Rotor for electric motor, electric supercharger, and electric-motor assisted supercharger

Patent metadata

Field	Value
Publication number	US-9979245-B2
Application number	US-201514957947-A
Country	US
Kind code	B2
Filing date	Dec 3, 2015
Priority date	Dec 5, 2014
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

A rotor for an electric motor and a rotor sub-assembly that is maintained at an appropriate position without using a spacer and without applying excessive compressive stress to a magnet. A magnet and an end-plate are press-fitted into a ring-shaped member to form a rotor sub-assembly. A shaft is passed through the rotor sub-assembly. A fastener is fastened onto the shaft, and fixes the axial position of the rotor sub-assembly with respect to the shaft. The shaft includes a step at which the shape of the shaft changes between a small-diameter portion and a large-diameter portion.

First claim

The invention claimed is:

1. An electric supercharger, comprising:
a ring-shaped rotor sub-assembly including a ring-shaped member, a magnet and an end-plate;
a shaft that passes through the rotor sub-assembly; and
a nut that is fastened to the shaft to cause a pressing force in an axial direction to act on the rotor sub-assembly, and that fixes an axial position of the rotor sub-assembly with respect to the shaft;
wherein:
the magnet is disposed between the ring-shaped member and the shaft so as to contact an inner wall of the ring-shaped member;
the shaft includes a step at which a shape of the shaft changes between a small-diameter portion and a large-diameter portion, and a reference face that is an end face of the large-diameter portion that is exposed to outside of the small-diameter portion; and
the end-plate includes a positioning portion, which is fixed to the ring-shaped member so as to oppose an axial end portion of the magnet, said positioning portion includes an opposing face contacting the reference face and a pressure receiving face receiving the pressing force produced by the nut, and said small-diameter portion is inserted into the positioning portion;
said electric supercharger further comprising;
a stator of an electric motor that is disposed at an outer circumference of the rotor sub-assembly; and
a compressor impeller that is mounted to the shaft so as to be positioned between the pressure receiving face of the positioning portion and the nut,
wherein the end-plate is mounted to the ring-shaped member so as to contact the axial end portion of the magnet.

2. The electric supercharger according to claim 1 , wherein:
said opposing face of the positioning portion of the end-plate faces the magnet, and said opposing face of the positioning portion contacts the reference face of the shaft;
an outer diameter of the shaft is maintained at a diameter that is less than an inner diameter of the magnet over a length that is equal to or greater than an internal length of the rotor sub-assembly from the reference face; and
the internal length is a length from the opposing face of the positioning portion to an end portion of the rotor sub-assembly on a different side to the positioning portion.

3. An electric-motor assisted supercharger, comprising:
an electric supercharger according to claim 2 ;
a turbine impeller that is mounted to the shaft so as to be positioned on an opposite side to the compressor impeller so as to sandwich the rotor sub-assembly therebetween; and
a turbine housing that guides exhaust gas of an internal combustion engine to the turbine impeller.

4. The electric-motor assisted supercharger according to claim 3 , wherein:
the rotor sub-assembly further comprises a turbine-side end-plate that is mounted to the ring-shaped member so as to oppose a second axial end portion of the magnet from a turbine impeller side, and that allows passage of the shaft therethrough; and
the turbine-side end-plate comprises a ceramic ring at a site that contacts the shaft.

Assignees

• Toyota Motor Co Ltd

Inventors

• Maeda Osamu

Classifications

• H02K7/003

  Couplings; Details of shafts (means for mounting rotors on shafts H02K1/28) · CPC title

• H02K1/28 Primary

  Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures · CPC title

• F02B37/10

  at least one pump being alternatively {or simultaneously} driven by exhaust and other drive, {e.g. by pressurised fluid from a reservoir or an engine-driven pump} · CPC title

• F05D2240/60

  Shafts · CPC title

• H02K9/22

  by solid heat conducting material embedded in, or arranged in contact with, the stator or rotor, e.g. heat bridges · CPC title