JP2011185144A - Electric centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably prevent a bearing shaft during assembly from making contact with an elastic member that forms a base bearing and to perform an efficient heat discharge process. <P>SOLUTION: A rotating shaft unit forming an electric centrifugal compressor includes a bearing shaft 22. The bearing shaft 22 has one axial end face 22b on an edge side which is inserted into a foil-type gas bearing during assembly. A chamfered section 22c that is tilted radially outwards in an axial direction, that is, tilted radially outwards in a backward direction with respect to the axial direction, is formed on the outer periphery of the one axial end face 22b. A cross-sectional arcuate section 22d for preventing contact with the elastic member forming the gas bearing is joined to the largest-diameter trailing end of the chamfered section 22c. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric centrifugal compressor that supports a rotary shaft unit by a foil type gas bearing.

  In general, an electric centrifugal compressor is employed as a supercharger that efficiently supplies compressed air. For example, it is used as an auxiliary machine that supplies compressed air to an engine or as an auxiliary machine that supplies compressed air that is an oxidant gas to a fuel cell.

  In this type of centrifugal compressor, a rotor having a permanent magnet is provided on the inner peripheral side of an annularly arranged stator, and the rotor is energized by energizing the winding wound around the stator. It is configured to be rotated.

  In recent years, it has been desired to rotate the rotor at a high speed. At that time, gas bearings and magnetic bearings are employed as bearings for supporting a rotor that rotates at high speed, because rotational accuracy is obtained with a relatively simple configuration and wear is suppressed in a non-contact manner.

  For example, in the compressor disclosed in Patent Document 1, the shaft 1 is supported by a journal bearing 2 and a thrust bearing 3 as shown in FIG. The journal bearing 2 is an air-lubricated tilting pad journal bearing, and the tilting pad 4 is supported on a flexible pivot 5.

Japanese National Patent Publication No. 9-509999

  By the way, when assembling the above-described compressor, an operation of mounting the tilting pad 4 of the journal bearing 2 on the outer periphery of the shaft 1 is performed. Here, the tip 1 a of the shaft 1 is provided with a tapered surface 1 b. When the tip 1 a is inserted into the tilting pad 4, the taper angle portion 1 c of the tip 1 a is the tilting pad 4. Easy to touch. Accordingly, there is a problem that the tilting pad 4 is deformed or damaged.

  The present invention solves this type of problem, and it is possible to reliably prevent the bearing shaft from coming into contact with the elastic member constituting the gas bearing during assembly, and to perform an efficient heat discharge process. An object is to provide a compressor.

  The present invention relates to a rotor in which an outer periphery of an annular permanent magnet is covered with a protective ring, a bearing shaft provided at at least one of axial end portions of the rotor, and an axial end opposite to the rotor side of the bearing shaft A rotary shaft unit including an impeller provided in a section, a casing provided in the casing in which the rotary shaft unit is accommodated, a stator that faces the outer peripheral surface of the rotor, and a counter shaft that is provided facing the outer peripheral surface of the bearing shaft. The present invention relates to an electric centrifugal compressor including a gas bearing that holds the bearing shaft by an elastic member having an elastic force in a direction.

  The protective ring is provided on the end surface on which the bearing shaft is provided with a protruding portion that protrudes axially outward from the end surface of the permanent magnet, and the bearing shaft has an axial end surface that contacts the protruding portion, A chamfered portion that is inclined radially outward from the outer periphery of the one end surface in the axial direction toward the axial direction is formed, and an arcuate section is connected to the end portion of the maximum diameter of the chamfered portion.

  The impeller is preferably fitted coaxially to the axial end of the bearing shaft.

  Furthermore, it is preferable that the bearing shaft is coaxially fitted to the protrusion of the protective ring.

  In the present invention, a chamfered portion that is inclined radially outward from the outer periphery toward the axial direction is formed on one end surface in the axial direction of the bearing shaft, and an arcuate section is formed at the maximum diameter end portion of the chamfered portion. It is connected. That is, a chamfered portion that expands toward the rear in the insertion direction of the bearing shaft is provided on one end surface side in the axial direction, and the maximum diameter end portion of the chamfered portion is in contact with the elastic member that constitutes the gas bearing. An arcuate section is formed to prevent it.

  For this reason, when the bearing shaft is inserted into the gas bearing, it is possible to reliably prevent the elastic member constituting the gas bearing from being caught in the bearing shaft under the action of the chamfered portion and the arcuate section. .

  In addition, by providing the chamfered portion and the cross-section arc-shaped portion, for example, the cooling volume can be effectively expanded as compared with the case where the outer periphery of the one end surface is configured only by the cross-section arc-shaped portion. Thereby, the heat of the rotating shaft unit at the time of rotation can be discharged | emitted efficiently.

It is a section explanatory view of the electric centrifugal compressor concerning the embodiment of the present invention. It is principal part cross-sectional explanatory drawing of the said electric centrifugal compressor. It is principal part expansion explanatory drawing of the bearing shaft which comprises the said electric centrifugal compressor. FIG. 4 is a sectional view of the electric centrifugal compressor taken along line IV-IV in FIG. 2. It is a perspective explanatory view of a thrust air bearing constituting the electric centrifugal compressor. FIG. 6 is a cross-sectional explanatory view taken along the line VI-VI in FIG. 5 of the thrust air bearing. It is explanatory drawing at the time of inserting the said bearing shaft in a journal air bearing. It is principal part explanatory drawing of the compressor currently disclosed by patent document 1. FIG.

  As shown in FIG. 1, an electric centrifugal compressor (supercharger) 10 according to an embodiment of the present invention includes a casing 12. A rotating shaft unit 14 is rotatably mounted in the casing 12.

  As shown in FIGS. 1 and 2, the rotary shaft unit 14 is provided with an annular permanent magnet 16 and a cylindrical shape that is provided on the outer periphery of the permanent magnet 16 and accommodates (for example, shrink fit) the permanent magnet 16. The rotor 20 constituted by the protective ring 18, at least one of axial end portions of the rotor 20, in this embodiment, bearing shafts 22, 24 provided on both, opposite to the rotor 20 side of the bearing shaft 22 And an impeller 26 provided at an end portion in the axial direction.

  The impeller 26 constitutes a centrifugal compression part 28 and an end surface thereof abuts on the large diameter part 30 a of the tension shaft 30. On the tension shaft 30, the bearing shaft 22, the rotor 20, and the bearing shaft 24 are arranged in this order from the impeller 26 side, and these are integrally held by a fixing member 32 that is screwed into the tension shaft 30.

  The fixed member 32 is provided with a canceller mechanism 34 having a function of relieving a thrust force generated in the arrow A1 direction when the rotary shaft unit 14 rotates. As shown in FIG. 1, the canceller mechanism 34 includes a canceller disk 38 that is slidable in the direction of the arrow A within the pressurizing chamber 36. Air generated by the rotation of the impeller 26 flows into the pressurizing chamber 36 through the passage 40.

  An annular stator 42 is mounted in the casing 12 so as to be positioned on the outer periphery of the rotor 20. The stator 42 and the rotor 20 constitute a motor unit 46.

  The protection ring 18 constituting the rotor 20 is required to have high rigidity and is made of a nickel-based superalloy, for example, Inconel (trade name of Special Metal). A plurality of cooling water flow paths 48 are formed around the outer periphery of the stator 42.

  As shown in FIG. 2, the protection ring 18 is provided with cylindrical protrusions 18 a and 18 b protruding outward in the axial direction from the end surfaces 16 a and 16 b of the permanent magnet 16 on the end surfaces where the bearing shafts 22 and 24 are provided.

  The bearing shaft 22 has a cylindrical portion 22a opened at the end in the arrow A1 direction that is the end in the axial direction, and one end surface in the axial direction that protrudes radially inward at the end in the arrow A2 direction (one end in the axial direction). 22b is formed. Similarly, the bearing shaft 24 has a cylindrical portion 24a opened at the end in the axial arrow A2 direction, and has an axial end surface 24b protruding radially inward at the end in the arrow A1 direction.

  One end surface 22b in the axial direction of the bearing shaft 22 is in contact with one cylindrical projection 18a of the protection ring 18, and one end surface 24b in the axial direction of the bearing shaft 24 is in contact with the other cylindrical projection 18b of the protection ring 18. Contact. The axial end surfaces 22b and 24b and the end surfaces 16a and 16b of the permanent magnet 16 are separated from each other by distances S1 and S2, respectively.

  As shown in FIG. 3, the bearing shaft 22 is formed with a chamfered portion 22c that is inclined radially outward (arrow B1 direction) from the outer periphery of the axial end face 22b toward the axial direction (arrow A1 direction). An R-shaped cross-section arc-shaped portion 22d is integrally connected to the maximum diameter end portion of the chamfered portion 22c. That is, a chamfered portion 22c whose diameter increases toward the rear in the insertion direction of the bearing shaft 22 is provided on the one end surface 22b side in the axial direction, and an elastic force in the radial direction is applied to the maximum diameter end portion of the chamfered portion 22c. An arcuate section 22d is formed to prevent the top foil 60, which is an elastic member, from being caught.

  The bearing shaft 24 is configured in the same manner as the bearing shaft 22 described above, and a detailed description thereof is omitted.

  As shown in FIGS. 1 and 2, a foil type gas bearing 50 that faces the outer peripheral surfaces of the bearing shafts 22 and 24 and holds the bearing shafts 22 and 24 is provided. The foil type gas bearing 50 includes journal air bearings 52 a and 52 b that hold the radial positions of the bearing shafts 22 and 24, and a thrust air bearing 54 that holds the axial position of the bearing shaft 22.

  The bearing shafts 22 and 24 constitute journal air bearings 52a and 52b, and are made of, for example, a nickel-based superalloy that is the same material as the protective ring 18. Each of the journal air bearings 52a and 52b includes ring members 56A and 56B that are arranged with a predetermined gap around the outer periphery of the bearing shafts 22 and 24. The ring members 56A and 56B rotatably support the bearing shafts 22 and 24 and are fixed so as not to rotate.

  As shown in FIG. 4, a corrugated bump foil 58 and a flat top foil 60 are arranged in this order on the inner peripheral surface 56a of the ring member 56A. The bump foil 58 is composed of one sheet or a plurality of sheets. One end 58a of the bump foil 58 is welded to the inner peripheral surface 56a of the ring member 56A, and the other end forms a free end. The top foil 60 has a flat plate curved in an annular shape, and one end 60a is welded to the inner peripheral surface 56a of the ring member 56A, while the other end is a free end. The ring member 56B is configured similarly to the ring member 56A described above.

  As shown in FIGS. 1 and 2, a large-diameter flange portion 62 constituting a thrust air bearing 54 is provided on the outer peripheral portion of the bearing shaft 22. Ring members 64a and 64b are arranged on both sides in the axial direction across the large-diameter flange portion 62.

  As shown in FIG. 5, the ring members 64 a and 64 b are provided with a corrugated bump foil 66 and a flat top foil 68 on the surfaces facing the large-diameter flange portion 62. A plurality of the bump foil 66 and the top foil 68 are arranged in an annular shape around the inner peripheral surfaces of the ring members 64a and 64b.

  As shown in FIG. 6, each bump foil 66 has one end 66a welded to the ring members 64a and 64b and the other end 66b constituting a free end. Each top foil 68 has one end 68a welded to the ring members 64a and 64b, while the other end 68b is a free end.

  As shown in FIG. 2, the axial end portion 26 a of the impeller 26 is fitted coaxially to the cylindrical portion 22 a of the bearing shaft 22 (inlay structure). The bearing shafts 22 and 24 have axial end surfaces 22b and 24b coaxially fitted to the cylindrical protrusions 18a and 18b of the protective ring 18 (inlay structure).

  In the casing 12, as shown in FIG. 1, a refrigerant flow passage 70 is formed between the protective ring 18 constituting the motor unit 46 and the stator 42. The inlet side of the flow passage 70 and the passage 40 of the canceller mechanism 34 communicate with the compressor outlet 72 of the centrifugal compressor 28. The air compressed by the rotation of the impeller 26 is blown from the compressor outlet 72 to the inlet side of the flow passage 70 and the passage 40 of the canceller mechanism 34.

  The operation of the electric centrifugal compressor 10 configured as described above will be described below.

  First, by energizing the stator 42 constituting the electric motor, the permanent magnet 16 and the protective ring 18 constituting the rotor 20 rotate integrally with the tension shaft 30. For this reason, the impeller 26 held by the tension shaft 30 rotates at a relatively high speed, and air is sucked from the atmosphere via the centrifugal compressor 28.

  The air sucked by the impeller 26 is pumped by the centrifugal compressor 28 and is sent to, for example, an oxidant gas supply system of a fuel cell (not shown). Fuel gas (hydrogen gas) is supplied to the fuel cell from a fuel gas supply system (not shown). Therefore, power generation is performed by a reaction between air supplied to the cathode side and hydrogen supplied to the anode side.

  A part of the air sucked by the centrifugal compressor 28 is compressed and supplied from the compressor outlet 72 to the flow passage 70 in the casing 12. The cooling air that passes through the flow passage 70 and cools the motor unit 46 is discharged to the outside.

  A part of the air sucked by the centrifugal compressor 28 is compressed and supplied from the compressor outlet 72 to the pressurizing chamber 36 through the passage 40 constituting the canceller mechanism 34. Accordingly, a pressing force is applied to the canceller disk 38 disposed in the pressurizing chamber 36 in a direction away from the impeller 26 (arrow A2 direction). Thereby, the thrust force acting in the direction of the arrow A <b> 1 by the rotation of the impeller 26 is alleviated by the canceller mechanism 34.

  By the way, when the electric centrifugal compressor 10 is assembled, the bearing shaft 22 has an axial end surface 22b of the bearing shaft 22 on the inner surface side of the top foil 60 constituting the journal air bearing 52a, as shown in FIG. Inserted.

  In this case, in the present embodiment, a chamfered portion 22c that increases in diameter toward the rear in the insertion direction of the bearing shaft 22 is provided on the one axial end surface 22b of the bearing shaft 22, and the maximum diameter end of the chamfered portion 22c. A circular arc-shaped portion 22d for preventing contact with the top foil 60 is formed in the portion.

  Therefore, it is possible to reliably prevent the top foil 60 from being caught in the bearing shaft 22 under the action of the chamfered portion 22c and the circular arc-shaped portion 22d.

  In particular, when only the chamfered portion 22c is provided and the corner portion E is formed at the maximum diameter end portion of the chamfered portion 22c, the top foil 60 is caught by the corner portion E, and the top foil 60 is deformed. There is a risk that. On the other hand, in the present embodiment, the cross-section arc-shaped portion 22d is connected to the maximum diameter end portion of the chamfered portion 22c, and the top foil 60 can be prevented from being caught as much as possible.

  In addition, a chamfered portion 22c and a cross-sectional arc-shaped portion 22d are provided on one end surface 22b in the axial direction of the bearing shaft 22. For this reason, for example, as shown in FIG. 7, the cooling volume can be expanded to the region S as compared with the case where the outer periphery of the one end surface is configured only by the arcuate section. Thereby, the heat of the rotating shaft unit 14 at the time of rotation can be discharged | emitted efficiently.

  In addition, in this embodiment, although the foil type gas bearing 50 is used as a gas bearing, it is not limited to this. As an elastic member having an elastic force in the radial direction, for example, it can be satisfactorily applied to an air-lubricated tilting pad journal bearing provided with a tilting pad.

DESCRIPTION OF SYMBOLS 10 ... Electric centrifugal compressor 12 ... Casing 14 ... Rotary shaft unit 16 ... Permanent magnet 16a, 16b ... End surface 18 ... Protection ring 18a, 18b ... Cylindrical protrusion 20 ... Rotor 22, 24 ... Bearing shaft 22a, 24a ... Cylindrical shape Part 22b, 24b ... One end surface in the axial direction 22c ... Chamfered part 22d ... Arc section 26 ... Impeller 30 ... Tension shaft 32 ... Fixing member 34 ... Canceller mechanism 36 ... Pressure chamber 38 ... Canceller disk 40 ... Passage 42 ... Stator 46 ... Motor 50 ... Foil type gas bearings 52a, 52b ... Journal air bearing 54 ... Thrust air bearings 56A, 56B ... Ring member 56a ... Inner peripheral surface 58, 66 ... Bump foils 60, 68 ... Top foil 70 ... Flow passage

Claims (3)

A rotor whose outer periphery of an annular permanent magnet is covered with a protective ring, a bearing shaft provided at at least one of axial ends of the rotor, and an axial end opposite to the rotor side of the bearing shaft A rotary shaft unit equipped with an impeller, and
A stator provided in a casing in which the rotating shaft unit is accommodated, and facing an outer peripheral surface of the rotor;
A gas bearing that is provided opposite to the outer peripheral surface of the bearing shaft and holds the bearing shaft by an elastic member having an elastic force in a radial direction;
An electric centrifugal compressor comprising:
The protective ring is provided on the end surface on which the bearing shaft is provided with a protruding portion that protrudes axially outward from the end surface of the permanent magnet,
The bearing shaft has an axial end surface that contacts the protrusion, a chamfered portion that is inclined radially outward from the outer periphery of the axial end surface toward the axial direction is formed, and the chamfered portion An electric centrifugal compressor characterized in that an arcuate section is connected to the end portion of the maximum diameter.   The electric centrifugal compressor according to claim 1, wherein the impeller is coaxially fitted to the axial end portion of the bearing shaft.   The electric centrifugal compressor according to claim 1 or 2, wherein the bearing shaft is coaxially fitted to the protrusion of the protective ring.

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