target gas discharged from the discharge flow path 6 into the gas-liquid separator 23, separates the cooling water, and supplies it to a consumption facility (not shown). Further, the cooling water separated by the gas-liquid separator 23 is removed of foreign matters by the filter 24 and introduced into the lubricating space 21 via the lubricating flow path 22. The cooling water introduced into the lubrication space 21 flows out into the suction flow path through the gap between the rotor shaft 7 and the partition wall 10 and is sucked into the rotor chamber 3 together with the target gas, thereby lubricating and cooling the rotor chamber 3 and the screw rotor 4. To do.

  In the present embodiment, since the cooling water is supplied to the lubrication space 21, dust does not enter the bearing shaft sealing chamber 8 from the suction flow path 5. Thereby, abnormal wear of the lip seal 15 can be prevented, and the life of the lip seal 15 is not shortened.

  FIG. 4 shows a screw compressor 1b according to a third embodiment of the present invention. The screw compressor 1b is a water-cooled screw compressor similar to that of the second embodiment, but the gap between the rotor shaft 7 and the partition wall 10 is small as in the conventional screw compressor. For this reason, the amount of cooling water leaking from the lubricating space 21 to the suction flow path is small, and the cooling water is mainly supplied directly to the rotor chamber 3. In the present embodiment, it is desirable to provide a regulator or the like for limiting the flow rate and pressure of the cooling water supplied to the lubrication flow path 22 in order to prevent the pressure in the lubrication space 21 from increasing.

The screw compressor of 1st Embodiment of this invention. The graph which shows the relationship between the magnitude | size of the clearance gap between a partition and a rotor shaft, and abrasion of a lip seal. The screw compressor of 2nd Embodiment of this invention. The screw compressor of 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a, 1b ... Screw compressor 2 ... Housing 3 ... Rotor chamber 4 ... Screw rotor 5 ... Suction flow path 8 ... Bearing shaft sealing chamber 10 ... Partition 11 ... Roller bearing 14 ... Lip seal 15 ... Lip seal 21 ... Lubrication space 22 ... Lubrication channel 23 ... Gas-liquid separator 24 ... Filter

Claims (8)

In a screw compressor in which a lip seal is disposed between a suction passage for sucking a target gas into a rotor chamber that houses a male and female screw rotor and a bearing that supports a rotor shaft on the suction side of the screw rotor,
A screw compressor characterized in that a gap between a partition wall between the suction passage and the lip seal and the rotor shaft is 0.5 mm or more.   The screw compressor according to claim 1, wherein a gap between the partition wall and the rotor shaft is 1.5 mm or less. In a screw compressor in which a lip seal is disposed between a suction passage for sucking a target gas into a rotor chamber that houses a male and female screw rotor and a bearing that supports a rotor shaft on the suction side of the screw rotor,
A screw compressor characterized in that a gap between a partition wall between the suction passage and the lip seal and the rotor shaft is 1/10 or more of a height of the lip seal.   The screw compressor according to claim 3, wherein a gap between the partition wall and the rotor shaft is 3/10 or less of a height of the lip seal. Forming a lubricating space for introducing a lubricating fluid between the lip seal and the partition;
The screw compressor according to any one of claims 1 to 4, further comprising a lubricating flow path for introducing a lubricating fluid into the lubricating space.   The screw compressor according to claim 5, wherein the lubricating fluid is water. A partition wall through which the rotor shaft penetrates a suction passage for sucking a target gas into a rotor chamber that houses a male and female screw rotor and a bearing chamber that holds a bearing that supports a rotor shaft on the suction side of the screw rotor In the screw compressor separated by
A lip seal that divides the bearing chamber on the suction flow path side from the bearing in the bearing chamber;
A screw compressor characterized in that a lubricating flow path is provided for introducing a lubricating fluid into a space closer to the suction flow path than the lip seal of the bearing chamber.   The screw compressor according to claim 7, wherein the lubricating fluid is water.

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