JP2002356190A - Power-assisted bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain large output torque without a speed reducer by a motor incorporated in a rear wheel and to reduce magnetic friction at the time of non-energization. SOLUTION: A motor of a brush-less structure incorporated in the rear wheel has the following structure. The motor is provided with a rotor core 321 made of magnetic substance and integrated with a hub of the rear wheel and a stator 38 disposed opposite to the rotor core. The rotor core 321 is provided with a plurality of openings arranged in the circumferential direction of the rear wheel In the openings, magnets 351 (N, S) are symmetrically arranged with a void 322D in the central area. In the magnet, voids 322E, 322F are formed in a part on the stator 38 side. A commutating pole part 323 is formed between the opening, respectively, by the rotor core 321. Among the magnetic fluxes of the magnets, the magnetic flux passing a bridge-like part 322BR between the voids 322D and 322E is contributed to the generation of torque, thereby reducing magnetic friction. Increase of torque can be obtained by action of the commutating pole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric assisted bicycle, and more particularly, to an electric assisted bicycle capable of minimizing a motor as an auxiliary driving source and reducing magnetic friction of the motor to enable light driving. About assistive bicycle.

[0002]

2. Description of the Related Art A manual drive system for transmitting a force applied to a pedal by human power, that is, a treading force to a rear wheel, and a motor drive system capable of adding auxiliary power to the human drive system in accordance with the treading force are provided. Electric assisted bicycles are known. Patent Publication 2829808 discloses an electric assist bicycle in which a motor, which is an auxiliary drive source of a motor drive system, is incorporated in a hub of a rear wheel. In this electrically assisted bicycle, when the motor does not assist, such as on a downhill, the rotation of the magnetic poles is stopped, while the rotation of the armature is maintained with the rotation of the rear wheel, so the motor acts as a generator. The current is supplied to the battery by the regenerative operation.

[0003]

In the above-described electric assisted bicycle, even when the vehicle is not performing a regenerative operation, such as during high-speed running,
Since the armature rotates together with the rear wheel, magnetic friction is generated. Generally, when the torque of the motor is increased, the magnetic friction increases. Therefore, simply trying to reduce the magnetic friction cannot increase the motor torque as desired. Therefore, in the electric assisted bicycle disclosed in the above publication, a torque reduction is provided by providing a speed reduction mechanism. However, since the structure is inevitably complicated and large, an improvement measure is desired.

An object of the present invention, in view of the above problems, is to provide a motor-assisted bicycle which can reduce the magnetic friction without losing a large torque and can simplify and reduce the structure.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an electric assisted bicycle in which a motor for assisting human-powered driving force is incorporated in wheels, wherein the motor has a brushless structure. A rotor core made of a magnetic material integral with a hub of the wheel; and a stator disposed opposite to the rotor core, the rotor core having an opening in an axial direction of the wheel, and a predetermined interval in a circumferential direction of the wheel. Are formed, a plurality of openings are formed, a permanent magnet is accommodated in the opening with a gap at both ends in the circumferential direction of the wheel, and a complementary pole is provided between the openings by the rotor core. And the polarity of the permanent magnet is
The first feature is that the difference is made between adjacent openings.

Further, the present invention is characterized in that the permanent magnets accommodated in the opening are distributed in the circumferential direction of the wheel with an air gap at the center in the opening, and the permanent magnet and the opening A second feature resides in that a gap is also formed in a part of the stator side between the inner circumference and the inner circumference.

[0007] According to the first feature, the air gap formed at both ends of the permanent magnet can reduce the leakage flux to the auxiliary pole and reduce the magnetic flux orthogonal to the air gap between the rotor core and the stator. Can be increased. Therefore, the generated torque of the motor can be increased.

According to the second feature, while the magnetic flux is increased by the auxiliary pole, the magnetic path from the permanent magnet toward the stator is narrowed by the partial gap of the permanent magnet provided on the stator side. Strong magnetic force is weakened, and excessive magnetic friction during high-speed running is reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a side view of the electric assist bicycle including the control device according to the embodiment of the present invention. A body frame 1 of the electric assist bicycle includes a head pipe 2 located in front of the vehicle body, a down pipe 3 extending rearward and downward from the head pipe 2, a rear fork 4 connected to the down pipe 3 and extending rearward, and a down pipe 3 And a seat post 5 that rises upward from the lowermost end of the seat post.

A front fork 6 is rotatably supported by the head pipe 2. A front wheel 7 is pivotally supported at a lower end of the front fork 6, and a steering handle 8 is attached to an upper end of the front fork 6. The steering handle 8 is provided with a brake lever 9, and a cable 10 drawn from the brake lever 9 is connected to a front wheel brake 11 fixed to the front fork 6. Similarly, a brake lever for a rear wheel brake is also provided on the steering handle 8, but is not shown. The brake lever 9 is provided with a brake sensor (not shown) for detecting that the brake lever 9 has been operated.

A pair of left and right stays 12 connected to the upper end of the seat post 5 extend rearward and downward, and are connected to the rear fork 4 near the lower end. A rear wheel 13 is supported by a member formed by connecting the rear fork 4 and the stay 12, and a motor 14 is supported by the member and coaxial with a hub of the rear wheel 13 as an auxiliary power source. As the motor 14, a three-phase brushless motor having high torque and low friction is preferable. The specific structure and control of the motor 14 will be described later.

A support shaft 16 having a seat 15 at the upper end is mounted on the seat post 5 so that the height of the seat 15 can be adjusted. Seat post 5 and rear wheel 1 below seat 15
3 and a battery 17 for supplying electric power to the motor 14.
Is provided. The battery 17 is held by a bracket 18 fixed to the seat post 5. A power supply 19 is provided on the bracket 18. The power supply 19 is connected to the motor 14 by an electric wire (not shown), and is connected to the battery 1.
7 electrodes. The upper part of the battery 17 is supported by the seat post 5 with a fastener consisting of a band 20 and a buckle fitting 21.

At the intersection of the down pipe 3 and the seat post 5, a crankshaft 22 extending to the left and right of the vehicle body is supported, and a pedal 24 is connected to the crankshaft 22 via a crank 23. A drive sprocket 25 is connected to the crankshaft 22 via a pedal force sensor (not shown), and the pedal force applied to the pedal 24 is transmitted to the drive sprocket 25 via the pedal force sensor. Drive sprocket 25
A chain 27 is stretched between the driven sprocket 26 and the driven sprocket 26 provided on the hub of the rear wheel 13. The tight side of the chain 27 and the drive sprocket 25 are covered with a chain cover 28. The crankshaft 22 is provided with a rotation sensor for the crankshaft 22 (not shown). As the rotation sensor, a known sensor such as a sensor used for detecting crankshaft rotation of an automobile engine can be used.

Next, a description will be given of a pedaling force detecting device mounted on the crankshaft 22. FIG. 3 is a cross-sectional view of the vicinity of the crankshaft 22, and FIG. 4 is a view taken in the direction of arrows AA in FIG. Ball bearings 102L, 10R are provided between caps 101L, 101R screwed into both ends of the support pipe 100 fixed to the down pipe 3 and a step formed on the crankshaft 22.
2R are respectively inserted and rotatably support the crankshaft 22.

At the left and right ends of the crankshaft 22, bolts 10
The cranks 23 are respectively fixed by nuts 103C conforming to 3B (only the right side is shown). The inner ring 105 of the one-way clutch 104 is fixed between the crank 23 and the support pipe 100. A drive sprocket 25 is rotatably supported on the outer periphery of the inner ring 105 via a bush 105A. The position of the drive sprocket 25 in the thrust direction is regulated by the nut 106A and the plate 106B.

A cover 107 is provided integrally with the drive sprocket 25, and a transmission plate 108 is provided in a space surrounded by the drive sprocket 25 and the cover 107.
Are arranged. The transmission plate 108 is coaxial with the drive sprocket 25 and is supported so that a predetermined amount of displacement is allowed in the rotation direction about the crankshaft 22.

Drive sprocket 25 and transmission play 1
A plurality of (here, six) windows 109 are formed so as to straddle 08, and compression coil springs 110 are housed inside the windows 109, respectively. Compression coil spring 1
10 is a drive sprocket 25 and a transmission plate 108
In the case where there is a shift in the rotational direction between them, they act to generate a drag against the shift.

A ratchet tooth 11 as an outer ring of the one-way clutch 104 is provided on the inner periphery of the hub of the transmission plate 108.
The ratchet teeth 111 are engaged with a ratchet pawl 113 supported by the inner ring 105 and radially urged by a spring 112. The one-way clutch 104 is provided with a cover 114 for dust prevention.

The transmission plate 108 is provided with a locking hole 116 with which a treading force transmitting projection 115 fixed to a treading force transmitting ring 124 is engaged. Drive sprocket 25
Is provided with a window 117 through which the projection 115 can be engaged with the locking hole 116, and the projection 115 penetrates the window 117 and is fitted into the locking hole 116.

A plurality (three in this case) of small windows other than the window 109 are formed over the drive sprocket 25 and the transmission plate 108, and a compression coil spring 118 is provided inside each of the small windows. Will be accommodated. The compression coil spring 118 moves the transmission plate 108 in its rotation direction 11.
It is arranged so as to urge to the 9 side. That is, the transmission plate 108 acts in a direction to absorb backlash at the connection portion between the drive sprocket 25 and the transmission plate 108.
Functions to be transmitted to the drive sprocket 25 with good responsiveness.

A sensor portion (pedal force sensor) 47 of a pedal force detecting device is mounted on the drive sprocket 25 near the vehicle body, that is, on the down pipe 3 side. The pedal force sensor 47 includes an outer ring 120 fixed to the drive sprocket 25,
A sensor main body 121 is provided rotatably with respect to the outer ring 120 and forms a magnetic circuit.

The outer ring 120 is formed of a material having electrical insulation, and is fixed to the drive sprocket 25 with bolts (not shown). A cover 122 is provided on the outer ring 120 on the drive sprocket 25 side, and is fixed to the outer ring 120 with a set screw 123.

FIG. 5 is an enlarged sectional view of the sensor main body 121. A coil 125 is provided concentrically with the crankshaft 22, and a pair of cores 126 disposed on both axial sides of the coil 125 and projecting in the outer circumferential direction of the coil 125.
A, 126B are provided. Further, the cores 126A,
Between the 126B, a cyclic first derivative 127 and a second derivative 128 are provided. First derivative 127 and second derivative 1
28 is configured to be displaceable in the circumferential direction with respect to each other in accordance with the treading force transmitted from the treading force transmission ring 124, and the displacement is configured to change the amount of overlap between the cores 126A and 126B. You. As a result, when the coil 125 is energized, the magnetic flux of the magnetic circuit including the cores 126A and 126B and the core collar 129, and the first and second inductors 127 and 128 changes according to the pedaling force. Thus, the coil 12 which is a function of this magnetic flux
5, the pedaling force can be detected. In FIG. 5, reference numerals 130 and 131 denote support members for the sensor main body 121, reference numeral 132 denotes a bearing,
Reference numeral 133 denotes a lead wire drawn from the coil 125.

The above-described pedal force sensor is described in further detail in the specification of a prior application (Japanese Patent Application No. 11-251870) filed by the present applicant. The treading force sensor is not limited to the one having the above-mentioned structure, and a known sensor may be used.

FIG. 1 is a sectional view of the motor 14. A cylinder 30 incorporating a transmission is supported by a shaft 31 on a plate 29 projecting rearward from a joint between the rear end of the rear fork 4 and the lower end of the stay 12. A wheel hub 32 is fitted on the outer periphery of the cylinder 30. The wheel hub 32 is an annular body having an inner cylinder and an outer cylinder, and the inner peripheral surface of the inner cylinder abuts the outer periphery of the cylinder 30. Wheel hub 3
2 has a connecting plate 33 projecting from the cylinder 30.
Are fixed by bolts 34. Neodymium magnets 35 constituting the rotor-side magnetic poles of the motor 14 are arranged at predetermined intervals on the inner periphery of the outer cylinder of the wheel hub 32. That is, the outer cylinder forms a rotor core holding the magnet 35.

A bearing 3 is provided on the outer periphery of the inner cylinder of the wheel hub 32.
6 are fitted, and the stator support plate 3
7 are fitted. A stator 38 is arranged on the outer periphery of the stator support plate 37 and is attached by bolts 40.
The stator 38 is arranged so as to have a predetermined gap with the rotor core, that is, the outer cylinder of the wheel hub 32, and a three-phase coil 39 is wound around the stator 38.

An optical sensor 41 is provided on a side surface of the stator support plate 37. When the wheel hub 32 rotates, the optical path of the optical sensor 41 is intermittently interrupted by the ring-shaped member 42 provided on the wheel hub 32, and as a result, a pulse waveform signal is output. The ring-shaped member 42 has a regular rectangular tooth shape so that the optical path of the optical sensor 41 can be intermittently interrupted during rotation. A position signal of the wheel hub 32 as a rotor is detected based on the pulse waveform signal. The optical sensors 41 are provided at three places corresponding to each phase of the motor 14 and function as a magnetic pole sensor and a rotation sensor of the motor 14.

A control board 43 is provided on a side surface of the stator support plate 37, and the optical sensor 4 as a magnetic pole sensor is provided.
The energization control to the three-phase coil 39 is performed in accordance with the position signal from 1. On the control board 43, control elements such as a CPU and an FET are mounted. The control board 43 can be integrated with the mounting board for the optical sensor 41.

A spoke 44 connected to a rim of a rear wheel (not shown) is fixed to the outer periphery of the wheel hub 32. Further, a bracket 46 is fixed to the stator support plate 37 on a side opposite to the side on which the control board 43 and the like are mounted by bolts 45, and the bracket 46 is connected to the plate 29 of the vehicle body frame by bolts (not shown). You.

The wheel hub 32 is provided with a window in which a transparent resin (clear lens) 32A is fitted, and the fixed cover 37A fixed to the stator support plate 37 is also provided with a window in which the clear lens 37B is fitted. Can be The clear lenses 32A and 37B allow the inside of the motor 14 to be seen from the outside, so that a special aesthetic effect can be obtained, and the wheel hub 32 and the fixed cover 37A can be obtained.
Can be obtained by reducing the weight by partially forming the resin.

As described above, the three-phase brushless motor 14 including the stator and the rotor arranged coaxially with the shaft 31 of the rear wheel 13 is provided, and adds to the human power transmitted by the chain 17 and the driven sprocket 26. Generates auxiliary power. Needless to say, the motor 14 may be provided on the front wheels.

FIG. 6 is a sectional view of a main part of the motor 14 taken along a plane perpendicular to the shaft 31, FIG. 7 is a front view of a rotor core holding the magnet 35, FIG. 8 is an enlarged view of the main part of the rotor core, and FIG. It is a principal part enlarged view of the rotor core of the state hold | maintained. As described above, the motor 14 of the present embodiment includes the stator 38,
And a wheel hub 32 as an outer rotor that rotates on the outer periphery of the stator 38.

Rotor core 321 holding magnet 35
Has an annular shape, and is inserted into the inner periphery of the outer cylindrical portion of the outer rotor 32. The rotor core 321 is formed by laminating silicon steel thin plates, and is provided with a total of 12 openings (slots) 322 at intervals of 30 ° in the circumferential direction. The magnet 35 inserted into the opening 322 is made of ferrite, and N poles (35N) and S poles (35S) are alternately arranged. The space between the adjacent openings 322 functions as the auxiliary pole 323. As shown in FIGS. 6 and 9, the magnet 35 has a thick (middle convex) drum-shaped cross section at the center.

The stator 38 includes a rotor core 321.
Similarly to the above, it is configured by laminating silicon steel thin plates, and includes a stator core 381 and stator salient poles 382. Each stator salient pole 382 has a stator winding 383 (a three-phase coil 39).
) Is wound in a monopolar centralized manner.

The shape of the opening 322 is not the same as the cross-sectional shape of the magnet 35. When the magnet 35 is inserted into the opening 322, the first gap 322A is formed on both sides along the circumferential direction of each magnet 35. Are formed, and a second gap 322B is formed on both ends of each magnet 35 on the side of the stator 38 (see FIGS. 6 and 9).

Next, the operation of the gaps 322A and 322B of the opening 322 formed between the magnet 35 and the magnet 35 will be described with reference to FIGS. FIG. 10 is a diagram illustrating a magnetic flux density distribution when power is supplied from the battery 17 to the motor 14, and FIG. 11 is a diagram illustrating a magnetic flux density distribution when the motor 14 is operated to perform regenerative operation.

When an exciting current is supplied from the battery 17 to each stator winding 383 through the control board 43,
As shown in FIG. 0, the stator salient pole 38 excited to the N pole
The magnetic lines of force generated in the radial direction from 2N pass through the stator-side surface of the S-pole magnet 35S toward the back surface, that is, in the outer circumferential direction, and most of the outer lines 3 of the wheel hub (outer rotor) 32.
The stator salient pole 382S excited to the adjacent S pole via the 2B and the auxiliary pole portion 323, and returns to the stator salient pole 382N excited to the N pole via the stator core 381.

At this time, since the first gaps 322A are formed on both sides along the circumferential direction of the magnet 35, the magnetic flux leaking from the side of each magnet 35 to the auxiliary pole 323 is reduced. Most of the lines of magnetic force are transmitted from the magnet 35 to the outer rotor 32.
And reaches the stator 38 via the auxiliary pole portion 323. As a result, the rotor core 321
Since the vertical component of the magnetic flux passing through the air gap between the motor and the stator salient pole 382 increases, the generated torque can be increased as compared with the case where the first air gap 322A is not provided. Furthermore, the rotor core 3 is formed by the second gap 322B.
Since the magnetic path along the inner circumference of the rotor 21 is restricted, the leakage magnetic flux passing through the inner circumference of the rotor core 321 also decreases.

FIG. 12 is an enlarged schematic view of the magnetic field lines in FIG. In FIG. 12, the magnetic flux B1 from the auxiliary pole 323 toward the stator salient pole 382S is
Due to one of the 22Bs 3220B, the leakage along the inner circumference 324 of the rotor core 321 (the portion indicated by the dotted line) is reduced,
The magnetic flux B1 is efficiently guided to the stator salient pole 382S.
Further, the other (3221B) of the second gap 322B prevents the magnetic flux B2 passing from the magnet 35N through the inner circumference 324 of the rotor core 321 from leaking to the auxiliary pole portion 323 side.
2 acts to efficiently lead to the stator salient pole 382S. As a result, the vertical component of the magnetic flux passing through the air gap between the rotor core 321 and the stator 38 further increases,
It is possible to further increase the driving torque as a motor.

On the other hand, when the motor 14 performs a regenerative operation,
As shown in FIG. 11, the magnetic flux generated from each magnet 35 forms a closed magnetic path together with the salient stator poles and the stator core, so that a generated current corresponding to the rotation speed of the rotor can be generated in stator winding 383.

A regulator for limiting the regenerative voltage of the motor 14 to a predetermined value is provided. When the regenerative voltage reaches a regulated voltage (for example, 14.5 V) of the regulator, an output control circuit (described later) of the motor 14 is provided. Power F
Of the ETs, the one on the ground side can be short-circuited.
As a result, a short-circuit current flows through each stator winding 383 in a delayed phase, the lines of magnetic force passing through the stator 38 decrease, and the leakage magnetic flux connecting the adjacent magnets 35 increases, so that the magnetic friction of the motor 14 decreases. .

FIG. 13 is an enlarged schematic view of the magnetic field lines in FIG. In FIG. 13, adjacent magnets 35S,
35N, the magnetic flux B3 passing through the outer circumferential portion 325 of the rotor core 321 and the auxiliary pole portion 323 of the rotor core 321
And the inner peripheral portion 32 of the rotor core 321
4 and a magnetic flux B6 passing through the inner circumferential portion 324 of the rotor core 321, the air gap, and the stator salient pole 382N.

As described above, according to the present embodiment, in the motor 14 having the auxiliary pole portion 323 between the magnets 35 held by the rotor core 321,
1, the air gaps 322A and 322B are provided, so that the leakage magnetic flux between the adjacent magnets 35 decreases, and the rotor core 32
The magnetic flux perpendicular to the air gap between the stator 1 and the stator 38 increases. Therefore, the torque generated by the motor 14 can be increased, and the increase in magnetic friction when the motor 14 performs regeneration can be prevented.

FIG. 14 is a front view of a rotor core according to a second embodiment of the present invention, and FIG. 15 is an enlarged view of a main part of the rotor core holding a magnet. The same reference numerals as those in FIGS. Part. In the second embodiment, the rotor core 32
One opening 322 has a substantially trapezoidal shape, and a magnet 35 having a rectangular cross section is inserted into the opening 322. On the short side of the magnet 35 having a rectangular cross section, an adjacent magnet 3
A first gap 322A for preventing magnetic flux leakage between the five gaps is formed. In addition, in order to limit the magnetic path along the inner peripheral side of the rotor core 321 at the corner of the magnet 35 on the stator side,
The second gap 322B is formed.

FIG. 16 is a front view of a rotor core according to a third embodiment of the present invention, and FIG. 17 is an enlarged view of a main part of the rotor core holding a magnet. The same reference numerals as those in FIGS. Part. In the third embodiment, the rotor core 32
One opening 322 is shaped like a drum, and the opening 322
A magnet 35 having a drum-shaped (middle protruding) cross section is fitted therein. On both sides of the magnet 35 in the circumferential direction of the rotor core 321, first air gaps 32 larger than those of the above-described embodiments for preventing magnetic flux leakage between adjacent magnets 35.
2A is formed. Further, a second gap 322B is formed at a corner of the magnet 35 on the stator side to limit a magnetic path along the inner peripheral side of the rotor core 321.

FIG. 18 is a front view of a rotor core according to a fourth embodiment of the present invention, and FIG. 19 is an enlarged view of a main part of the rotor core holding a magnet. The same reference numerals as those in FIGS. Part. In the fourth embodiment, the rotor core 32
One opening 322 has an irregular shape in which notches are provided on both sides of the drum-shaped portion, and a magnet 35 having a drum-shaped cross section is inserted into the opening 321. On both sides of the magnet 35 in the circumferential direction of the rotor core 321, first gaps 322 </ b> A for preventing leakage magnetic flux between adjacent magnets 35 are formed. Also,
A second gap 322 </ b> B is formed at the stator side corner of the magnet 35 in order to restrict a magnetic path along the inner peripheral side of the rotor core 321. In the fourth embodiment, the first gap 322A
And the second gap 322B are integrally connected, and the second gap 32
2B has a relatively large size.

FIG. 20 is a front view of a rotor core according to a fifth embodiment of the present invention, and FIG. 21 is an enlarged view of a main part of a rotor core 321 holding magnets. It is an equivalent part. In the fifth embodiment, the opening 322 of the rotor core 321 has an irregular drum shape, and the magnet 35 having a drum-shaped cross section is inserted into the opening 322.
On both sides of the magnet 35 in the circumferential direction of the rotor core 321, first gaps 322 </ b> A for preventing leakage magnetic flux between adjacent magnets 35 are formed.

Further, in the fifth embodiment, a notch 322C extending toward both corners of the magnet 35 from the inner peripheral side of the rotor core 321 is formed instead of the second gap 322B. The notch 322C can limit the magnetic path along the inner peripheral side of the rotor core 321 and has the same function as the second gap 322B.

FIG. 22 is a front view of a rotor core according to a sixth embodiment of the present invention, and FIG. 23 is an enlarged view of a main part of a rotor core holding a magnet. The same reference numerals as those in FIGS. Part. In the sixth embodiment, the rotor core 32
One opening 322 is shaped like a drum, and the opening 322
A drum-shaped magnet 35 having a cross section is fitted therein. On both sides of the magnet 35 in the circumferential direction of the rotor core 321, first gaps 322 </ b> A for preventing leakage magnetic flux between adjacent magnets 35 are formed. Further, a second gap 322B for limiting a magnetic path along the inner peripheral side of the rotor core 321 is formed at a corner of the magnet 35 on the stator side.

FIG. 24 is a front sectional view of a main part of a motor 14 according to a seventh embodiment of the present invention. The same reference numerals as in FIG. 6 denote the same or equivalent parts. In the seventh embodiment, the magnet held by the rotor core 321 is separated into two parts. In other words, a plurality of sets (8 sets) are formed at intervals of 45 ° along the circumferential direction of the rotor core 321 as two sets of magnets having the same polarity.
Be placed. For example, in FIG. 24, the magnets 351S,
Attention is paid to 352S. The two magnets 351S and 352S having a rectangular cross-section have the same polarity (S-pole), and both are neodymium magnets. Both magnets 351S and 3
A third gap 322D is provided between 52S,
On the stator 38 side of both magnets 351S and 352S,
Fourth gaps 322E and 322F are formed respectively. The third gap 322D of the magnet 351S and the magnet 352S is biased toward the outer periphery of the rotor core 321. In addition,
The provision of the auxiliary pole portion 323 between a plurality of sets of magnets is the same as in each of the above-described embodiments.

The manner of forming the magnetic flux by the above configuration will be described. Since neodymium magnets are very powerful, in order to reduce magnetic friction, of the magnetic flux from each magnet,
What passes through the bridge-like portion 322BR between the third gap 322D and the fourth gap 322E contributes to torque generation. For example, the magnetic flux B10 from the N-pole magnets 351N and 352N passes through the bridge portion 322BR, passes through the air gap between the rotor core 321 and the stator 38, and reaches the salient stator poles 382Sa and 382Sb. Then, through the salient stator poles 382N, the bridge portions 322BR reach the S pole magnets 351S, 352S. Further, through the S pole magnets 351S and 352S, the back surface (rotor core 321
The magnetic flux B <b> 11 passing through the auxiliary pole portion 323 reaches the stator salient pole 382 </ b> Sb. The S pole magnet 351
Part of the magnetic flux B11 penetrating to the back surface through the S and 352S becomes a leakage magnetic flux (shown by a dotted line) to the adjacent N-pole magnet 351N.

As described above, the N pole magnets 351N, 352N
The lines of magnetic force flowing from the air through the air gap to the stator 38 side are bridge portions 322BR surrounded on both sides by air gaps.
, So there is little magnetic flux. Therefore, the motor 14
However, at the time of high-speed running in which the motor is not energized and has no regenerative action, the magnetic friction can be reduced. On the other hand, motor 1
4, when a current is applied to the magnetic flux (complementary magnetic flux) B11,
The torque is increased.

At the time of regenerative output, as described above, the magnetic flux generated from each magnet forms a closed magnetic path together with the stator salient poles and the stator core, so that a generated current corresponding to the number of rotations of the rotor is generated in the stator winding 383. What can be done is the same as in the previous embodiments.

FIG. 25 is an output control circuit diagram of the motor 14, and FIG. 26 is a diagram showing energization timing and energization duty. In FIG. 25, a full-wave rectifier 71 includes FETs (generally, individual switching elements) 71a, 71b, 71c, 71d, connected to a three-phase stator coil 39.
The FETs 71a to 71f are energized and controlled by a driver 72. The energization duty is set by the duty setting unit 73 based on an instruction supplied from the motor torque calculation unit 64, and is input to the driver 72. The motor torque calculation unit 64 calculates a torque required for the motor 14 based on the vehicle speed, the output of the treading force sensor 47, the number of rotations of the motor 14, and the like, for example, so as to generate a driving force according to the actual running resistance of the vehicle. I do. An example of a method of calculating the required motor torque by the motor torque calculation unit 64 is described in the patent application (Japanese Patent Application No. 2001-553) relating to the control device for the electric assist bicycle previously proposed by the present applicant.
No. 99).

At the drive timing for applying the auxiliary power, an energization duty is supplied from the duty setting section 73 to the driver 72, and the driver 72 energizes the FETs 71a to 71f in accordance with the energization duty, and
7 to supply current. On the other hand, when the regenerative current is generated, the energizing duty is supplied from the duty setting unit 73 to the driver 72 at the regenerative timing shifted by 180 electrical degrees from the drive timing.
Energizes the FETs 71a to 71f in accordance with the energization duty. When the FETs 71a to 71f are energized at the regenerative timing, the current generated in the stator coil 39 becomes FE
The current is rectified at T71a to 71f and supplied to the battery 17.

The drive timing or the regenerative timing is determined by the torque determining section 74 based on the required motor torque T supplied from the motor torque calculating section 64. When the required value T of the motor torque is positive, the energizing timing is set to the drive timing, and when the required value T of the motor torque is negative, the energizing timing is set to the regenerative timing.

In FIG. 26, the FETs 71a to 71f are energized by setting the conduction angle to an electrical angle of 120 degrees. This figure shows the energization timing at the drive timing, and the high-side FETs 71a, 71c, 71e at the regeneration timing.
Is shifted by 180 electrical degrees from this drive timing.

In each of the above embodiments, the motor 14
Is described as an outer rotor type, that is, an external rotation type. However, the present invention is not limited to this case, and is similarly applicable to an internal rotation type motor in which a rotor rotates inside a stator.

FIG. 27 is a front view showing an example in which the motor 14 is transformed into an adduction type, and only the main parts are shown. Motor 1
4 includes a substantially cylindrical stator 90 and a substantially cylindrical rotor 80 rotating inside the stator 90. Both the rotor 80 and the stator 90 are formed by laminating silicon steel thin plates.

A stator winding 92 is wound around each of the stator salient poles 91 of the stator 90. The rotor 80 has twelve openings 811 having a substantially arc-shaped cross section and having a permanent magnet 85 made of neodymium-based material inserted in the axial direction at intervals of 30 degrees in the circumferential direction. . The magnet 85 is arranged such that the swelling side is located at the rotation center of the rotor 80. The space between the adjacent openings 811 functions as an auxiliary pole 813.

Also in this modification, the shape of the opening 811 and the sectional shape of the magnet 85 are not the same, and the opening 811
When the magnets 85 are inserted into the magnets 85, air gaps 812 are formed on both sides along the circumferential direction of each magnet 85.

According to this configuration, when an exciting current is supplied from the battery 17 to each of the stator windings 92, as shown in an enlarged view in FIG.
The magnetic field lines generated from (N) escape from the stator side surface of the S pole magnet 85S to the back surface (outer peripheral side), and most of the
Then, the motor returns to the stator salient pole 91 (N) excited by the N-pole via the stator salient pole 91 (S) excited by the adjacent S-pole via S13.

In this modification, air gaps 812 are formed on both sides of each magnet 85 along the circumferential direction.
Of the magnetic flux from each magnet 85 to the stator 90 via the auxiliary pole portion 813. As a result, the rotor 80
Since the vertical component of the magnetic flux passing through the air gap between the motor and the stator 90 increases, the driving torque can be increased as compared with the case where the air gap 812 is not provided.

On the other hand, when the motor 14 is regenerated,
Since the magnetic flux generated from each magnet 85 forms a closed magnetic path together with the stator salient poles 91 and the core of the stator 90, it is possible to generate a generated current in the stator winding according to the rotation speed of the rotor 80.

Further, a neodymium-based magnet having a strong magnetic force is adopted as the magnet 85, and the arc-shaped magnet 85 is disposed so as to be convex toward the center of rotation, so that the outer surface of the magnet 85 is transferred to the stator 90. Since the direct magnetic force is reduced, the friction when functioning as a generator can be significantly reduced.

[0066]

As is clear from the above description, according to the first or second aspect of the present invention, since a part of the hub of the rear wheel is used as the rotor core of the motor, the rear wheel can be directly driven by the motor. When the vehicle decelerates, the power of the motor can be charged by the regenerative action. Moreover, the motor has a brushless structure, and generates a sufficient torque by the action of the auxiliary pole formed between the permanent magnets accommodated in the rotor core and the gap between the permanent magnets and the rotor core holding the permanent magnets. be able to. Therefore, the rear wheels can be driven by a motor without using a complicated structure such as a speed reduction mechanism.

In particular, according to the second aspect of the present invention, at the time of high-speed operation in which neither motor energization nor regenerative action is performed, magnetic flux can be reduced by leakage magnetic flux passing between the rotor cores. The friction can be reduced at the time of high-speed operation, that is, at the time of non-energization of the motor.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a motor used in a battery-assisted bicycle according to one embodiment of the present invention.

FIG. 2 is a side view of the electric assisted bicycle according to one embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a human-powered driving unit including a treading force detection device.

FIG. 4 is a view as viewed in the direction of arrows AA in FIG. 3;

FIG. 5 is an enlarged sectional view of a main part of FIG. 3;

FIG. 6 is a cross-sectional view of a main part in a plane orthogonal to the axis of the motor.

FIG. 7 is a front view of a rotor core holding a permanent magnet.

FIG. 8 is an enlarged view of a main part of a rotor core.

FIG. 9 is an enlarged view of a main part of a rotor core holding a permanent magnet.

FIG. 10 is a view for explaining the function (at the time of electric power) of a gap provided in the rotor core.

FIG. 11 is a diagram for explaining a function (at the time of regeneration) of a gap provided in the rotor core.

FIG. 12 is an enlarged view of a main part of FIG. 10;

FIG. 13 is an enlarged view of a main part of FIG. 11;

FIG. 14 is a front view of a rotor core of the motor according to the second embodiment.

15 is an enlarged view of a main part in a state where a permanent magnet is fitted into the opening of FIG. 14;

FIG. 16 is a front view of a rotor core of a motor according to a third embodiment.

FIG. 17 is an enlarged view of a main part in a state where a permanent magnet is fitted into the opening of FIG. 16;

FIG. 18 is a front view of a rotor core of a motor according to a fourth embodiment.

19 is an enlarged view of a main part in a state where a permanent magnet is fitted into the opening of FIG. 18;

FIG. 20 is a front view of a rotor core of a motor according to a fifth embodiment.

FIG. 21 is an enlarged view of a main part in a state where a permanent magnet is fitted into the opening of FIG. 20;

FIG. 22 is a front view of a rotor core of a motor according to a sixth embodiment.

FIG. 23 is an enlarged view of a main part in a state where a permanent magnet is fitted into the opening of FIG. 22;

FIG. 24 is an essential part cross-sectional view in a plane orthogonal to the axis of the motor according to the seventh embodiment.

FIG. 25 is a control circuit diagram of a motor.

FIG. 26 is a timing chart showing motor control timing.

FIG. 27 is a front view of a motor according to a modification.

FIG. 28 is an enlarged view of a main part of FIG. 27.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Body frame, 5 ... Seat post, 8 ... Steering handle, 9 ... Brake lever, 14 ... Motor, 1
7 ... battery, 22 ... crankshaft, 24 ... pedal,
27: chain, 32: wheel hub (outer rotor), 35: permanent magnet, 37: stator support plate,
38: stator core, 39: stator coil, 41
... Light sensor, 43 ... Substrate, 47 ... Tread force sensor, 8
0: rotor, 90: stator, 321: rotor core, 322: opening, 322A: first gap, 32
2B: second gap, 323: auxiliary pole portion, 382: stator salient pole, 383: stator winding

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 29/06 H02K 29/06 Z (72) Inventor Kaoru Hatanaka 1-4-1, Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (reference)

Claims (2)

[Claims] 1. A motor-assisted bicycle in which a motor for assisting human-powered driving force is incorporated in a wheel, wherein the motor has a brushless structure, and a magnetic rotor core integrated with a hub of the wheel. The rotor core includes a stator disposed opposite to the rotor core. The rotor core is formed with a plurality of openings that are open in the axial direction of the wheel and are arranged at predetermined intervals in a circumferential direction of the wheel. A permanent magnet is accommodated with a gap at both ends in the circumferential direction of the wheel, and a supplementary pole is formed in the rotor core between the openings, and the polarity of the permanent magnet is adjacent to the opening. A battery-assisted bicycle characterized by being different between clubs. 2. A motor-assisted bicycle in which a motor for assisting a driving force by human power is incorporated in a wheel, wherein the motor has a brushless structure, and a magnetic rotor core formed integrally with a hub of the wheel. The rotor core includes a stator disposed opposite to the rotor core. The rotor core is formed with a plurality of openings that are open in the axial direction of the wheel and are arranged at predetermined intervals in a circumferential direction of the wheel. The permanent magnets arranged in the circumferential direction of the wheel with a gap in the center are accommodated with a gap also in a part of the stator side, and the rotor core is provided between the openings. And a polarity of the permanent magnet is different between adjacent openings.