JP2010057209A - Variable field motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the iron loss generated, when a motor is rotated from the outside, and to reduce the influence of the cogging torque. <P>SOLUTION: In a variable field motor which can arbitrarily change a magnetic filed, by arranging a stator 20 so as to be displaceable with respect to a rotor 10, and displacing the stator through external operation; a relation between the number of magnetic poles of a magnet 14 and the number of slots of the stator 20 is set to be 8:9 (for example, 32 poles and 36 slots), and 10:12. Since the opposing area for both members where magnetic flux is generated between both the members can be made variable; and since the effective magnetic flux of the motor can be reduced as the stator is separated from the rotor, iron loss generated in the motor, when the motor is rotated from the outside, can be suppressed low. Then, by constituting the motor having the least common multiple of the number of the magnetic poles and the number of the slots, the motor reduced in the cogging torque can be obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a variable field motor.

2. Description of the Related Art Conventionally, there is an electric vehicle that uses a variable field motor that can adjust a magnetic field so as to obtain an appropriate rotation speed and torque according to a use situation as a power source. In general, a variable field motor is provided such that one of a stator or a rotor is movable with respect to the other, and the variable mechanism section changes the relative position of the stator and the rotor to increase or decrease the facing area between the two. Increase or decrease the field. When such a motor is applied to an electric vehicle, the opposing area is increased when the automobile is accelerated to increase the field, so that a high torque can be obtained. The field can be reduced and high-speed rotation is possible (see, for example, Patent Document 1).
Japanese Patent Application No. 2006-332985

  In the above variable field motor, when the vehicle is coasted, the motor is not energized to stop driving the motor. However, in the case where the motor is directly connected to the wheel, the wheel rotates. As long as the motor is running, the motor is running. At that time, the iron loss of the motor occurs, and the friction corresponding to the loss occurs. In that case, there is a problem that not only wasteful running resistance occurs but also the temperature of the motor increases.

  Further, in the case of extremely low speed such as when getting off the vehicle body and pushing like a motorcycle, vibration and noise such as rattling are likely to occur due to the cogging torque of the motor. Noise is likely to occur due to backlash particularly when a gear reduction device is provided. Furthermore, in the case of a high-power motor, the cogging torque also increases, and when it is driven at a very low speed, a large force is required to turn the motor (press the vehicle body), resulting in poor usability. .

  In order to solve such problems, and to reduce the occurrence of iron loss when the motor is rotated from the outside and to reduce the influence of cogging torque, in the present invention, the rotor, A variable field motor comprising a stator that is coaxial with a rotor and that is displaceable in an axial direction of a rotation shaft of the rotor, and a stator moving unit that displaces the stator in the rotation shaft direction. The number of magnetic poles and the number of slots of the rotor and the stator are a combination of integer multiples of 10 poles, 12 slots, or 8 poles, 9 slots.

  As described above, according to the present invention, since the variable field motor in which the stator is displaceably provided with respect to the rotor is used, the opposing area of both the members in which the magnetic flux is generated between the two members can be made variable. Since the effective magnetic flux of the motor can be reduced as the stator is moved away from the stator, the iron loss generated in the motor when the motor is rotated from the outside can be kept low. Further, since the cogging torque decreases as the least common multiple of the number of magnetic poles and the number of slots increases, the number of magnetic poles and the number of slots consist of combinations of 10 poles, 12 slots, or 8 poles, 9 slots, each integer multiple, A motor having a large least common multiple of values can be configured, and thus a motor having a small cogging torque can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a variable field motor provided on a drive wheel in a motorcycle as an electric vehicle to which the present invention is applied, and FIG. 2 is a front view seen from the arrow II line of FIG. .

  As shown in FIG. 1, the variable field motor M according to the first embodiment is an outer rotor type motor, and is used as an in-wheel motor on the knuckle 1 of the vehicle body so as to constitute a part of the wheel of the electric vehicle. It is fixed.

  A stator base 2 as a stator support structure is fixed to a knuckle 1 provided in the vehicle body. The stator base 2 has a cylindrical cylindrical portion 3 arranged coaxially with the axis A of the rotation axis of the motor M, and radially outwards at both axial ends of the cylindrical portion 3 via outward flange portions. In the illustrated example provided in FIG. 3, the first projecting portion 4 and the second projecting portion 5 are formed by three. The 1st and 2nd protrusion parts 4 * 5 are arrange | positioned at three places at intervals of 120 degree | times in the circumferential direction, respectively. A flat bracket is formed so as to connect any two of the three of the second projecting portions 5, and a rotation sensor (not shown) of the motor M is attached to the bracket. Is provided.

  Three guide shafts 6 are provided between the first and second projecting portions 4 and 5 facing each other so as to be spanned in parallel with the axis A. The guide shaft 6 is fixed by press-fitting both axial ends thereof into the first and second projecting portions 4 and 5. Further, on the knuckle 1 side of the stator base 2, a cable fixing portion 8 for fixing and supporting a cable end portion of a wire type traction device 30 as a stator moving means to be described later is provided.

  A shaft 11 as a rotating shaft of the motor M is rotatably supported in a cylinder of the cylindrical portion 3 of the stator base 2 via a pair of bearings 7a and 7b. At the axial end of the shaft 11 opposite to the knuckle 1, the center of the bottom of the bottomed cylindrical rotor body 12 that opens to the knuckle 1 is fixed coaxially. A rotor 10 is configured. A wheel of the drive wheel W is attached to the outer periphery of the rotor 10. A plurality of magnets 14 in which N and S poles are alternately arranged in the circumferential direction are disposed on the inner peripheral surface of the peripheral wall 13 of the rotor body 12.

  A stator 20 is provided so as to be surrounded by the plurality of magnets 14. The stator 20 includes an annular portion 22 that is slidably supported on the three guide shafts 6 via three bushes 24 made of, for example, ball bushes, and is integrally assembled with the annular portion 22 and radially outward. The stator core 21 is made of a laminated steel plate having a plurality of protruding teeth, and the armature coil 23 is wound around each tooth portion of the stator core 21. In this way, the stator 20 is provided in the motor M so as to be capable of reciprocating in the direction of the axis A.

  In the wire-type traction device 30 described above, an inner cable 31 as an axial force transmission member having one end connected to the annular member 22 and an outer casing 32 that supports the inner cable 31 so as to be movable in the axial direction; It is comprised by the manual traction apparatus 33 (FIG. 3) provided in the driver's seat of the vehicle main body so that manual operation by a driver | operator was possible. One end of the outer casing 32 is fixed to the cable fixing portion 8 of the stator base 2, and the other end is fixed to the casing 34 of the manual traction device 33 as shown in FIG.

  The end portion of the inner cable 31 on the motor M side passes through the cable fixing portion 8 and is connected to the annular portion 22 of the stator 20, and the other end is connected to a drum 35 which is a displacement portion of the manual traction device 33 as shown in FIG. 3. It is connected. The drum 35 is rotatably provided on the casing 34. A manual lever 36 is fixed to the drum 35 so as to rotate the drum 35 by a predetermined amount by a tilting operation. By tilting the lever 36 in a direction in which the inner cable 31 is wound, the stator 20 is separated from the rotor 10 (see FIG. 1 (direction of arrow a).

  The position at which the lever 36 is most tilted is the stator maximum removal position. For example, when the state where the magnetic pole surface of the magnet 14 and the facing surface of the stator core 21 completely overlap each other (full insertion) is 100%, The maximum extraction position may be set to an arbitrary value of 0 to 50%. Further, by tilting the lever 36 in the direction of unwinding the inner cable 31 (position side indicated by a solid line in the figure), the stator 20 is brought into the recess of the rotor 10 by, for example, the magnetic attractive force of the magnet 14 or a return spring (not shown). You can get back. When tilted to the maximum in that direction, the stator 20 is in the fully inserted position in the rotor 10 and is in a state where it overlaps 100%.

  The inner cable 31 and the outer casing 32 may be those generally used as brake cables for motorcycles and bicycles. A push-pull cable or the like may be used as an alternative to the cable. In the illustrated example, the manual traction device 33 that is manually operated is shown. However, the axial force generation means of the wire type traction device 30 may be an automatic traction device that rotates the drum 35 by a motor device. In the case of an automatic traction device, since it can be remotely controlled by an electrical signal, the length of the inner cable 31 and the outer casing 32 can be set short, and the automatic traction device can be installed integrally with the motor M, making the device compact. Can be

  In the illustrated example, as shown in FIG. 2, 32 magnets 14 are provided, and 36 slots (teeth) of the stator core 21 are provided. These numbers are when the relationship between the number of magnetic poles and the number of slots is 8: 9. The relationship between the number of magnetic poles and the number of slots may be 10:12. In either case, the number of magnetic poles and the number of slots that are integral multiples of the number expressed by the ratio are provided. Since the cogging torque is the sum of the magnetic attractive forces acting in the rotational direction, theoretically, combinations of 10 poles, 12 slots, 8 poles, 9 slots, etc. have the effect of canceling the magnetic attractive forces. It is effective as low cogging.

  In this way, the variable field motor is capable of variably controlling the field, and the relationship between the number of magnetic poles and the number of slots is a combination that can reduce cogging torque. By operating 36 to the stator maximum extraction position, the stator 20 can be moved to the maximum extraction position as shown in FIG. Thereby, the effective magnetic flux area between the magnet 14 and the stator core 21 becomes the minimum value in the design, the generation amount of iron loss at the time of coasting can be reduced, and the generation of friction (drag) for the loss can be suppressed. Unnecessary running resistance is reduced and the temperature rise of the motor M is also suppressed.

  Also, when traveling at an extremely low speed just before stopping or when driving down and pushing the vehicle body, it is easily affected by the cogging torque of the motor M, but the relationship between the number of magnetic poles and the number of slots is set as described above. As a result, even when the stator 20 is fully inserted, the cogging torque is reduced. Further, by positioning the stator 20 at the maximum extraction position, the effective magnetic flux is reduced, so that the cogging torque is further reduced. Therefore, by setting the stator 20 at the maximum extraction position at the extremely low speed as described above, the iron resistance is small, the running resistance is small, and the influence of the cogging torque is further reduced. When getting off and pushing while driving, handling becomes easier and quieter.

1 is a cross-sectional view showing a variable field motor provided on drive wheels in a motorcycle as an electric vehicle to which the present invention is applied. It is the front view seen from the arrow II line of FIG. It is a principal part fracture side view showing an example of a wire type traction device. It is a figure corresponding to FIG. 1 which made the stator the maximum extraction position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotor 14 Magnet 20 Stator 21 Stator core 22 Annular part 23 Armature coil 24 Bush 30 Wire-type traction device M Motor W Drive wheel

Claims (1)

A variable field having a rotor, a stator that is coaxial with the rotor and provided so as to be displaceable in the axial direction of the rotation axis of the rotor, and a stator moving means that displaces the stator in the rotation axis direction. A motor,
A variable field motor characterized in that the number of magnetic poles and the number of slots of the rotor and the stator is a combination of integer multiples of 10 poles, 12 slots, or 8 poles, 9 slots.

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