JP6410037B2 - Outer rotor type variable field motor - Google Patents

Description

  The present invention relates to a structure of an outer rotor type brushless motor that automatically changes (shifts) in accordance with the magnitude of load torque in both forward and reverse rotation directions. The present invention relates to an outer rotor type variable field motor.

  Variable field and automatic variable field motors are larger and heavier, more expensive to manufacture, and more time-consuming (deteriorated) due to their complicated structure compared to ordinary motors. Is required.

  As is well known, there are electric motors that are used at full rated output for a long time, such as blower fans and compressors. On the other hand, there are cases where an electric motor that can freely change output characteristics from low speed to high speed and from high torque to low torque, such as an electric vehicle or an electric motorcycle, may be required. Even when it is necessary to change the power characteristics, there is a method of changing the characteristics using a mechanical transmission or the like without changing the characteristics of the motor itself. In this case, problems such as the size, weight, cost, life (change with time), and noise (vibration) of the entire power source arise. In addition, there is a method of changing the power characteristics of the motor by using a variable field using hydraulic pressure or an electric device. In this case, the mechanism and control are complicated as compared with a normal motor, and problems such as the size, weight, cost, life (time-dependent change), and maintenance (maintenance) of the entire apparatus occur.

As shown in Fig. 16, even with a DC motor of the same output, a motor with low speed rotation and high torque characteristics (first speed) ← (expressed in this way because it resembles the low gear characteristics of a manual transmission of an automobile) There are motors with different characteristics, such as motors with high speed rotation and low torque characteristics (5-speed).
In general, the former has a flat motor shape with a large diameter and the latter has a thin pencil type motor shape. Taking an electric vehicle as an example, the former is a motor characteristic that is advantageous as the power of a vehicle that climbs up a hill with heavy loads. However, without a transmission or the like, the speed does not increase even on a flat road with a light load.
The latter is a motor characteristic that is advantageous as power for a car that runs on a flat road at high speed. However, if there is no transmission or the like, the driving force of the car is insufficient when climbing a steep slope or when accelerating rapidly.

  If the amount of electric power applied to the motor is increased or decreased, a motor with any characteristics such as (1st speed) to (5th speed) shown in FIG. It seems that it can be used as an electric motor that can freely change the motor output from low to low torque. However, as long as the motor characteristics (slope of the graph) do not change, even if the amount of power applied to the motor is forcibly increased or decreased, each TN characteristic line only moves in parallel, and only the torque and rotational speed are increased or decreased independently. There is a limit. For example, using a (5-speed) motor with high-speed rotation and low-torque characteristics, if you try to obtain a high torque by forcibly increasing the amount of power (voltage) to be applied, the torque will be as if it was a (1-speed) motor. The motor does not rise, and the motor generates heat exceeding the allowable output and burns out.

There is a motor called a series winding motor that automatically reduces the induced electromotive force constant (performs field weakening) as the rotational speed of the rotor increases. The principle diagram of the motor is shown in FIG.
Usually, the field of a brushed DC motor is composed of a permanent magnet. However, as shown in FIG. 17, when the armature coil 101 and the field coil 102 are connected in series with the electromagnet field, the variable field (weak field) automatically increases as the rotational speed increases. Can be given. A motor of this system in which the armature coil 101 and the field coil 102 are connected in series is referred to as a series-winding motor. In addition to this, a split-winding motor that connects the armature coil 101 and the field coil 102 in parallel, or a multi-winding motor in which only one of the field coils is connected in series and the remaining one is connected in parallel with the armature coil; There is a motor called. In addition, there is another excitation type motor in which an armature coil and a field coil are independently connected. Here, the direct winding motor of FIG. 17 will be described.

The direct-winding motor is a so-called automatically variable field motor that automatically changes the inclination of the TN diagram shown in FIG. 16 according to the magnitude of the rotational speed. When the motor is started, a large current flows because the armature coil 101 and the field coil 102 have only winding resistance. At this time, since the field magnet has a high magnetic flux density and a large current flows through the armature coil 101, a large starting torque can be obtained. When the motor increases in rotational speed, a back electromotive voltage due to an induced electromotive voltage is generated in the armature coil 101 and acts in the opposite direction to the voltage supplied from the battery 105. As a result, the current flowing through the armature coil 101 and the field coil 102 decreases, and the magnetic flux density of the field decreases. The induced electromotive force constant is reduced, and a field weakening function is created.
Since the series-winding motor shown in FIG. 17 includes the brush 103 and the commutator 104, the change with time (wear and deterioration) is large. The direct-winding motor shown in FIG. 17 is a system that automatically weakens the field by increasing the rotation speed.

  The variable field motor described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-50251) functions only in the forward rotation direction (when moving forward in an electric motorcycle), but automatically changes in the reverse rotation direction and regenerative braking. I do not. In addition, since the cam and the cam follower are in the vicinity of the central axis, when the displacement amount (lift amount) is large, the pressure angle becomes large, and an excessive force is applied to the cam follower (in Japanese Patent Application Laid-Open No. 2003-86260), resulting in significant wear.

JP 2014-50251 A JP 2013-46440 A JP 2011-50206 A JP 2008-141900 A JP 2008-216110 A JP 2010-57209 A JP 2010-51159 A JP 2008-259364 A

  The variable field motor of Patent Document 1 functions only in the forward rotation direction, but does not generate a variable field in the reverse rotation direction or regenerative braking. When used as a power source for an electric motorcycle or the like, a variable field is automatically generated in accordance with the magnitude of the load torque during forward movement, but no variable field is generated during regenerative braking. In addition, when used as a power source for an electric vehicle or the like, no variable field is generated even during reverse or regenerative braking.

  Further, the variable field motor of Patent Document 1 is long because the spring and the rotor are arranged in series (in series) in the motor output shaft direction. Further, since the bearings that support the sliding motion of the rotor are arranged in series (in series) in the motor output shaft direction, there is a problem that the bearing becomes longer in the motor output shaft direction. In the diagram of Patent Document 1, the overlap margin between the rotor and the stator core can be varied from 75% to about 100%. Therefore, the variable field quantity is as small as about 25%.

Furthermore, the variable field motor of Patent Document 1 has an IPM (embedded magnet type) structure and uses electromagnetic steel plates laminated on both the stator and the rotor. In general, the inner rotor type has a smaller maximum torque than the outer rotor type. In order to obtain the required torque, it is necessary to increase the diameter of the motor or to increase the axial length (stack thickness) of the rotor and the stator core. As a result, the motor becomes heavy.
Furthermore, since the variable field motor of Patent Document 1 is an inner rotor type and IPM (embedded magnet type), the torque per motor weight is small. Generally, many inner rotor type motors have high-speed rotation and low torque characteristics. In order to increase torque, the inner rotor type motor needs to use a reduction gear or increase the diameters of the rotor and the stator.
As described above, in the variable field motor of Patent Document 1, since the cam and the cam follower are in the vicinity of the central axis, the circumferential length of the cam is short and the displacement amount (lift amount) cannot be increased. If the displacement amount (lift amount) is large, the pressure angle becomes large and an excessive force is applied to the cam follower (in Patent Document 1, the pin), so that the pin and the cam are significantly worn.

In addition to Patent Document 1, Patent Document 3, Patent Document 6, Patent Document 7, Patent Document 8, Patent Document 4, and the like have poor environmental resistance against water, muddy water, dust and the like.
In Patent Document 3, Patent Document 6, Patent Document 7, Patent Document 8, Patent Document 4, and the like, the electric wire may bend and break due to the structure that moves the stator.

  The present invention is an outer rotor type brushless motor that automatically changes (changes speed) in accordance with the magnitude of the load torque in both the forward and reverse rotation directions, and also when used as a regenerative brake, It is an object of the present invention to provide an outer rotor type variable field motor capable of automatically performing variable field according to the height.

In order to solve the above problems, the present invention provides an outer rotor type variable field motor that performs a variable field by sliding an outer rotor disposed radially outward of the stator in the motor axial direction with respect to the stator. The outer rotor has a split structure of an inner rotor body that slides in the motor axial direction and an outer rotor body, a magnet is mounted on the inner surface side of the outer peripheral cylindrical portion of the inner rotor body , and the inner rotor body A cam follower is disposed on the outer peripheral cylindrical portion of the outer rotor body , and an axial cam surface is formed on the outer peripheral cylindrical portion of the outer rotor body , and the cam follower moves along the cam surface in accordance with a load applied to the motor shaft. The outer rotor is configured to slide substantially in the motor axial direction with respect to the stator.
The sliding movement of the outer rotor in the motor axial direction is the axial position of the inner rotor body that slides in the motor axial direction by a cam surface provided in the outer rotor body and a resilient mechanism arranged in parallel with the motor shaft. Is to control.
A plurality of the cam followers that move along the cam surface of the cam of the outer rotor main body are arranged in the inner rotor main body.
The cam surface has a substantially V shape with a valley in the motor shaft direction.
The cam surface shape is that a stopper structure for locking the cam follower is provided at the uppermost point of a substantially V shape having a valley in the motor shaft direction.

  According to the present invention, although it is a high-performance brushless motor that automatically changes the field torque according to the magnitude of the load torque in both the forward and reverse rotation directions, it is small (flat), lightweight, low cost, high torque, high A high-efficiency motor can be made in a wide rotation range. Also, when using as a regenerative brake, if a large amount of regenerative energy is extracted even at low speed rotation, a variable field is automatically generated according to the magnitude of the load torque (in this case, the braking torque) (induction The regenerative energy can be recovered more (regenerative braking works well).

The present invention can be downsized (flattened) by arranging functional parts such as a rotating shaft, a spring, a bearing, a stator, a rotor, a cam, and a cam follower in a radial direction. In addition, in order to prevent tilting and shaking during the sliding movement of the rotor, it is created by bearings for both rotation and sliding, three sets of cams and cam followers installed on the outer periphery of the rotor, and a spring that presses them. In this way, it is possible to prevent tilting and shaking so that the tripod placed on the floor is stabilized by gravity.
The outer rotor type has an SPM (surface magnet type) structure in which the magnet is directly installed (adhered) inside the yoke (magnetic path), and the centrifugal force applied to the magnet is directed outward (yoke side), so it can be centrifuged even at high speeds. There is no falling off of the magnet due to force. In that regard, the SPM (surface magnet type) inner rotor type requires a drop prevention ring outside the magnet.

  The original form of the present invention is an outer rotor type brushless motor. In general, the outer rotor type has a larger rotor diameter than the inner rotor type, and therefore has a relatively high torque and low speed rotation. Therefore, the torque per weight of the motor is large. Applications can be expected in fields that require high torque, such as in-wheel motors and direct drive motors.

  As in the present invention, when the overlap between the rotor and the stator core can be varied from about 25% to about 100% (variable field quantity is 4 times), the diagram of Japanese Patent Application Laid-Open No. 2014-50251 is further elongated in the axial direction. It is.

In the present invention, both the forward and reverse rotation directions are automatically variable-fielded according to the magnitude of the load torque. Variable field is automatically generated even during regenerative braking.
As a power source for electric vehicles and electric motorcycles, a variable field that automatically and continuously changes its characteristics according to the magnitude of load torque from high torque characteristics at low rotational speed to low torque characteristics at high rotational speed An electric motor having a function can be provided.

The structure of an outer rotor type variable field motor that automatically changes the magnetic field according to the magnitude of the load torque according to the embodiment of the present invention applied to the outer rotor type brushless motor is shown. It is a longitudinal cross-sectional view. FIG. 2 is a longitudinal sectional view when the load torque is maximum in the structure of the outer rotor type variable field motor of FIG. 1. It is a figure which shows the spring seat of FIG. It is a front view which shows the positional relationship of a magnet, a yoke, a stator, a magnetic sensor, etc. (A) is a front view which shows the external appearance of an outer rotor type variable field motor. FIG. 6B is a right side view of FIG. 5A showing the inner rotor body and the outer rotor body. FIG. 2 is a cross-sectional view showing the position of a magnet in a state where a load torque is about 25% in the outer rotor type variable field motor of FIG. 1. FIG. 2 is a cross-sectional view showing the position of a magnet in a state where the load torque is about 50% in the outer rotor type variable field motor of FIG. 1. FIG. 2 is a cross-sectional view showing the position of a magnet in a state where the load torque is about 75% in the outer rotor type variable field motor of FIG. 1. FIG. 2 is a cross-sectional view showing the position of a magnet in a state where the load torque is about 100% in the outer rotor type variable field motor of FIG. 1. It is a wave form diagram which shows the waveform of the induced electromotive voltage in a state whose load torque is about 25%. It is a wave form diagram which shows the waveform of the induced electromotive voltage of a state whose load torque is about 50%. It is a wave form diagram which shows the waveform of the induced electromotive voltage in a state whose load torque is about 75%. It is a wave form diagram which shows the waveform of the induced electromotive voltage in a state whose load torque is about 100%. FIG. 4 is a development view showing the relative positions of the inner rotor and the stator core, where (a) shows the positional relationship when the load torque is 100% or more, (b) shows the positional relationship when the load torque is about 75%, (c ) Is a diagram showing the positional relationship when the load torque is about 50%, and (d) is a diagram showing the positional relationship when the load torque is about 25%. It is a longitudinal cross-sectional view which shows the structure of the outer rotor type | mold variable field motor by other embodiment of this invention. It is a diagram showing the rotational speed and torque characteristics of a conventional motor. It is a figure which shows the principle of the direct-winding motor in which a field current also reduces automatically with the raise of the conventional rotational speed.

Embodiments of an outer rotor type variable field motor according to the present invention will be described below in detail with reference to the drawings shown in FIGS.
FIG. 1 shows the structure of an open-type outer rotor type variable field motor that automatically changes the field in accordance with the magnitude of the load torque in both the forward and reverse rotation directions applied to the brushless motor. FIG. 2 is a view showing a state in which the inner rotor main body is moved by the action of the cam and cam follower of the outer rotor type variable field motor of FIG. FIG. 1 shows the positional relationship between the inner rotor body and the outer rotor body with respect to the stator when the magnitude of the load torque received by the motor shaft is about 25% or less of the maximum torque, and the position of the fourth speed state in the automobile. FIG. 2 shows the positional relationship between the inner rotor body and the outer rotor body with respect to the stator when the magnitude of the load torque received by the motor shaft is about 100% or more of the maximum torque, and the position of the first speed state in the automobile. Yes.

  1 and 2, the outer rotor type variable field motor according to the present embodiment includes a motor body 1 and a pair of rotary bearings 2 and 3 on the inner peripheral surface side of the cylindrical portion 1a of the motor body 1. The motor shaft 4 is rotatably supported, the stator 5 is provided on the outer peripheral surface side of the cylindrical portion 1a, and is supported on one end portion of the motor shaft 4 and at a certain interval on the outer peripheral side of the stator 5. The magnet 6 is provided with an outer rotor 7 arranged so as to be movable in the axial direction.

The motor body 1 is provided with an end plate 1b on one end outer peripheral surface side of the cylindrical portion 1a, and a substrate 8 is attached to a plurality of boss portions 1c provided on the inner side of the end plate 1b via screws 9. It has been. A sliding bearing 10 is provided on the inner peripheral surface side of the cylindrical portion 1a, and a clearance is provided on the inner surface side of the sliding bearing 10 so that the rotary bearing 3 is slidable in the axial direction.
The rotary bearing 2 on the left side in the figure supports the motor shaft 4 with respect to the motor body 1 with only one degree of freedom of rotation. The right rotary bearing 3 supports the motor shaft 4 only in the radial direction. In the bearing 3, the inner ring is slidably disposed on the outer peripheral surface of the motor shaft 4, and the outer ring is assembled with a gap on the inner surface side of the sliding bearing 10. For this reason, the bearing 3 is movable in the motor axial direction in accordance with the sliding movement of the inner rotor body 72 described later. The sliding bearing 10 supports the outer ring of the right rotating bearing 3 so as to be slidable with a gap.
Between the rotary bearing 2 and the rotary bearing 3, a plurality of coil springs 11 serving as a resilient mechanism for applying an urging force in the axial direction are spaced around the motor shaft 4 in the circumferential direction. Are arranged. As shown in FIG. 3, both ends of the coil spring 11 are engaged with a pair of disk-shaped spring seats 12 arranged on the inner surface of the cylindrical portion 1a. The pair of spring seats 12 are arranged to face each other between the rotary bearing 2 and the rotary bearing 3 and support both ends of the coil springs 11 arranged at regular intervals in the circumferential direction. The spring seat 12 arranged on the rotary bearing 3 side is arranged to be slidable in the axial direction along with the sliding of the rotary bearing 3.

  The stator 5 is composed of a stator core 51 in which steel plates are laminated, and a stator coil 53 wound around an insulator 52 assembled to the stator core 51, and is assembled to the outer peripheral surface side of the cylindrical portion 1a via a mounting screw 54. ing. Both ends of the stator coil 53 are connected to the circuit of the substrate 8, and driving power and control signals are sent by an electric wire 13 composed of an external power line and a control line connected to this circuit. As shown in FIG. 4, the stator core 51 has nine pole teeth 51a formed at every angle of 40 degrees, and the stator coil 53 is configured by winding a winding 53a around each pole tooth 51a. An insulator 52 formed of an insulating material is assembled in advance on the stator core 51 to keep the insulation between the stator core 51 and the stator coil 53.

The outer rotor 7 includes a bottomed cylindrical outer rotor body 71 having a central portion attached to a base end portion of the motor shaft 4, and slides in the axial direction of the motor shaft 4 inside the outer rotor body 71. A bottomed cylindrical inner rotor body 72 that is movably arranged is divided into two parts. As shown in FIG. 5B, the outer rotor main body 71 is curved so as to form a concave cam surface 73a having an inclined surface in the axial direction along the circumferential direction. In the illustrated example, three cams 73 are formed at predetermined intervals in the circumferential direction. The cam surface 73a of the cam 73 is formed in a substantially V shape having a valley in the motor shaft direction.
The cam surface 73a of the cam 73 forms an inclined portion 73c that gradually rises from the lowest point 73A of the bottom portion 73b of the valley formed in a substantially V shape to the opposite direction at the highest point 73B of the upper portion 73d of the valley. The stopper portion 73e curved so as to draw a substantially semicircle is formed.
On the other hand, a radial cam follower shaft 74 is mounted at each apex position on the outer peripheral cylindrical portion 72a of the inner rotor body 72 so as to form an equilateral triangle, and the cam follower shaft 74 is attached to the cam surface 73a. Cam followers 75 that roll and move along are respectively mounted. A central base end portion 72b of the inner rotor body 72 is attached to a ring-shaped rotary slide bearing 76. The rotary slide bearing 76 can be rotated and slid by inserting the motor shaft 4 on an axis. It is supported by. As shown in FIG. 1, the rotary slide bearing 76 is in sliding contact with the right side surface of the inner ring of the right rotary bearing 3 and is in sliding contact with the motor shaft 4.
Reference numeral 14 denotes a rotational position detecting magnetic sensor disposed between the stator pole teeth 51 a of the stator 5, and the rotational position detecting magnetic sensor 14 determines the position of the inner rotor body 72 in the rotational direction relative to the stator 5. To detect. The position of the inner rotor body 72 in the motor shaft direction is not detected. As shown in FIGS. 1 and 2, even if the inner rotor main body 72 slides in the motor axial direction, the position of the inner rotor main body 72 in the rotational direction relative to the stator 5 can be detected in the entire region. Reference numeral 15 denotes a vent for releasing the pressure fluctuation caused by the change in volume of the air chamber between the rotary bearings 2 and 3 to the atmosphere and mitigating it.

As shown in FIG. 4, the magnet 6 is mounted on the inner surface side of the outer peripheral cylindrical portion 72 a of the inner rotor body 72. The magnet 6 has a permanent magnet 61 in which the polarity of the N pole is on the inner peripheral side and the polarity of the S pole on the outer peripheral side, the polarity of the S pole on the inner peripheral side, and the polarity of the N pole on the outer peripheral side. The six permanent magnets 62 are alternately arranged in the circumferential direction to form six sets of poles. The permanent magnet 61 and the permanent magnet 62 are assembled to the inner surface side of the outer peripheral cylindrical portion 72 a of the inner rotor main body 72 via a cylindrical yoke 63. The yoke 63 forms a magnetic path, and is attached to the outer peripheral cylindrical portion 72a of the inner rotor body 72 via a yoke set screw 64.
As shown in FIG. 4, the magnet 6 is installed inside a yoke (magnetic path) 63 and is magnetized in the radial direction. The yoke 63 is installed inside the inner rotor body 72. Since the surface magnet type outer rotor type magnet is less likely to fall off due to centrifugal force or the like than the inner rotor type magnet, a drop preventing ring is often unnecessary. Thus, the magnet 6 can be closer to the stator core 51 in the radial direction. For this reason, the maximum torque to be generated also increases.

Next, the relationship among the inner rotor body 72, the cam 73, and the cam follower 75 will be described.
Inside the inner rotor main body 72, three magnets 6 and a yoke (magnetic path) 63 are provided, and three cam followers 75 are provided on the outer periphery at regular intervals. As shown in FIGS. 1 and 2, the inner rotor main body 72 is pushed in the vicinity of the center by the coil spring 11 and the spring seat 12 in the right direction in the figure. As described above, the three cams 73 and the cam follower 75 are arranged in an equilateral triangle when the motor is viewed from the front.
As a result, the inner rotor body 72 is supported by the outer rotor body 71 (three cam surfaces) so that the tripod stands stably, and stably rotates and slides relative to each other. Positioning of the inner rotor body 72 in the radial direction is performed by the rotary slide bearing 3 fitted with a gap on the motor shaft 4 as shown in FIGS.
The position of the inner rotor body 72 in the rotational direction relative to the outer rotor body 71 changes depending on the magnitude of the load torque received by the motor shaft 4 (integrated with the outer rotor body 71). At this time, the position of the inner rotor body 72 in the motor axial direction also changes with respect to the outer rotor body 71 by the action of the cam 73 and the cam follower 75 provided on the outer rotor body 71 and the inner rotor body 72.
In the example of FIG. 1, the inner rotor body 72 is closest to the outer rotor body 71 when the magnitude of the load torque received by the motor shaft 4 is about 25% or less of the maximum torque. 6 to 9 also show the position of the magnet 6 relative to the stator core 51 when the load torque receives a torque of about 25% or less to 100% or more. 6 to 9, there are four stages from the fastest 4th speed state (see FIG. 6) to the 3rd speed state (see FIG. 7), the 2nd speed state (see FIG. 8) to the 1st speed state (see FIG. 9). Indicates the state. In this case, since the inner rotor body 72 slides steplessly in the axial direction of the motor according to the magnitude of the load torque applied to the motor shaft 4, the overlap margin of the magnet 6 and the stator core 51 changes steplessly. The induced electromotive voltage at these four stages is shown in FIGS. As a result, the motor is automatically variable in a stepless manner.

The operation of the coil spring 11 at this time will be described.
As described above, the coil spring 11 presses the cam follower 75 installed on the outer periphery of the inner rotor body 72 against the cam 73 installed on the outer periphery of the outer rotor body 71. As shown in FIG. 1, the force of the coil spring 11 includes the coil spring 11, the right spring seat 12, the inner ring of the right rotating bearing 3, the rotating sliding bearing 76, the inner rotor body 72, the cam follower 75, the cam 73, and the outer rotor body 71. The power is transmitted to the motor shaft 4, the right shaft retaining ring 22 of the left rotary bearing 2, and the left spring seat 12, and the force returns to the coil spring 11 (the force is closed). Thus, since the force of the coil spring 11 does not act as a thrust force on the rotary bearings 2 and 3 that support the rotation of the motor shaft 4, the force of the coil spring 11 does not directly become the rotational load resistance of the motor shaft 4. As shown in FIG. 3, a plurality of coil springs 11 (six examples are shown in FIG. 3) are arranged around the motor shaft 4. By dividing the coil spring 11 into a plurality of pieces, the spring load can be shared and the wire diameter of the coil spring 11 can be reduced. As shown in FIG. 1, even when the contact length is small, the number of turns of each coil spring 11 can be increased, so that the spring constant can be set in a wider range. Moreover, the utilization efficiency of the space in which the coil spring 11 is installed also increases. The coil spring 11 is supported by counterbore holes provided on the spring seat 12 at both ends. The force of the coil spring 11 is collected by the spring seat 12, and can be transmitted to the next part near the motor shaft 4 by a projection (seat) provided near the motor shaft 4.

  The relationship between the cam 73 and the cam follower 75 will be described with reference to FIGS. 5B and 14A, 14B, 14C, and 12D. The cam 73 is formed on the outer periphery of the outer rotor body 71 as viewed from the front of the motor. Are arranged on the outer peripheral portion of the inner rotor body 72 so as to be equilateral triangles. The right side of FIGS. 1 and 14 (d) represents a time when the magnitude of the load torque received by the motor shaft 4 is about 25% or less of the maximum torque. At this position, the outer rotor body 71 and the inner rotor body 72 are closest to each other. At the lowest point 73A, the radius of the contact surface of the cam 73 is slightly increased with respect to the radius of the roller of the cam follower 75 in order to reduce the impact during the movement of the cam 73 and the cam follower 75. 2 and 14 (a) show the case where the magnitude of the load torque received by the motor shaft 4 receives 100% or more of the maximum torque. Also at the uppermost point 73B, the radius of the contact surface of the cam 73 is slightly increased. As shown in FIGS. 5B and 14A, the uppermost point 73B is provided with a stopper 73e. A cam surface 73a connecting the lowest point 73A and the highest point 73B is connected by a curved surface. FIG. 14B shows a time when the load torque is about 75% of the maximum torque. FIG. 14C shows the case where the load torque is about 50% of the maximum torque.

Next, the operation of the outer rotor type variable field motor according to the embodiment of the present invention will be described.
As shown in FIG. 1, the outer rotor 7 is rotated by a rotating magnetic field generated between the stator 5 and the outer rotor 7, and the rotation of the outer rotor body 71 directly connected to the motor shaft 4 is transmitted to the motor shaft 4. A load assembled to the shaft 4 is driven. If the load is an automobile, the rotation of the motor shaft 4 is transmitted to the wheels, and traveling is started. In the outer rotor 7, the rotation of the inner rotor body 72 is transmitted to the outer rotor body 71 via the cam 73 and the cam follower 75, and the motor shaft 4 is driven.
When a load is applied to the motor shaft 4, a displacement due to rotation occurs between the outer rotor body 71 directly connected to the motor shaft 4 and the inner rotor body 72 attached to the rotary slide bearing 76, and the inner rotor The cam follower 75 of the main body 72 rotates along the cam surface 73a of the cam 73 of the outer rotor main body 71 to move the inner rotor main body 72 in the axial direction. The inner rotor body 72 sequentially moves from FIG. 6 to FIG. 9 against the urging force of the coil spring 11. Waveforms of the induced electromotive voltage at this time are shown in FIGS.
As shown in FIGS. 6 to 9, the induced electromotive force constant (torque constant) is changed by changing the relative overlap of the stator core 51 and the magnet 6 by the coil spring 11, the cam 73, and the cam follower 75. The characteristics of the motor (the inclination of the TN line in FIG. 16) are changed.
In this way, the outer rotor type brushless motor that automatically changes (changes speed) in accordance with the magnitude of the load torque in the forward and reverse rotation directions by the coil spring 11, the cam 73, and the cam follower 75 shown in FIG. Functions and structures can be formed.

During regenerative braking, the variable field is automatically generated according to the magnitude of the load torque (here, according to the magnitude of the braking torque). Even when the motor rotates at a low speed, as shown in FIGS. 6 to 9, the variable field is automatically generated and the induced electromotive force constant is changed from FIG. 10 to FIG. Since it becomes large as shown, the effect of regenerative braking becomes larger. Therefore, the regenerative power can be collected more effectively.
The thrust load by the coil spring 11 is not applied to the rotary bearings 2 and 3 that support the motor shaft 4. Thus, there is no increase in rotational resistance due to the addition of the variable field function.
Since the inertia (moment of inertia) of the inner rotor main body 72 is small, the variable field function at the time of start-up is quick. As a result, when the motor is started, even if the load torque applied to the motor shaft 4 is large and the rise of the rotation of the outer rotor body 71 is delayed, the variable field effect appears more quickly, and the torque constant increases more rapidly. The rise of the axis 4 becomes faster.

As shown in FIG. 1, an open-type outer rotor brushless motor that automatically changes the field torque according to the magnitude of the load torque in both the forward and reverse rotation directions has an outer rotor 7 and a stator 5 with an open-type structure. Therefore, the effect of air cooling is high.
Since only the inner rotor body 72 slides in the motor axial direction inside the motor, the total length of the motor does not change.
By covering or molding the stator core 51, the substrate 8, the magnet 6 and the yoke (magnetic path) with a resin, environmental resistance such as drip-proofing is improved.
By providing the outer rotor body 71 and the inner rotor body 72, the so-called variable field function is realized by a method of changing the overlap margin (in the motor axis direction) between the outer rotor 7 and the stator 5, while the stator 5 also has the outer rotor body 71. Is not moved (in the motor axis direction).
Functional components such as the motor shaft 4, the coil spring 11, the sliding bearing 10, the stator core 51, the magnetic sensor 14 for detecting the rotational position of the inner rotor body 72, the magnet 6, the yoke (magnetic path) 63, the cam follower 75, the cam 73, and the like in the radial direction. The outer rotor brushless motor structure that is flat and has high torque is realized by overlapping the arrangement.

FIG. 15 shows a sealed outer rotor type variable field motor according to another embodiment of the present invention. The same parts as those in FIG. 1 and FIG. Will be omitted.
The upper half of FIG. 15 represents the time when the magnitude of the load torque received by the same motor shaft 4 as in FIG. 1 is about 25% or less of the maximum torque. The lower half of FIG. 15 represents the time when the magnitude of the load torque received by the same motor shaft 4 as in FIG. 2 is 100% or more.
The motor main body 1 includes a motor main body front portion 16 and a motor main body rear portion 17, and a sealed motor is configured by fastening the outer peripheral cylindrical portion 16 a and the outer peripheral cylindrical portion 17 a provided on the outer peripheral portion with screws 18. . The motor main body rear portion 17 is provided with a boss portion 17b in the central portion, and a rotary bearing 32 is disposed in the boss portion 17b to create a sealing structure.
As described above, the sealed motor has the same basic performance and function as the open motor shown in FIG. 1, and the motor body 1 has a sealed structure. Is expensive.

According to the outer rotor type variable field motor according to the above embodiment, the variable field is automatically variable according to the magnitude of the load torque in both the forward and reverse rotation directions. High torque can be output at startup even during reverse (reverse rotation).
Also during regenerative braking, variable field is automatically generated according to the magnitude of the load torque (in this case, braking torque). For this reason, regenerative electric power can be more effectively collected even in a state of low speed rotation.
Further, since the outer rotor body 71, the inner rotor body 72, the stator 5, the spring 11, and the motor shaft 4 are arranged in the radial direction and the thickness portion is formed in a flat shape, a high torque is generated at the time of startup. Moreover, high speed rotation is possible by variable field.
Furthermore, since the open motor has a high air cooling effect and is light, the output per weight can be increased.
On the other hand, since the sealed motor has high environmental resistance, it can be used in places where use conditions are severe, such as an electric vehicle and an electric motorcycle.
Further, since only the inner rotor main body 72 slides in the motor axial direction inside the motor during the variable field, the total length of the motor does not change even during the variable field. Little change in the center of gravity of the motor.
Further, since the stator coil 53 does not slide (movable) in the motor axial direction during the variable field, the electric wire 13 does not bend and fatigue.
Furthermore, the force of the spring 11 for creating a function of automatically changing the field according to the magnitude of the load torque is closed in the rotor 7. That is, the force of the spring 11 does not act as a thrust force on the rotary bearings 2 and 3 that support the rotation of the motor shaft 4. Therefore, since the force of the spring 11 does not become a direct rotational load resistance of the motor shaft 4, it does not cause a loss of the motor.

Note that the present invention is not limited to the above-described embodiment, and the outer rotor type variable field motor is not limited to an electric vehicle or an electric motorcycle. It can also be used for loads. In the above-described embodiment, the case where three sets of cams 73 and cam followers 75 are used has been described, but three or more sets of cams 73 and cam followers 75 such as four sets, five sets, and six sets may be used. Corresponding to this, the rotational position detecting magnetic sensors 14 of the inner rotor main body 72 can also be used in four sets, five sets, six sets, and the like. Further, FIGS. 6 to 9 show the relationship between the position of the magnet and the cam when the load torque is about 25% to 100% in the outer rotor type variable field motor. By doing so, the magnitude of the load torque can be arbitrarily set within a range narrower than about 25% to 100%, for example, about 30% to 80%, or about 40% to 90%, for example. .
In addition, it goes without saying that the present invention can be appropriately modified and implemented within a range that does not change the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Motor body 1a Cylindrical part 2 Rotating bearing 3 Rotating bearing 4 Motor shaft 5 Stator 6 Magnet 7 Outer rotor 8 Substrate 9 Screw 10 Sliding bearing 11 Coil spring 12 Spring seat 13 Electric wire 14 Rotation position detection magnetic sensor 15 Vent 16 Front of motor body Part 17 Motor body rear part 18 Screw 53 Stator coil 63 Yoke (magnetic path)
71 Outer rotor body 72 Inner rotor body 73 Cam 74 Cam follower shaft 75 Cam follower 76 Rotating sliding bearing

Claims (5)

In an outer rotor type variable field motor that performs a variable field by sliding an outer rotor arranged radially outside the stator with respect to the stator in the motor axial direction,
The outer rotor has a split structure of an inner rotor body that slides in the motor axial direction and an outer rotor body,
A magnet is mounted on the inner surface side of the outer peripheral cylindrical portion of the inner rotor body, and
A cam follower is disposed on the outer peripheral cylindrical portion of the inner rotor body , and an axial cam surface is formed on the outer peripheral cylindrical portion of the outer rotor main body. The cam surface is applied to the cam follower according to a load applied to the motor shaft. The outer rotor type variable field motor is characterized in that the outer rotor is slidable in the motor axial direction with respect to the stator.   The sliding movement of the outer rotor in the motor axial direction is the axial position of the inner rotor body that slides in the motor axial direction by a cam surface provided in the outer rotor body and a resilient mechanism arranged in parallel with the motor shaft. The outer rotor type variable field motor according to claim 1, wherein the outer rotor type variable field motor is controlled.   3. The outer rotor type variable field motor according to claim 1, wherein a plurality of the cam followers that move along a cam surface of the cam of the outer rotor main body are arranged in the inner rotor main body.   4. The outer rotor type variable field motor according to claim 1, wherein the cam surface has a substantially V shape with a valley in the motor axial direction. 5.   5. The outer rotor type variable according to claim 4, wherein the cam surface shape is provided with a stopper structure for locking the cam follower at an uppermost point of a substantially V shape having a valley in the motor shaft direction. Field motor.

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