JP2001071984A - Leg-power detecting device of motor-assisted vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a leg-power regardless of the dimensional accuracy and assembling accuracy of members. SOLUTION: This detecting device is so formed that a transfer plate 40 is rotated via a one-way clutch by operation of a pedal, with this rotation transmitted to a drive sprocket 80 via a spring 56. The misalignment between the transfer plate 40 and the sprocket 80 which matches load on a rear wheel is converted into the misalignment between a first guide and a second guide through a projection 48 and a leg-power transfer plate 5. Depending on the size of the misalignment, the first guide and the second guide change a passage through which magnetic flux produced by a coil passes. Thus, magnetic circuit resistance which matches the leg-power can be detected as the inductance of the coil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pedaling force detection device for an electrically assisted vehicle, and more particularly to a device for detecting a pedaling force based on a change in inductance of a coil, which is suitable for reducing a variation in detection accuracy. The present invention relates to a tread force detection device.

[0002]

2. Description of the Related Art Vehicles, such as bicycles, which are provided with a treading force detecting device for detecting a driving torque, that is, a treading force by human power, and which assist a treading force by energizing an electric motor coupled to a drive system in accordance with the detected treading force. Are known. Various types of pedal force detection devices have been proposed. For example, JP-A-8-9
In the electric bicycle described in Japanese Patent Publication No. 1281, a coil is provided around an axle, and a magnetic member is disposed so as to face a front surface of the coil, that is, a surface orthogonal to the axle. The magnetic member pivots so that the area covering the coil changes according to the pedaling force. When the area where the magnetic member covers the coil changes due to the pivotal movement, the inductance of the coil changes accordingly, and the voltage applied to the coil changes accordingly. By detecting the change in the voltage, the pedaling force can be detected.

[0003]

The electric bicycle described in the above publication has a problem that the detection accuracy of the treading force is low. The magnetic member of the electric bicycle is a plurality of plates provided so as to be pivotable, and the area covering the coil changes by pivoting the plates according to the treading force. However, it is difficult to avoid the dimensional variation of the plate itself, the dimensional variation of the pin for urging the plate and the long hole with which the pin engages, and the variation of the position of the plate in the thrust direction of the pivot. is there. These variations directly affect the resistance of the magnetic circuit generated by the coil, which causes a problem that the detection accuracy of the pedaling force is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pedaling force detection device for an electrically assisted vehicle that can solve the above-described problems and can prevent a reduction in the pedaling force detection accuracy due to variations in the dimensions of components and variations in assembly.

[0005]

In order to achieve the above object, the present invention provides a coil provided concentrically with a rotary shaft to which a human-powered torque for driving a vehicle is applied, and a coil provided on both axial sides of the coil. A pair of guide members extending in the outer circumferential direction of the coil, provided between the guide members,
It is characterized in that a magnetic path resistance variable member that changes the resistance of the magnetic circuit between the guide members according to the change in the torque is provided.

According to the above feature, the magnetic flux generated by the coil passes through the magnetic circuit passing through the guide member and the variable magnetic path resistance member. The magnetic path resistance variable member changes the resistance of the magnetic circuit according to a change in torque applied to a rotating shaft. Therefore, for example, by detecting a change in inductance due to a change in resistance of the magnetic circuit, it is possible to detect a manual torque applied to the rotating shaft.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 3 is a side view of an electric assisted bicycle suitable for applying the pedaling force detection device of the present invention. In the figure, a bicycle frame 67 includes a head pipe 68 located at the front part of the bicycle, a down pipe 69 extending rearward and downward from the head pipe 68, and affixed to the rear end of the down pipe 69, and rises slightly obliquely rearward. Seat post 7
1 is provided. A front fork 72 is supported on the head pipe 68 so as to be steerable, and a front wheel 73 is pivotally supported at a lower end of the front fork 72. Front fork 7
A steering handle 74 is provided at the upper end of 2.

A rear wheel 7 serving as a driving wheel is provided at the rear ends of a pair of right and left rear forks 70 extending rearward from the seat post 71.
8 is supported. A pair of left and right stays 77 is connected to the rear end of the rear fork 70, and the upper end of the stay 77 is connected to the upper part of the seat post 71. The seat post 71 has a support shaft 75 having a seat 76 at the upper end.
Is mounted so that the position of the seat 76 can be adjusted up and down.

At the lower end of the seat post 71, a support pipe (to be described later with reference to FIG. 1) extending to the left and right of the vehicle body is fixed, and a crank shaft 83 is provided through the support pipe and supported by bearings. . A pedal 79 to which pedaling force is applied by a driver is provided at the tip of the crank connected to the crankshaft 83. The crankshaft 83 is provided with a driving sprocket 80 to which rotation of the crankshaft 83 is transmitted via a power transmission device described later, and the rotation of the driving sprocket 80 is transmitted to a driven sprocket 81 on the rear wheel 78 side via a chain 82. You. Behind the driving sprocket 80, a chain 82 for the driving sprocket 80 is provided.
There is provided a tensioner 36 for increasing the winding angle of and for adjusting the tension.

The electric assist unit 86 is suspended by a part thereof being connected to the seat post 71 via a bracket (not shown) and the other part being connected to the down pipe 69 by a bracket 93. An electric auxiliary unit 86 is disposed in front of the crankshaft 83, and an electric sprocket 84 connected to an output shaft of the electric auxiliary unit 86 is engaged with the chain 82 to assist the driving of the driving sprocket 80. I have.

The cover 91 of the chain 82 includes a cover 92A for the electric sprocket 84, a cover 92B for the tension side of the chain 82, and a cover 92C for the drive sprocket 80. These covers are integrally formed. I have. The whole color of the chain cover 91 is not painted in the same color. In particular, a paint color that makes the cover 92C and the cover 92B of the driving sprocket 80 part stand out from the frame 67 can be used. And cover 9
By painting 2A preferably in the same color as the frame 67, the presence of the electric sprocket 84 can be made invisible.

A battery holder 87 is provided on the seat post 71.
Is fixed, and the battery 2 that supplies electric power to the electric auxiliary unit 86 is detachably supported on the battery holder 87. Band 89 for holding the upper part of battery 2 and metal fitting 88 for attaching and detaching band 89
Is provided. The metal fitting 88 is rotatably mounted on the seat post 71, and is configured such that the battery 2 is tightened or loosened by the band 89 depending on the rotating direction of the metal fitting 88. A power supply component 90 is attached below the battery holder 87, and power is supplied from the battery 2 to the electric auxiliary unit 86 through the power supply component 90.

FIG. 4 is a side view of the vicinity of the crankshaft 83 with the chain cover 91 removed. Note that the tensioner 36 shows a modified example different from FIG. In the figure, a tensioner 36 is composed of two small sprockets 37A and 37B supported at the lower end of a bracket 32 fixed to a rear fork 70. These small sprockets 3
The tension of the chain 82 can be set as desired by adjusting the mounting angle of the brackets 7A and 37B with respect to the bracket 32.

Next, a description will be given of a manual driving device mounted on the crankshaft 83. FIG. 1 shows the crankshaft 83
FIG. 2 is a cross-sectional view of the periphery, and FIG. Caps 38L and 38R are screwed into both ends of the support pipe 24 fixed to the down pipe 69, and ball bearings 39L and 39R are provided between the caps 38L and 38R and the step formed on the crankshaft 83, respectively. It is inserted. That is, the ball bearing 39L,
39R rotatably supports the crankshaft 83 by receiving loads in the thrust direction and the radial direction applied to the crankshaft 83.

The left and right ends of the crankshaft 83
A is provided, respectively (only the right side is shown), and is fixed by a nut 83C that fits a bolt 83B formed at the end of the crankshaft 83. On the crankshaft 83, the inner race 42 of the one-way clutch 41 is fixed between the crank 83A and the support pipe 24. A drive sprocket 80 is rotatably supported on the outer periphery of the inner ring 42 via a bush 42A. The position of the drive sprocket 80 in the thrust direction is regulated by the nut 50A and the plate 50B.

A cover 64 is provided integrally with the driving sprocket 80, and a transmission plate 40 is provided in a space surrounded by the driving sprocket 80 and the cover 64. The transmission plate 40 is coaxial with the drive sprocket 80 and is supported so that a predetermined amount of displacement is allowed in the rotation direction about the crankshaft 83.

A plurality of (here, six) windows 54 are formed over the drive sprocket 80 and the transmission plate 40, and the compression coil spring 5 is provided inside the windows 54.
6 are accommodated respectively. The compression coil spring 56 acts so as to generate a resistance to the displacement between the drive sprocket 83 and the transmission plate 40 when the rotational displacement occurs between them.

Ratchet teeth 46 as outer rings of the one-way clutch 41 are formed on the inner periphery of the hub of the transmission plate 40. The ratchet teeth 46 are supported by the inner ring 42 and urged radially by a spring 45. And engage with the ratchet pawl 44. The one-way clutch 41 is provided with a cover 66 for dust prevention.

The transmission plate 40 is provided with a locking hole 52 with which a projection 48 for transmitting the treading force (to be described in detail later) is engaged. The drive sprocket 80 is provided with a window 51 for allowing the projection 48 to engage with the locking hole 52, and the projection 48 penetrates the window 51 and fits into the locking hole 52. Is done.

A plurality of (three in this case) small windows 60 separate from the window 54 are formed so as to extend over the driving sprocket 80 and the transmission plate 40. Inside the small window 60, a compression coil spring 63 is provided. Are accommodated respectively. The compression coil spring 63 moves the transmission plate 40 in its rotation direction 5.
It is arranged so as to urge toward the 8 side. That is, it acts in the direction of absorbing play at the joint between the drive sprocket 80 and the transmission plate, and functions to transmit the displacement of the transmission plate 40 to the drive sprocket 80 with good responsiveness.

The sensor portion 1 of the treading force detecting device is provided on the drive sprocket 80 near the vehicle body, that is, on the down pipe 69 side.
Is installed. The sensor part 1 is a driving sprocket 8
It has an outer ring 2 fixed to 0 and a sensor main body 3 rotatably provided with respect to the outer ring 2 to form a magnetic circuit. The sensor body 3 and its supporting portions, that is, the members 10, 11 and the like will be described later with reference to FIG.

The outer ring 2 is made of a material having electrical insulation properties, and is fixed to the driving sprocket 80 with bolts (not shown). A cover 49 is provided on the outer ring 2 on the drive sprocket 80 side, and is fixed to the outer ring 2 with a set screw 53.

FIG. 14 is a sectional view of the electric auxiliary unit 86. FIG. 15 is a sectional view taken along line BB of FIG. In FIG. 14, a casing 94 of the electric auxiliary unit 86 is connected to the first casing half 95 and forms a first storage chamber 98 between the first casing half 95. It comprises a second casing half 96 and a cover 97 which forms a second storage chamber 99 between the first casing half 95 and is connected to the first casing half 95.

In the second storage chamber 99, the crankshaft 8 is provided.
A drive motor 21 having an axis parallel to 3 is housed, and the drive motor 21 is fixedly supported by the first casing half 95. The output of the drive motor 21 is driven (electrically driven) by a drive sprocket 84 via a reduction roller type reduction gear 100, a reduction gear train 101 and a second one-way clutch 102 in order to assist the pedaling force applied to the pedal 79.
Is transmitted to

Referring also to FIG. 15, the speed reduction roller type speed reducer 100 includes a motor shaft 103 of the drive motor 21.
A bowl-shaped outer ring 85 surrounding the motor shaft 103; and a plurality (three in this case) of deceleration rollers 104, 10 which can roll by contacting the outer surface of the motor shaft 103 and the inner surface of the outer ring 85.
5 and 106, and the drive motor 21
Gear train 1 by quietly reducing the assist power from the vehicle
It performs the function of transmitting to the 01 side.

The motor shaft 103 is connected to the first casing half 9
5 is rotatably supported via a ball bearing 108 on a first cylindrical bearing portion 107 provided in the cylindrical member 5, and protrudes from the second storage chamber 99 toward the first storage chamber 98. Outer ring 85
The motor shaft 103 is disposed in the first storage chamber 98 so as to surround the protruding end of the motor shaft 103 toward the first storage chamber 98, and the center of the closed end of the outer ring 85 is the base end of the output shaft 115. Are coaxially fixed. On the other hand, the second casing half 96 is provided with a cylindrical second bearing 109 corresponding to the tip of the output shaft 115, and the tip of the output shaft 115 is connected to the second bearing via a ball bearing 110. The part 109 is rotatably supported.

The deceleration rollers 104, 105, and 106 are rotatably supported by roller shafts 111, 112, and 113 via needle bearings 116, 117, and 118, respectively. Each roller shaft 111-11 is supported by the first casing half 95.
The other end of 4 is supported by a support plate 119. Support plate 119
Are fastened by screw members 121 to bosses 120 provided integrally with the first casing half 95 between the speed reduction rollers 104 to 106.

Among the speed reduction rollers 104 to 106, the speed reduction rollers 104 and 105 are fixed at a position along the circumferential direction of the motor shaft 103, and the left casing half 95 and the support plate 1 are fixed.
19 are provided in the first casing half 95 so as to fit one ends of the roller shafts 111 and 112 of the reduction rollers 104 and 105 respectively.

Further, among the deceleration rollers 104 to 106,
When the motor shaft 103 rotates, the speed reduction roller 106 frictionally engages with the motor shaft 103 so that the motor shaft 103 and the outer ring 8 are rotated.
5 so that the position along the circumferential direction of the motor shaft 103 can be changed within a limited range so that the first casing half 95 and the support plate 119 can be moved.
Supported by

The first casing half 95 is provided with a bottomed fitting hole 123 into which one end of the roller shaft 113 of the speed reduction roller 106 is fitted.
A spring 124 for urging a pin (not shown) for pressing the pin 13
Is provided. The deceleration roller 106 is a motor shaft 10
It is urged by a spring 124 in a direction to bite between the outer ring 85 and the outer ring 85.

Of the reduction rollers 104 to 106, the reduction rollers 104 and 106 have the same outer diameter, while the outer diameter of the reduction roller 105 is
The outer diameter of the output shaft 115 is eccentric with respect to the axis of the motor shaft 103.

According to the speed reduction roller type speed reducer 120, the motor shaft 10 is driven in accordance with the operation of the drive motor 21.
When 3 rotates in the direction of arrow 125 in FIG. 9, deceleration roller 106 is drawn in between motor shaft 103 and outer ring 85 to perform a wedge action. Then, the contact surface pressure between each of the reduction rollers 104 to 106, the motor shaft 103 and the outer ring 85 increases, and the output torque of the drive motor 21 increases from the motor shaft 103 to each of the reduction rollers 104 to 106.
And transmitted to the output shaft 115 via the outer ring 85. At this time, the motor shaft 103 is restrained by the deceleration rollers 104, 105, and 106 from three directions around the motor shaft 103.
Since a force proportional to the drive torque of the drive motor 21 acts between the reduction rollers 104 to 106 and the motor shaft 103, the vibration generated by the drive motor 21 can be attenuated by the reduction roller type reduction gear 100.

The reduction gear train 101 includes a driving gear 126 as a power transmission unit and a driven gear 127 meshed with the driving gear 126. The driving gear 126 is connected to the second bearing 109 of the second casing half 96. And the outer ring 85,
The output shaft 115 is provided integrally.

In the reduction roller type reduction gear 100 described above, the motor shaft 103 is supported by the first bearing portion 107 of the first casing half 95 via the ball bearing 108, and the output shaft 115 is supported via the ball bearing 110. Although the cantilever is supported by the second bearing portion 109 of the second casing half 96, the length LA from the center of the ball bearing 108 to the axial center of each of the reduction rollers 104 to 106 corresponds to each reduction in the motor shaft 103. Roller 104 ~
106 is larger than twice the outer diameter DA of the contact portion (LA
> DA × 2) is set, and the speed reduction rollers 104 to 10
6, the length LB from the axial center to the axial center of the ball bearing 110 is set to be larger than の of the inner diameter DB of the outer ring 85 (LB> DB × １ ／).

According to such a dimension setting, the assembling precision of the reduction rollers 104 to 106 and the motor shaft 103 of the reduction roller type reduction gear 100 is set relatively coarsely.
The supporting length of the motor shaft 113 from the ball bearing 108 and the output shaft 11 so that the influence is minimized at the meshing portion of the driven gear 127 with the driving gear 126 of the output shaft 115.
The cantilever support length from the ball bearing 110 of No. 5 is appropriately set.

The driven gear 127 of the reduction gear train 101 is disposed so as to surround the rotary drive shaft 128 coaxially, and the rotary drive shaft 128 is connected to the second casing half 96 via a ball bearing 129. It is rotatably supported by the first casing half 95 via a ball bearing 130 and is rotatably supported.
The drive sprocket 84 is fixed to the protruding end of the second casing half 96 from the second sprocket.

A ball bearing 131 is provided between the rotary drive shaft 128 and the driven gear 127.
A second one-way clutch 102 is provided. The second one-way clutch 102 has a clutch outer ring 132 provided integrally with the driven gear 127 and a clutch inner ring 133 provided integrally with the rotary drive shaft 128, and is configured similarly to the first one-way clutch 41. The second one-way clutch 102 is operated by the drive motor 21 so that the speed reduction roller type speed reducer 100 and the speed reduction gear train 1
01 is transmitted to the rotary drive shaft 128, that is, the drive sprocket 84, but when the operation of the drive motor 21 is stopped, the pedal 79 is stopped.
In order to prevent the rotation of the drive sprocket 69 from being hindered by the pedaling force, the rotation drive shaft 109 idles. Hanger part 1 formed in casing 94
33 is a bracket 9 fixed to the down pipe 69.
3

A control unit 134 for controlling the operation of the drive motor 21 is housed beside the drive motor 21 in the second storage chamber 99. The control unit 134 controls the aluminum substrate 13 mounted on the first casing half 95.
5, a printed circuit board 136 attached to the first casing half 95 with a space between the aluminum substrate 135 and the diode 28 or FET disposed on the aluminum substrate 135.
27, etc., and a capacitor 29, a relay 30, a CPU 20 and the like arranged on a printed board 136.

Between the aluminum substrate 135 and the printed substrate 136, the diodes 2
8 and FE27 are secured.
Further, the aluminum substrate 13 of the first casing half 95 is provided.
5 is provided on the back side of the surface on which the driven gear 127 is mounted.
A speed sensor 145 for detecting the rotational speed of the driven gear 127 by detecting the magnetic body 144 provided in the motor is provided.

In operation, when the pedal 79 is depressed in the driving direction by human power, the inner ring 42 fixed to the crankshaft 83 rotates, and the rotation is transmitted to the ratchet teeth 46 via the ratchet pawl 44. The rotation of the transmission plate 40 is transmitted to the driving sprocket 80 via the compression coil spring 56, but the rotation of the transmission plate 40 is not immediately transmitted to the driving sprocket 80 because a load is applied to the driving sprocket 80. First, the compression coil spring 56 bends according to the load, and when the load and the load are balanced, the drive sprocket 80 rotates. Thus, the transmission plate 40 and the driving sprocket 80 rotate with a rotational direction shift corresponding to the load, and apply a driving force to the rear wheels through the chain 82. The load applied to the drive sprocket 80 is detected as a force on the driver to press the pedal 79, that is, a pressing force.

The projection 48 projecting from the sensor portion 1 of the treading force detecting device rotates together with the transmission plate 40, and is fixed to the treading force transmission ring (inner ring) 5 supporting the projection 48 and the driving sprocket 80. The relative position with respect to the outer ring 2 is determined according to the pedaling force. This relative position is detected by the sensor portion 1 and supplied to a control device (described later) for detecting a pedaling force.

When the pedal 79 is depressed in the opposite direction to the driving direction, or when the pedal is stopped during traveling, the engagement between the ratchet pawl 44 and the ratchet teeth 46 is released.
Therefore, the driving sprocket 80 does not rotate, and the driving sprocket 80 rotates independently of the crankshaft 83 during traveling.

The sensor section 1 will be described in detail. FIG.
Is an enlarged side view of a main part of the sensor part 1, and FIG.
FIG. 2 is a front view, that is, a view as seen from the driving sprocket 80 side. Outer ring 2 is formed of an electrically insulating material, and bolt holes 30 are formed in bolt holes 30 so that bolts for fixing outer ring 2 to driving sprocket 80 can pass therethrough.
It is provided in several places. A first derivative 4A is arranged along the inner peripheral surface of the outer ring 2, and a second derivative 4B is arranged adjacent to the first derivative 40A. Further, the treading force transmission ring 5 is arranged so that the outer circumference is along the second derivative 4B.
Is provided. First derivative 4A and second derivative 4
B is made of a high-conductivity material such as aluminum or brass or a soft magnetic material, and is locked to the outer ring 2 and the pedaling force transmission ring 5, respectively (details will be described later).

The first derivative 4A and the second derivative 4B
A pair of ring-shaped core plates 6 and 7 are disposed with the core plate 8 therebetween, and a core collar 8 is disposed on the inner peripheral side of the core plates 6 and 7. The core plates 6, 7 and the core collar 8 are made of a soft magnetic material such as soft ferrite. A coil 9 is wound around the outer periphery of the core collar 8, and a magnetic flux generated when the coil 9 is energized penetrates through the core plates 6, 7 and the core collar 8, and the first derivative 4A and the second derivative 4B. Thus, a magnetic circuit is formed. The core plates 6, 7 and the core collar 8 are supported by a sleeve 10 and a flange 11 having a male thread matching the female thread of the sleeve 10. The rotation of the sleeve 10 and the flange 11 is regulated by the support pipe 24.

A lead wire 12 for supplying a current to the coil 9 passes through the sleeve 10 and is drawn out to the outside.
It is connected to a control device described later. Ring 2 and sleeve 1
0, an oil seal 13 is provided, and seals 14, 15 are provided between the ring 2 and the pedaling force transmission ring 5, and between the pedaling force transmission ring 5 and the flange 11, respectively. The projection 48 projecting at right angles from the treading force transmission ring 5 faces outside through an opening 49A provided in the cover 49 so as to be able to engage with the locking hole 51.

FIG. 7 is a front view of the first derivative 4A, and FIG. 8 is a sectional view of the same. The first derivative 4A has a ring shape as a whole, and has a plurality of teeth 44 formed on an inner periphery thereof. A tooth similar to the tooth 44 is also provided on the second derivative 4B, and these teeth overlap each other to form a part of a passage through which the magnetic flux generated by the coil 9 passes. Tooth 4
Projection portions 4c protruded outward from the bottom of the cap-shaped first derivative 4A are formed at two places between the four.
The protrusion 4c is set so as to fit into a recess formed in the outer ring 2 so that the first derivative 4A can rotate integrally with the outer ring 2.

FIG. 9 is a sectional view of the second derivative 4B. The second derivative 4B has the same shape as the first derivative 4A. However, the outer circumference is formed smaller than the first derivative 4A. Further, as shown in FIG.
B has a projection 4d that is projected inward from the bottom of the cap-shaped second derivative 4B. This projection 4
d is set so as to fit into a concave portion provided in the inner ring 5 in contact with the second derivative 4B.

FIG. 10 is a schematic view showing a passage through which a magnetic flux generated by the coil 9 passes. In the figure, the magnetic flux Φ generated when the coil 9 is energized is changed by the core plates 6 and 7 and the core collar 8 and the first derivative 4.
A magnetic circuit including A and the second derivative 4B is formed. Here, the inductance of the coil 9 is a function of the resistance of the path through which the magnetic flux Φ passes, that is, the resistance of the magnetic circuit. On the other hand, in the first derivative 4A and the second derivative 4B, the teeth (the teeth 44 in the first derivative 4A) provided on the inner periphery thereof are substantially formed by the magnetic flux Φ.
Pass through the first derivative 4A and the second derivative 4B
The magnetic circuit resistance of this portion is determined by the amount of overlap of the respective teeth.

As described above, the outer ring 2 and the inner ring 5 are displaced from each other according to the pedaling force, and accordingly, the relative positions of the first derivative 4A and the second derivative 4B are also displaced. As a result, the first derivative 4A and the second derivative 4A
The degree of overlap of each tooth of the derivative 4B also changes according to the pedaling force.

FIG. 11 shows the first derivative 4 due to the difference in pedaling force.
It is a figure which shows the difference of the overlapping degree of each tooth of A and 2nd derivative | guide_body 4B. FIG. 11A shows a case where the pedaling force is small, and FIG. 11B shows a case where the pedaling force is large.
As shown in these figures, when the pedaling force is small, the first
The degree of overlap between the teeth of the derivative 4A and the second derivative 4B is increased to reduce the magnetic circuit resistance. When the pedaling force is large, the teeth of the first derivative 4A and the second derivative 4B are reduced. The engagement positions of the first derivative 4A and the second derivative 4B with the outer ring 2 and the inner ring 5 are set so that the degree of overlap is reduced and the magnetic circuit resistance is increased.

As described above, since the resistance of the passage through which the magnetic flux Φ passes can be changed in accordance with the pedaling force, the pedaling force can be detected by detecting the inductance of the coil 9 which is a function of the magnetic circuit resistance.

FIG. 12 is a circuit diagram of a control device for detecting the treading force based on the inductance of the coil 9, and FIG.
FIG. 4 is a waveform diagram showing a voltage at a predetermined position of the circuit. The oscillation circuit 17, the peak hold circuit 18, and the resistor 19 included in the control device 16 constitute a main part of the pedaling force detection device together with the coil 9. The output of the peak hold circuit 18 is processed by the CPU 20. The oscillation circuit 17 outputs an alternating current of a predetermined frequency (shown in FIG. 13A as a waveform at a point a). When the degree of overlap between the teeth of the first derivative 4A and the second derivative 4B is large, the magnetic circuit resistance of the magnetic flux Φ generated by the coil 9 is large, and thus the amplitude of the waveform at the point b is large (see FIG. b)). The amplitude of the point B is peak-held by the peak hold circuit 18, and the peak hold value, that is, the amplitude value of the point c (see FIG. 13C) is input to the CPU 20 as the pedaling force value.

The controller 16 includes an electric auxiliary unit 86
The drive motor 21 included in FIG. 3 is connected as a load, and the battery 2 is connected as a power supply.
Further, a charger 25 can be connected to the control device 16 and the battery 2 through the coupler 22 and the main switch 23.

The drive circuit of the drive motor 21 is
ET 27, diode 28, and capacitor 29 are included. The plus terminal of the drive motor 21 is connected to the plus electrode of the battery 2 through the contact 30, and the minus terminal is connected to the minus electrode of the battery 2 through the FET 27.

The contact 30 is turned on by energizing the coil 31 in accordance with a command from the CPU 20. The current supplied to the drive motor 21
It is determined by the voltage applied to the gate of T27.
The CPU 20 obtains a voltage value corresponding to the treading force value by referring to a treading force value / voltage table corresponding to the treading force value or performing an operation according to a predetermined arithmetic expression, and supplies a voltage corresponding to the voltage value to the gate of the FET 27. Apply. It is preferable to set the pedal force value / voltage table and the arithmetic expression so that the output of the dry motor 21 increases as the pedal force value input to the CPU 20 increases.

According to the present embodiment, for example, the assembling accuracy varies and the first derivative 4A and the second derivative 4B
When the positions of the core plates 6 and 7 are shifted in the axial direction between the first derivative 4A and the core plate 6, the distance between the second derivative 4B and the core plate 7 increases. Conversely, when the distance between the first derivative 4A and the core plate 6 increases, the distance between the second derivative 4B and the core plate 7 decreases. In this manner, a change in one interval is canceled by a change in the other interval, and the magnetic circuit resistance is kept constant as a whole.

The first derivative 4A and the second derivative 4
When the positions of the core plates 6 and 7 are shifted in the radial direction between B and the overlap between the first derivative 4A and the second derivative 4B and the core plates 6 and 7 is increased in the radial direction, the radial direction On the other hand, the first derivative 4A and the second derivative 4A
The overlap between the derivative 4B and the core plates 6, 7 is reduced. Accordingly, on the one hand, the magnetic circuit resistance increases, and on the other hand, the magnetic circuit resistance decreases, and as a result, the magnetic circuit resistance is kept constant as a whole.

[0058]

As is apparent from the above description, according to the first to fifth aspects of the present invention, the resistance of the passage through which the magnetic flux penetrates between a pair of guide members arranged concentrically with the coil is changed. Since the members are provided, the magnetic circuit resistance is maintained constant even if the dimensions of the members forming the passages and the assembling accuracy vary, so that the change in the human-powered torque can be accurately detected. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an electric assist vehicle incorporating a pedaling force detection device according to an embodiment of the present invention.

FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;

FIG. 3 is a side view of the electric assist vehicle incorporating the pedaling force detection device according to one embodiment of the present invention.

FIG. 4 is a side view of the periphery of a crankshaft of the electrically assisted vehicle.

FIG. 5 is a sectional view of a main part of a sensor portion of the treading force detecting device.

FIG. 6 is a front view of a sensor portion of the pedaling force detection device.

FIG. 7 is a front view of the first conductor.

FIG. 8 is a sectional view of a first conductor.

FIG. 9 is a sectional view of a second conductor.

FIG. 10 is a schematic diagram showing a magnetic circuit through which a magnetic flux generated by a coil passes.

FIG. 11 is a diagram showing a degree of overlap between a first conductor and a second conductor.

FIG. 12 is a tread force detection circuit of the control device.

FIG. 13 is a diagram showing a relationship between a voltage of a coil and a pedaling force.

FIG. 14 is a sectional view of the electric auxiliary unit.

FIG. 15 is a sectional view taken along a line BB in FIG. 14;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sensor part, 2 ... Outer ring, 3 ... Sensor main body, 4A ... 1st derivative, 4B ... 2nd derivative, 5 ... Tread force transmission ring, 6, 7 ... Core plate, 8 ... Core collar, 9 ... Coil, 10 ... Sleeve, 11 ... Flange, 12 ... Lead wire, 40 ... Transmission plate, 5
6: Compression coil spring, 80: Drive sprocket, 8
3 ... Crankshaft

Claims (5)

[Claims] A coil provided concentrically with a rotary shaft to which a human-powered torque for driving a vehicle is applied; and a pair of coils provided on both sides in the axial direction of the coil and extending in an outer circumferential direction of the coil. An electric motor comprising: an induction member; and a magnetic path resistance variable member that is provided between the extended induction members and that changes a resistance of a magnetic circuit between the induction members according to a change in the torque. Treading force detection device for auxiliary vehicles. 2. A drive sprocket for transmitting the manual torque to a rear wheel, wherein the variable magnetic path resistance member comprises a pair of members that are overlapped with each other in the axial direction of the coil. The pedaling force detection device for an electrically assisted vehicle according to claim 1, wherein the amount of the overlap is changed according to a difference between a torque due to a wheel load and the human-powered torque. 3. The guide member according to claim 1, wherein the guide member is formed of a soft magnetic material.
The pedaling force detection device for an electrically assisted vehicle according to claim 1. 4. The electric assist vehicle according to claim 1, wherein the coil, the induction member, and the magnetic path resistance variable member are arranged along the drive sprocket. Tread force detection device. 5. A transmission plate for transmitting the rotation of the rotating shaft, and an elastic member provided between the transmission plate and the driving sprocket for transmitting the rotation of the transmission plate to the driving sprocket. The transmission plate is engaged with one of the magnetic path resistance variable members to transmit the rotation, and the drive sprocket is engaged with the other of the magnetic path resistance variable members to transmit the rotation. The pedaling force detection device for an electrically assisted vehicle according to any one of claims 1 to 3, wherein