JP2009239999A - Motor and temperature rise suppressing method of bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor which can prevent a rise of a temperature of a bearing (motor bearing) by a simple structure, and can prolong the lifetime of the bearing by preventing the rise of the temperature, and to provide a temperature rise suppressing method of the bearing. <P>SOLUTION: In the motor A which comprises a rotating shaft 10, a cylindrical rotor 1 fixed to the rotating shaft 10, a stator 20 arranged so as to oppose the external peripheral face of a rotor 1, and the bearings 30A, 30B for rotatably supporting the rotating shaft 10, the motor is such that annular recesses 2b, 2c are formed, at least at one of end faces 2B, 2C of the rotor 1 along the external periphery of the rotating shaft 10. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for suppressing temperature rise of a motor and a bearing.

As is well known, a motor as a rotating machine has a stator disposed opposite to a circumferential surface of a rotor, and the rotor is rotatably supported by a bearing. Heat generation in such motors is mainly caused by iron loss and copper loss generated in the stator and rotor, but when the temperature of the bearing rises due to heat propagation from the stator and rotor, the lubricating oil in the bearing volatilizes and so on. The lifespan of the product is reduced.
In Patent Document 1 below, as a cooling technique for such a motor, a bearing cooling flow path is formed so as to surround a bearing supporting a rotor, and cooling water is allowed to flow through the bearing cooling flow path to cool the bearing. Techniques to do this are disclosed.
Japanese Patent No. 3320200

  However, since the bearing cooling technology needs to provide a cooling passage for the bearing, there is a problem that the motor becomes complicated, large, heavy, and / or expensive. Further, when the motor is complicated by providing the bearing cooling flow path, there is a problem that the production efficiency of the motor is deteriorated.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to prevent a temperature rise of a bearing (motor bearing) with a simple structure and to thereby extend the life of the bearing.

In order to achieve the above object, the present invention employs the following means.
That is, the present invention provides, as a first solving means related to a motor, a rotating shaft, a cylindrical rotor fixed to the rotating shaft, a stator disposed so as to face the outer peripheral surface of the rotor, In a motor including a bearing that rotatably supports a rotating shaft, a means is adopted in which a recess is formed in an annular shape along the outer periphery of the rotating shaft on at least one of the end surfaces of the rotor.

  Further, as the second solving means relating to the motor, in the first solving means, a means is adopted in which the hollow portion has a shape having no corners in a cross section along the axial direction of the rotating shaft. To do.

Further, as the third solving means relating to the motor, a means is adopted in which, in the first or second solving means, the recess is formed in a circumferential groove shape.
Further, as a fourth solving means relating to the motor, a means is adopted in which, in the third solving means, a plurality of the recessed portions are formed concentrically around the axis of the rotating shaft.

  Further, as a means for solving the temperature rise suppression method of the bearing, there is provided a temperature rise suppression method for a bearing that rotatably supports a cylindrical rotor fixed to a rotating shaft, wherein at least one of the two end surfaces has the rotation A means is employed in which a rotor having an annular recess formed along the outer periphery of the shaft is used.

  According to the present invention, since the hollow portion is formed in an annular shape along the outer periphery of the rotating shaft, the volume of the rotor is reduced and the iron loss is reduced by this hollow portion. Thereby, the temperature of the rotor becomes lower than that in the case where the hollow portion is not provided, the temperature of the bearing becomes lower, and the motor efficiency can be improved. Therefore, the temperature rise of the bearing can be prevented with a simple structure, and this can extend the life of the bearing.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view taken along a rotation center axis P of a motor A according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in the longitudinal sectional view.
The motor A is a permanent magnet type synchronous motor, and includes a rotor 1, a rotating shaft 10, a stator 20, a pair of bearings 30 </ b> A and 30 </ b> B, and a casing 40.

  The rotor 1 is composed of a cylindrical rotor core 2 and eight permanent magnets 3 (3N, 3S), and a rotary shaft 10 is press-fitted and fixed in a through hole 2a provided on the central axis of the rotor core 2. ing.

  The rotor core 2 is a laminated steel plate in which a plurality of hollow disk-shaped steel plates are laminated, and recesses 2b and 2c are formed in an annular shape along the outer periphery of the rotary shaft 10 at the end faces 2B and 2C.

The recesses 2b and 2c are the most characteristic components of the motor A. The details of the recesses 2b and 2c will be described. The recesses 2b and 2c are configured as shown in FIG.
The recessed portions 2b and 2c are formed in a circumferential groove shape along the outer periphery of the rotating shaft 10 on the end surfaces 2B and 2C, respectively. The recesses 2b and 2c are formed by laminating steel plates and then grooving them by cutting.

  These hollow portions 2b and 2c have a shape having no corners in a cross section along the direction of the rotation center axis P of the rotation shaft 10. Specifically, the cross-sectional shape of the depressions 2b and 2c is formed in a substantially U shape, and the surfaces forming the depressions 2b and 2c are connected via a curved part.

Returning to FIGS. 1 and 2, the permanent magnets 3 (3N, 3S) are formed in an arc shape, and the permanent magnet 3N having the polarity of the N pole and the permanent magnet 3S having the polarity of the S pole on the outer peripheral side. Are pasted on the circumferential surface of the rotor core 2. Specifically, two pieces of the same polarity in the central axis direction of the rotor core 2 (see FIG. 1), and four pieces of permanent magnets 3N and permanent magnets 3S are alternately arranged in the circumferential direction of the rotor core 2 (see FIG. 1). 2), that is, a total of 8 sheets are attached.
With such a configuration, the rotor 1 includes four magnetic poles.

  The rotating shaft 10 is a cylindrical member having a plurality of diameters and formed in a multistage shape. The rotor core 2 is fixed to a portion having the maximum diameter of the rotary shaft 10, and bearings 30A and 30B are press-fitted and fixed on both sides so as to sandwich the portion having the maximum diameter.

The stator 20 includes a substantially cylindrical stator core 21 and a winding 22 wound around the stator core 21.
The stator core 21 is configured by laminating a plurality of metal core plates, and includes 24 teeth 21b formed in an annular shape and projecting from the yoke 21a toward the inner peripheral side at equal angular intervals. The tip portion of the tooth 21b forms a generally circular inner peripheral surface 20a as a whole.

  A plurality of windings 22 are wound around the teeth 21b, and the molding agent 23 fixes the position of the windings 22 with respect to the teeth 21b.

  With such a configuration, the stator 20 includes 24 magnetic poles, and the inner peripheral surface 20a faces the outer peripheral surface (permanent magnet 3) of the rotor 1 through a predetermined gap.

  The bearings 30 </ b> A and 30 </ b> B are ball bearings, and an inner ring is fixed to the rotating shaft 10 and an outer ring is fixed to the casing 40 to support the rotating shaft 10 rotatably.

  The casing 40 is formed in a substantially cylindrical shape centered on the rotation center axis P, and is a rotor that is rotatably supported in the internal space by the stator 20 and the bearings 30A and 30B so that the rotation center axis P becomes the rotation center. 1 is housed.

Specifically, the casing 40 has a cylindrical wall portion 40a having the rotation center axis P as an axis, and substantially circular end wall portions 40b arranged at both ends of the cylindrical wall portion 40a and centering on the rotation center axis P. 40c, bearing wall portions 40b, 40c provided near the center, bearing mounting portions 40d, 40e to which the bearings 30A, 30B are respectively fixed, and openings 40f, 40g through which the end portions of the rotary shaft 10 are inserted. ing. The substantially cylindrical stator 20 is accommodated in a space surrounded by the cylindrical wall portion 40a and the end wall portions 40b and 40c, and the rotor 1 is accommodated inside the stator 20 and between the bearing mounting portions 40d and 40e. Further, the outer rings of the bearings 30A and 30B are fixed to the bearing mounting portions 40d and 40e.
In such a casing 40, a cooling water flow path (cooling flow path 40h) supplied from the outside is formed in the cylindrical wall portion 40a along the outer periphery of the stator 20.

Next, the operation of the motor A having the above configuration will be described.
When the winding 22 is energized, a magnetic circuit is formed by the plurality of windings 22, the stator core 21, and the permanent magnet 3, and the rotor 1 rotates by switching the energization to the winding 22.

  At this time, copper loss occurs in the winding 22 and iron loss occurs in the stator core 21, so that the winding 22 and the stator core 21 generate heat and the temperature of the stator 20 rises. Further, when iron loss occurs in the rotor 1, the rotor core 2 generates heat and the temperature of the rotor 1 rises.

  Heat generated in the rotor 1 is transferred from the outer peripheral surface of the rotor 1 to the stator 20 via air, or transferred from the end surfaces 2B and 2C to the bearings 30A and 30B via the rotary shaft 10 or air. The stator 20 is cooled by the cooling flow path 40 h and the rotating shaft 10 hardly generates heat, so that the rotor 1 has a higher temperature than the stator 20 and the rotating shaft 10.

  FIG. 4 is a graph comparing a motor A and a grooveless motor in which other components are the same as those of the motor A without providing the recesses 2b and 2c. FIG. 4 (a) shows a predetermined time from the operation. 4 is a graph comparing the temperatures of the bearings 30A and 30B, respectively, and FIG. 4B is a graph comparing motor efficiency.

  In any case of the bearing 30A and the bearing 30B, as shown in FIG. 4A, the bearing 30A of the motor A is compared with the temperature of the bearing of the grooveless motor configured without the recesses 2b and 2c. , 30B shows a low value, and as shown in FIG. 4B, the motor efficiency of the motor A is higher by several percent than the motor efficiency of the grooveless motor.

  Comprehensively interpreting the results shown in FIGS. 4A and 4B, the volume of the rotor core 2 is reduced by providing the recesses 2b and 2c, and the iron loss is reduced by this reduction. Can be considered. Since the iron loss is reduced, the temperature of the rotor 1 of the motor A is lower than that of the grooveless motor. Therefore, it can be considered that the temperature of the bearings 30A and 30B is reduced and the motor efficiency is increased.

  According to this embodiment, since the recesses 2b and 2c are formed in an annular shape along the outer periphery of the rotating shaft 10, the volume of the rotor core 2 is reduced and the iron loss is reduced only by the recesses. . As a result, the temperature of the rotor 1 becomes lower than that in the case where the recesses 2b and 2c are not provided, and the temperatures of the bearings 30A and 30B become lower and the motor efficiency can be improved. Therefore, the temperature rise of the bearings 30A and 30B can be prevented with a simple structure, and this makes it possible to extend the life of the bearings 30A and 30B.

  Furthermore, since the recesses 2b and 2c are formed in a circumferential groove shape and have a shape having no corners in the cross section along the direction of the rotation center axis P, the magnetic flux density is locally increased. There is no. As a result, the operation of the motor A does not become unstable, and the performance is not deteriorated due to a change in the magnetic field.

As described above, it is estimated that the iron loss is reduced by providing the recesses 2b and 2c. However, the recesses 2b and 2c act as heat resistance, and the heat generated in the rotor 1 is generated by the bearings 30A and 30B. It can also be assumed that it will be difficult to communicate.
That is, in the vicinity of the end faces 2B and 2C, the heat transferred from the stator 20 side to the bearings 30A and 30B through the rotating shaft 10 by heat conduction reaches the rotating shaft 10 by forming the recessed portions 2b and 2c. Since the reach distance increases, it is easy to radiate heat to the internal space of the casing 40 by this increased distance, and it can be considered that the amount of heat transfer to the bearings 30A and 30B has decreased.
In addition, the heat transferred to the bearings 30A and 30B by heat radiation from the vicinity of the recesses 2b and 2c through the internal space has a longer reach to the bearings 30A and 30B by the amount of the recesses 2b and 2c. It can be considered that the electromagnetic wave is less likely to reach the bearings 30A and 30B by the longer distance, and the amount of heat transfer is reduced.
Further, it can be considered that the above factors act in a superimposed manner and the temperatures of the bearings 30A and 30B are lowered.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the recesses 2b and 2c are formed in the shape of a circumferential groove, but this is made in consideration of the thermal resistance action of the recesses 2b and 2c. It is not always necessary to form the recess in a circumferential groove shape.
For example, as in Modification 1 shown in FIG. 5A, a plurality of small hole-like depressions 2 e may be formed in an annular shape along the outer periphery of the rotating shaft 10. Further, as in Modification 2 shown in FIG. 5B, concavity portions 2f are formed concentrically around the rotation center axis P (axial center) of the rotation shaft 10 outside the concavity portions 2b and 2c. May be.
Furthermore, a plurality of depressions may be provided scattered on the end faces 2B and 2C of the rotor 1, or a plurality of depressions having a long hole shape may be formed and arranged in an annular shape. Needless to say, the above-described effects can be obtained even if the depressions are provided only on one of the end faces 2B and 2C.

(2) In the above embodiment, the depressions 2b and 2c are configured to have no corners in the cross section along the direction of the rotation center axis P, but this is because the magnetic flux density concentrates on the corners and the motor A This is to eliminate unstable elements of operation, and is not necessarily an essential process.
(3) In the above embodiment, the present invention is applied to the permanent magnet type synchronous motor. However, the present invention can also be applied to other inner rotor type motors.

(4) In the above embodiment, the rotor 1 and the rotary shaft 10 can be separated from each other. However, for example, the rotor 1 and the rotary shaft 10 may be integrally formed by cutting. Similarly, the rotor core 2 does not need to be laminated and may be integrally formed.

(5) In the said embodiment, although the hollow parts 2b and 2c were set as the structure with hollow, you may fix a heat insulating material to the hollow parts 2b and 2c, and this may be fixed with an adhesive agent.
(6) In the above embodiment, the recesses 2b and 2c are formed by grooving the end faces 2B and 2C by cutting. However, the recess is formed using, for example, a steel plate in which the recesses are formed by stacking. 2b and 2c may be configured.

(7) The various shapes and combinations of the constituent members are merely examples, and various changes can be made based on design requirements and the like without departing from the spirit of the present invention. For example, the number of magnetic poles and the shape of the casing may be changed as appropriate.

It is the figure which showed schematic structure figure of the motor A which concerns on one Embodiment of this invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1 in the embodiment of the present invention. In one embodiment of the present invention, it is a figure showing end faces 2B and 2C of rotor 1. FIG. FIG. 4 (a) is a graph comparing the temperatures of the bearings 30A and 30B, and FIG. 4 (b) is a graph comparing the motor A and the grooveless motor according to an embodiment of the present invention. It is the graph which compared motor efficiency. In one embodiment of the present invention, FIG. 5A is a diagram showing a modification example of the motor A, FIG. 5A is a diagram showing the modification example 1, and FIG. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Rotor 2B, 2C ... End surface 2b, 2c ... Recessed part 10 ... Rotating shaft 20 ... Stator 30A, 30B ... Bearing A ... Motor

Claims (5)

In a motor comprising a rotating shaft, a cylindrical rotor fixed to the rotating shaft, a stator disposed so as to face the outer peripheral surface of the rotor, and a bearing that rotatably supports the rotating shaft,
A motor having an annular recess formed along an outer periphery of the rotating shaft on at least one of end faces of the rotor.   The motor according to claim 1, wherein the recess has a shape having no corners in a cross section along the axial direction of the rotation shaft.   The motor according to claim 1, wherein the recess is formed in a circumferential groove shape.   The motor according to claim 3, wherein a plurality of the recessed portions are formed concentrically around the axis of the rotating shaft. A temperature rise suppression method for a bearing that rotatably supports a cylindrical rotor fixed to a rotating shaft,
A method for suppressing temperature rise of a bearing, wherein a rotor having an annular recess formed along the outer periphery of the rotating shaft is used on at least one of two end faces.

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