JP2002218708A - Auxiliary bearing structure for high-speed motor driven compressor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the rotor shaft length, improve the stability of the rotating shaft, and further simplify the structure, thereby facilitating manufacture and assembly. Provided is an auxiliary bearing structure for a motor-driven compressor. SOLUTION: A rotatable rotor 42, a non-rotating stator 33 opposed to the rotor with a predetermined gap, and a thrust direction movement of the rotor with a predetermined gap. A non-rotating thrust magnetic bearing 48, a non-rotating radial magnetic bearing 49 having a predetermined gap to regulate the radial direction of the rotor, and a non-rotating displacement sensor 50 for observing displacement of the rotor; The rotating side or the non-rotating side or both are auxiliary bearings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary bearing structure for a high-speed motor driven compressor having high stability of a rotating shaft, which can prevent a magnetic bearing from being damaged when power is not supplied and can shorten a rotor shaft length.

[0002]

2. Description of the Related Art A turbo compressor is more suitable for increasing the capacity and miniaturization than a reciprocating compressor or a screw compressor, and is easily oil-free. For this reason, turbo compressors are frequently used as general-purpose compressors for air sources in factories, raw air for air separation, and air sources for processes.

Conventional turbo compressors include those in which a turbo compressor or the like is directly driven by a high-speed motor, and those in which the rotating part is supported by magnetic bearings.

FIG. 3 is a schematic diagram of a single-shaft, two-stage compressor in which a turbo compressor is directly connected to and driven by a high-speed rotary motor composed of a stator for generating a rotating magnetic field and a rotating rotor. This figure further shows an auxiliary bearing structure of a high-speed motor driven compressor in which a single-stage and a two-stage impeller of a single-shaft two-stage compressor are arranged at respective rotor shaft ends.

In FIG. 3, a stator 3 is mounted on an inner peripheral surface of a casing (not shown) of the high-speed motor driven compressor 1. The stator 3 includes a stator core 5 and a stator winding 6 forming a stator portion 4 of the high-speed motor. The stator core 5 is formed by laminating a plurality of thin steel plates in the axial direction to reduce iron loss.

On the other hand, a rotor 12 of a high-speed motor is rotatably arranged while maintaining a predetermined gap with the inner peripheral surface of the stator section 4. The rotor 12 includes a rotor core 14 forming a rotor portion 13 at a central portion, and a rotor shaft 15 extending on both sides thereof.
Consists of A one-stage impeller 10 and a two-stage impeller 11 are attached to an end of the rotor shaft 15.

In FIG. 3, the rotor shaft 15 has shaft portions 17 on both side surfaces 16 of the rotor portion 13 having a diameter smaller than the outer diameter of the rotor portion 13. Further, a substantially L-shaped thrust magnetic bearing 18 stored in a shaft box (not shown) is disposed at a position facing the both side surfaces 16 of the rotor portion 13 with a predetermined gap. The thrust magnetic bearing 18 controls displacement of the rotor 12 in the thrust direction. The thrust magnetic bearing 18 has a gap even with the shaft portion 17.

A radial magnetic bearing 19 for restricting radial movement of the rotor shaft 15 is provided between each thrust magnetic bearing 18 and the first-stage impeller 10 and the second-stage impeller 11. Are arranged. Further, on the opposite side of the radial magnetic bearing 19 from the thrust magnetic bearing 18, a non-rotational displacement sensor 20 having a gap with the rotor shaft 15 to observe the displacement of the rotor 12.
Are attached to a fixing device (not shown). Therefore, as shown in FIG.
7, and thrust magnetic bearing 18, radial magnetic bearing 1
9 and the displacement sensor 20 form the magnetic bearing of the high-speed motor.

As shown in FIG. 3, between the one-stage impeller 10 and the two-stage impeller 11 of the small-diameter shaft portion 17 of the rotor shaft 15, a shaft portion 2 having a smaller diameter than the small-diameter shaft portion 17 is provided.
1 and 21 are connected. The small-diameter shaft portion 21 has an auxiliary bearing 2 for a so-called magnetic bearing such as a ball bearing (this figure) or a metal bearing stored in a shaft box (not shown) with a predetermined gap.
2 are arranged. This auxiliary bearing forms an auxiliary bearing part of the high-speed motor.

The auxiliary bearing is mounted to prevent the rotor 13 and the stator 4 from contacting each other and causing breakage or damage when the magnetic bearing is de-energized. Therefore, the gap between the auxiliary bearing 22 and the shaft portion 21 is formed smaller (for example, half) than all the other gaps described above. Since the gap is reduced in this manner, the rotor shaft can be supported by the auxiliary bearing before the rotor shaft or the like comes into contact with the fixed portion even when the magnetic bearing is de-energized due to a power failure. Thereby, breakage and damage of each component such as the rotor shaft forming the high-speed motor can be prevented.

[0011]

However, since the auxiliary bearing is arranged on the small-diameter shaft portion 21 of the stepped rotor shaft as described above, the overall length of the rotor shaft becomes longer. For this reason, the rigidity of the rotor shaft is reduced, and the rotor shaft is bent, causing runout and vibration. As a result, there has been a problem that the stability of the rotating shaft is deteriorated and the permissible rotation speed is reduced. Further, since the auxiliary bearing portion is disposed, the rotor shaft is cut into a stepped shape, so that the number of manufacturing steps increases. Further, there are also problems that the number of assembling members is large and the number of assembling steps is increased due to the complexity of assembling.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a high-speed motor capable of shortening the rotor shaft length, improving the stability of the rotating shaft, and further simplifying the structure, thereby facilitating manufacture and assembly. An object of the present invention is to provide an auxiliary bearing structure for a driving compressor.

[0013]

According to the present invention, a rotatable rotor (42) of a high-speed motor-driven compressor, and a non-rotating stator which is disposed opposite to the rotor with a predetermined gap therebetween. A non-rotating thrust magnetic bearing for controlling displacement of the rotor in the thrust direction with a predetermined gap;
A non-rotating radial magnetic bearing (49) for controlling the radial displacement of the rotor with a predetermined gap, and a non-rotating displacement sensor (50) for monitoring the displacement of the rotor; An auxiliary bearing structure for a high-speed motor driven compressor is provided, wherein the rotating side, the non-rotating side, or both are auxiliary bearings.

With this configuration, since the rotating side, the non-rotating side, or both are the auxiliary bearings, the auxiliary bearing portions near the both ends of the rotor shaft can be omitted. Therefore, the length of the rotor shaft can be reduced, and the rigidity of the rotor shaft can be improved. Further, the stability of the rotating shaft can be improved.
Furthermore, since the auxiliary bearing portion can be omitted, the number of constituent members can be reduced, the structure can be simplified, and the manufacturing and assembling can be facilitated to reduce the cost.

According to a preferred embodiment of the present invention, the rotor (42) has a rotor portion (43) formed by a rotor core (44) and a rotor conductor near a center portion, and has shafts on both side surfaces of the rotor portion. A stepped rotatable rotor shaft (45) having a portion (47), wherein the outer peripheral surface of the rotor shaft is coated with a non-magnetic material or a non-magnetic material sleeve is fitted to the rotor shaft itself. Is an auxiliary bearing.

According to this structure, since the outer peripheral surface of the rotor shaft forming the rotor is coated with a non-magnetic material or the sleeve of the non-magnetic material is fitted, the rotor shaft itself has an auxiliary bearing structure. it can. Therefore, even when the magnetic bearing is de-energized, the rotor shaft itself is an auxiliary bearing, and can be supported by the stator or the like. This can prevent the rotor shaft itself forming the high-speed motor and the components on the fixed side from being damaged or damaged. Further, since the auxiliary bearing provided on the small-diameter shaft portion at the end of the rotor shaft forming the stepped shaft is deleted, the length of the rotor shaft can be reduced, and the rigidity of the rotor shaft can be improved. Further, the stability of the rotating shaft can be improved. Further, since the auxiliary bearing can be omitted, the number of constituent members can be reduced, the structure can be simplified, and the manufacturing and assembling can be facilitated to reduce the cost.

According to another preferred embodiment of the present invention, the stator (33) is a stator plate and a stator core (35) made of laminated steel plates, and the inner peripheral surface of the steel plate. Is coated with a non-magnetic material or a sleeve made of a non-magnetic material is fitted, and the stator itself is an auxiliary bearing.

According to this configuration, the stator can be used as an auxiliary bearing by coating the inner peripheral surface of the stator with a non-magnetic material or by fitting a sleeve made of a non-magnetic material. Therefore, even when the magnetic bearing is de-energized, the rotor shaft can be supported because the stator itself is the auxiliary bearing. Further, since the auxiliary bearing is omitted, the length of the rotor shaft can be shortened, and the stability of the rotating shaft can be improved.

The coating of the non-magnetic material is preferably performed by spraying a non-ferrous metal, resin or ceramic.

According to this configuration, the outer peripheral surface of the rotor shaft and the inner peripheral surface of the stator portion, which together form the high-speed motor, and the inner peripheral surface of the thrust magnetic bearing, the radial magnetic bearing, and the displacement sensor on the rotor shaft side. A solid lubricant (eg, graphite) or Teflon (registered trademark) is applied to a brass-based alloy or the like which is a non-magnetic material to be coated at a low temperature of 100 to 200 ° C.
Such as synthetic resin or ceramic powder granules at a high speed using a thermal spray gun to rapidly cool by instantaneous cooling, for example, high-speed gas flame thermal spraying, etc. A coating can be applied. Therefore, an auxiliary bearing can be provided on the surface of any member.

The compressor is a single-shaft one-stage compressor or a single-shaft two-stage compressor, and a non-magnetic material is sprayed on the back surface of an impeller disposed at the shaft end of a rotor shaft of a rotor. . In either case, a non-magnetic material is sprayed on the back surface of the impeller, and the rotating side can be used as an auxiliary bearing together with the spraying performed on the outer peripheral surface of the rotor shaft.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the common parts in the respective drawings, and the duplicate description will be omitted.

FIG. 1 is a first embodiment showing an auxiliary bearing structure of a single-shaft, two-stage high-speed motor-driven compressor according to the present invention. In FIG. 1, the high-speed motor drive compressor 31 has a stator 33 attached to an inner peripheral surface of a casing (not shown). The stator 33 includes a stator core 35 and a stator winding 36 forming a stator portion 34 of the high-speed motor. The stator core 35 has a plurality of thin steel plates laminated in the axial direction to reduce iron loss. On the other hand, the stator winding 36 is accommodated in a groove (not shown) inside the stator core 35, and is connected to a polyphase power supply to form a rotating magnetic field.

On the other hand, the rotor core 44 and the rotor shaft 45 are rotatably arranged while keeping a predetermined gap from the inner peripheral surface of the stator portion 34. The rotor core 44 has a one-stage impeller 40 and a two-stage impeller 41 attached to both shaft end portions, and forms a rotor portion 43 that forms the rotor 42 of the high-speed motor near the center. As shown in FIG. 1, a motor portion of a high-speed motor that rotates at high speed (for example, 100,000 min ⁻¹ or more) between the rotor portion 43 of the rotor 42 and the stator portion 34 of the stator 33 is formed. I have.

In FIG. 1, the rotor shaft 45 has shaft portions 47 on both side surfaces 46 of the rotor portion 43 whose diameter is smaller than the outer diameter of the rotor portion 43. The shaft portions 47 are each a single-stage impeller 40.
And the two-stage impeller 41. Further, a substantially L-shaped thrust magnetic bearing 48 stored in a shaft box (not shown) is disposed at a position facing the both side surfaces 46 of the rotor portion 43 with a predetermined gap. Thrust magnetic bearing 48
Controls the displacement in the thrust direction generated on the rotor shaft 45 constituting the rotor 42. The thrust magnetic bearing 48
Has a gap even with the shaft portion 47.

Further, between each of the thrust magnetic bearing 48, the first-stage impeller 40, and the two-stage impeller 41, a radial magnetic bearing 49, which is stored in a shaft box (not shown) and regulates the radial movement, is connected to the rotor shaft 45. They are arranged with a gap. Further, on the opposite side of each radial magnetic bearing 49 from the thrust magnetic bearing 48, a plurality of (for example, four equally) displacement sensors 50 that are non-rotating are mounted on a fixing device (not shown). . This displacement sensor 50
The displacement of the rotor 42 is observed with a gap from the rotor shaft 45. As shown in FIG. 1, the shaft portion 47 of the rotor shaft 45,
The thrust magnetic bearing 48, the radial magnetic bearing 49, and the displacement sensor 50 form a magnetic bearing portion of a high-speed motor.

Also, as shown by the bold solid line in FIG.
6, the entire outer circumferential surface of the rotor shaft 45 including both shaft portions 47 and 1
Back portions 51, 5 of the stepped impeller 40 and the two-step impeller 41
2 is coated with a non-magnetic material to be described later, and the rotation side of the rotor shaft itself including the impeller serves as an auxiliary bearing.

As described above, since the outer peripheral surface of the rotor shaft including the back surface of the impeller and forming the rotor is coated with the non-magnetic material, the rotor shaft itself can be used as an auxiliary bearing. Therefore, even when the magnetic bearing is de-energized, the rotor shaft itself is an auxiliary bearing, and can be supported by the fixed stator or the like. This can prevent breakage and damage of the rotor shaft itself and the fixed-side components that form the high-speed motor. In addition, since the auxiliary bearing portion provided on the small-diameter shaft portion at the rotor shaft end forming the stepped shaft has been deleted,
The rotor shaft length can be shortened, the rigidity of the rotor shaft can be improved, and the stability of the rotating shaft can be improved. Further, since the conventional auxiliary bearing can be omitted, the number of constituent members can be reduced to simplify the structure, and the manufacturing and assembly can be facilitated to reduce the cost. Instead of this coating, a sleeve made of a non-magnetic material may be fitted on the outer peripheral surface of the rotor shaft, and the rotating side may have an auxiliary bearing structure.

The back parts 51 of the impellers 40, 41,
The coating of the non-magnetic material on the outer peripheral surface of the rotor shaft 45 forming the rotor 42 including the rotor 52 is performed by spraying a non-ferrous metal, a resin, or a ceramic. Such a material to be coated (base material) of the impeller or the rotor shaft is coated at a low temperature of 100 to 200 ° C., so that it is possible to perform coating with a low heat input and a good thickness. That is, a non-ferrous metal that disperses a solid lubricant (eg, graphite) in a non-magnetic material, such as brass, or a synthetic resin such as Teflon, or ceramic powder particles is collided at a high speed using a thermal spray gun to cool instantly. The coating can be performed while the material to be coated is kept at a low temperature by a build-up spraying, for example, a high-speed gas flame spraying. Therefore, the surface of any member can be a high quality auxiliary bearing.

Next, FIG. 2 is a diagram showing a second embodiment of an auxiliary bearing structure of a single-shaft, two-stage high-speed motor-driven compressor according to the present invention. In the first embodiment of FIG. 1, the auxiliary bearing has a nonmagnetic material coated on the outer peripheral surface of the rotor shaft or a sleeve is fitted on the rotor shaft. On the other hand, in the second embodiment, as shown by a bold solid line in FIG. 2, the fixed side is attached to the inner peripheral surface of a casing (not shown), and has a gap with the outer peripheral surface of the rotor shaft 45 on the rotating side. The inner surface of the stator 33 having the stator portion 34 which is opposed to each other in the axial direction, and the inner surface of the thrust magnetic bearing 48, the radial magnetic bearing 49, and the displacement sensor 50 on the side of the rotor shaft (mother). Non-ferrous metals such as copper and aluminum, which are non-magnetic materials for coating,
Alternatively, a synthetic resin such as Teflon or ceramic powder is sprayed with a high-speed gas flame by a spray gun, and the surface of these members is used as an auxiliary bearing. In addition, although it takes time and effort for mounting, an auxiliary bearing can be formed by fitting a sleeve made of a non-magnetic material to these inner peripheral surfaces instead of the coating process. Thus, even when the fixed side has the auxiliary bearing structure, the same advantages and effects as those of the above-described rotating side are obtained.

Further, in addition to separately forming auxiliary bearings by coating or the like, such as the rotor shaft of the rotor on the rotating side, the impeller, or the stator on the non-rotating side, both the rotating side and the non-rotating side are used. Auxiliary bearings can also be formed by coating or the like. In this case, the production cost increases,
The effect as an auxiliary bearing is improved.

The present invention is not limited to the above-described embodiment. For example, an auxiliary bearing structure may not be applied to all members but may be applied to some members as appropriate, or may be applied to the shaft box. Of course, various modifications can be made without departing from the spirit of the present invention.

[0033]

According to the above-described auxiliary bearing structure of the high-speed motor driven compressor of the present invention, the length of the rotor shaft can be reduced, the stability of the rotating shaft can be improved, and the structure can be simplified. And has excellent effects such as facilitating manufacture and assembly.

[Brief description of the drawings]

FIG. 1 is a first embodiment showing an auxiliary bearing structure of a high-speed motor-driven compressor according to the present invention.

FIG. 2 is a diagram showing a second embodiment of the auxiliary bearing structure of the high-speed motor-driven compressor according to the present invention.

FIG. 3 is a schematic diagram showing a conventional auxiliary bearing for a magnetic bearing of a single-shaft, two-stage compressor.

[Explanation of symbols]

 1, 31 High-speed motor driven compressor 3, 33 Stator 4, 34 Stator section 5, 35 Stator core 6, 36 Stator winding 10, 40 1-stage impeller 11, 41 2-stage impeller 12, 42 Rotor 13, 43 rotor part 14,44 laminated iron core (rotor core) 15,45 rotor shaft 16,46 side face 17,21,47 shaft part 18,48 thrust magnetic bearing 19,49 radial magnetic bearing 20,50 displacement sensor 22 auxiliary bearing 51,52 Back

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Takahashi 2-1-1 Toyosu, Koto-ku, Tokyo Inside Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo First Plant (72) Inventor Takeshi Kuwata 2-1-1 Toyosu, Koto-ku, Tokyo No. 1 Ishikawajima Harima Heavy Industries Co., Ltd., Tokyo Daiichi Plant (72) Inventor Sonya Shuniya 2-1-1 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Tokyo Daiichi Plant F-term (reference) 3J102 AA01 BA03 CA19 DA09 FA06 FA13 FA22 5H607 AA11 BB01 BB14 BB26 CC01 DD01 DD02 DD03 DD09 DD16 DD19 FF07 FF13 GG01 GG03 GG09 GG21 GG29 HH01 HH05

Claims (5)

[Claims] A rotatable rotor (42) and a non-rotating stator (3) disposed to face the rotor with a predetermined gap therebetween.
3), a non-rotating thrust magnetic bearing (48) having a predetermined gap to control the displacement of the rotor in the thrust direction, and a non-rotating thrust magnetic bearing having a predetermined gap to control the radial displacement of the rotor. A rotating radial magnetic bearing (49) and a non-rotating displacement sensor (50) for observing displacement of the rotor, wherein the rotating side or the non-rotating side or both are auxiliary bearings. Auxiliary bearing structure for high-speed motor driven compressors. 2. The stepped rotor (42) has a rotor portion (43) formed by a rotor core (44) and a rotor conductor near a central portion, and has shaft portions (47) on both side surfaces of the rotor portion. A rotatable rotor shaft (45) having a shape,
2. The high-speed motor driven compressor according to claim 1, wherein the outer peripheral surface of the rotor shaft is coated with a non-magnetic material or a sleeve made of a non-magnetic material is fitted, and the rotor shaft itself is an auxiliary bearing. Auxiliary bearing structure. 3. The stator (33) is a stator plate and a stator core (35) made of laminated steel plates, and the inner peripheral surface of the steel plate is coated with a non-magnetic material or is made of a non-magnetic material. 2. The auxiliary bearing structure for a high-speed motor driven compressor according to claim 1, wherein said sleeve is fitted with said sleeve and said stator portion itself is an auxiliary bearing. 4. The auxiliary bearing structure for a high-speed motor driven compressor according to claim 1, wherein the coating of the non-magnetic material is performed by spraying a non-ferrous metal, a resin, or a ceramic. . 5. The compressor according to claim 1, wherein the compressor is a single-shaft, single-stage compressor or a single-shaft, two-stage compressor, and a non-magnetic material is thermally sprayed on a back surface of an impeller disposed at an axial end of a rotor shaft of a rotor. The auxiliary bearing structure for a high-speed motor-driven compressor according to claim 1 or 2, wherein: