JP2018061368A - Rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor which can effectively cool a permanent magnet while securing sufficient strength to a centrifugal force at the time of rotation.SOLUTION: A rotor 10 includes a permanent magnet 14, and a rotor core 11 having a shaft hole 113 composed of a plurality of magnetic steel plates laminated and into which a rotation axis is fitted and having a plurality of magnet holes 112a and 112b into which the permanent magnet 14 is inserted. On a surface of each magnetic steel plate, a magnet hole peripheral groove 21 in each periphery of a plurality of magnet holes 112a and 112b and an inner peripheral side connection groove 22 connecting the magnet hole peripheral groove 21 and the shaft hole 113 are formed. A heat conductive member 20 of a non-magnetic material is embedded in the magnet hole peripheral groove 21 and the inner peripheral side connection groove 22, and a cold source is in contact with an end part 22a of a shaft hole side of the heat conductive member 20 embedded in the inner peripheral side connection groove 22.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rotor.

  An electric motor used for an electric vehicle or a hybrid vehicle includes a rotor, a stator, and a rotating shaft. The rotor includes a rotor core that is fixed to the outer diameter side of the rotating shaft, and a plurality of permanent magnets that are fixed to the rotor core. As a rotor core, one formed by laminating a plurality of magnetic steel plates provided with magnet holes for inserting permanent magnets in the axial direction is known. The stator has a coil. When a current flows through this coil, a rotating magnetic field is generated, and the rotor is rotated by an electromagnetic action acting between this rotating magnetic field and the rotor.

  The electric motor generates heat by the current flowing through the stator coil during rotation. In particular, when the electric motor is rotated at a high speed or when the electric motor is large, the amount of heat generated by the electric motor at the time of rotation is significantly increased, and thereby the temperature of the permanent magnet is remarkably increased. When the temperature of the permanent magnet rises significantly, the magnetic flux that generates the torque of the electric motor decreases, so the performance of the electric motor deteriorates. For these reasons, it is necessary to cool the permanent magnet when the electric motor rotates.

  In Patent Document 1, an outer peripheral radial flow groove connecting the magnet hole gap and the outer periphery of the magnetic plate as a refrigerant flow groove on the surface of a magnetic plate (magnetic steel plate), and an axial flow channel A rotor (rotor) provided with an inner peripheral radial flow channel 53b that connects the hole and the magnet hole gap is described. It is said that the permanent magnet can be effectively cooled by flowing the gas refrigerant through the groove for the refrigerant flow path when the electric motor rotates.

JP 2015-2111573 A

  However, in the rotor described in Patent Document 1, the strength of the groove portion of the magnetic steel sheet is reduced by providing the coolant channel groove on the surface of the magnetic steel sheet. For this reason, when the electric motor is rotated at high speed, the rotor may not have sufficient strength to withstand the centrifugal force during rotation.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a rotor capable of effectively cooling a permanent magnet while ensuring sufficient strength against centrifugal force during rotation. To do.

  The present invention is a rotor including a permanent magnet, a rotor core having a plurality of stacked magnetic steel plates and having a shaft hole into which a rotating shaft is inserted and a plurality of magnet holes into which the permanent magnet is inserted, On the surface of each magnetic steel plate, a magnet hole peripheral groove around each of the plurality of magnet holes and an inner peripheral side connection groove connecting the magnet hole peripheral groove and the shaft hole are formed, and the magnet hole peripheral groove and A non-magnetic heat conduction member is embedded in each of the inner peripheral side connection grooves, and a cold heat source is brought into contact with the end portion on the shaft hole side of the heat conduction member embedded in the inner peripheral side connection grooves. Is.

  According to the present invention, it is possible to effectively cool a permanent magnet while ensuring sufficient strength against centrifugal force during rotation.

It is a perspective view which shows schematic structure of the rotor concerning this Embodiment. It is the enlarged view to which the area | region enclosed with the dashed-dotted line sector in FIG. 1 was expanded. It is sectional drawing which follows the III-III line of FIG.

Embodiments of the present invention will be described below with reference to the drawings.
First, a schematic configuration of the rotor 10 according to the present embodiment will be described with reference to FIG. The rotor 10 is used for an electric motor used in an electric vehicle, a hybrid vehicle, and the like. The electric motor includes a cylindrical stator that is disposed around the rotor 10 with a predetermined gap therebetween. The stator has a coil that generates a rotating magnetic field when a current flows. The rotor 10 is rotated by an electromagnetic action acting between the rotating magnetic field and the rotor 10.

  FIG. 1 is a perspective view showing a schematic configuration of the rotor 10. In FIG. 1, reference numerals are given only to the areas surrounded by the one-dot chain lines, and the reference numerals are omitted for the areas other than the areas surrounded by the one-dot chain lines. As shown in FIG. 1, the rotor 10 includes a rotor core 11 and a permanent magnet 14.

  The rotor core 11 is formed by laminating magnetic steel plates punched into an annular shape in the axial direction Z. The plurality of magnetic steel plates constituting the rotor core 11 are integrally connected by caulking, bonding, welding, or the like. In order to reduce energy loss due to eddy currents generated in the rotor core 11 as much as possible, the magnetic steel plates constituting the rotor core 11 are electrically insulated from each other by insulating films formed on both surfaces.

  The rotor core 11 is formed with a shaft hole 113 for fitting the rotating shaft and magnet holes 111, 112a, 112b for inserting the permanent magnets 14. The shaft hole 113 is formed at the center position of the rotor core 11. The shaft hole 113 is a through hole that penetrates the rotor core 11 in the axial direction Z. The magnet hole 111 is formed so as to extend in the circumferential direction in the vicinity of the outer edge portion of the rotor core 11. The pair of magnet holes 112 a and 112 b are formed so as to extend in the radial direction on both sides of the magnet hole 111, respectively. The magnet holes 111, 112 a, 112 b are through holes that penetrate the rotor core 11 in the axial direction Z.

  Further, the rotor core 11 is formed with a magnetic flux leakage suppression hole 114 for suppressing leakage magnetic flux from the permanent magnet 14. The magnetic flux leakage suppression hole 114 is formed between a radially inner end (radial center side) end of the magnet hole 112a and a radially inner end of the magnet hole 112b. The magnetic flux leakage suppression hole 114 is a through hole that penetrates the rotor core 11 in the axial direction Z.

  In the rotor core 11, the pattern shown in the region surrounded by the one-dot chain line in FIG. 1 is repeated eight times at a 45 ° pitch along the circumferential direction.

  FIG. 2 is an enlarged view enlarging the region surrounded by the alternate long and short dash line in FIG. As shown in FIG. 2, on the surface of each magnetic steel plate, the magnet hole peripheral groove 21 around each of the magnet holes 111, 112 a, 112 b and the inner peripheral side connection groove connecting the magnet hole peripheral groove 21 and the shaft hole 113. 22 is formed.

  3 is a cross-sectional view taken along line III-III in FIG. As shown in FIG. 3, a non-magnetic heat conducting member 20 is embedded in the magnet hole surrounding groove 21 formed on the surface of each magnetic steel plate. As with the magnet hole surrounding groove 21, the nonmagnetic heat conduction member 20 is also embedded in the inner peripheral side connection groove 22 formed on the surface of each magnetic steel plate shown in FIG. 2. The end 22a on the shaft hole 113 side of the heat conducting member 20 embedded in the inner peripheral side connection groove 22 is in contact with a cooling heat source such as cooling oil.

  On the surface of each magnetic steel plate, an outer peripheral side connection groove 23 that connects the magnet hole peripheral groove 21 and the outer periphery 115 of the magnetic steel plate or a connecting groove 24 that connects adjacent magnet hole peripheral grooves 21 may be formed. In the outer peripheral side connecting groove 23 and the connecting groove 24, similarly to the magnet hole surrounding groove 21, a non-magnetic heat conducting member 20 is embedded. By increasing the cooling path, the permanent magnet 14 can be cooled more effectively.

  Since it is necessary to reduce energy loss due to eddy current generated in the rotor core 11 as much as possible, the material of the heat conducting member 20 is selected from a non-magnetic material. The material of the heat conductive member 20 is, for example, aluminum (thermal conductivity: 236 W / m · K), silver (thermal conductivity: 426 W / m · K), stainless steel (thermal conductivity: 16.7 to 20.9 W). / M · K), carbon nanotubes (thermal conductivity: 3000 to 5500 W / m · K), and the like. In particular, carbon nanotubes have extremely high thermal conductivity and can be processed into a fine shape. Therefore, if the problem of cost is solved, the carbon nanotube is very preferable as a material for the non-magnetic heat conductive member 20.

  When the cold heat source comes into contact with the end portion 22a on the shaft hole 113 side of the heat conducting member 20 embedded in the inner peripheral side connecting groove 22, the cold heat is transferred to the shaft hole of the heat conducting member 20 embedded in the inner peripheral side connecting groove 22. Conduction is conducted from the end 22a on the 113 side to the end connected to the magnet hole peripheral groove 21. Further, the cold heat is conducted to the heat conducting member 20 embedded in the magnet hole surrounding groove 21, and the heat conducting member 20 embedded in the magnet hole surrounding groove 21 is cooled. When the heat conducting member 20 embedded in the magnet hole surrounding groove 21 is cooled, the permanent magnet 14 fitted in the magnet holes 112a and 112b is cooled through the heat conducting member 20 embedded in the magnet hole surrounding groove 21. Is done. Thereby, the permanent magnet 14 can be cooled effectively.

  If grooves for cooling the permanent magnets 14 such as the magnet hole peripheral groove 21 and the inner peripheral side connection groove 22 are formed on the surface of each magnetic steel plate of the rotor core 11, the strength of the groove portion of the magnetic steel plate decreases. The strength of the groove portion of the magnetic steel sheet is reinforced by embedding the solid heat conduction member 20 in the groove for cooling the permanent magnet 14. Thereby, sufficient intensity | strength is securable with respect to the centrifugal force at the time of rotation.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. In the above embodiment, the magnet hole peripheral groove and the inner peripheral side connection groove in which the non-magnetic heat conduction member is embedded only on the surface of one side of each magnetic steel plate of the rotor core are formed, but the present invention is not limited to this. . A magnet hole peripheral groove and an inner peripheral connection groove in which a non-magnetic heat conducting member is embedded may be formed on both surfaces of each magnetic steel plate of the rotor core.

DESCRIPTION OF SYMBOLS 10 Rotor 11 Rotor core 14 Permanent magnet 20 Heat conduction member 21 Magnet hole surrounding groove 22 Inner peripheral side connection groove 22 Inner peripheral side connection groove 22a End 23 Outer peripheral side connection groove 24 Connection groove 111, 112a, 112b Magnet hole 113 Shaft hole 114 Magnetic flux leakage suppression hole 115

Claims (1)

A rotor including a permanent magnet, a shaft hole configured by a plurality of laminated magnetic steel plates and having a rotation shaft inserted therein, and a rotor core having a plurality of magnet holes into which the permanent magnet is inserted,
On the surface of each magnetic steel plate, a magnet hole peripheral groove and a magnet hole peripheral groove and an inner peripheral side connection groove that connects the shaft hole are formed around each of the plurality of magnet holes,
A non-magnetic heat conduction member is embedded in each of the magnet hole peripheral groove and the inner peripheral connection groove,
A rotor in which a cold heat source is brought into contact with the end portion on the shaft hole side of the heat conducting member embedded in the inner peripheral side connection groove.

Images