JP2017163744A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for improvement in the efficiency of a screw compressor.SOLUTION: A motor 1 connected directly with the screw rotor 32 of a screw compressor 31 via an output shaft 4 includes a rotor 2 where the output shaft 4 is penetrating the center thereof, a stator 3 arranged around the rotor 2 oppositely thereto and movable in the axial direction of the output shaft 4, and rotating the rotor 2 by generating an electromagnetic force therebetween, and a linear motor 41 for moving the stator 3 in the axial direction of the output shaft 4. The linear motor 41 moves the stator 3 in the opposite direction to a thrust force acting on the screw rotor 32.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric motor directly connected to a screw rotor of a screw compressor via an output shaft.

  Conventionally, an electric motor is used to rotate a screw rotor of a screw compressor. The structure in which the electric motor and the screw compressor are directly connected without using a drive belt or gears can reduce power transmission loss and increase the efficiency of the screw compressor.

  Here, in the screw compressor, the reaction force of the compressed gas acts on the screw rotor as a thrust force from the discharge side toward the suction side. Therefore, a thrust load is applied to the bearing that supports the screw rotor, and the long-term durability and life of the bearing are reduced.

  Therefore, Patent Document 1 discloses an oil-free screw compressor that cancels the thrust force applied to the rotor shaft by the back pressure acting on the balance piston. In patent document 1, back pressure is made to act on a balance piston by supplying pressure oil to the columnar space part which accommodates a balance piston.

  Patent Document 2 discloses a screw compression device that cancels a thrust force by the pressure of a fluid acting on a balance piston. In patent document 2, the pressure of the fluid which acts on a balance piston is adjusted according to the capacity | capacitance of a compressor main body.

  Patent Document 3 discloses a compressor that applies a reverse thrust load to a thrust plate. In Patent Document 3, a working fluid is supplied to the balance mechanism in order to press the balance mechanism toward the thrust plate.

JP 2002-317782 A JP2013-241915A Japanese Patent Laying-Open No. 2015-83776

  However, in Patent Documents 1 and 2, the amount of oil agitated by the balance piston increases, and the power loss increases. On the other hand, in Patent Document 3, since the thrust plate is not directly supported by the working fluid, power loss can be reduced. However, in Patent Document 3, friction loss occurs because the thrust bearing is brought into contact with the thrust plate. Therefore, the efficiency of the screw compressor is deteriorated.

  An object of the present invention is to provide an electric motor capable of improving the efficiency of a screw compressor.

  The present invention relates to an electric motor directly connected to a screw rotor of a screw compressor via an output shaft, a rotor having the output shaft inserted through the center, and a shaft of the output shaft disposed around the rotor so as to face each other. A stator that can move in the direction and generates an electromagnetic force between the rotor and the rotor, and a moving unit that moves the stator in the axial direction of the output shaft. And the moving means moves the stator in a direction opposite to a thrust force acting on the screw rotor.

  According to the present invention, the stator is moved in the direction opposite to the thrust force acting on the screw rotor. Thereby, in a cross-sectional view parallel to the rotation axis of the rotor, the direction of the electromagnetic force generated between the rotor and the stator is inclined from the direction orthogonal to the axial direction of the output shaft. At this time, the component of the electromagnetic force that does not contribute to rotation can be decomposed into a component orthogonal to the rotation axis and a component parallel to the rotation axis. Among these components, the component orthogonal to the rotation axis cancels out with the component orthogonal to the rotation axis in the electromagnetic force symmetrical to 180 degrees, but the component parallel to the rotation axis remains. The component parallel to the rotation axis is a force that moves the rotor in the direction opposite to the thrust force. With this force, the rotor moves in the direction opposite to the direction of the thrust force, so that the thrust force can be reduced. At this time, since no working fluid such as pressure oil is used, no power loss occurs. Further, since the member is not in contact with a rotating body such as a thrust plate, no friction loss occurs. Therefore, the efficiency of the screw compressor can be improved.

It is sectional drawing of an electric motor and a screw compressor. It is sectional drawing of an electric motor and a screw compressor. It is sectional drawing of an electric motor and a screw compressor.

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

[First Embodiment]
(Configuration of electric motor)
The electric motor 1 according to the first embodiment of the present invention includes a cylindrical rotor (rotor) 2 and a stator (stator) disposed around the rotor 2 as shown in FIG. 3. The electric motor 1 rotates the rotor 2 by generating an electromagnetic force between the rotor 2 and the stator 3.

  The rotor 2 is disposed in the stator 3 so that its axis coincides with the axis of the stator 3 (coaxial). The rotor 2 and the stator 3 are accommodated in a space formed by the casing 5 and the casing 6. The casing 5 and the casing 6 are not fixed.

  The rotor 2 has a rotor core 11 in which a permanent magnet (not shown) is embedded. That is, the electric motor 1 of this embodiment is an IPM (Interior Permanent Magnet) motor. A permanent magnet may be attached to the surface of the rotor core 11. In this case, the electric motor 1 is an SPM (Surface Permanent Magnet) motor.

  The rotor core 11 is formed, for example, by laminating ring plate-shaped electromagnetic steel plates in the axial direction. An output shaft (shaft) 4 that extracts the rotation of the rotor 2 to the outside is inserted through the center of the rotor core 11. The output shaft 4 is rotatably supported by bearings 7 and 8 on both sides thereof. The bearing 7 is provided at the center of the support 9 disposed inside the casing 5, and the bearing 8 is provided at the center of the casing 6. A bearing 10 that is slidably in contact with the inner surface of the casing 5 is provided at the end of the support 9.

  The rotor 2 is not limited to a configuration using a hard magnetic material such as a permanent magnet, and may be a configuration using a soft magnetic material. That is, any configuration may be used as long as an electromagnetic force is generated between the rotor 2 and the stator 3.

  The stator 3 rotates the rotor 2 by generating an electromagnetic force between the stator 3 and the rotor 2. The stator 3 is fixed to the casing 5.

  The stator 3 includes a cylindrical stator core 21 and a winding 22 wound around the inner peripheral surface of the stator core 21.

  The stator core 21 is formed by, for example, laminating a plurality of electromagnetic steel plates (silicon steel plates or the like) in the axial direction. Slots and teeth are alternately and continuously formed along the circumferential direction on the inner peripheral surface of the stator core 21, and a winding 22 is wound around the teeth. A rotating magnetic field is formed by supplying a current having a predetermined phase difference to the windings 22 wound around the plurality of teeth. Thereby, magnet torque and reluctance torque are generated in the rotor 2, and the rotor 2 rotates. Here, the reluctance torque is generated when the rotor 2 rotates with respect to the stator 3 so as to cause a magnetic flux to flow in a place where the magnetic resistance is difficult to flow, that is, where the magnetic resistance is difficult to flow. Torque.

  The electric motor 1 includes a linear motor (moving means) 41 that moves the casing 5 in the axial direction of the output shaft 4. As the casing 5 moves, the stator 3 moves in the axial direction. In FIG. 1, the stator 3 located at the origin position is shown.

  When the stator 3 is located at the origin position, the direction of the electromagnetic force generated between the rotor 2 and the stator 3 in the sectional view parallel to the rotation axis X of the rotor 2 is relative to the rotation axis X. Orthogonal. At this time, the component that does not contribute to the rotation of the electromagnetic force is only the component orthogonal to the rotation axis X. The component orthogonal to the rotation axis X cancels out with the component orthogonal to the rotation axis X in the electromagnetic force symmetric to 180 degrees. In addition, the component which contributes to rotation among the electromagnetic forces faces the tangential direction of the rotor 2.

(Configuration of screw compressor)
The electric motor 1 is directly connected to the screw compressor 31. The screw compressor 31 has two male and female screw rotors 32. One of the screw rotors 32 and the rotor 2 are directly connected via the output shaft 4. The two screw rotors 32 are accommodated in the casing 33. The casing 33 is fixed to the casing 6. The casing 33 is provided with a suction port 34 and a discharge port 35, respectively. The left end of the output shaft 4 is rotatably supported by a bearing 36 provided in the casing 33.

  In the screw compressor 31, the reaction force of the compressed gas acts on the screw rotor 32 as a thrust force from the discharge side toward the suction side. In FIG. 1, the suction port 34 is located on the left side of the screw rotor 32, and the discharge port 35 is located on the right side of the screw rotor 32. Therefore, the thrust force acts leftward in the figure along the output shaft 4.

(Electric motor operation)
As shown in FIG. 2 which is a cross-sectional view, when a thrust force is acting on the screw rotor 32, the casing 5 (stator 3) is moved in the direction opposite to the thrust force (right direction) by the linear motor 41. Let Thereby, in a cross-sectional view parallel to the rotation axis X of the rotor 2, the direction of the electromagnetic force generated between the rotor 2 and the stator 3 is inclined from the direction orthogonal to the axial direction of the output shaft 4. . At this time, a component of the electromagnetic force that does not contribute to rotation can be decomposed into a component orthogonal to the rotation axis X and a component parallel to the rotation axis X.

  Of the electromagnetic force, the component orthogonal to the rotation axis X cancels out with the component orthogonal to the rotation axis X in the electromagnetic force symmetric to 180 degrees, but the component parallel to the rotation axis X remains. The component parallel to the rotation axis X is a force that moves the rotor 2 in the direction opposite to the thrust force. Due to this force, the rotor 2 moves in the direction opposite to the direction of the thrust force, so that the thrust force can be reduced. At this time, since no working fluid such as pressure oil is used, no power loss occurs. Further, since the member is not in contact with a rotating body such as a thrust plate, no friction loss occurs. Therefore, the efficiency of the screw compressor 31 can be improved.

  When the arrangement relationship between the suction port 34 and the discharge port 35 is reversed, the thrust force acts in the right direction in the figure. In this case, the casing 5 (stator 3) is moved in the left direction, which is the direction opposite to the thrust force. As a result, the component parallel to the rotation axis X of the electromagnetic force is directed to the left, so that the thrust force can be reduced.

(effect)
As described above, according to the electric motor 1 according to the present embodiment, the stator 3 is moved in the direction opposite to the thrust force acting on the screw rotor 32. Thereby, in a cross-sectional view parallel to the rotation axis X of the rotor 2, the direction of the electromagnetic force generated between the rotor 2 and the stator 3 is inclined from the direction orthogonal to the axial direction of the output shaft 4. . At this time, a component of the electromagnetic force that does not contribute to rotation can be decomposed into a component orthogonal to the rotation axis X and a component parallel to the rotation axis X. Among these, the component orthogonal to the rotation axis X cancels out with the component orthogonal to the rotation axis X in the electromagnetic force symmetric to 180 degrees, but the component parallel to the rotation axis X remains. The component parallel to the rotation axis X is a force that moves the rotor 2 in the direction opposite to the thrust force. Due to this force, the rotor 2 moves in the direction opposite to the direction of the thrust force, so that the thrust force can be reduced. At this time, since no working fluid such as pressure oil is used, no power loss occurs. Further, since the member is not in contact with a rotating body such as a thrust plate, no friction loss occurs. Therefore, the efficiency of the screw compressor 31 can be improved.

[Second Embodiment]
(Configuration of electric motor)
Next, the electric motor 201 according to the second embodiment of the present invention will be described. In addition, about the same component as the component mentioned above, the same reference number is attached | subjected and the description is abbreviate | omitted. The electric motor 201 of the present embodiment is different from the electric motor 1 of the first embodiment in that a sensor (detection means) that detects the displacement of the output shaft 4 in the axial direction of the output shaft 4 as shown in FIG. ) 51 and a controller (control means) 52 that controls the linear motor 41 to move the stator 3 in the direction opposite to the direction in which the output shaft 4 is displaced.

  The sensor 51 is provided on the left side of the casing 33, detects the displacement of the left end of the output shaft 4 through the opening 33 a provided in the casing 33, and determines the amount of displacement of the output shaft 4 in the axial direction. taking measurement. The sensor 51 is preferably one that detects and measures in a non-contact manner using a laser or a camera. The displacement amount is a deviation amount from the origin position of the output shaft 4. The origin position of the output shaft 4 is the position of the output shaft 4 when the rotor 2 is located at the origin position.

  The controller 52 controls the linear motor 41 so as to move the stator 3 in the opposite direction (right direction) to the direction in which the output shaft 4 is displaced. Thereby, the force which moves the rotor 2 arises in the opposite direction to a thrust force. Due to this force, the rotor 2 moves in the direction opposite to the direction of the thrust force and the thrust force is reduced, so that the amount of displacement of the output shaft 4 can be reduced. By performing this until the amount of displacement of the output shaft 4 becomes zero, the thrust force can be canceled out.

  The position of the sensor 51 is not limited to the left side of the casing 33. For example, the sensor 51 may be provided in the casing 5 to detect the displacement of the right end of the output shaft 4. The sensor 51 may detect not the displacement of the output shaft 4 but the displacement of the rotor 2 or the displacement of the screw rotor 32.

(effect)
As described above, according to the electric motor 201 according to the present embodiment, the displacement of the output shaft 4 is detected, and the linear motor 41 is moved so as to move the stator 3 in the direction opposite to the direction in which the output shaft 4 is displaced. Control. As a result, a force for moving the rotor 2 is generated in a direction opposite to the thrust force. By this force, the rotor 2 moves in the direction opposite to the direction of the thrust force, and the thrust force is reduced, so that the amount of displacement of the output shaft 4 can be reduced. By performing this until the amount of displacement of the output shaft 4 becomes zero, the thrust force can be canceled out.

  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.

DESCRIPTION OF SYMBOLS 1,201 Electric motor 2 Rotor 3 Stator 4 Output shaft 5, 6 Casing 7, 8 Bearing 9 Support body 10 Bearing 11 Rotor core 21 Stator core 22 Winding 31 Screw compressor 32 Screw rotor 33 Casing 34 Suction port 35 Discharge port 36 Bearing 41 Linear motor (moving means)
51 Sensor (detection means)
52 Controller (Control means)

Claims (2)

In the motor directly connected to the screw rotor of the screw compressor via the output shaft,
A rotor inserted around the output shaft;
A stator that is arranged around the rotor and is movable in the axial direction of the output shaft, and that generates an electromagnetic force with the rotor to rotate the rotor;
Moving means for moving the stator in the axial direction of the output shaft;
Have
The electric motor according to claim 1, wherein the moving means moves the stator in a direction opposite to a thrust force acting on the screw rotor. Detecting means for detecting displacement of the output shaft in the axial direction of the output shaft;
Control means for controlling the moving means to move the stator in a direction opposite to the direction in which the output shaft is displaced;
The electric motor according to claim 1, further comprising:

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