JP2013223291A - Rotor of rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cooling performance of a rotor core in a rotary electric machine.SOLUTION: Ventilation holes 26, 28 are provided in a rotor core 16 of a rotor 10 of a rotary electric machine. The ventilation holes 26, 28 include large openings 26a, 28b at an inlet side, and small openings 26b, 28b at an outlet side. Air-guiding plates 30, 32 rotating with the rotor are arranged in the vicinity of inlets of the ventilation holes 26, 28 to guide air flow into the ventilation holes 26, 28. Flow rate of the air flow becomes higher at smaller sectional areas of the ventilation holes 26, 28 to promote heat transmission from the rotor core 16 into the air flow.

Description

  The present invention relates to a rotor of a rotating electrical machine, and more particularly to cooling thereof.

  An electric motor that converts electrical energy into rotational kinetic energy, a generator that converts rotational kinetic energy into electrical energy, and an electric device that functions as both the motor and the generator are known. Hereinafter, these electric devices are referred to as rotating electric machines. The rotating electrical machine has two members that are arranged coaxially and relatively rotate. Normally, one is fixed and the other rotates. A coil is arranged on a fixed member (stator), and a rotating magnetic field is formed by supplying electric power to the coil. The other member (rotor) is rotated by the interaction with the magnetic field.

  The following Patent Document 1 discloses a rotating electric machine having a cylindrical outer shell that houses a stator (stator) and sending air blown by a cooling fan along the inner peripheral wall of the outer shell. 1 etc.). The rotor (rotor) includes a field permanent magnet (see paragraph 0024 and the like).

JP-A-8-11964

In Patent Document 1, blown air flows on the outer peripheral side of the stator. This is preferable for cooling the stator, but does not function sufficiently for cooling the rotor (rotor). When a permanent magnet is provided on the rotor, demagnetization of the permanent magnet may occur if the rotor, particularly the permanent magnet, is not sufficiently cooled.
An object of this invention is to provide the rotor of the rotary electric machine which has a structure advantageous for cooling.

  In the rotor of the rotating electrical machine according to the present invention, the rotor core is provided with ventilation holes that extend in the rotation axis direction of the rotor and through which airflow flows. And the cross-sectional area of this ventilation hole is large at the inlet side of the airflow, and is small at the outlet side.

  The cross-sectional area of the vent hole can be gradually changed from the inlet side toward the outlet side.

  A plurality of ventilation holes are arranged in the circumferential direction, and the shape of the ventilation holes adjacent in the circumferential direction can be different from each other.

  Moreover, the direction of the airflow which flows through the ventilation hole adjacent in the circumferential direction can be made into mutually reverse direction.

  Furthermore, it is possible to provide an air guide member integrally with the rotor core at the inlet of the vent hole, and to guide the air flow into the vent hole by the air guide member.

  Ventilation holes are provided in the rotor core, and the cross-sectional area is increased on the inlet side and decreased on the outlet side, thereby increasing the flow velocity of the airflow on the outlet side and promoting heat transfer from the rotor core to the airflow.

It is sectional drawing orthogonal to the rotating shaft line of the rotor of this embodiment. FIG. 2 is a combined cross-sectional view taken along line AA and line BB shown in FIG. 1. It is the figure which looked at a part of rotor from the direction orthogonal to an axis. It is sectional drawing which shows an example of a ventilation hole.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a cross section perpendicular to the rotation axis 12 of the rotor 10 of the rotating electrical machine of the present embodiment. 2A and 2B are combined cross-sectional views including the rotation axis 12, wherein FIG. 2A shows a cross section taken along the line AA in FIG. 1, and FIG. 2B shows a cross sectional view taken along the line BB in FIG. In each figure, only the lower half is shown, and the upper side is omitted. Further, the rotation axis 12 appears as the rotation center O in FIG. In the following description, the simple “radial direction” means the radial direction of the rotor 10, that is, the direction orthogonal to the rotation axis 12, and the simple “circumferential direction” means the circumferential direction of the rotor 10. That is, it means a direction around the rotation axis 12.

  The rotor 10 includes a rotor shaft 14 and a cylindrical rotor core 16 disposed coaxially with the rotor shaft 14. The rotor shaft 14 and the rotor core 16 are fixed to each other and rotate together. A fixing structure in which the rotor shaft 14 and the rotor core 16 are integrated is not shown for simplicity. A stator (not shown) is disposed around the rotor 10, and the rotor 10 is rotationally driven by a rotating magnetic field generated by the stator. The rotor core 16 is formed by laminating a large number of electromagnetic steel sheets punched into a predetermined shape in the direction of the rotation axis of the rotor. The rotor 10 has permanent magnets 18 arranged in the circumferential direction on or near the outer periphery of the rotor core 16. In particular, in the illustrated embodiment, the rotor core 16 is provided with a magnet arrangement hole 20 extending in the rotation axis direction of the rotor, and the permanent magnet 18 is arranged in this hole. The permanent magnet 18 is plate-shaped or rectangular parallelepiped. In the rotor 10, one magnetic pole is formed by two permanent magnets 18 a and 18 b arranged in a V shape. The permanent magnet 18 and the rotating magnetic field formed by the stator are magnetically coupled, and the rotor 10 rotates.

  Both ends of the rotor core 16 are open at both end faces 22 and 24 in the direction of the rotational axis 12 of the rotor core 16, and ventilation holes 26 and 28 are provided so as to connect the openings. The openings 26a and 26b; 28a and 26b at both ends of the ventilation holes 26 and 28 have different opening areas (sizes). That is, the openings at both ends of one ventilation hole have different opening areas. Specifically, in the ventilation hole 26 shown in FIG. 2A, the opening 26a opened in the end face 22 is larger than the opening 26b opened in the opposite end face 24. On the other hand, in the ventilation hole 28 shown in FIG. 2B, the opening 28b opened in the end face 24 is larger than the opening 28a opened in the end face 24 on the opposite side. Therefore, in the ventilation hole 26 and the ventilation hole 28, the direction in which the cross-sectional area of the ventilation hole decreases is opposite. The cross-sectional area of each ventilation hole 26, 28 can be gradually reduced from one opening 26a, 28b toward the other opening 26b, 28a. Moreover, it can also be made smaller stepwise. Changing the cross-sectional area of the ventilation holes 26 and 28 can be realized by changing the shape of the hole corresponding to the ventilation holes provided in the laminated electromagnetic steel sheets. In order to change to a staircase shape, electrical steel sheets of a type corresponding to the number of steps of the staircase are prepared, and these are laminated in order to form a vent hole. If the number of steps is increased, the cross-sectional area of the channel gradually changes, and finally, if all the electromagnetic steel sheets have different shapes, the step is the smallest and the cross-sectional area of the channel is reduced. It will gradually change.

  In this embodiment, the cross-sectional shape of the cross section of the ventilation holes 26, 28 orthogonal to the rotation axis 12 is substantially pentagonal in any cross section. In the cross section, the radially inner side of the substantially pentagon extends in the circumferential direction or the tangential direction, and the outer two sides are substantially parallel to the permanent magnet 18. A side side connecting the inner side and the outer side extends substantially in the radial direction. The cross-sectional shapes of the cross-sections of the ventilation holes are similar, and the center position is common in the cross-section orthogonal to the rotation axis 12. Center lines 34 and 36 connecting the center positions are shown in FIGS. 2 (a) and 2 (b). The center lines 34 and 36 are parallel to the rotation axis 12.

  The openings 26a. Air guide plates 30 and 32 are provided on 28b, respectively. FIG. 3 shows the ventilation hole 26 and the air guide plate 30 as viewed from below in FIG. The air guide plates 30 and 32 are provided so as to protrude obliquely in the direction of the rotation axis 12 from the end faces 22 and 24 of the rotor core 16. When the rotor rotates in the direction of the arrow C shown in FIG. 3, the air guide plate 30 also rotates integrally therewith, and the air hitting the air guide plate 30 changes its flow direction due to the inclination of the air guide plate. Bent as shown by the arrow D and guided into the ventilation hole 26. Similarly, with respect to the air guide plate 32, air is introduced into the ventilation hole 28. The air introduced into the ventilation holes 26 and 28 from the openings 26a and 28b provided with the air guide plates 30 and 32 is discharged from the openings 26b and 28a on the opposite side through the ventilation holes 26 and 28. The direction of the airflow flowing through the ventilation hole 26 is opposite to the direction of the airflow flowing through the ventilation hole 28.

  The ventilation holes 26, 28 can be arranged radially inward corresponding to the set of permanent magnets 18 that are convex outward (Λ shape) in the radial direction of the rotor 10. As shown in FIG. 1, one of the permanent magnets 18 a and 18 c forming adjacent magnetic poles is arranged in a Λ shape outward in the radial direction of the rotor 10, and the ventilation holes 26 and 28 are disposed inside these permanent magnets. Is arranged. The same number of the air holes 26 and 28 as the number of magnetic poles can be arranged in the circumferential direction. In the rotor 10, since the number of magnetic poles is eight, the number of ventilation holes can be eight (four ventilation holes 26 and 28, respectively). However, the number of ventilation holes can be made larger or smaller than the number of magnetic poles. The extending direction of the individual ventilation holes 26 and 28 can be a direction along the rotation axis 12 or a direction parallel to the rotation axis 12. Further, it may extend in the spiral direction, that is, in a direction parallel to the rotation axis 12 and also in the circumferential direction.

  In the portion where the cross-sectional area of the ventilation holes 26 and 28 is small, the flow velocity of the air flowing through the ventilation holes is increased. For this reason, the flow is disturbed near the boundary with the wall surface of the ventilation holes 26 and 28 as compared with the case where the flow velocity is low, and the heat transfer from the rotor core 16 to the airflow in the ventilation holes is promoted. Therefore, the heat generated in the rotor core 16 can be efficiently radiated, and the temperature rise of the rotor 10, particularly the temperature rise of the permanent magnet 18 can be suppressed. The cross-sectional area of the vent holes 26 and 28 changes in the direction of the center lines 34 and 36 of the vent hole, and the efficiency at the small cross-sectional area is good, but the efficiency at the large cross-sectional area is higher Is not good. That is, while the efficiency of heat radiation is good on the outlet side of the vent holes 26 and 28, the efficiency is not good on the inlet side. Therefore, the rotor 10 is arranged such that the direction of the airflow is reversed in the air guide holes adjacent in the circumferential direction.

  The cross-sectional shape of the ventilation hole is not limited to the above-described substantially pentagon. Moreover, the cross-sectional shape in each cross section orthogonal to the rotation axis may not be similar. For example, the change in the radial direction may be made larger than the change in the dimension in the circumferential direction so that the shape gradually becomes flat as the cross-sectional area becomes smaller. Moreover, the perimeter of the hole corresponding to the ventilation hole in each cross section can also be made constant. Thereby, the contact area between the airflow and the rotor core can be maintained even in the region where the cross-sectional area of the ventilation hole is small.

  Furthermore, the center line of the ventilation hole may not be parallel to the rotation axis 12. For example, like the ventilation hole 38 shown in FIG. 4, the center line 40 may be separated from the rotation axis 12 on the outlet side. As shown in FIG. 4, the distance between the radially outer wall surface of the ventilation hole 38 and the permanent magnet 18 may be constant. Since the object to be cooled is mainly the permanent magnet 18, the ventilation hole 38 is preferably disposed near the permanent magnet 18. This can be achieved by the arrangement of the vent holes 38 in FIG. Furthermore, it is preferable to make the circumferential length of the outer wall surface of the ventilation hole 38 constant. According to this, as the ventilation hole 38 goes to the exit side, the radial dimension is shortened, but the circumferential dimension is maintained, and thus the shape is crushed in the radial direction. Thereby, even if it reduces the cross-sectional area of a ventilation hole, the area of the part which the permanent magnet 18 and the airflow oppose can be maintained.

  The direction of change in the cross-sectional area of the ventilation holes, in other words, the direction of the airflow flowing through the ventilation holes may be made to coincide with each other. Moreover, you may make it provide the ventilation means which sends an airflow to a ventilation hole other than a rotor core. For example, an axial fan may be provided on the rotor shaft 14 so that air is sent to the end face of the rotor core and the airflow is allowed to flow through the ventilation holes. In this case, it is preferable that the direction of the change in the cross-sectional area of the ventilation holes is matched between the ventilation holes.

Desirable aspects of the rotating electric machine are shown below.
A rotor having a rotor core and a permanent magnet provided on the rotor core;
A blowing means for sending cooling air to the rotor;
A rotating electric machine having
The rotor core is provided with an inlet provided on one end face of the rotor for receiving the cooling air and a vent hole connecting the outlet provided on the other end face, and the cross-sectional area of the vent hole is large on the inlet side. Small,
Rotating electric machine.

  DESCRIPTION OF SYMBOLS 10 Rotating machine rotor, 12 Rotating axis, 14 Rotor shaft, 16 Rotor core, 18 Permanent magnet, 22, 24 End face of rotor core, 26, 28 Ventilation hole, 30, 32 Ventilation plate, 34, 36 Center line of ventilation hole, 38 vent holes, 40 vent hole center line.

Claims (5)

A rotor of a rotating electric machine,
Rotor core,
A permanent magnet provided on the rotor core;
Have
The rotor core is provided with ventilation holes that extend in the direction of the rotation axis of the rotor and through which airflow flows, and the cross-sectional area of the ventilation holes is large on the inlet side of the airflow and small on the outlet side.
Rotor for rotating electrical machines.   The rotor of a rotating electrical machine according to claim 1, wherein the cross-sectional area of the ventilation hole gradually changes.   The rotor of a rotating electrical machine according to claim 1 or 2, wherein a plurality of the ventilation holes are arranged in the circumferential direction, and the shapes of the ventilation holes adjacent in the circumferential direction are different.   The rotor of a rotating electrical machine according to claim 3, wherein the direction of the airflow in the ventilation holes adjacent in the circumferential direction is opposite.   5. The rotor of a rotating electrical machine according to claim 1, further comprising: a wind guide member that is provided integrally with a rotor core at an inlet of the ventilation hole and guides an airflow into the ventilation hole. 6. Rotor.

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