Rotor and motor

1. A rotor comprising:

a first rotor core having a substantially disk-like first core base and a plurality of first claw poles located at equal intervals around an outer circumference of the first core base, the first claw poles projecting radially outward and extending in an axial direction;

a second rotor core having a substantially disk-like second core base and a plurality of second claw poles located at equal intervals around an outer circumference of the second core base, the second claw poles projecting radially outward and extending in the axial direction, wherein the second claw poles are each located between corresponding ones of the first claw poles of the first rotor core;

a field magnet placed between the first core base and the second core base in the axial direction, the field magnet being magnetized in the axial direction so that the first claw poles function as first magnetic poles and the second claw poles function as second magnetic poles; and

at least one of a group of one or more auxiliary magnets that are each located between first and second claw poles in a circumferential direction and magnetized to be magnetic poles of the same polarity as the first and second claw poles and another group of one or more auxiliary magnets that are each located on a rear side of the first and second claw poles and magnetized to have radially outer portions of the same polarity as the first and second magnetic poles,

wherein the auxiliary magnets are arranged to protrude beyond at least one of axial end surfaces of the first core base and the second core base.

2. The rotor according to claim 1 , wherein the auxiliary magnets are interpole magnets each located between first and second claw poles in the circumferential direction and magnetized to be magnetic poles of the same polarity as the first and second claw poles.

3. The rotor according to claim 1 , wherein the auxiliary magnets are rear-side magnets located on the rear side of the first claw poles or the second claw poles and magnetized to have radially outer portions of the same polarity as the first claw poles or the second claw poles.

4. The rotor according to claim 1 further comprising a fixing member, wherein the auxiliary magnets each have a portion protruding beyond at least one of the axial end surfaces of the first core base and the second core base, and the fixing member fixes the protruding portions.

5. The rotor according to claim 4 , wherein the fixing member is made of plastic and formed by plastic-molding the protruding portions of the auxiliary magnets extending beyond the core base.

6. The rotor according to claim 4 , wherein the fixing member is provided only on each of axial end surfaces of the rotor, and the protruding portions extending beyond the core base are fixed by the fixing member.

7. The rotor according to claim 4 , wherein the fixing member is a fixing plate and the protruding portions of the auxiliary magnets protruding beyond the core base are fixed by the fixing plate on an axial end surface of the rotor.

8. The rotor according to claim 7 , wherein the fixing plate is made of a nonmagnetic material and the protruding portions of the auxiliary magnets extending beyond the core base are fixed by the fixing plate on at least one of axial end surfaces of the rotor.

9. The rotor according to claim 7 , wherein the fixing plate is made of a magnetic material and protruding portions of auxiliary magnets extending from the rotor are fixed by the fixing plate on at least one of axial end surfaces of the rotor.

10. The rotor according to claim 9 , wherein the fixing plate is made of a magnet and the protruding portions extending from the rotor are fixed by the fixing plate on at least one of the axial end surfaces of the rotor.

11. A tandem-structured rotor formed by stacking a plurality of rotors according to claim 4 , wherein the protruding portions of the auxiliary magnets extending between the stacked rotors are fixed by the fixing member.

12. A tandem-structured rotor formed by stacking a plurality of rotors according to claim 4 , wherein the protruding portions of the auxiliary magnets extending from the stacked rotors are fixed by the fixing member on least one of axial end surfaces of the rotor.

13. A motor comprising a rotor, the rotor including:

a first rotor core having a substantially disk-like first core base and a plurality of first claw poles located at equal intervals around an outer circumference of the first core base, the first claw poles projecting radially outward and extending in an axial direction;

a second rotor core having a substantially disk-like second core base and a plurality of second claw poles located at equal intervals around an outer circumference of the second core base, the second claw poles projecting radially outward and extending in the axial direction, wherein the second claw poles are each located between corresponding ones of the first claw poles of the first rotor core;

a field magnet placed between the first core base and the second core base in the axial direction, the field magnet being magnetized in the axial direction so that the first claw poles function as first magnetic poles and the second claw poles function as second magnetic poles; and

at least one of a group of one or more auxiliary magnets that are each located between first and second claw poles in a circumferential direction and magnetized to be magnetic poles of the same polarity as the first and second claw poles and another group of one or more auxiliary magnets that are each located on a rear side of the first and second claw poles and magnetized to have radially outer portions of the same polarity as the first and second magnetic poles, wherein

the auxiliary magnets are arranged to protrude beyond at least one of axial end surfaces of the first core base and the second core base, and

the motor further comprises a sensor for detecting the auxiliary magnets.

14. A motor comprising a rotor, the rotor including:

a first rotor core having a substantially disk-like first core base and a plurality of first claw poles located at equal intervals around an outer circumference of the first core base, the first claw poles projecting radially outward and extending in an axial direction;

a second rotor core having a substantially disk-like second core base and a plurality of second claw poles located at equal intervals around an outer circumference of the second core base, the second claw poles projecting radially outward and extending in the axial direction, wherein the second claw poles are each located between corresponding ones of the first claw poles of the first rotor core;

a field magnet placed between the first core base and the second core base in the axial direction, the field magnet being magnetized in the axial direction so that the first claw poles function as first magnetic poles and the second claw poles function as second magnetic poles; and

at least one of a group of one or more auxiliary magnets that are each located between first and second claw poles in a circumferential direction and magnetized to be magnetic poles of the same polarity as the first and second claw poles and another group of one or more auxiliary magnets that are each located on a rear side of the first and second claw poles and magnetized to have radially outer portions of the same polarity as the first and second magnetic poles,

wherein the auxiliary magnets are arranged to protrude beyond at least one of axial end surfaces of the first core base and the second core base.