JP2011256973A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration damping characteristics.SOLUTION: A rod member 19 which is loosely inserted into a plurality of weights 8 is provided in a motor casing 13 so as to be projected therefrom. At least one of the plurality of weights 8 is connected to a base plate 16, while at least one of the plurality of weights 8 is not connected to the base plate 16. When the motor casing 13 vibrates, the rod member 19 and the weights 8 collide with each other, so that vibration energy dissipates. Even in a low amplitude area, relative displacement is suitably generated between the weight 8a connected to the base plate 16 and the weight 8 not connected to the base plate, and sliding friction is generated therebetween, thereby the vibration energy dissipates.

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 a cantilever motor direct-coupled screw compressor, since a motor with a large mass is cantilevered, it is difficult to obtain a large bending rigidity of a rotor shaft that is an integral structure of a motor shaft and a screw shaft. For this reason, there is a problem that vibration is likely to increase due to resonance due to an excitation force caused by the electromagnetic force of the drive system or motor during rotation, or an unstable phenomenon inherent to the rotor shaft.

  Therefore, by adding vibration damping to the motor casing, it is necessary to reduce the resonance magnification (vibration transmissibility during resonance) to suppress the increase in amplitude, or to make the unstable region against the unstable phenomenon a stable region. There is.

  As a method of reducing the vibration of the motor casing, 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, and the rod-like body protruding from the motor casing collides with the plate (mass body), so that vibration energy is consumed. The vibration of the motor casing is reduced. Moreover, when a relative displacement occurs between the plurality of plates (mass bodies), sliding friction occurs between them, and vibration energy is consumed. This also reduces the vibration of the motor casing.

  Further, as a method of reducing vibration of the motor casing, there is a method of providing a vibration damping mechanism that uses shear deformation of a viscoelastic material having a large damping property between the base plate on which the motor casing is placed and the motor casing. . Due to the vibration of the motor casing, the restraint plate attached to the motor casing and the restraint plate coupled to the base plate move relatively, so that shear deformation occurs in the viscoelastic material between them, and the vibration energy is viscoelastic. The vibration of the motor casing is reduced by being converted into thermal energy by friction within the bridges between the molecules of the material. The characteristic of this vibration damping mechanism is that the spring characteristic and the damping characteristic due to the viscoelastic material are generated simultaneously.

Japanese Patent Laid-Open No. 2003-343641

  However, in the vibration reducing method described in Patent Document 1, sliding friction does not efficiently occur between a plurality of plates (mass bodies) unless the amplitude of the motor casing is increased to some extent. Therefore, in the low amplitude region, the vibration reduction effect of the motor casing due to the sliding friction cannot be sufficiently obtained, and there is a problem that the vibration damping property in the low amplitude region is low.

  In addition, in the vibration reduction method provided with the vibration damping mechanism, the spring characteristic of the vibration damping mechanism is added to the spring characteristic of the mount, so that the natural frequency of the screw compressor becomes high and the vibration transmission rate to the base plate is high. As a result, there is a problem that the vibration damping property is lowered.

For example, a screw compressor having a weight of 100 kg having a vibration isolating mount with a spring constant of 6 × 10 ⁵ N / m, a shear elastic modulus of 1 × 10 ⁶ N / m ² and a loss factor of 0.5. When a thermoplastic viscoelastic resin is applied and the viscoelastic resin portion is 50 mm wide × 50 mm high × 5 mm thick, the loss factor including the mount is 0.1. The frequency ranges from 25 Hz to 54 Hz, and the frequency region where the vibration transmissibility from the compressor body to the base plate is 1 or less is 35 Hz or more to 78 Hz or more, and the vibration damping property is reduced.

Therefore, it is conceivable to lower the natural frequency of the screw compressor by lowering the spring constant of the mount. However, in the above example, the spring constant of the mount must be lowered to 1 × 10 ⁵ N / m. This is unrealistic because it falls outside the allowable range for the weight of the screw compressor.

  The objective of this invention is providing the screw compressor which can improve a vibration damping property.

  A screw compressor according to the present invention includes a screw rotor, a screw shaft that is coaxial with the male rotor of the screw rotor and integrated with the male rotor, a screw casing that houses the screw rotor and the screw shaft, A motor shaft that is coaxial with the screw shaft and integrated with the screw shaft and is cantilevered on the screw rotor side; a motor that includes a motor casing and rotates the motor shaft inside the motor casing; A base plate on which the screw casing and the motor casing are placed via a vibration isolator, a rod-like member projecting from the motor casing along the axial direction of the motor shaft, and a loose insertion in the rod-like member A plurality of weights, wherein at least one of the plurality of weights is coupled to the base plate Wherein at least one of said plurality of weight is not coupled to the base plate.

  According to said structure, with respect to the vibration of a motor casing, a vibration energy is dissipated by a rod-shaped member and a weight colliding, As a result, the vibration of a motor casing reduces. Furthermore, at least one of the plurality of weights is coupled to the base plate, and at least one of the plurality of weights is not coupled to the base plate, so that the weight and base plate coupled to the base plate can be coupled even in a low amplitude range. Relative displacement is preferably generated between the unconnected weights and sliding friction is efficiently generated between the two. Thereby, the vibration energy is dissipated even in the low amplitude region, and as a result, the vibration of the motor casing is reduced. Therefore, vibration damping can be improved.

  In the screw compressor according to the present invention, the weight closest to the motor casing is not coupled to the base plate, and is provided between the weight closest to the motor casing and the motor casing. There may be further provided a spring for urging the weight not coupled to the weight toward the weight coupled to the base plate. According to the above configuration, the weight not coupled to the base plate is coupled to the base plate by urging the weight not coupled to the base plate toward the weight coupled to the base plate with a spring. It is stably held without tilting between the weight and the motor casing. As a result, when the motor casing vibrates, the weight that is not coupled to the base plate stably collides with the rod-shaped member without wobbling. In addition, since the weights are brought into close contact by the biasing force of the spring, sliding friction between the weights is efficiently performed by the relative displacement generated between the weight coupled to the base plate and the weight not coupled to the base plate. To occur. Thereby, the vibration damping effect can be obtained stably.

  Further, in the screw compressor according to the present invention, the plurality of weights is three or more, and at least two weights are coupled to the base plate, and the weights coupled to the base plate are between the weights. At least one weight that is not coupled to the base plate may be disposed. According to said structure, the weight which is not couple | bonded with a base plate is couple | bonded with a base plate by arrange | positioning the weight which is not couple | bonded with a base plate between the weights couple | bonded with the base plate. The weights are stably held without being inclined. As a result, when the motor casing vibrates, the weight that is not coupled to the base plate stably collides with the rod-shaped member without wobbling. Further, sliding friction is efficiently generated when a weight not coupled to the base plate collides with an adjacent weight in the axial direction. Thereby, the vibration damping effect can be obtained stably.

  Moreover, in the screw compressor in this invention, the elastic body may be provided between the weight couple | bonded with the said base plate and the said base plate. According to said structure, it can suppress that a vibration transmits to the base plate from the weight couple | bonded with the base plate by the elastic body.

  According to the screw compressor of the present invention, the vibration energy is dissipated by the collision between the rod-shaped member and the weight against the vibration of the motor casing, and as a result, the vibration of the motor casing is reduced. Furthermore, even in a low amplitude region, relative displacement is preferably generated between the weight coupled to the base plate and the weight not coupled to the base plate, and sliding friction is efficiently generated between the two. Vibration energy is dissipated even in the amplitude range, and as a result, vibration of the motor casing is reduced. Therefore, vibration damping can be improved.

It is a side section schematic diagram showing the screw compressor concerning a 1st embodiment of the present invention. It is a side cross-sectional schematic diagram which shows the screw compressor which concerns on 2nd Embodiment of this invention. It is a side cross-sectional schematic diagram which shows the screw compressor which concerns on 3rd Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
(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 accommodates a pair of male and female screw rotors 4, a screw shaft 3 that is coaxial with the male rotor 4 a of the screw rotor 4 and integrated with the male rotor 4 a, and the screw rotor 4 and the screw shaft 3. A screw casing 12. The screw shaft 3 is supported at both ends by a bearing 14 and a bearing 15.

  The male rotor 4a and the screw shaft 3 of the screw rotor 4 are manufactured by machining from one steel material. The male rotor 4a and the screw shaft 3 may be manufactured separately and then rigidly connected (integrated connection). Further, the screw shaft 3 and a motor shaft 7 to be described later are also manufactured by machining from a single steel material and have an integral structure. The screw shaft 3 and the motor shaft 7 that are integrally formed with each other constitute a rotor shaft 11 that rotates. The screw shaft 3 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 coaxial with the screw shaft 3 and is integrated with the screw shaft 3 and is cantilevered on the screw rotor 4 side. Specifically, the motor shaft 7 is cantilevered by a bearing 14 (and a bearing 15) on the screw rotor 4 side.

  The motor side end surface 7 a of the motor shaft 7 is located closer to the screw rotor 4 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 is formed in the center of the end member 10. The end member 10 is coaxial with the motor shaft 7. 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 passes through a hole formed in the center of the end member 10.

  The screw casing 12 and the motor casing 13 are placed on the base plate 16 via a mount (vibration isolator) 17. The mount 17 has vibration insulation performance by having predetermined spring characteristics. That is, the mount 17 reduces the vibration transmitted from the screw casing 12 and the motor casing 13 to the base plate 16.

(Bar-shaped member and weight)
A rod-like member 19 is projected from the lower portion of the motor casing 13 along the axial direction of the motor shaft 7 on the side opposite to the screw rotor 4 side. A plurality of annular weights 8 are loosely inserted into the rod-like member 19. In the present embodiment, the number of weights 8 is three, but the number is not limited to three and may be one.

  The cross-sectional shape of the rod-shaped member 19 is circular, but is not necessarily circular, and may be, for example, a quadrangle. The hole formed in the center of the weight 8 is also the same, and may be not a circle but a square, for example. The shape of the hole formed at the center of the weight 8 is matched with the cross-sectional shape of the rod-shaped member 19.

  Of the three weights 8, the weight 8 a farthest from the motor casing 13 is coupled to the base plate 16 via an anti-vibration rubber (elastic body) 20, and the other two weights 8 are It is not coupled to the base plate 16. Two weights 8 which are located between the weight 8a connected to the base plate 16 and the motor casing 13 and are not connected to the base plate 16 from the end of the rod-shaped member 19 by the weight 8a connected to the base plate 16. It is designed not to jump out and drop out. Further, the vertical center of the hole formed at the center of the weight 8 a coupled to the base plate 16 coincides with the vertical vibration center of the motor casing 13. The weight 8a may be coupled to the base plate 16 via a sponge or a spring.

  When the shaft diameter of the rod-shaped member 19 is d1 mm and the inner diameter of the weight 8 is d2 mm, the displaceable amount of the weight 8 in the direction perpendicular to the axis (vertical direction) is (d2-d1). When the motor casing 13 vibrates, the two weights 8 not coupled to the base plate 16 are displaced in the vertical direction together with the rod-shaped member 19 and collide with the rod-shaped member 19. Further, since the weight 8a coupled to the base plate 16 is restrained from moving in the axial direction and the direction orthogonal to the axis (vertical direction), when the motor casing 13 vibrates, a hole formed in the center of the weight 8a Among them, the rod-shaped member 19 is displaced in the vertical direction. Also by this, the weight 8 a collides with the rod-shaped member 19.

  Further, when the motor casing 13 vibrates, a relative displacement is generated between the weights 8, thereby causing a sliding friction between the two. In particular, since the weight 8a farthest from the motor casing 13 is coupled to the base plate 16, it is coupled to the base plate 16 not only when the vibration amplitude in the motor casing 13 is large to some extent but also in the low amplitude region. Relative displacement is preferably generated between the weight 8a and the weight 8 not connected to the base plate 16, and sliding friction is efficiently generated between the two.

(effect)
According to the screw compressor 1 of the present embodiment, the vibration energy is dissipated by the collision of the rod-shaped member 19 and the weight 8 with respect to the vibration of the motor casing 13, and as a result, the vibration of the motor casing 13 is reduced.

  Further, in the screw compressor 1 of the present embodiment, of the three weights 8, the weight 8 a farthest from the motor casing 13 is coupled to the base plate 16, and the other two weights 8 are coupled to the base plate 16. Not. If none of the three weights 8 is coupled to the base plate 16, the sliding friction generated between the weights 8 in the low amplitude region is limited. As a result, in the low amplitude region, the sliding friction is caused by sliding friction. The vibration reduction effect of the motor casing 13 cannot be sufficiently obtained. However, by providing the weight 8a coupled to the base plate 16 and the weight 8 not coupled to the base plate 16 as in the present embodiment, the weight 8a coupled to the base plate 16 even in the low amplitude region. And a weight 8 that is not coupled to the base plate 16 is preferably relatively displaced, and sliding friction is efficiently generated between the two. Thereby, the vibration energy is dissipated even in the low amplitude region, and as a result, the vibration of the motor casing 13 is reduced. Therefore, the vibration damping property of the screw compressor 1 can be improved.

  Further, the vibration isolating rubber 20 can suppress vibration from being transmitted to the base plate 16 from the weight 8 a coupled to the base plate 16.

(Modification)
In addition, by providing a spacer in the gap between the weight 8 closest to the motor casing 13 and the motor casing 13 and bringing the weights 8 close to or close to each other in the axial direction, sliding friction is easily generated between the weights 8. May be.

  Further, in the present embodiment, the rod-shaped member 19 is protruded on the opposite side of the motor casing 13 from the screw rotor 4 side. However, the rod-shaped member 19 may be protruded on the screw rotor 4 side of the motor casing 13. . In this case, the entire screw compressor 1 can be made compact.

[Second Embodiment]
Next, the screw compressor 101 which concerns on 2nd Embodiment of this invention is demonstrated. The main difference between the screw compressor 1 of the first embodiment and the screw compressor 101 of the present embodiment is that the screw compressor 101 of the present embodiment has a coiled spring 21 as shown in FIG. It is the point which comprises.

(Spring)
The spring 21 is provided between the motor casing 13 and the weight 8 that is closest to the motor casing 13 and is not coupled to the base plate 16. The spring 21 is positioned between the weight 8a that is farthest from the motor casing 13 and is coupled to the base plate 16 and the motor casing 13, and the two weights 8 that are not coupled to the base plate 16 are Each is urged toward the weight 8a coupled to the plate 16. By the spring 21, the weights 8 are in close contact with each other, and each of the two weights 8 that are not coupled to the base plate 16 is stable without being inclined between the weight 8 a coupled to the base plate 16 and the motor casing 13. Retained.

(effect)
If there is a gap between the weight 8 closest to the motor casing 13 and the motor casing 13, each of the two weights 8 that are not coupled to the base plate 16 is inclined. As a result, when the motor casing 13 vibrates, Not only does it not collide with the rod-shaped member 19 stably, but also sliding friction due to relative displacement between the weights 8 is less likely to occur. Therefore, in the screw compressor 101 of the present embodiment, the two weights 8 not coupled to the base plate 16 are urged by the springs 21 toward the weight 8a coupled to the base plate 16. Thus, each of the two weights 8 not coupled to the base plate 16 is stably held without being tilted between the weight 8 a coupled to the base plate 16 and the motor casing 13. As a result, at the time of vibration of the motor casing 13, each of the two weights 8 not coupled to the base plate 16 collides stably with the rod-shaped member 19 without wobbling. Further, since the weights 8 are brought into close contact with each other by the biasing force of the spring 21, the relative displacement generated between the weight 8a coupled to the base plate 16 and the weight 8 not coupled to the base plate 16 causes Sliding friction is efficiently generated between them. Thereby, the vibration damping effect can be obtained stably.

[Third Embodiment]
Next, a screw compressor 201 according to a third embodiment of the present invention will be described. The main difference between the screw compressor 1 of the first embodiment and the screw compressor 201 of the present embodiment is that, as shown in FIG. 3, between the weights 8a and 8b coupled to the base plate 16, The weight 8 that is not coupled to the base plate 16 is disposed.

(Bar-shaped member and weight)
Also in the present embodiment, the number of weights 8 is three, of which the weight 8a farthest from the motor casing 13 and the weight 8b closest to the motor casing 13 are slightly larger than one weight. The weights 8 are connected to the base plate 16 and are not connected to the base plate 16 therebetween. In this way, by placing the weight 8 not coupled to the base plate 16 between the weights 8a and 8b coupled to the base plate 16, the weights 8 are close to each other and coupled to the base plate 16. The unweighted weight 8 is stably held without tilting between the weights 8a and 8b coupled to the base plate 16.

  The distance between the weight 8a farthest from the motor casing 13 and the weight 8b closest to the motor casing 13 is one weight, and the weights 8 are brought into close contact with each other in the axial direction. Sliding friction may be easily generated.

(effect)
If there is a gap between the weight 8b closest to the motor casing 13 and the motor casing 13, and the weight 8b closest to the motor casing 13 is not coupled to the base plate 16, the two weights not coupled to the base plate 16 As a result, when the motor casing 13 vibrates, not only does it stably collide with the rod-like member 19 but also sliding friction due to relative displacement between the weights 8 is less likely to occur. Therefore, in the screw compressor 201 of the present embodiment, the weight 8a farthest from the motor casing 13 and the weight 8b closest to the motor casing 13 are coupled to the base plate 16 respectively, and the weight coupled to the base plate 16 A weight 8 that is not coupled to the base plate 16 is disposed between 8a and 8b. As a result, the weight 8 that is not coupled to the base plate 16 is stably held without being tilted between the weights 8a and 8b that are coupled to the base plate 16. As a result, when the motor casing 13 vibrates, the weight 8 that is not coupled to the base plate 16 stably collides with the rod-shaped member 19 without wobbling. Further, sliding friction is efficiently generated when the weight 8 not coupled to the base plate 16 collides with the adjacent weights 8a and 8b in the axial direction. Thereby, the vibration damping effect can be obtained stably.

(Modification of this embodiment)
The embodiment of the present invention has been described above, but only specific examples are illustrated, and the present invention is not particularly limited, and the specific configuration and the like can be appropriately changed in design. Further, the actions and effects described in the embodiments of the invention only list the most preferable actions and effects resulting from the present invention, and the actions and effects according to the present invention are described in the embodiments of the present invention. It is not limited to what was done.

  For example, the embodiments shown in FIGS. 1 to 3 can be implemented in combination as appropriate.

DESCRIPTION OF SYMBOLS 1,101,201 Screw compressor 2 Screw main-body part 3 Screw shaft 4 Screw rotor 5 Rotor 6 Stator 7 Motor shaft 8, 8a, 8b Weight 9 Bolt 10 End member 11 Rotor shaft 12 Screw casing 13 Motor casing 14, 15 Bearing 16 Base plate 17 Mount (anti-vibration body)
19 Bar-shaped member 20 Anti-vibration rubber (elastic body)
21 Spring 30 Motor part

Claims (4)

A screw rotor;
A screw shaft coaxial with the male rotor of the screw rotor and integrated with the male rotor;
A screw casing that houses the screw rotor and the screw shaft;
A motor shaft that is coaxial with the screw shaft and integrated with the screw shaft and is cantilevered on the screw rotor side;
A motor comprising a motor casing and rotating the motor shaft inside the motor casing;
A base plate on which the screw casing and the motor casing are placed via a vibration isolator,
A rod-shaped member protruding from the motor casing along the axial direction of the motor shaft;
A plurality of weights loosely inserted into the rod-shaped member;
Have
A screw compressor, wherein at least one of the plurality of weights is coupled to the base plate, and at least one of the plurality of weights is not coupled to the base plate. The weight closest to the motor casing is not coupled to the base plate,
A spring provided between the weight closest to the motor casing and the motor casing and biasing the weight not coupled to the base plate toward the weight coupled to the base plate; The screw compressor according to claim 1.   The plurality of weights is three or more, and at least two weights are coupled to the base plate, and between the weights coupled to the base plate, at least a weight not coupled to the base plate The screw compressor according to claim 1, wherein one screw compressor is arranged.   The screw compressor according to any one of claims 1 to 3, wherein an elastic body is provided between the weight coupled to the base plate and the base plate.

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