JP2018080587A - Electric supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric supercharger capable of preventing an outer race from sticking to a holding member. A first bearing (20) has an inner race (21) that rotates together with a shaft (12) and an outer race (23) that faces the inner race (21). The electric supercharger 1 further has a coil spring 25 that urges the outer race 23 of the bearing 20 in the direction of the rotation axis of the shaft 12, and a part of the outer peripheral surface 23a of the outer race 23 comes into contact with the holding member 51. The first bearing 20 is held by the holding member 51 in a state where the other portion of the outer peripheral surface 23a of the outer race 23 is separated from the holding member 51. [Selection diagram] Fig. 1

Description

  The present invention relates to an electric supercharger.

  As a conventional electric supercharger, for example, one disclosed in JP2013-24059A (Patent Document 1) is known.

JP2013-24059A

  Patent Document 1 discloses a structure in which a ball bearing is held by a cylindrical large-diameter sleeve.

  Of the pair of bearings that support the turbocharger shaft, the bearing on the side to which preload is applied has the outer race of the bearing held by the holding member with a clearance fit, and there is a slight gap between the outer race and the holding member. Clearance is provided. The outer race can be rotated relative to the holding member.

  In the conventional structure in which the outer ring of the bearing is held by a cylindrical sleeve, powder generated by wear may enter between the outer race and the sleeve.

  This powder has a problem that the outer race is fixed and cannot move in the direction of the rotation axis, and an appropriate preload cannot be applied.

  Accordingly, the present invention has been made to solve the above problems, and an object thereof is to provide an electric supercharger capable of improving the performance and durability of a bearing by applying an appropriate preload. To do.

  An electric supercharger according to the present invention includes a shaft provided with a compressor wheel, a motor that rotationally drives the shaft, a bearing that rotatably holds the shaft, a holding member that contacts the bearing and holds the bearing, The bearing has an inner race that rotates with the shaft and an outer race that faces the inner race, and the fit between the outer race and the holding member is a loose fit The electric supercharger further includes biasing means for biasing the outer race of the bearing in the direction of the rotation axis of the shaft, a part of the outer peripheral surface of the outer race is in contact with the holding member, and the outer periphery of the outer race The bearing is held by the holding member with the other part of the surface being separated from the holding member.

  In the electric supercharger configured as described above, a part of the outer peripheral surface of the outer race is held in contact with the holding member, and the other part of the outer peripheral surface of the outer race is separated from the holding member. Even if the powder enters between the outer peripheral surface and the holding member, the powder moves to a portion of the outer peripheral portion that is separated from the holding member, so that the outer peripheral surface can be prevented from adhering to the holding member. As a result, an appropriate preload can be applied.

  Preferably, the holding part further includes a first holding part, a second holding part, and a third holding part that contact the outer peripheral surface of the outer race to hold the outer race, and the first holding part, the second holding part, and the first holding part The three holding portions are provided at a distance from each other. In this case, the outer peripheral surface can be stably held by the first to third holding portions.

  Preferably, the first to third holding portions are in line contact with the outer peripheral surface of the bearing. In this case, since it is a line contact, a contact area can be made small compared with a surface contact. As a result, it is possible to further prevent the outer peripheral surface from adhering to the holding member.

  Preferably, the first to third holding portions have a cylindrical or columnar shape, and the outer peripheral surface of the cylinder or the column and the outer peripheral surface of the outer race are in contact with each other. In this case, since the contact area between the first to third holding portions and the outer race becomes small, the outer race can easily slide with respect to the first to third holding portions.

  Preferably, the holding member has a cylindrical cylindrical portion, and the cylindrical portion includes a contact area that contacts the outer peripheral surface of the outer race on the inner peripheral surface.

  Preferably, the cylindrical portion further includes a non-contact region separated from the outer peripheral surface of the outer race on the inner peripheral surface, and the contact region of the cylindrical portion is at least a first holding region that makes a line contact with the outer race, The first holding area, the second holding area, and the third holding area are provided separately from each other along the circumferential direction of the outer race.

  Preferably, the cylindrical portion has a cylindrical shape, and the cylindrical portion is provided with a plurality of openings penetrating in the thickness direction of the cylindrical portion.

  According to this invention, it is possible to prevent the outer race from adhering to the holding member and to apply an appropriate preload to the outer race.

1 is a cross-sectional view of an electric supercharger according to a first embodiment. FIG. 3 is a perspective view of a holding member used in the electric supercharger according to the first embodiment. FIG. 3 is a perspective view of a holding member and a bearing held by the holding member according to the first embodiment. FIG. 3 is a perspective view of a holding member and a bearing and a shaft held by the holding member according to the first embodiment. FIG. 10 is a front view of a holding member having first to fourth holding portions according to the second embodiment. FIG. 10 is a front view of a holding member having a cylindrical holding portion according to a third embodiment. It is a front view of the holding member which has a cylindrical holding part according to Embodiment 4. FIG. 10 is a perspective view of a holding member having a cylindrical holding portion according to a fifth embodiment. It is sectional drawing along the IX-IX line in FIG.

  Hereinafter, an electric supercharger according to each embodiment of the present invention will be described with reference to the drawings. In the following description, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
(Constitution)
FIG. 1 is a cross-sectional view of the electric supercharger according to the first embodiment. FIG. 2 is a perspective view of a holding member used in the electric supercharger according to the first embodiment. As shown in FIGS. 1 and 2, the electric supercharger 1 has a housing 11 that houses a motor 15 therein. For example, the electric supercharger is arranged in an intake path of an internal combustion engine such as a gasoline engine or a diesel engine to supercharge intake air. Examples of the internal combustion engine include a reciprocating engine, a rotary engine, a gas turbine engine, and a jet engine.

  The motor 15 includes a rotor 13 fixed to the shaft 12 and a stator 14 disposed to face the rotor 13. When electric power is supplied to the motor 15 via a power source and an inverter (not shown), the motor 15 converts the electric power into a rotational force and applies the rotational force to the shaft 12. That is, the motor 15 drives the shaft 12 to rotate.

  The shaft 12 extends from one end to the other end. One end side of the shaft 12 is rotatably held by the first bearing 20. The other end is rotatably held by the second bearing 120. The shaft 12 has a step shape and has different outer diameters at different locations. The shaft 12 has a shape in which a plurality of cylinders having different outer diameters are connected. The outer diameter of the shaft 12 may be constant. The 1st bearing 20 is a bearing which comprises the electric supercharger 1 of this invention.

  A rotor 13 is fixed to the thickest part of the shaft 12. When motor 15 is a three-phase AC motor, rotor 13 has a core and a permanent magnet embedded in the core.

  A first bearing 20 and a second bearing 120 that hold the shaft 12 are provided on both sides of the rotor 13. Rolling bearings such as ball bearings and roller bearings are used for the first bearing 20 and the second bearing 120. In this embodiment, it is a ball bearing. The first bearing 20 and the second bearing 120 include inner races 21 and 121 that are attached to the shaft 12 by press-fitting or interference fitting, outer races 23 and 123 that face the inner races 21 and 121, and inner races 21 and 121. Rolling elements (balls in this embodiment) 22 and 122 interposed between the outer races 23 and 123, and a cage for holding the rolling elements.

  A compressor wheel 31 is provided at the other end of the shaft 12 so as to be rotatable integrally with the shaft 12. The compressor wheel 31 is a wheel for compressing intake air (intake gas). The intake air sucked from the axial center side of the compressor wheel 31 is compressed as the compressor wheel 31 rotates, and the compressed intake air is discharged toward the outer periphery of the compressor wheel 31.

  Between the compressor wheel 31 and the housing 11, there is provided a plate 34 that constitutes a diffuser passage for guiding intake air discharged from the compressor wheel 31 to the scroll passage. The plate 34 is located on the back side of the compressor wheel 31. The shaft 12 is provided so as to penetrate the hole formed in the plate 34.

  The first housing 30 is provided so as to cover the compressor wheel 31. The first housing 30 has an intake inlet 39 and a scroll passage 35. Air or exhaust gas recirculation (EGR) gas introduced from the intake inlet 39 is compressed by the compressor wheel 31 and sent to the scroll passage 35. The first housing 30 and the plate 34 constitute a compressor housing that houses the compressor wheel 31.

  An end plate 151 is fixed to the housing 11. A holding member 51 including a first holding portion 52a, a second holding portion 52b, and a third holding portion 52c is attached and fixed to the surface of the end plate 151 facing the motor 15 with a predetermined interval therebetween. Yes. The first bearing 20 is held by a first holding portion 52a, a second holding portion 52b, and a third holding portion 52c that are in contact with the outer peripheral surface of the outer race 23. A ring member 24 is in contact with the thrust surface of the outer race 23 of the first bearing 20. A lid member 28 is fixed to the end plate 151 with bolts 28a. A coil spring 25 is disposed between the lid member 28 and the ring member 24 in a compressed state.

  The coil spring 25 biases the ring member 24 in the axial direction. For this reason, the ring member 24 biases the outer race 23 in the axial direction. That is, the coil spring 25 biases the outer race 23 of the first bearing 20 toward the compressor wheel 31 via the ring member 24. Thereby, a preload is applied to the first bearing 20.

  The first holding part 52a, the second holding part 52b, and the third holding part 52c attached to the end plate 151 are cylindrical members. The first holding part 52a, the second holding part 52b, and the third holding part 52c are provided around the through hole 59 at equal intervals. In addition, the distance between the 1st holding | maintenance part 52a, the 2nd holding | maintenance part 52b, and the 3rd holding | maintenance part 52c may be uneven. The first holding part 52a, the second holding part 52b, and the third holding part 52c may be cylindrical members.

  FIG. 3 is a perspective view of the holding member and the bearing held by the holding member according to the first embodiment. FIG. 4 is a perspective view of the holding member and the bearing and shaft held by the holding member according to the first embodiment. As shown in FIGS. 3 and 4, the outer peripheral surface 23a of the cylindrical outer race 23 of the first bearing 20 is in line contact with the first holding portion 52a, the second holding portion 52b, and the third holding portion 52c. In the contact regions 152a, 152b, and 152c, contact lines between the first holding portion 52a, the second holding portion 52b, the third holding portion 52c, and the outer peripheral surface 23a extend in parallel with the shaft 12. The outer peripheral surface 23a of the cylindrical outer race 23 of the first bearing 20 may be in surface contact with the first holding portion 52a, the second holding portion 52b, and the third holding portion 52c. Between the contact regions 152a, 152b, 152c, the outer peripheral surface 23a is exposed from the first holding part 52a, the second holding part 52b, and the third holding part 52c. That is, a part of the outer peripheral surface 23 a of the outer race 23 is held in contact with the first holding part 52 a, the second holding part 52 b, and the third holding part 52 c which are part of the holding member 51. The other part of the surface 23 a is separated from the holding member 51.

  The electric supercharger 1 is in contact with the shaft 12 on which the compressor wheel 31 is provided, the motor 15 that rotationally drives the shaft 12, the first bearing 20 that rotatably holds the shaft 12, and the first bearing 20. A holding member 51 that holds one bearing 20. The first bearing 20 has an inner race 21 that rotates together with the shaft 12 and an outer race 23 that faces the inner race 21, and the fit between the outer race 23 and the holding member 51 is a clearance fit. The supercharger 1 further includes a coil spring 25 as an urging means for urging the outer race of the first bearing 20 in the rotation axis direction of the shaft 12, and a part of the outer peripheral surface 23 a of the outer race 23 is a holding member 51. The first bearing 20 is held by the holding member 51 in a state in which the other portion of the outer peripheral surface 23 a of the outer race 23 is separated from the holding member 51. The holding member 51 further includes a first holding portion 52a, a second holding portion 52b, and a third holding portion 52c that are in contact with the outer peripheral surface 23a of the outer race 23 and hold the outer race 23. The two holding parts 52b and the third holding part 52c are provided at a distance from each other. The first holding portion 52a, the second holding portion 52b, and the third holding portion 52c are in line contact with the outer peripheral surface 23a of the outer race 23. The first holding part 52a, the second holding part 52b, and the third holding part 52c are cylindrical or columnar, and the outer peripheral surface of the cylinder or column and the outer peripheral surface 23a of the outer race 23 are in contact with each other.

(Operation and effect)
In a state where supercharging is required, electric power is supplied to the motor 15. As the rotor 13 rotates the shaft 12, the compressor wheel 31 rotates. The gas introduced from the intake inlet 39 is supercharged by the compressor wheel 31 and sent to the scroll passage 35.

  As the shaft 12 rotates, the inner race 21 also rotates. As the inner race 21 rotates, the ball 22 revolves while rotating. The outer race 23 in contact with the ball 22 receives a force (rotational force) from the revolution of the ball 22. When this rotational force becomes larger than the frictional force between the outer peripheral surface 23a of the outer race 23 and the contact areas 152a, 152b, 152c, the outer race 23 is moved to the first holding portion 52a, the second holding portion 52b, and the third holding portion 52c. Rotate against. With wear due to rotation, the outer race 23 and any one of the first holding portion 52a, the second holding portion 52b, and the third holding portion 52c may be worn and wear powder may be generated. However, the outer peripheral surface 23a is exposed from the first holding part 52a, the second holding part 52b, and the third holding part 52c between a certain contact area 152a, 152b, 152c and another contact area 152a, 152b, 152c. Therefore, the powder is easily discharged to the outside. As a result, it is possible to prevent powder from entering between the outer race 23 and the first holding portion 52a, the second holding portion 52b, and the third holding portion 52c of the holding member 51. Therefore, the outer race 23 does not adhere to the first holding portion 52a, the second holding portion 52b, and the third holding portion 52c, and it is possible to continue to apply an appropriate preload to the outer race 23 by the coil spring 25. As a result, the performance and durability of the first bearing 20 can be improved. Furthermore, since the outer peripheral surface 23a of the outer race 23 and the first holding part 52a, the second holding part 52b, and the third holding part 52c are in line contact, the contact area is reduced and the sliding resistance is reduced.

(Embodiment 2)
FIG. 5 is a front view of a holding member having first to fourth holding portions according to the second embodiment. As shown in FIG. 5, the holding member 51 has a first holding part 52a, a second holding part 52b, a third holding part 52c, and a fourth holding part 52d. The first holding part 52a, the second holding part 52b, the third holding part 52c, and the fourth holding part 52d are arranged at equal intervals on the circumference. In this embodiment, the number of holding units is four, but a larger number of holding units may be provided. The first holding portion 52a, the second holding portion 52b, the third holding portion 52c, the fourth holding portion 52d, and the outer peripheral surface 23a of the outer race 23 are in line contact with each other through the contact regions 152a, 152b, 152c, and 152d.

  The electric supercharger according to the second embodiment configured as described above has the same effect as the electric supercharger according to the first embodiment.

(Embodiment 3)
FIG. 6 is a front view of a holding member having a cylindrical holding portion according to the third embodiment. As shown in FIG. 6, a rectangular cylindrical holding member 53 is attached to the end plate 151. The rectangular holding member 53 contacts the outer peripheral surface 23a of the outer race 23 of the bearing at four locations. In the contact regions 153a, 153b, 153c, and 153d, the linear holding member 53 and the curved outer peripheral surface 23a are in line contact. The holding member 53 has a cylindrical cylindrical portion, and the cylindrical portion includes contact areas 153a, 153b, 153c, and 153d that contact the outer peripheral surface 23a of the outer race 23 on the inner peripheral surface. The cylindrical portion further includes a non-contact region 153e separated from the outer peripheral surface 23a of the outer race 23 on the inner peripheral surface, and the contact region of the cylindrical portion is at least as a first holding region that makes line contact with the outer race. A contact region 153a, a contact region 153b as a second holding region, and a contact region 153c as a third holding region, and the first holding region, the second holding region, and the third holding region are each of the outer race 23; They are spaced apart along the circumferential direction.

  With wear due to rotation of the outer race 23, either the outer race 23 or the holding member 53 may be worn and powder may be generated. However, in the non-contact area 153e between one contact area 153a, 153b, 153c, 153d and the other contact area 153a, 153b, 153c, 153d, the outer peripheral surface 23a is not in contact with the holding member 53. It collects at the corner of the member 53. As a result, powder can be prevented from entering the contact portion between the outer race 23 and the holding member 53. Therefore, the outer race 23 does not adhere to the holding member 53.

(Embodiment 4)
FIG. 7 is a front view of a holding member having a cylindrical holding portion according to the fourth embodiment. As shown in FIG. 7, a round cylindrical holding member 54 is provided. The circular holding member 54 has a first holding part 55a, a second holding part 55b, and a third holding part 55c.

  In the contact regions 155a, 155b, and 155c, the outer peripheral surface 23a of the outer race 23 of the bearing and the first holding portion 55a, the second holding portion 55b, and the third holding portion 55c are in contact with each other at three locations. In the contact regions 155a, 155b, and 155c, the curved first holding portion 55a, the second holding portion 55b, the third holding portion 55c, and the curved outer peripheral surface 23a are in line contact. The holding member 54 is cylindrical, and the inner peripheral surface of the cylinder holds the outer peripheral surface 23 a of the outer race 23. First to third holding portions 55a, 55b, and 55c that are in line contact with the outer race 23 are provided on the inner peripheral surface of the cylinder.

  As the outer race 23 wears due to rotation, the outer race 23 and any one of the first holding portion 55a, the second holding portion 55b, and the third holding portion 55c may be worn to generate powder. However, the outer peripheral surface 23a is not in contact with the first holding part 55a, the second holding part 55b, and the third holding part 55c between a certain contact area 155a, 155b, 155c and another contact area 155a, 155b, 155c. Therefore, the powder accumulates between the first holding part 55a, the second holding part 55b, and the third holding part 55c. As a result, powder can be prevented from entering the contact portions of the outer race 23 and the first holding portion 55a, the second holding portion 55b, and the third holding portion 55c of the holding member 51. Therefore, the outer race 23 does not adhere to the first holding part 55a, the second holding part 55b, and the third holding part 55c.

(Embodiment 5)
FIG. 8 is a perspective view of a holding member having a cylindrical holding portion according to the fifth embodiment. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. As shown in FIGS. 8 and 9, the holding member 54 according to the fifth embodiment has a cylindrical shape. The cylindrical holding member 54 contacts the outer peripheral surface 23a of the outer race 23 of the bearing at four locations. In the contact regions 154a, 154b, 154c, and 154d, the curved first holding portion 54a, the second holding portion 54b, the third holding portion 54c, the fourth holding portion 54d, and the curved outer peripheral surface 23a are in surface contact. Yes.

  An opening 56 is provided on the outer peripheral surface of the cylindrical holding member 54. The cylindrical holding member 54 constituting the tube portion is provided with a plurality of openings 56 penetrating in the thickness direction of the tube portion. The number of openings 56 may be one or more. The opening 56 penetrates the holding member 54 in the thickness direction. Therefore, the powder adhered to the outer peripheral surface 23a is discharged from the opening 56 to the outside.

  As the outer race 23 rotates, the outer race 23 and any one of the first holding portion 54a, the second holding portion 54b, the third holding portion 54c, and the fourth holding portion 54d may wear and generate powder. . However, between one contact area 154a, 154b, 154c, 154d and another contact area 154a, 154b, 154c, 154d, the outer peripheral surface 23a is a first holding part 54a, a second holding part 54b, a third holding part 54c, Since it is not in contact with the fourth holding portion 54 d and is exposed through the opening 56, the powder is discharged from the opening 56. As a result, it is possible to prevent powder from entering the contact portion between the outer race 23 and the holding member 54. Therefore, the outer race 23 does not adhere to the holding member 54.

  Although the embodiment has been described above, the above disclosure is illustrative in all respects and is not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be used, for example, in the field of electric superchargers mounted on vehicles.

  DESCRIPTION OF SYMBOLS 1 Electric supercharger, 11 Housing, 12 Shaft, 13 Rotor, 14 Stator, 15 Motor, 20 1st bearing, 21,121 Inner race, 22,122 Ball, 23,123 Outer race, 23a Outer surface, 24 Ring member , 25 coil spring, 28 sealing member, 28a, 34a bolt, 30 compressor housing, 31 compressor wheel, 34 plate, 35 scroll passage, 39 intake inlet, 51, 53, 54 holding member, 52a, 54a, 55a first holding Part, 52b, 54b, 55b second holding part, 52c, 54c, 55c third holding part, 52d, 54d fourth holding part, 56 opening, 59 through hole, 120 second bearing, 151 end plate, 152a, 152b, 152c, 152d, 1 53a, 153b, 153c, 153d, 154a, 154b, 154c, 154d, 155a, 155b, 155c Contact area.

Claims (7)

A shaft provided with a compressor wheel;
A motor for rotationally driving the shaft;
A bearing for rotatably holding the shaft;
An electric supercharger comprising: a holding member that contacts the bearing and holds the bearing;
The bearing has an inner race that rotates together with the shaft, and an outer race that faces the inner race, and the outer race and the holding member are fitted with a clearance fit.
The electric supercharger further includes biasing means for biasing the outer race of the bearing in the rotation axis direction of the shaft,
In a state where a part of the outer peripheral surface of the outer race is in contact with the holding member and the other part of the outer peripheral surface of the outer race is separated from the holding member, the bearing is held by the holding member. Electric supercharger.   The holding member further includes a first holding part, a second holding part, and a third holding part that contact the outer peripheral surface of the outer race to hold the outer race, and the first holding part and the second holding part The electric supercharger according to claim 1, wherein the third holding portion is provided at a distance from each other.   The electric supercharger according to claim 2, wherein the first to third holding portions are in line contact with an outer peripheral surface of the outer race.   The electric supercharger according to claim 2 or 3, wherein the first to third holding portions have a cylindrical or columnar shape, and an outer peripheral surface of the cylinder or column and an outer peripheral surface of the outer race are in contact with each other.   2. The electric supercharging according to claim 1, wherein the holding member has a cylindrical cylindrical portion, and the cylindrical portion includes a contact area that contacts an outer peripheral surface of the outer race on an inner peripheral surface. Machine.   The cylindrical portion further includes a non-contact region separated from the outer peripheral surface of the outer race on the inner peripheral surface, and the contact region of the cylindrical portion is at least a first holding region that is in line contact with the outer race. The second holding area and the third holding area, and the first holding area, the second holding area, and the third holding area are provided apart from each other along the circumferential direction of the outer race. The electric supercharger according to claim 5.   The electric supercharger according to claim 5, wherein the cylindrical portion has a cylindrical shape, and the cylindrical portion is provided with a plurality of openings penetrating in the thickness direction of the cylindrical portion.

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