JP2013079620A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cantilever type motor-direct connected screw compressor having a damping structure capable of directly reducing vibration of a rotor shaft itself, while making unbalance force during rotation of the rotor shaft hard to occur.SOLUTION: The screw compressor 1 includes a screw rotor 41, a motor shaft 7 integrally constructed with the screw rotor 41 and cantilevered at the screw rotor side, and a motor for rotating the motor shaft 7. The screw compressor 1 has a cylinder member 43 loosely inserted and disposed along an inner surface of a rotator 5 substantially coaxially with the motor shaft 7 in a space between a motor side end surface 7a of the motor shaft 7 and an end member 10, and a weight 8 (vibrating body) loosely inserted and disposed substantially coaxially with the motor shaft 7 in an inner side of the cylinder member 43. The natural frequency of the cylinder member 43 is matched with the natural frequency of the rotor shaft 11.

Description

  The present invention relates to a screw type compressor.

  A screw compressor having a structure directly connected to an electric motor has a higher energy conversion efficiency than that of a power transmission system through a drive belt. Moreover, in the screw compressor which employ | adopts the rotational speed control system using an inverter, the screw compressor of a motor direct connection structure has become mainstream. Here, for the purpose of cost reduction and mechanical loss reduction, the motor shaft is often a cantilever type motor direct connection type screw compressor in which no bearing is provided on one side of the motor shaft.

  In the case of a cantilever screw compressor, the rotor shaft system is usually designed so that the critical speed is much higher than the operating rotational speed. However, in a screw compressor in which an excitation force of a pressure pulsation component is generated, the vibration of the rotor shaft system portion may increase at a rotational speed much lower than the critical speed (rotational speed) of the rotor shaft. In addition, when high-order components of vibration due to unbalance determined by the shaft rotational speed are greatly generated due to rattling of the rotor shaft system, the rotor shaft system part is still at a rotational speed lower than the critical speed (rotational speed). Vibration may increase.

  Here, as a method of reducing the vibration of the screw compressor, a method using a vibration damping device such as a dynamic vibration absorber using a vibration-proof rubber, or a rotation of the rotor shaft so as to skip a rotation speed range in which the vibration is increased. There are ways to control the number.

  However, in a method using a vibration damping device such as a dynamic vibration absorber, if the installation conditions such as the vibration-proof rubber part change due to rubber deterioration or loose mounting, the resonance frequency of the rotor shaft system part changes and a vibration damping effect is obtained. There is a problem that it becomes impossible. Further, in the case of a screw compressor that employs a rotational speed control method using an inverter, a dynamic vibration absorber having a damping effect only at a specific frequency cannot cope with vibrations in the entire rotational speed range.

  On the other hand, in the method of controlling the rotational speed of the rotor shaft so as to skip the rotational speed range where the vibration becomes large, it is necessary to skip the rotational speed area around the rotational speed where the vibration becomes large for safety reasons. May cause problems.

  As a method that can reduce vibration regardless of the natural frequency of the screw compressor (a method that can reduce vibration in the entire rotation speed range), for example, there is a method described in Patent Document 1. Patent Document 1 discloses a screw characterized in that a rod-like body is provided in a horizontal direction with respect to a motor casing, and a plate (mass body) having a hole having relatively large play is inserted into the rod-like body. A compressor is described. According to this structure, the plate (mass body) is displaced in the vertical direction due to the vibration of the motor casing, the rod-like body protruding from the motor casing collides with the plate (mass body), and the vibration energy is consumed, and the vibration of the motor casing. Is reduced.

Japanese Patent Laid-Open No. 2003-343641

  Here, in the case of a cantilever type motor direct-coupled screw compressor, when the vibration of the rotor shaft system portion of the screw compressor increases, the whirling vibration of the rotor shaft increases significantly, and the rotor and stator of the motor The distance between is widened or narrowed. At this time, since the magnetic attraction force acting between the rotor and the stator changes, not only the rotor but also the stator side is affected by the magnetic attraction force, and the motor casing on which the stator is installed becomes magnetic. Vibrates by being vibrated with suction force. In this way, not only the rotor side of the electric motor but also the stator side vibrates, so that the electric motor's rotor and the motor casing vibrate in a coupled state. The stator may come into contact. As a result, the stator side may be damaged and it may be difficult to continue operation.

  As described above, in the vibration reduction method described in Patent Document 1, a “motor casing” is formed by a rod-like body protruding from the motor casing and a vertically displaceable plate (mass body) inserted therein. Vibration is reduced. For this reason, the vibration on the rotor side does not increase due to the vibration of the motor casing. However, when the vibration of the screw shaft of the screw compressor is large, for example, when the vibration exceeds the allowable load of the bearing, some measures against vibration are required for the rotor shaft of the screw compressor. In addition, when taking a countermeasure against vibration on the rotor shaft itself, it is necessary to devise that the countermeasure against vibration does not act as an unbalanced force (unbalance force) when the rotor shaft rotates.

  Moreover, in the structure of the rod-shaped body protrudingly provided on the motor casing and the plate (mass body) that is inserted in the rod-shaped body and can be displaced in the vertical direction, a space for arranging the rod-shaped body and the plate (mass body) is provided outside the motor casing. It is necessary to ensure this, which may restrict the package layout of the compressor. In addition, it becomes a constraint for heat balance.

  The present invention has been made in view of the above circumstances, and its purpose is to directly reduce vibration of the rotor shaft itself while making it difficult to generate unbalanced force (unbalance force) during rotation of the rotor shaft. A cantilever electric motor direct-coupled screw compressor having a vibration damping structure that can be provided is provided.

  In order to achieve the above object, the present invention includes a screw rotor, a screw casing that houses the screw rotor, a motor shaft that is integrated with the screw rotor and cantilevered on the screw rotor side, A motor that rotates the motor shaft, and the motor includes a rotor fixed to an outer periphery of the motor shaft, a stator disposed outside the rotor, the rotor and the stator. A motor casing that houses the motor side end surface of the motor shaft, which is positioned closer to the screw rotor side than the motor side end surface of the rotor, and is coaxial with the motor shaft on the motor side end surface of the rotor. An end member is fixed, and is arranged in the space between the motor side end surface of the motor shaft and the end member so as to be substantially coaxial with the motor shaft and along the inner surface of the rotor. A cylindrical member that is loosely inserted, and a vibration body that is loosely inserted and arranged substantially coaxially with the motor shaft inside the cylindrical member, wherein the natural frequency of the cylindrical member is such that the screw rotor and the motor Provided is a screw compressor characterized in that a rotor shaft constituted by a shaft is adjusted to a resonating frequency.

  According to this configuration, with respect to the bending vibration of the rotor shaft, the vibrating member collides with or rubs against the cylindrical member or the stroke end (for example, the motor side end surface of the motor shaft) in the axial direction, The vibration energy is dissipated and the vibration of the rotor shaft is reduced. In addition, since the natural frequency of the cylindrical member is matched with the frequency at which the rotor shaft resonates, when resonance occurs in the rotor shaft, a large vibration is excited in the cylindrical member portion, and this vibration causes vibration of the vibrating body. Is promoted, and vibration reduction performance due to collision and friction is further improved.

  Further, since the cylindrical member and the vibrating body are arranged substantially coaxially with the motor shaft, an unbalanced force (unbalance force) during rotation of the rotor shaft is unlikely to occur.

  According to the present invention, it is possible to directly reduce vibration of the rotor shaft itself while making it difficult to generate an unbalanced force (unbalance force) during rotation of the rotor shaft.

It is a side section schematic diagram showing the screw compressor concerning a 1st embodiment of the present invention. It is the A section enlarged view of FIG. 1, and its XX sectional drawing. It is a side cross-sectional schematic diagram which shows the screw compressor which concerns on 2nd Embodiment of this invention. It is the B section enlarged view of FIG. 3, and its YY sectional drawing. FIG. 3 is a partially enlarged schematic side sectional view showing a modification of the screw compressor shown in FIGS. 1 and 2.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic side sectional view showing a screw compressor 1 according to a first embodiment of the present invention. 2 is an enlarged view of a portion A in FIG. 1 (FIG. 2A) and an XX sectional view thereof (FIG. 2B).

(Configuration of screw compressor)
As shown in FIG. 1, the screw compressor 1 is a screw compressor having an electric motor direct connection structure including a screw main body 2 and a motor unit 30 (motor).

(Screw body)
The screw main body 2 includes a screw rotor 41 and a screw casing 12 that houses the screw rotor 41. The screw rotor 41 includes a screw tooth portion 4 and a screw shaft 3 that is coaxial with the screw tooth portion 4 and is integrated with the screw tooth portion 4. The screw shaft 3 is supported at both ends by a bearing 14 and a bearing 15.

  The screw tooth portion 4 and the screw shaft 3 are manufactured by machining a single steel material. Alternatively, the screw tooth portion 4 and the screw shaft 3 may be manufactured separately and then rigidly connected (integrated connection). Further, the screw rotor 41 and a motor shaft 7 to be described later are manufactured from one steel material by machining or the like, and have an integral structure. A rotor shaft 11 that rotates with the screw rotor 41 and the motor shaft 7 that are integrated with each other is configured. The screw rotor 41 and the motor shaft 7 may be manufactured separately and then rigidly connected (integrated connection). As a method of rigid connection (integrated structure), there is a flange connection or the like.

(Motor part)
The motor unit 30 (motor) is a drive source for rotating the rotor shaft 11, and includes a rotor 5 fixed to the outer periphery of the motor shaft 7, a stator 6 disposed outside the rotor 5, And a motor casing 13 that accommodates the rotor 5 and the stator 6. The motor shaft 7 is coaxially connected to the screw rotor 41 (screw shaft 3) and is integrated with the screw rotor 41 (screw shaft 3) and is cantilevered on the screw rotor 41 side. Specifically, the motor shaft 7 is cantilevered by the bearing 14 (and the bearing 15) on the screw rotor 41 side.

  The motor side end surface 7 a of the motor shaft 7 is located closer to the screw rotor 41 than the motor side end surface 5 a of the rotor 5. A disc-shaped end member 10 is fixed to the motor-side end surface 5a of the rotor 5 with a bolt (not shown) or the like. A hole 10 a is formed in the center of the end member 10. The end member 10 is coaxial with the motor shaft 7.

(Vibration control mechanism)
A cylindrical member 43 is inserted into the space between the motor-side end surface 7 a of the motor shaft 7 and the end member 10. The cylindrical member 43 is loosely arranged with respect to the rotor 5, the end member 10, and the motor shaft 7 along the inner surface of the rotor 5 substantially coaxially with the motor shaft 7.

  The length of the cylindrical member 43 is smaller than the distance between the motor-side end surface 7a and the end member 10. The axially movable amount of the cylindrical member 43 is, for example, about 0.5 mm to several mm. Further, the outer diameter of the cylindrical member 43 is smaller than the inner diameter of the rotor 5. The amount of displacement of the cylindrical member 43 in the direction orthogonal to the axis is set to be approximately the same as the fitting dimension between the rotor 5 and the stator 6, for example, about 0.02 mm to about 0.5 mm.

  A bolt 9 is fixed to the motor side end surface 7 a of the motor shaft 7 coaxially with the motor shaft 7 (at the rotation center of the motor shaft 7). The bolt 9 disposed inside the rotor 5 is an example of a rod-shaped sliding member according to the present invention.

  As shown in FIG. 2A, the bolt 9 is a sliding shaft portion fixed to the motor side end surface 7 a of the motor shaft 7 in such a form as to penetrate the hole 10 a formed at the center of the end member 10. 16 and a head 17 (large diameter portion) formed at the end of the sliding shaft portion 16. The outer diameter of the head 17 is larger than the shaft diameter of the sliding shaft portion 16. The shaft diameter of the sliding shaft portion 16 is smaller than the shaft diameter of the motor shaft 7.

  Here, a plurality of plate-like and annular weights 8 are accommodated inside the cylindrical member 43 while being loosely inserted into the sliding shaft portion 16 of the bolt 9. In the present embodiment, six weights 8 are used, but the number is not limited to six. It may be one. The weight 8 is an example of a plate-shaped annular body (vibrating body) in the present invention.

  The total thickness of the six weights 8 is smaller than the distance between the motor side end surface 7 a and the end member 10. That is, the weight 8 is movable in the axial direction of the motor shaft 7. The axially movable amount of the weight 8 is, for example, about 0.5 mm to several mm. Further, the outer diameter (diameter) of the weight 8 is smaller than the inner diameter of the cylindrical member 43. As described above, since the weight 8 is loosely inserted into the sliding shaft portion 16 of the bolt 9, the weight 8 can also move (displace) in the direction perpendicular to the axis of the motor shaft 7. The amount by which the weight 8 can be displaced in the direction perpendicular to the axis is set to be approximately the same as the fitting dimension between the rotor 5 and the stator 6, and is, for example, about 0.02 mm to about 0.5 mm.

  Here, in FIG. 2A, the weight 8 is shown coaxially with the motor shaft 7. However, in a state where the weight 8 is loosely inserted into the sliding shaft portion 16 of the bolt 9 and is stationary, strictly speaking, only the displaceable amount (about 0.02 mm to 0.5 mm) of the weight 8 in the direction perpendicular to the axis can be obtained. The shaft center of the weight 8 is lowered in the vertically downward direction from the shaft center of the motor shaft 7. That is, in the present invention, the weight 8 (vibrating body) is arranged substantially “coaxially” with the motor shaft 7, which means that the weight is vertically lower than the axis of the motor shaft 7 by an amount that can be displaced in the direction perpendicular to the axis. This represents that the axis 8 (vibrating body) is in a lowered state.

  The same applies to the cylindrical member 43, and in the present invention, the cylindrical member 43 is disposed “substantially” coaxially with the motor shaft 7. The amount of displacement in the direction perpendicular to the axis (about 0.02 mm to 0.5 mm). Only the axial center of the cylindrical member 43 is lowered in the vertically downward direction from the axial center of the motor shaft 7.

  In this manner, the weight 8 is arranged substantially coaxially with the motor shaft 7 in such a manner that it collides with surrounding members such as the motor-side end surface 7a of the motor shaft 7 and the end member 10 in the axial direction. In this embodiment, since a plurality of weights 8 are used, they collide with each other in the axial direction.

  Note that the cross-sectional shape of the sliding shaft portion 16 is circular, but it is not necessarily circular, and may be, for example, a quadrangle. The hole 8a formed at the center of the weight 8 is also the same, and may be a square instead of a circle. The shape of the hole 8 a formed at the center of the weight 8 is matched with the cross-sectional shape of the sliding shaft portion 16. Further, the cross-sectional shape of the head 17 is a hexagon, but it is not necessarily a hexagon, and may be, for example, a circle.

(Natural frequency of cylindrical member)
Here, the natural frequency of the cylindrical member 43 is matched with the natural frequency of the rotor shaft 11 constituted by the screw rotor 41 and the motor shaft 7. The natural frequency of the rotor shaft 11 is obtained by calculation in consideration of components that rotate integrally with the rotor shaft 11, that is, components such as the rotor shaft 11, the rotor 5, the bolt 9, and the end member 10, for example. The natural frequency of the cylindrical member 43 is adjusted by selecting its length, thickness, outer diameter, inner diameter, material, and the like.

(Action / Effect)
According to the screw compressor 1, against the bending vibration of the rotor shaft 11 mainly caused by the rotation of the screw rotor 41, the cylindrical member 43 and the stroke end before and after the axial direction (the motor side end surface 7a of the motor shaft 7 and the end member). 10 end face) and the weight 8 (vibrating body) collide with each other or rub against each other, the vibration energy is dissipated (dissipation of vibration energy due to the axial collision), and the vibration of the rotor shaft 11 is reduced. That is, the vibration of the rotating rotor shaft 11 itself can be directly reduced by the weight 8 that moves and collides in the axial direction or the like. Further, since the weight 8 is disposed at the end opposite to the cantilever support side of the motor shaft 7 (in the vicinity of the end member 10), which is a portion where the bending vibration of the rotor shaft 11 becomes large, vibration due to an axial collision. Energy dissipation efficiency can be further increased.

  In addition, by making the natural frequency of the cylindrical member 43 coincide with the natural frequency of the rotor shaft 11, a large vibration is excited near the natural frequency of the rotor shaft 11, and the weight 8 is excited by this vibration. The vibration of the (vibrating body) is promoted, and the vibration reduction performance due to collision and friction can be further improved.

  In addition, since both the cylindrical member 43 and the weight 8 (vibrating body) are disposed substantially coaxially with the motor shaft 7, an unbalanced force (unbalance force) during rotation of the rotor shaft 11 is unlikely to occur. It should be noted that a configuration in which the weight 8 (vibrating body) is loosely inserted into the bolt 9 arranged coaxially with the motor shaft 7 causes more unbalanced force (unbalance) during rotation of the rotor shaft 11. It can be difficult. Furthermore, the weight 8 is a plate-shaped annular body, and its center of gravity is the axial center of the weight 8, so that an unbalanced force (unbalance force) is less likely to occur.

  Furthermore, since the plurality of weights 8 are arranged adjacent to each other in the axial direction, the vibration energy can be dissipated even when the weights 8 collide with each other in the axial direction or are rubbed.

  Also, by accommodating the cylindrical member 43 and the weight 8 in the space between the motor side end surface 7a of the motor shaft 7 and the end member 10, the axial length of the entire screw compressor is made substantially the same as that of the conventional machine. Is done.

  The natural frequency of the cylindrical member 43 may be matched with the frequency at which the rotor shaft 11 resonates (the frequency at which damping is desired to be added to the rotor shaft 11). That is, it is preferable to match the natural frequency of the cylindrical member 43 with the natural frequency of the rotor shaft 11, but this is an example, and the natural frequency of the cylindrical member 43 is not necessarily equal to the natural frequency of the rotor shaft 11. There is no need to match the numbers. If the natural frequency of the cylindrical member 43 is matched with the frequency at which the rotor shaft 11 resonates (the frequency at which the rotor shaft 11 is desired to be attenuated), the resonance occurs at the rotor shaft 11 (the frequency at which the damping is desired to be added). Is generated in the rotor shaft 11), a large vibration is excited in the cylindrical member 43, and the vibration of the weight 8 is promoted by this vibration, and the vibration reduction performance due to collision and friction is improved.

  The frequency at which the rotor shaft 11 resonates is a frequency at which the bending vibration of the rotor shaft 11 increases in a specific vibration mode, and includes the natural frequency of the rotor shaft 11. The frequency at which damping is desired to be applied to the rotor shaft 11 is a frequency at which the bending vibration of the rotor shaft 11 is increased so as to hinder the operation of the screw compressor 1. Includes numbers.

  Further, in the screw compressor 1 described above, one end of the bolt 9 is fixed to the motor-side end surface 7a of the motor shaft 7 by screwing or the like, and the other end portion (head 17) of the bolt 9 is brought into strong contact with the end member 10. By doing so, the bolt 9 is supported at both ends, but only the end of the bolt 9 is fixed to the motor side end surface 7a, or only the end (head 17) of the bolt 9 is fixed to the end member 10, etc. The bolt 9 may be cantilevered.

(Second Embodiment)
FIG. 3 is a schematic side sectional view showing the screw compressor 102 according to the second embodiment of the present invention. 4 is an enlarged view of a portion B in FIG. 3 (FIG. 4A) and a YY sectional view thereof (FIG. 4B). In FIG. 3 and FIG. 4, the same code | symbol is attached | subjected about the member similar to the screw compressor 1 of 1st Embodiment.

  The main difference between the screw compressor 1 of the first embodiment and the screw compressor 102 of the present embodiment is that a plurality of spherical bodies 44 are used as vibrating bodies in the screw compressor 102 of the present embodiment. Is a point.

(Spherical)
A plurality of spherical bodies 44 are gently inserted into the space between the cylindrical member 43 and the bolt 9. One spherical body 44 is arranged on one side of the bolt 9 in the radial direction of the rotor shaft 11. In this way, the plurality of spherical bodies 44 are arranged in a layer along the axial direction of the rotor shaft 11 on one side of the bolt 9. A plurality of spherical bodies 44 are arranged in four layers around the bolt 9. However, it is not always necessary to have four layers.

  Similar to the weight 8 of the first embodiment, the axially movable amount of the spherical body 44 is, for example, about 0.5 mm to several mm, and the axial orthogonal direction displaceable amount is, for example, about 0.02 mm to about 0.5 mm. In such a form, the plurality of spherical bodies 44 are provided with small backlash between each other, and are disposed substantially coaxially with the motor shaft 7 as a whole.

  Further, as in the first embodiment, the natural frequency of the cylindrical member 43 is made to coincide with the natural frequency of the rotor shaft 11, for example.

(Action / Effect)
Similar to the screw compressor 1 of the first embodiment, according to the screw compressor 102, the spherical bodies 44 (vibrating bodies) collide with each other against the bending vibration of the rotor shaft 11 mainly caused by the rotation of the screw rotor 41. Or the spherical member 44 (vibrating body) collides with or rubs with the cylindrical member 43 or the stroke end in the axial direction (the motor side end surface 7a of the motor shaft 7 and the end surface of the end member 10). As a result, vibration energy is dissipated and vibration of the rotor shaft 11 is reduced. That is, the vibration of the rotating rotor shaft 11 itself can be directly reduced by the spherical body 44.

  Further, if the natural frequency of the cylindrical member 43 is matched with the natural frequency of the rotor shaft 11, a large vibration is excited in the cylindrical member 43 portion in the vicinity of the natural frequency of the rotor shaft 11. The vibration of 44 (vibrating body) is promoted, and the vibration reduction performance due to collision and friction can be further improved.

  Further, since both the cylindrical member 43 and the spherical body 44 (the spherical body 44 as a whole) are disposed substantially coaxially with the motor shaft 7, an unbalanced force (unbalance force) during rotation of the rotor shaft 11 is generated. Hateful.

  In the present embodiment, a plurality of spherical bodies 44 are arranged in a layer along the axial direction of the rotor shaft 11 on one side of the bolt 9. In the space between the cylindrical member 43 and the bolt 9, two (double) or more spherical bodies 44 may be arranged adjacent to each other in the radial direction of the rotor shaft 11 on one side of the bolt 9, as in this embodiment. In addition, it is preferable to arrange a plurality of spherical bodies 44 in a layered manner along the axial direction of the rotor shaft 11. As a result, an unbalanced force (unbalance force) during rotation of the rotor shaft 11 is less likely to occur.

  If a commercially available ball (such as a steel ball) that is a mass-produced product is used as the spherical body 44 (vibrating body), the cost can be reduced.

(Modification)
In the present embodiment, one cylindrical member 43 and one spherical body 44 (per one side of the bolt 9) are arranged between the rotor 5 and the bolt 9, but in the radial direction of the bolt 9, The layered spherical bodies 44 and the cylindrical members 43 may be alternately stacked to form a layered structure including the layered spherical bodies 44 and the cylindrical members 43.

  FIG. 5 is a partially enlarged schematic side sectional view showing a modification of the screw compressor 1 shown in FIGS. 1 and 2, both of which are shown in FIG. 2 (a) showing a part of the screw compressor 1. It is an equivalent figure.

  In the modification shown in FIG. 5A, not only the cylindrical member 43 and the weight 8 are disposed in the space between the end member 10 and the motor side end surface 7a, but also the viscous body 24 is enclosed. By sealing the viscous body 24, it is also possible to generate a viscous damping on the sliding surface of the weight 8, and as a result, the vibration of the rotor shaft 11 can also be reduced by this viscous damping. Here, the sliding surface of the weight 8 means a surface where the weight 8 and the sliding shaft portion 16 are in contact, a surface where the weight 8 and the cylindrical member 43 are in contact, and the like. Examples of the viscous body 24 include high viscosity grease and silicone oil. A viscous body 24 having a viscosity of about 10,000 cSt to 100,000 cSt is preferable. Similarly, in the screw compressor 102 of the second embodiment, not only the cylindrical member 43 and the spherical body 44 are disposed in the space between the end member 10 and the motor side end surface 7a but also the viscous body 24 is enclosed. Good.

  Further, as shown in FIG. 5B, a disc-shaped weight 27 without a hole is placed in the space between the end member 10 (no hole) and the motor side end surface 7a along the inner surface of the cylindrical member 43. A plurality of loose insertions may be arranged. That is, the bolt 9 shown in FIG. 2 (a) may be omitted. Even in this embodiment, the cylindrical member 43 and the stroke end in the axial direction (the motor-side end surface 7a of the motor shaft 7 and the end surface of the end member 10) and the weight 27 (vibrating body) may collide or rub against each other. Thus, the vibration energy is dissipated and the vibration of the rotor shaft 11 is reduced. Further, by arranging the disc-shaped weight 27 substantially coaxially with the motor shaft 7, it is possible to make it difficult to generate an unbalance force (unbalance force) when the rotor shaft 11 rotates. Further, when the natural frequency of the cylindrical member 43 is adjusted to the frequency to which damping is desired to be added to the rotor shaft 11 (for example, the natural frequency of the rotor shaft 11), vibration having the frequency to be damping occurs. A large vibration is excited at the cylindrical member 43 portion, and the vibration of the weight 27 is promoted by this vibration, and the vibration reduction performance due to collision and friction is further improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

1: Screw compressor 2: Screw body 3: Screw shaft 5: Rotor 6: Stator 7: Motor shaft 8: Weight (vibrating body)
9: Bolt (rod-like sliding member)
10: End member 11: Rotor shaft 12: Screw casing 13: Motor casing 30: Motor part (motor)
41: Screw rotor 43: Cylindrical member

Claims (4)

A screw rotor;
A screw casing for housing the screw rotor;
A motor shaft that is integrated with the screw rotor and cantilevered on the screw rotor side;
A motor for rotating the motor shaft;
With
The motor is
A rotor fixed to the outer periphery of the motor shaft;
A stator disposed outside the rotor;
A motor casing that houses the rotor and the stator;
Have
The motor side end surface of the motor shaft is positioned closer to the screw rotor side than the motor side end surface of the rotor,
An end member is fixed to the motor side end surface of the rotor coaxially with the motor shaft,
In the space between the motor side end surface of the motor shaft and the end member, a cylindrical member that is loosely inserted along the inner surface of the rotor substantially coaxially with the motor shaft;
A vibrating body that is loosely inserted and arranged substantially coaxially with the motor shaft inside the cylindrical member;
Further comprising
The screw compressor according to claim 1, wherein the natural frequency of the cylindrical member is adjusted to a frequency at which a rotor shaft constituted by the screw rotor and the motor shaft resonates. The screw compressor according to claim 1,
A screw compressor, wherein the natural frequency of the cylindrical member and the natural frequency of the rotor shaft are made to coincide. The screw compressor according to claim 1 or 2,
A rod-shaped sliding member having a smaller shaft diameter than the shaft diameter of the motor shaft disposed inside the rotor and coaxially with the motor shaft;
The screw compressor according to claim 1, wherein the vibrating body is a plate-shaped annular body that is loosely inserted into the rod-shaped sliding member. The screw compressor according to claim 1 or 2,
A rod-shaped sliding member having a smaller shaft diameter than the shaft diameter of the motor shaft disposed inside the rotor and coaxially with the motor shaft;
The screw compressor according to claim 1, wherein the vibrating body is a plurality of spherical bodies loosely inserted between the cylindrical member and the rod-shaped sliding member.