JP2015070751A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive member on which stress concentration due to torsional torque generated by a rotational shaft contacting the conductive member is reduced, the life of which as the components is prolonged as a result, and to provided an electric motor using the conductive member.SOLUTION: A conductive member 60, which electrically conducts an inner ring 401 and an outer ring 402 of a bearing 42 to each other, comprises: a contact portion 61 that contacts a center of an output rotary shaft 31 journaled by the inner ring 401; a holding portion 62 that is mounted in the outer ring 402, and surrounds the contact portion 61 while being apart from it at an axial-direction opposite side of the output rotary shaft 31; a connection portion 63 that extends in a curved manner, at an angle (a rotation direction angle θ) formed by a solid line R relative to a dotted line R', from an outer peripheral edge 61E of the contact portion 61 to an inner peripheral edge 62E of the holding portion 62 and holds the contact portion 61 horizontally.

Description

  The present invention relates to an electric motor.

  A potential difference is generated between the inner ring and the outer ring of the ball bearing that supports the rotating shaft of the electric motor due to the presence of a non-conductive substance such as grease. Due to this potential difference, electric discharge is generated between the inner ring and the outer ring, and electrolytic corrosion marks are generated on the ball and the rolling surface. The electric corrosion mark inhibits the rotation of the ball and reduces the performance of the ball bearing. There is known a conducting member that electrically connects a rotating shaft supported by an inner ring of a ball bearing and an outer ring of the ball bearing to reduce a potential difference between the inner ring and the outer ring of the ball bearing (for example, patents). Reference 1 and Patent Document 2).

JP 2002-139056 A JP 2003-92850 A

  An object of the present invention is to provide a conducting member in which stress concentration on the conducting member due to a torsional torque generated by a rotating shaft in contact with the conducting member is reduced, and a component life is further extended, and an electric motor using the conducting member.

  In order to solve the above problems, an electric motor of the present invention includes a rotating shaft made of a conductive material, an outer ring and an inner ring made of a conductive material, a bearing that supports the rotating shaft with the inner ring, and the outer ring. An electric motor comprising a bracket made of a conductive material in which a bearing house is formed, and a conductive member that is disposed between the rotating shaft and the bracket and connects the inner ring and the outer ring of the bearing, The conducting member includes a contact portion that contacts an end surface of the rotating shaft, a connecting portion that extends radially from the contact portion, and an annular holding portion that is connected to the connecting portion, and the rotation direction of the rotating shaft Is a line connecting the contact portion side end of the connecting portion and the center of the holding portion with respect to a line segment connecting the holding portion side end portion of the connecting portion and the center of the holding portion. The angle between the minutes has a positive angle .

  According to the electric motor of the present invention, it is possible to obtain an electric motor using a conductive member in which stress concentration due to torsion torque generated by a rotating shaft that contacts the conductive member is reduced, and the life of the component is further extended.

It is a schematic sectional drawing of the mold motor in embodiment. (A) of the conduction | electrical_connection member in embodiment is a top view, (b) is a side view. (A) of the conduction | electrical_connection member in other embodiment is a top view, (b) is a side view. (A) of the conduction | electrical_connection member in the modification 1 is a top view, (b) is a side view. (A) of the conduction | electrical_connection member in the modification 2 is a top view, (b) is a side view. (A) of the conduction | electrical_connection member in a comparative example is a top view, (b) is a side view.

  Hereinafter, a molded motor 100 as an example of an electric motor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view of a molded motor 100.

(First embodiment)
In FIG. 1, a molded motor 100 includes a stator core 10, an outer shell 20, a rotor 30, an output rotation shaft 31 that is a conductive rotation shaft pressurized in the axial direction, and one end side (end surface) of the output rotation shaft 31. 311 side) with a conductive inner ring 421, a bearing 42, a conductive bracket 52 formed with a bearing house 520 for holding a conductive outer ring 422 of the bearing 42, one end of the output rotating shaft 31, and a bracket And a conduction member 60 disposed between the two.

  The stator core 10 is configured by laminating steel plates, and includes an annular yoke portion (not shown) and a plurality of teeth portions 11 extending from the yoke portion toward the inner diameter side. An insulator 12 is formed on the stator core 10 by pre-molding, and a winding 13 is wound around the tooth portion 11 via the insulator 12. The stator core 10 around which the windings 13 are wound is molded with a molding resin except for the inner peripheral surface to form a cylindrical outer shell 20, thereby forming a stator. The insulator 12 may be molded separately from the stator core 10 and attached to the stator core 10 without using pre-molding.

  A metal bracket 52 made of, for example, a galvanized steel plate is integrally embedded on the opposite output side of the outer shell 20. The bracket 52 on the non-output side is in a state where the bearing house 520 in which the bearing 42 on the non-output side is accommodated is exposed from the outer shell 20.

  The rotor 30 includes an output rotating shaft 31 and a permanent magnet 32 having a plurality of magnetic poles. The magnetic poles of the permanent magnet 32 are arranged around the output rotating shaft 31 (not shown) so that the magnetic poles of the permanent magnet 32 are spaced at equal intervals and alternately adjacent to each other, and are integrated with the output rotating shaft 31. ing. The permanent magnet 32 can be formed as a ferrite-bonded magnet by mixing a ferrite magnetic material into a resin material and magnetizing it. The permanent magnet 32 is not limited to this, and a rare earth magnet may be used instead of the ferrite magnet, and a sintered magnet may be used instead of the bonded magnet.

  The rotor 30 is accommodated oppositely with a predetermined gap (gap) inside the inner periphery of the stator core 10. The output rotating shaft 31 is rotatably supported by an output-side bearing 41 and a counter-output-side bearing 42. Ball bearings are used for the output-side bearing 41 and the counter-output-side bearing 42, and include balls 410 and 420 as rolling elements, inner rings 411 and 421, and outer rings 412 and 422.

  The output-side bearing 41 is accommodated in an output-side bearing house 510 formed on a metal output-side bracket 51 made of, for example, a galvanized steel plate. The output side bracket 51 is fitted to the output side surface of the outer shell 20.

  The rotor 30 is subjected to a load (pressurization) on the non-output side by a preload spring 43 disposed between the bracket 51 and the outer ring 412 of the output side bearing 41. By applying pressure to the non-output side by the preload spring 43, there is no gap between the outer ring 412, the ball 400, and the inner ring 411, and the rotation of the output rotating shaft 31 is stabilized (blurring in the rotating shaft direction is reduced). When preload is applied to the outer ring 412 by the preload spring 43, the inner ring 411 and the output rotating shaft 31 that is pivotally supported by the inner ring 411 via the ball 400 are also pushed to the opposite output side. The pressurization is about 20N to 30N, for example, 25.7N is applied.

  The bearing house 520 on the non-output side is formed into a bottomed cylindrical shape by, for example, pressing. An annular bearing receiver 44 and a bearing 42 are accommodated inside the bearing house 520 on the non-output side, and a conducting member 60 is disposed on the inner diameter side of the bearing receiver 44.

  Below, the conduction | electrical_connection member 60 in embodiment is demonstrated in detail. 2A is a plan view of the conducting member 60, and FIG. 2B is a side view. 1 and 2, the conducting member 60 is a conducting member 60 that electrically connects the inner ring 421 and the outer ring 422 of the bearing 42, and contacts the end surface 311 of the output rotation shaft 31 that is pivotally supported by the inner ring 421. The rotation part (counterclockwise direction) of the output rotating shaft 31 from the outer peripheral edge 61E of the contact part 61 to the inner peripheral edge 62E of the holding part 62. And a connecting portion 63 that extends radially while bending and holds the contact portion 61 horizontally. Accordingly, the contact portion 61 and the holding portion 62 are connected by the connecting portion 63. The contact portion side end 631 of the connection portion 63 and the center O of the contact surface 610 with respect to a line segment (dotted line R ′) connecting the holding portion side end portion 632 of the connection portion 63 and the center O of the contact surface 610. An angle formed by a line segment (solid line R) connecting the two is defined as a rotation direction angle θ.

  The shape of the contact portion 61 is a disk shape, and has a circular contact surface 610 that contacts the end surface 311 of the output rotation shaft 31. The center O of the circular contact surface 610 and the rotation center of the output rotation shaft 31 are preferably arranged so as to coincide with each other. Here, the contact surface 610 is not limited to a flat surface, but may be a spherical surface that swells toward the output rotation shaft 31. Since the output rotation shaft 31 is slow in the vicinity of the rotation center, if the center O of the contact surface 610 and the rotation center of the output rotation shaft 31 coincide with each other, friction and sliding between the output rotation shaft 31 and the contact surface 610 are reduced. .

  The holding portion 62 has an annular shape, has an outer diameter smaller than the inner diameter of the bearing receiver 44, and is placed on the bearing house 520 on the inner diameter side of the bearing receiver 44. By holding the holding portion 62 on the bearing house 520, the holding portion 62 and the outer ring 422 are electrically connected via the bracket 52. In FIG. 2B, the contact surface 610 of the contact portion 61 is disposed so as to protrude from the holding portion 62 by d in the rotation axis direction. This d corresponds to the height of the conducting member 60, and in the present embodiment, d is arranged at a distance of 1 mm, for example.

  The shape of the connecting portion 63 is a spiral shape in a plan view, but the conducting member 60 has a height d, and thus has a spiral shape in a stereoscopic view. The connecting part 63 is preferably formed so as to be equidistant around the outer peripheral edge 61E of the contact part 61 and the inner peripheral edge 62E of the holding part 62. In addition, it is preferable to provide three or more connecting portions 63.

  The conducting member 60 is made of a metal having conductivity, springiness and rigidity, and is made of a material made of, for example, stainless steel having these properties. The conductive member 60 may be formed of a material made of iron, steel, brass, phosphor bronze, or the like as long as it has conductivity, springiness, and rigidity.

  According to the conducting member 60 and the molded motor 100 of the present invention, when the end surface 311 of the output rotating shaft 31 to which pressure is applied and the contact portion 61 come into contact with each other, the contact portion 61 is pushed toward the holding portion 62 and displaced. To do. The contact portion 61 has a preload applied to the output rotation shaft 31 and a reaction force applied from the conducting member 60 to the output rotation shaft 31 (if the contact portion 61 is displaced toward the holding portion 62 by the end surface 311 and is displaced) The portion 61 is displaced to a position where it balances with the force for returning to the original position. In this embodiment, when the contact portion 61 is pushed toward the holding portion 62, d is displaced to, for example, 0.8 mm. When the output rotary shaft 31 to which the preload is applied pushes the contact portion 61, stress is generated in the connecting portion. In this embodiment, since the output rotation shaft 31 rotates counterclockwise, the contact portion 61 is pulled in the same rotation direction as the output rotation shaft 31 (torsion torque), and the connection portion 63 rotates in the rotation direction due to this torsion torque. Pulled on.

  Here, the connecting portion 63 that connects the contact portion 61 and the holding portion 62 extends so that the rotation direction angle θ has a predetermined angle in the rotation direction of the output rotation shaft 31. That is, the connecting portion 63 extends radially so as to vortex along the rotation direction (counterclockwise) of the output rotation shaft 31. Therefore, since the length of the connecting portion 63 can be increased by increasing the rotation direction angle θ, the contact portion is easily displaced when the contact portion 61 is pushed toward the holding portion 62 by the end surface 311. Thus, the force that the contact portion 61 tries to return to the original position, that is, the reaction force to the output rotation shaft 31, can be suppressed to a small value, and thereby the stress generated in the connecting portion 63 can be suppressed. Even if the connecting portion 63 is pulled in the rotational direction of the output rotating shaft 31 by the torsional torque, the holding portion side end portion 632 and the contact portion side end portion 631 are respectively tangential to the inner peripheral edge 62E and the outer peripheral edge 61E. Since it extends, the stress concentration to the connection part by applying a load in a direction different from the length direction of the connection part 63 is suppressed, and the deterioration of the connection part 63 due to the stress is suppressed.

  In addition, since the contact portion 61 is kept horizontal, the contact portion 61 is in stable contact with the rotation center of the output rotation shaft 31, and the stress applied to the connecting portion 63 is further suppressed. Further, when three or more connecting portions 63 are formed at substantially equal intervals in the rotation direction of the output rotation shaft 31, three or more contact portion side end portions at which the contact portions 61 are spaced at substantially equal intervals are provided. Since it is supported by 631, even if it is pushed by the end surface 311, the contact part 61 can be kept more horizontal, and the deviation from the rotation center of the output rotating shaft 31 is also suppressed.

  In the present embodiment, the rotation direction angle θ of the connecting portion 63 is 360 °. Therefore, the connecting portion 63 extends in a substantially tangential direction of the outer peripheral edge 61E of the contact portion 61. For example, when the conducting member 60 is made of stainless steel, and the thickness of the connecting portion 63 is 0.2 mm and the width is 0.2 mm, the conducting member 60 has a reaction force in the direction of the output rotation shaft 31, and the reaction force is 0.03N. If the length of the connecting portion 63 is extended and the displacement in the direction of the output rotation shaft 31 is the same, the ratio of displacement becomes small, so the reaction force becomes small. Further, the reaction force decreases as the width decreases. The stress generated in the connecting part 63 was 62.20 MPa.

  The reaction force is preferably a magnitude that does not break the balance of the pressurization that suppresses blurring of the output rotation shaft 31 in the rotation axis direction, and is preferably about 1/100 of the pressurization applied to the output rotation shaft 31. In this embodiment, the reaction force was about 1/100 against a pressure of 20 to 30 N. Further, the stress generated in the connecting portion 63 is preferably a yield stress of 250 MPa or less of stainless steel as the material of the connecting portion 63, and is preferably 1/2 to 1/5 of the yield stress in consideration of the safety factor. In this embodiment, it was about 1/4.

(Other embodiments)
FIG. 3A is a plan view of the conducting member 60A in the present embodiment, and FIG. 3B is a side view. 3A, the present embodiment has the same material and the same configuration as the embodiment except that the rotation direction angle θ of the connecting portion 63A is changed from 360 ° to 180 ° of the connecting portion 63A. The same parts as those in the embodiment are denoted by the same reference numerals.

  By changing the rotation direction angle θ from 360 ° to 180 °, the length of the connecting portion 63A is shortened. The reaction force of the conductive member 60A was 6.13N. Moreover, the stress which arises in the connection part 63A was 222.19 MPa. Since the reaction force of the conducting member 60A can be increased by setting the rotation direction angle θ to 180 °, the end surface 311 of the output rotation shaft 31 can be obtained while obtaining the same effect as that of the first embodiment. On the other hand, the contact part 61 can be more reliably contacted.

The modification of embodiment is shown below. In the modification, the number of connecting portions and the rotation direction angle are different from those of the embodiment. The same parts as those in the embodiment are denoted by the same reference numerals.
(Modification 1)
FIG. 4A is a plan view of a conducting member 60B in this modification, and FIG. 4B is a side view. In FIG. 4A, eight connecting portions 63B are formed. The connecting portion 63B has a thickness of 0.2 mm, a width of 0.2 mm, and a rotation direction angle θ of 45 °.

(Modification 2)
FIG. 5A is a plan view of a conducting member 60C in the present modification, and FIG. 5B is a side view. In FIG. 5A, three connecting portions 63C are formed. The connecting portion 63C has a thickness of 0.2 mm, a width of 0.2 mm, and a rotation direction angle θ of 45 °.

(Comparative example)
6A is a plan view of the conducting member 600 in the comparative example, and FIG. 6B is a side view. 6, the conducting member 600 includes an annular holding portion 620 and a contact piece 630 that extends from the inner peripheral edge of the holding portion 620 toward the center of the output rotation shaft 31 that is pivotally supported on the inner ring 401 shown in FIG. 1. Yes. A contact portion 640 that contacts the center of the output rotation shaft 31 is formed at the tip of the contact piece 630. When the thickness of the contact piece 630 was 0.2 mm and the width was 2.34 mm, the reaction force was 0.31 N. The stress generated in the contact piece 630 was 509.15 MPa.

  The mold motor 100 rotates the rotor 30 together with the output rotary shaft 31 by causing a current to flow through the winding 13 and generating a rotating magnetic field in the stator according to the rotational position of the rotor 30 detected by a position detection sensor (not shown). Can be made. In addition, although the mold motor 100 with a position detection sensor was demonstrated, a sensorless mold motor may be used. The mold motor 100 can be used as, for example, an electric motor that drives a blower fan mounted on an air conditioner. When used in an indoor unit, a cross flow fan is attached to the output rotating shaft 31, and the outdoor motor In use, a propeller fan is attached to the output rotating shaft 31.

  In the molded motor 100 according to the embodiment, the shape of the connecting portion of the conductive member is a curved shape, but the present invention is not limited to this, and the rotation direction is positive in the clockwise direction with respect to the radial direction of the output rotation shaft If it extends with an angle, it may be linear. Further, in the molded motor 100 according to the embodiment, the holding portion has an annular shape and the contact portion has a disc shape. However, the present invention is not limited thereto, and may be, for example, a polygonal shape. Furthermore, the present invention is not limited to a mold motor, and can be applied as long as the output rotation shaft is an electric motor made of a conductive material. For example, a steel plate bracket motor whose outer shell is made of a steel plate may be used.

DESCRIPTION OF SYMBOLS 10 Stator core 11 Teeth part 12 Insulator 13 Winding 20 Outer shell 30 Rotor 31 Output rotating shaft 311 End surface 32 Permanent magnet 400 Ball 401 Inner ring 402 Outer ring 41 Output side bearing 42 Anti-output side bearing 43 Preload spring 44 Bearing receiver 51 Output side Bracket 510 Output-side bearing house 52 Non-output-side bracket 520 Non-output-side bearing house 60 Conductive member 60A Conductive member 60B Conductive member 60C Conductive member 61 Contact portion 61E Outer peripheral edge 62 Holding portion 62E Inner peripheral edge 63 Connecting portion 631 Contact portion Side end 632 Holding portion side end 63A Connection portion 63A1 Contact portion side end 63A2 Holding portion side end 63B Connection portion 63B1 Contact portion side end 63B2 Holding portion side end 63C Connection portion 63C1 Contact portion side end 63C2 Holding Part side end 100 Mall Motor 600 Conducting member 610 Contact surface 620 Holding portion 630 Contact piece 640 Contact portion O Rotation center R Line segment connecting contact portion side end 631 (63A1, 63B1, 63C1) of connecting portion 63 and center O of contact surface 610 ( solid line)
A line segment (dotted line) connecting the holding portion side end 632 (63A2, 63B2, 63C2) of the R ′ connecting portion 63 and the center O of the contact surface 610.
θ Rotational direction angle d Height of contact part (distance between holding part and contact part)

Claims (3)

A rotating shaft made of a conductive material;
A bearing composed of an outer ring and an inner ring made of a conductive material, and supporting the rotating shaft with the inner ring;
A bracket made of a conductive material in which a bearing house for holding the outer ring is formed;
An electric motor that is disposed between the rotating shaft and the bracket and includes a conductive member that conducts the inner ring and the outer ring of the bearing,
The conducting member has a contact portion that contacts an end surface of the rotating shaft, a connecting portion that extends radially from the contact portion, and an annular holding portion that is connected to the connecting portion.
When the rotation direction of the rotating shaft is positive,
The angle formed by the line connecting the contact part side end of the connecting part and the center of the contact part with respect to the line connecting the holding part side end of the connecting part and the center of the contact part is positive. An electric motor having an angle of   The electric motor according to claim 1, wherein three or more connecting portions are provided. The electric motor according to claim 1, wherein the angle is 180 ° or more.

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