JP5207822B2 - Screw compressor - Google Patents

Description

  The present invention relates to a screw compressor used for refrigerant compression of a refrigerator, for example.

  Generally, in this type of screw compressor, a screw rotor is disposed in a casing, and two gate rotors are disposed at right angles to both sides of the screw rotor. These gate rotors mesh with the screw grooves of the screw rotor, rotate following the tooth surfaces of the screw rotor, block the space between the screw grooves of the screw rotor and the casing, and fluid (for example, refrigerant gas) in this space It has a function to compress. One end side (high pressure side) of the shaft of the screw rotor is supported by a bearing box via a bearing, and the other end side of the shaft of the screw rotor is connected to a motor (not shown).

  Accordingly, when the screw rotor is rotated by driving the motor, the refrigerant gas is sucked into the screw groove, and the sucked refrigerant gas is compressed along the screw groove by the gate rotor that rotates following the tooth surface of the screw rotor. Then, it is discharged into a discharge flow path inside the compressor.

  By the way, in a screw compressor, the discharge flow path (outer peripheral high-pressure region) side in which the screw groove of the screw rotor is opened during operation has a high pressure and the bearing side has a lower pressure, and a differential pressure is generated between them. Therefore, a seal portion is provided between the screw rotor and the bearing box. For example, between the screw rotor and the bearing housing, a stepped seal portion provided with a thrust seal portion made of a spiral groove and a radial seal portion made of a plurality of annular grooves is provided, and the discharge channel (outer peripheral high pressure region) side And the lower-pressure bearing side are separated by a stepped seal part, and the reverse pressure phenomenon that occurs under transient operating conditions such as startup, that is, the pressure on the low-pressure side against the gap pressure in the thrust seal part Even if the rising phenomenon occurs, there is one in which the gap pressure of the thrust seal portion can be raised in a short time by a spiral groove having continuous inner and outer peripheries to oppose the reverse pressure (for example, Patent Documents) 1).

JP-A-6-101672 (FIG. 1)

  In screw compressors, high-pressure fluid on the discharge flow path (outer peripheral high-pressure region) side where the screw groove of the screw rotor is opened passes between the screw rotor and the bearing housing and leaks to the lower-pressure bearing side. If it does, the performance of a compressor will fall. Therefore, in the case where the pressure on the discharge flow channel (outer peripheral high pressure region) side is always applied to the thrust seal portion so as to be contrary to the purpose of the seal, there is a difficulty in terms of reliability.

  By the way, it is effective to reduce the gap between the screw rotor and the bearing box in order to suppress the deterioration of the seal performance. However, in this case, if the gap is excessively reduced, there is a high possibility that a problem that the screw rotor and the bearing box are burned out occurs, and the reliability of the compressor is lowered. For this reason, it was in the situation where improvement of a sealing performance fall did not progress.

  The technical problem of the present invention is to improve the reliability of the compressor by enhancing the sealing function of the radial seal portion and preventing the fluid from leaking in the axial direction of the screw rotor. There is.

A screw compressor according to the present invention includes a screw rotor that is rotatably accommodated in a casing, a bearing box that surrounds a discharge-side shaft end portion of the screw rotor in the casing, and is supported via a bearing, A seal portion that is provided on the facing surface of the opening edge and the screw rotor and divides the inner space of the bearing box at a lower pressure than the high pressure region on the outer periphery of the screw rotor. And a radial seal portion that is opposed to each other in the radial direction, and a force to send a fluid from the low pressure side to the outer peripheral portion in the high pressure region along with the rotation of the screw rotor on one of the opposing surfaces of the radial seal portion. Rutotomoni provided occurrence cause spiral groove, the other opposing surface of the radial seal portion, also provided with a covering member made of soft material than the screw rotor and the bearing housing It is.

In the screw compressor according to the present invention, the radial surface of the radial seal portion facing the screw rotor and the bearing box is opposed to one of the opposing surfaces of the radial direction from the low pressure side to the outer peripheral high pressure region. Rutotomoni provided a spiral groove which makes generating a force to send fluid, the other opposing surface of the radial seal portion, since the provided cover member made of soft material than the screw rotor and the bearing housing, the screw rotor is rotated Then, a force is generated in the radial seal portion to send the fluid from the low pressure side toward the outer peripheral portion high pressure region. Therefore, the fluid that tries to leak from the outer peripheral high-pressure region side to the low-pressure side through the radial seal portion is subjected to pressure resistance in which the force to send the fluid by the spiral groove is added to the low-pressure side pressure. The amount is suppressed. Further, the covering member made of a material softer than the screw rotor and the bearing box provided on the other of the opposing surfaces of the radial seal portion reduces a gap through which fluid leaks from the radial seal portion. For this reason, the leakage suppression effect can be further enhanced and the performance of the compressor can be further improved.

Embodiment 1 FIG.
The present invention will be described below with reference to illustrated embodiments.
FIG. 1 is a structural view including a partial cross-sectional display around a seal portion of a screw compressor according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged cross-sectional view showing a seal portion A in FIG.

  As shown in FIG. 1, the screw compressor of the present embodiment includes a casing 6, a screw rotor 1 disposed in the casing 6, and a shaft end 7 on one end side (high pressure side) of the screw rotor 1 via a bearing 8. And a bearing box 2 to be supported.

  The screw rotor 1 has a plurality of screw grooves 9, and two gate rotors (only one is shown) 10 arranged at right angles to the both sides of the screw rotor 1 are engaged with the screw grooves 9. As is well known, the gate rotor 10 rotates following the tooth surface of the screw rotor 1 to block the space between the screw groove 9 of the screw rotor 1 and the casing 6, and fluid (for example, refrigerant gas) in this space. Has a function of compressing. The shaft portion at the other end of the screw rotor 1 is connected to a motor (not shown).

  Further, a seal portion A is provided between the screw rotor 1 and the opening edge of the bearing housing 2. As shown in FIG. 2, the seal part A includes a radial seal part B in which the screw rotor 1 and the bearing box 2 are opposed to each other in the radial direction, and a radial seal part B continuous with the screw rotor 1 and the bearing box 2 in the axial direction. It is formed in the shape of a stepped seal comprising an opposed thrust seal portion C.

  More specifically, the radial seal portion B is arranged on one of the opposing surfaces, here the surface on the bearing housing 2 side, from the low pressure side (bearing 8 side) to the outer peripheral portion high pressure region direction as the screw rotor 1 rotates. That is, the spiral groove 4 for generating lift is provided in the direction of the discharge flow path 11 in which the screw groove 9 of the screw rotor 1 is opened during operation.

  The thrust seal portion C is provided with a labyrinth composed of a plurality of concentric annular grooves 3 on one of the opposing surfaces, here the surface on the bearing housing 2 side.

  In the screw compressor of the present embodiment configured as described above, when the screw rotor 1 is rotated by driving the motor, the refrigerant gas is sucked into the screw groove 9, and the sucked refrigerant gas is absorbed by the teeth of the screw rotor 1. It is compressed along the screw groove 9 by the gate rotor 10 that rotates following the surface, and is discharged to the discharge flow path 11 inside the compressor.

  In the screw compressor according to the present embodiment, the radial direction from the low pressure side to the outer peripheral high pressure region along with the rotation of the screw rotor on one of the opposing surfaces of the radial seal portion in which the screw rotor and the bearing housing are opposed in the radial direction. Since the spiral groove 4 for generating lift is provided in the radial seal portion B, when the screw rotor 1 rotates, the fluid is sent from the low pressure side to the outer peripheral portion high pressure region by the transfer function by the side wall of the spiral groove 4. Force is generated. Therefore, the fluid that tries to leak to the low pressure side through the radial seal portion B from the outer peripheral high pressure region side receives the resistance of the pressure obtained by adding the lift by the spiral groove 4 to the low pressure side pressure, and the amount of leakage is suppressed. Is done. For this reason, the performance of the compressor is improved.

  Here, the description has been given by taking as an example the case where the spiral groove 4 of the radial seal portion B and the annular groove 3 of the thrust seal portion C are provided on the surface on the bearing housing 2 side. Needless to say, it may be provided on the surface of the screw rotor 1.

Embodiment 2. FIG.
FIG. 3 is an enlarged cross-sectional view showing a seal part, which is a main part of the screw compressor according to the second embodiment of the present invention. In the figure, the same parts as those in the first embodiment are denoted by the same reference numerals. It is. In the description, reference is made to FIG.

  As shown in FIG. 3, the screw compressor of the present embodiment is made of a material softer than the screw rotor 1 or the bearing housing 2 (for example, manganese phosphate) on the other side of the radial seal portion B, that is, the surface on the screw rotor 1 side. And the covering member 5 is formed continuously on the other of the opposing surfaces of the thrust seal portion C, that is, the surface on the screw rotor 1 side, and these radial seal portions B are provided. In addition, the gap through which fluid leaks from the thrust seal portion C is reduced. All other configurations are the same as those of the first embodiment described above, and all the functions of the first embodiment are provided.

  In the screw compressor of this embodiment, since the gap through which the fluid leaks from the radial seal portion B and the thrust seal portion C is reduced by the covering member 5, the effect of suppressing the leakage amount can be further enhanced. The performance can be further improved.

  In addition, when the opposing surfaces of the radial seal portion B and the thrust seal portion C are in contact with each other, the covering member 5 is worn and avoids the occurrence of defects due to seizure, so that reliability can be ensured. .

  Here, the example in which the covering member 5 is provided on the surface on the screw rotor 1 side has been described as an example, but it goes without saying that the covering member 5 may be provided on the bearing box 2 side.

It is a structural diagram including a partial cross-sectional display around the seal portion of the screw compressor according to Embodiment 1 of the present invention. It is sectional drawing which expands and shows the seal | sticker part A of FIG. It is sectional drawing which expands and shows the seal part which is the principal part of the screw compressor which concerns on Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Screw rotor, 2 Bearing box, 3 Annular groove, 4 Spiral groove, 5 Cover member, 6 Casing, 7 Shaft end part (discharge side shaft end part), 8 Bearing, 11 Discharge flow path (outer peripheral high pressure area), A Seal part, B radial seal part, C thrust seal part.

Claims (3)

A screw rotor rotatably accommodated in a casing;
A bearing box that surrounds the discharge-side shaft end portion of the screw rotor in the casing and supports the bearing through a bearing;
A seal portion that is provided on the opposed surface of the opening edge of the bearing box and the screw rotor and that partitions the inner space of the bearing box at a lower pressure than the high-pressure area of the outer periphery of the screw rotor;
The seal portion is provided with a radial seal portion in which the screw rotor and the bearing housing are opposed to each other in the radial direction, and the low pressure side of the radial seal portion is rotated along with the rotation of the screw rotor. the outer peripheral portion high range direction is provided a spiral groove which makes generating a force to send fluid Rutotomoni from, the other of the opposing surfaces of the radial seal portion, coating of soft material than the screw rotor and the bearing housing A screw compressor comprising a member . A thrust seal portion is provided continuously to the radial seal portion so that the screw rotor and the bearing housing face each other in the axial direction. A plurality of concentric circular rings are formed on one of the opposing surfaces of the thrust seal portion. screw compressor according to claim 1 Symbol mounting, characterized in that a labyrinth consisting of the groove. 3. The screw compressor according to claim 2 , wherein a coating member made of a material softer than the screw rotor and the bearing box is provided on the other of the opposing surfaces of the thrust seal portion.

Images