JP3495433B2 - Electric bicycle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has both a human-powered driving unit and a motor-driven electric driving unit, drives the electric motor according to the magnitude of the human-powered driving force, and drives the human-powered driving force of the electric motor. The present invention relates to an electric bicycle assisted by driving force.

[0002]

2. Description of the Related Art Conventionally, in such an electric bicycle, as shown in Japanese Patent Application Laid-Open No. 4-358987 (B62M 23/02), a drive system driven by human power and a drive system driven by electric motor are provided in parallel, and the drive system driven by human power is used. It is known that the drive force of a drive system is detected to control the output of an electric motor.

In this electric bicycle, in order to detect the driving force of the driving system due to human power, that is, the rotational torque of the pedal, a planetary gear mechanism is interposed in the driving system due to human power, and the driving reaction force when the pedal is stepped on the planet. It is a mechanism that detects in the middle of the gear mechanism.

However, in such a structure, since the driving portion is located away from the rear wheels, there is a large loss of force before the driving force is transmitted to the rear wheels, and in order to transmit power to the rear wheels, pedals and The vertical rotation of the electric motor must be converted to the horizontal rotation of the drive shaft, and must also be converted to the vertical rotation to rotate the rear wheels, which complicates the configuration and increases the size. Will cause problems such as failure.

In addition to the above-mentioned embodiment, for example, in Japanese Patent Laid-Open No. 4-321482 (B62M 23/12),
In order to detect the driving force of the driving system by the human power, that is, the rotational torque of the pedal, load detecting means for detecting the driving force in the middle of the drive shaft for transmitting the driving force, which is provided between the pedal and the rear wheel. A configuration provided with is disclosed.

However, when the load detecting means is attached to the drive shaft having such a structure, wiring or the like is required to send the detected signal to the control circuit in order to detect the load, and the structure becomes very complicated. However, there arises a problem that the size becomes large.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and accurately detects a torque caused by human power with a simple structure, and drives the electric motor accurately according to the torque. An object is to provide an electric bicycle that assists power.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an elastic body is interposed between a pedal and a wheel, and a human-powered drive unit for rotating the wheel through the elastic body by the pedaling force of the pedal is provided. An electric drive unit that rotates wheels, a torque detection unit that detects expansion and contraction of the elastic body, a control unit that drives and controls the electric motor based on the detection of the torque detection unit, the electric drive unit, and the torque detection unit. And a board-shaped casing containing the control unit, wherein the board-shaped casing is
It is divided into a fixed casing that fixes the electric drive unit and the control unit and a rotating casing that rotates with the wheels, and the torque detection unit includes a coil provided in the fixed casing and the rotating side. It is characterized in that it is provided in the vicinity of the coil of the casing and is formed of a magnetic material that moves due to expansion and contraction of the elastic body.

Further, the magnetic material is cylindrical and has notches at equal intervals and has a first rotating plate that rotates together with the rotating casing, and notches at equal intervals with the notches of the first rotating plate. And a second rotary plate that rotates together with the rotary casing coaxially with the first rotary plate and that moves in the rotational direction by the expansion and contraction of the elastic body.

Further, the magnetic material has a disk-shaped first rotating plate having notches at equal intervals and rotating together with the rotating casing, and notches equally spaced from the notches of the first rotating plate. And a second rotary plate that rotates coaxially with the first rotary plate together with the rotary casing and that moves in the rotational direction by expansion and contraction of the elastic body.

Then, an elastic body is interposed between the pedal and the wheel, and a human-powered drive unit that rotates the wheel through the elastic body by the pedaling force of the pedal, and an electric drive unit that rotates the wheel by driving an electric motor. A torque detection unit that detects expansion and contraction of the elastic body, a control unit that drives and controls the electric motor based on the detection of the torque detection unit, and a board that includes the electric drive unit, the torque detection unit, and the control unit. -Shaped casing, the plate-shaped casing is divided into a fixed-side casing that fixes the electric drive unit and the control unit, and a rotating-side casing that rotates together with the wheels, and the torque detection unit, The primary coil provided in the stationary casing, the secondary coil provided facing the primary coil in the rotating casing, and the value that can change as the elastic body expands and contracts. A resistor, characterized in that connected to the secondary coil.

[0012]

According to the present invention, when the user depresses the pedal, the wheel provided on the rotating side casing rotates through the elastic body, and the elastic body expands and contracts according to the magnitude of the human torque. The magnetic material moves and changes the magnetic force generated by the coil. By detecting this change, the torque of the pedaling force can be detected, and the electric motor is driven by the driving force according to the torque.

Specifically, claim 2 or claim 3
As described in, when the elastic body expands and contracts, the first rotating plate and the second rotating plate
The notches formed on the rotating plate shift and rotate on the coil, and the notches overlap and close due to the displacement of each rotating plate, and the movement of these rotating plates causes the coil to move. The magnetic resistance changes. By detecting this, the torque of the pedaling force can be detected, and the electric motor is driven according to its magnitude.

When the elastic body expands and contracts, the primary coil and the secondary coil are
The next coil rotates by being displaced by the amount of expansion and contraction, and is displaced and the resistance value of the variable resistor changes. That is, the load of the secondary coil changes and the inductance of the primary coil changes.
By detecting this change, the pedaling torque can be detected. The electric motor is driven based on this torque.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

Reference numeral 1 denotes an electric bicycle main body, which is provided with an electric motor 8 which will be described later. The electric power of the electric motor 8 is changed in accordance with the magnitude of the torque due to the human power, and the force due to the human power is applied to the electric motor. It is driven by the force of 8.

Reference numerals 2 and 3 denote front wheels and rear wheels provided on the main frame 4, the front wheels 2 being rotatably supported, and a disk-shaped casing 5 is provided at a portion of the rotary shaft of the rear wheels 3. It is provided. The disk-shaped casing 5 is composed of a rotating side casing 6 and a fixed side casing 7, and the rotating side casing 6 rotates together with the rear wheel 3. An electric motor 8 is built in the plate-shaped casing 5 and is driven when electric driving is required to rotate the rotating side casing 6 together with a human power drive unit 10 described later. The drive portion including the board-shaped casing 5 is referred to as an electric drive portion 9.

10 is a chain 12 by pressing the pedal 11.
It is a human-powered driving unit that rotates the rear wheel 3 via the. In the present invention, the chain 12 is used as the transmission member.
Instead of, a belt, a gear or the like may be used.

Reference numeral 13 is a steering wheel for steering the front wheels 2.

Reference numerals 14 and 15 are left and right brake levers. Pulling the brake levers 14 and 15 pulls wires 16 and 17, and the wires 16 and 17 operate front and rear brake devices 18 and 19, respectively. Has become. Further, a brake switch 20 is provided in the middle of the wires 16 and 17, so that the power supply to the electric motor 8 is stopped when the brake levers 14 and 15 are operated.

Reference numeral 21 is a saddle.

Reference numeral 22 denotes a battery unit which serves as a power source of the electric motor 8. The battery unit 22 is composed of a battery case 23 slidably mounted on the frame 4 and a single-type rechargeable battery housed in the battery case 23. It is configured. This power supply voltage is about 24 volts.

Next, referring to FIG. 10, the electric drive unit 9
Will be described.

FIG. 10 shows the internal structure of the disk-shaped casing 5. Reference numeral 7 denotes a fixed casing fixed to the electric bicycle main body 1. The fixed casing 7 has a control board 24, The control unit 26 including the heat sink 25, the electric motor 8,
A speed reduction mechanism 30 including three pulleys, that is, a first pulley 27, a second pulley 28, and a final stage pulley 29, and a transmission belt 31 that connects the speed reduction mechanism 30 are arranged. The reduction mechanism 30
The final stage pulley 29 is fixed to the rotating side casing 6, and when the electric motor 8 rotates, the first to the final stage pulleys are rotated by the transmission belt 31 and are decelerated and the final stage pulley 29 and the rotating side casing 6 are rotated. Rotates.
Also, a one-way clutch is interposed in the smaller pulley of the second pulley 28, which connects the second pulley 28 and the final stage pulley 29, so that the electric motor 8 is actuated when a force is applied from the pedal 11. The pedal 11 is light so as not to turn it.

Reference numeral 32 is a pressing member for adjusting the tension of the transmission belt 31.

Reference numeral 33 is an adjusting screw for adjusting the tension of the transmission belt 31, and a long hole is formed in the mounting portion of the rotating shaft of the first pulley 27, so that the first pulley 27 is connected to the transmission belt 31. The first pulley 27 is fixed by the adjusting screw 33 in the moved state.

Reference numeral 37 denotes a chain sprocket for transmitting the driving force from the chain 12 to the rotating side casing 6, and a one-way clutch 38 is provided between the chain sprocket 37 and the rotating side casing 6. Therefore, when the chain 12 rotates in the reverse direction, the driving force from the chain 12 is not transmitted to the rotating side casing 6.

Reference numeral 39 is an axle of the rear wheel 3.

The final stage pulley 29 will be described in detail with reference to FIGS. 1 and 2.

Reference numeral 40 denotes an elastic body, that is, a spring, which is provided inside the final stage pulley 29 at two locations axially symmetrical with respect to the axle 39. The spring 40 has one side fixed to the final stage pulley 29 and the other side. It is openable and retractable.

Reference numeral 41 designates a pressure receiving member which comes into contact with the open side of the spring 40. The pressure receiving member 41 has a portion smaller than the diameter of the spring 40 and a large portion, and the small portion enters the spring 40 and the large portion. Is provided so as to cover the spring 40.

42 is provided on the axle 39 via a bearing, and the rotation of the chain sprocket 37 causes the axle 39 to rotate.
A rotary plate that rotates around the center of the chain sprocket.
A pressing member 43 that presses by rotating 37 is provided.

The rotating plate 42 is concentrically inserted inside the final stage pulley 29, and the pressing member 43 is attached to the spring 40.
By pressing, it rotates together with the final stage pulley 29. Further, the pressing member 43 has a curved contact surface because the pressing position is slightly displaced when pressing the pressure receiving member 41.

Reference numeral 47 is a rubber plate for preventing the pressing member 43 pressed by the urging of the spring 40 from an impact.

Reference numeral 48 is a cover for covering the spring 40.

49 is electrically connected to the control unit 26,
A circular coil disposed inside the fixed casing 7 around the axle 39, and the coil 49 is fixed by a guide 50.

Reference numeral 51 is a magnetic material, and the coil 49
Is a first rotary plate which is rotated around the coil 49 in the vicinity of the coil 49 and is provided on the rotary plate 42. The first rotary plate 51 is a disk-shaped base on which a cylindrical wall is formed in the longitudinal direction of the axle 39. 52 is formed, and notches 53 are formed in the wall 52 at equal intervals.

Reference numeral 54 denotes a second rotary plate which is made of a magnetic material and is inserted into the first rotary plate 51 so that the first rotary plate 51 and the notch 53 have the same interval. Is a wall and 56 is a notch. The second rotary plate 54 is mounted on the final stage pulley 29 coaxially with the axle 39.

The upper first rotary plate 51 and the second rotary plate 54 are shown in FIG.
And shown in FIG.

These spring 40, rotating plate 42, first rotating plate
51, the second rotating plate 54, and the coil 49 are combined to make a torque detection unit.
57.

Next, the operation of the torque detector 57 will be described.

When the electric bicycle main body 1 starts running, the user applies a force to the pedal 11 to run. At this time, the rear wheel 3
Since the force to stop is large, the chain sprocket 37 and the rotating plate 42 try to rotate, and the spring 40 presses the spring 40 to press the final stage pulley 29, and the rotation side casing 6 fixed to the final stage pulley 29. , The rear wheel 3 rotates and travels. At this time, since a large torque is generated during traveling, the spring 40 contracts greatly, that is, the contraction of the spring 40 causes a twist between the first rotary plate 51 and the second rotary plate 54, and the state shown in FIG. To the state shown in FIG. At this time, since the magnetic material moves on the coil 49, the magnetic resistance of the coil 49 shifts from a large state to a small state. That is, the state where the inductance of the coil 49 is small changes to the state where it is large.

The circuit diagram and waveforms are shown in FIGS. 7 and 8.

A square wave signal from a microcomputer (not shown) shown in FIG. 8A is inputted to the coil 49, and if the rotating plates 51 and 54 are in the state shown in FIG. Has a small inductance and has a waveform shown by a solid line in FIG. Then, the DC converter 60 converts the DC component into a DC component shown in FIG. 8C, the amplifier 61 amplifies the DC component, and inputs the amplified DC component to a microcomputer (not shown). Further, assuming that the rotating plates 51 and 54 are brought into the state of FIG. 6 due to the pedaling force of human power being applied, the inductance of the coil 49 becomes large, and FIG.
The output becomes smaller as shown by the broken line in (B). And
Similarly to the above, the DC converter 60 converts the waveform into the waveform shown by the broken line in FIG. 8C, is amplified by the amplifier 61, and is input to the microcomputer.

As described above, since the magnitude of the signal input to the microcomputer differs depending on the pedal effort of the human power, the electric motor 8 is driven according to this magnitude to assist the human power.

Here, the coil 49 shown in FIG.
Since the inductance changes with the rotation of 1 and 54,
It is shown as variable.

When the user does not apply the pedaling force when stopping, going downhill, or running on a level ground, the notches 53 and 56 of the first and second rotating plates 51 and 54 are in an overlapped state. Therefore, as shown in FIG. 5, the first rotary plate 51 and the second rotary plate 54 maintain a state in which the gap between the cutouts is widest.

Further, the case where the user accelerates on a flat ground or an uphill will be described.
The first rotating plate 51 is twisted with respect to the second rotating plate 54 by the amount of the applied pedaling force, that is, the torque, and the gap between the notches becomes narrow. By detecting this as a change in the inductance of the coil 49, the degree of twist can be detected.
Then, a signal based on this change is input to the microcomputer, and the electric motor 8 is driven according to this change.

Next, a second embodiment will be described with reference to FIGS. 11 and 12.

Since this embodiment is different from the above-mentioned embodiment only in the shapes of the first rotary plate and the second rotary plate, the description of the same parts will be omitted and the first rotary plate and the second rotary plate will be described. To do.

Reference numeral 70 denotes a first rotary plate which is provided on the rotary plate 42 and rotates together with the rotary plate 42. The first rotary plate 70 is disk-shaped and has notches 71 at equal intervals formed on the periphery thereof. ing.

Reference numeral 72 denotes a second pulley mounted on the final stage pulley 29 and coaxial with the first rotary plate 70.
It is a rotating plate. The second rotary plate 72 has the same shape as the first rotary plate 70 and has notches 73 formed at equal intervals.
Both the rotary plates 70 and 72 are made of a magnetic material. The cutout 71 of the first rotary plate 70 and the cutout 73 of the second rotary plate 72 are attached so that the cutouts overlap each other.

These spring 40, rotating plate 42, first rotating plate
70, the second rotary plate 72, the coil 49, the torque detector
74.

The movement of the first rotary plate 70 and the second rotary plate 72 will be described.

In FIG. 12, the portion shown by the solid line is the first rotating plate 70, and the portion shown by the broken line is the second rotating plate 72.

Similar to the above-described embodiment, FIG. 12 shows only when the pedaling force is applied, such as at the start of traveling, during normal traveling or acceleration on a level ground, or when traveling uphill, and the amount corresponding to the pedaling force. As described above, the second rotary plate 72 is displaced from the first rotary plate 70 by θ. When it is deviated by θ, the magnetic resistance is decreased and the inductance of the coil 49 is increased as in the first embodiment, and the electric motor 8 is driven by the driving force corresponding to this θ.

Regarding the detection by the change of the inductance of the coil 49, it can be detected by the change of the signal level as in the first embodiment as shown in the circuit diagrams and the waveforms shown in FIGS.

Next, the third embodiment will be described with reference to FIGS.
A description will be given based on 4.

Also in this embodiment, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals, and only different parts will be described.

Reference numeral 80 denotes a circular primary coil fixed to the fixed casing 7, and the primary coil 80 is fixed around the rotary shaft 39.

Reference numeral 81 is a secondary coil that is provided concentrically at a position facing the primary coil 80 and that operates together with the rotary plate 42 of the rotary casing 6.

The gear 82 is provided with a gear 84 that meshes with a gear 83 formed on the rotary plate 42 so as to rotate with the rotation of the rotary plate 42. The resistance value changes as the gear 84 rotates. The variable resistor 82 is connected to the secondary coil 81 in a loop shape, and the resistance value of the variable resistor 82 is changed by the movement of the rotating plate 42 by the pedaling force, that is, the secondary coil 81. Load changes.

The operation when the torque due to the pedaling force is applied will be described. When the pedaling force is applied, the rotating plate 42 tries to rotate and presses the spring 40 so that the spring 40 presses the final stage pulley 29, as in the previous embodiment. Press and hold the final stage pulley
The rotation side casing 6 fixed to 29 and the rear wheel 3 rotate and travel. At this time, since a large torque is generated during traveling, the spring 40 contracts greatly and the primary coil 80 and the secondary coil 81
Twist occurs between and. At this time, the resistance value of the secondary coil 81 is changed by the variable resistor 82, and the variable coil 82 rotates on the primary coil 80 in the changed state, so that the inductance of the primary coil 80 changes. This change changes according to the expansion and contraction of the spring 40, and is set so that the inductance of the primary coil 80 increases as the torque increases, and the magnitude of the torque is detected by the same circuit as the above-described embodiment. be able to.

In the present embodiment, as in the above-described embodiments, only when the pedaling force is applied, such as when the vehicle starts running, when the vehicle is normally traveling or accelerating on a flat ground, or when traveling on an uphill road, the amount corresponding to the pedaling force,
The electric motor 8 assists.

With the above-mentioned structure, the structure can be made compact and simple, and the torque can be detected in consideration of the total weight of the portion such as the rotating casing 6 that is moved by human power. The human power torque can be accurately detected, and therefore the drive by the electric motor 8 can be delicately changed, and accurate driving force can be assisted. Further, since the processing is performed using the pulse signal, the resistance to noise is increased and the accuracy is increased.

Further, according to the first embodiment, the rotary plate 51,
Since the notches 53 and 56 of 54 can be assembled on the same axis by aligning them with each other, the assembling is easy and the rotating plate 5 is placed on the coil 49.
Since 1 and 54 rotate, the inductance of the coil 49 can be changed accurately, and the torque can be reliably detected.

According to the second embodiment, the rotary plate 70,
Since the coil 72 covers the coil 49, it is possible to accurately detect a change in inductance according to the pedaling force, and it is possible to reliably detect torque and assist the electric motor 8.

According to the third embodiment, only the secondary coil 81 and the variable resistor 82 are provided in the rotating side casing 6, and the torque is detected by the change in the inductance of the fixed side casing 7. Since the fixed side casing 7 performs signal processing without providing electrical components for processing signals, complicated electrical components are not provided on the rotating side, which facilitates assembly and reduces failures. Become.

Further, since the one-way clutch 38 is interposed between the human-powered drive unit 11 and the spring 40, the torque can be detected only in the traveling direction of the human-powered drive unit 11, which improves usability.

[0070]

According to the present invention, an elastic body is interposed between a pedal and a wheel, and a human-powered driving unit for rotating the wheel through the elastic body by the pedaling force of the pedal is provided, and the expansion and contraction of the elastic body changes the inductance of the coil. Since the electric motor is detected and detected by the drive control, a compact structure can be achieved, and the torque can be detected in consideration of all the weight of the portion moved by human power such as the rotating side casing. It is possible to detect accurately, and therefore, the drive by the electric motor can be changed subtly, and it is possible to assist the accurate driving force. Further, since the processing is performed by using the pulse signal, the resistance to noise is increased and the accuracy is increased.

Further, according to the structure of claim 2, since the notches of the rotary plate can be assembled coaxially with each other, the assembling is easy and the rotary plate rotates on the coil when the torque is detected. The inductance of the coil can be changed accurately, and the torque can be reliably detected.

Further, according to the third aspect of the present invention, since the rotating plate completely covers the coil, the inductance of the coil can be changed according to the pedaling force, and the torque can be reliably detected and the electric motor can be used. It can assist.

According to the structure of claim 4, only the secondary coil and the variable resistor are provided in the rotating side casing, and the torque is detected by the change in the inductance of the fixed side casing. Since the fixed side casing performs signal processing without providing any electrical component for processing, the rotating side does not have a complicated electrical component, which greatly improves the assemblability and reduces failures.

Since the one-way clutch is interposed between the manual drive section and the elastic body, the torque can be detected only in the traveling direction of the manual drive section, which improves usability.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a final stage pulley of an electric bicycle showing an embodiment of the present invention.

FIG. 2 is a side sectional view of the same plate-shaped casing.

FIG. 3 is an exploded perspective view of the relevant part.

FIG. 4 is an assembly diagram of the relevant part.

FIG. 5 is a plan view of the same main part.

FIG. 6 is a plan view of the relevant part.

FIG. 7 is a circuit diagram of the torque detection unit.

FIG. 8 is a diagram showing a waveform of each portion in the same circuit.

FIG. 9 is an overall perspective view of an electric bicycle according to the present invention.

FIG. 10 is a configuration diagram showing an arrangement of parts of the same board-shaped casing.

FIG. 11 is a side sectional view showing a configuration of a final stage pulley of the electric bicycle showing the second embodiment of the present invention.

FIG. 12 is a plan view of the relevant part.

FIG. 13 is a plan view showing a configuration of a final stage pulley of an electric bicycle showing a third embodiment of the present invention.

FIG. 14 is a side sectional view of the same plate-shaped casing.

[Explanation of symbols]

11 pedals 3 wheels (rear wheels) 40 Elastic body (spring) 10 manpower drive 8 electric motor 9 Electric drive 56 Torque detector 26 Control unit 5 disk casing 7 Fixed side casing 6 Rotating side casing 49 coils 51 1st rotating plate 54 Second rotating plate 53 cutout 56 cutout 70 First rotating plate 72 Second rotating plate 71 notches 73 cutout 80 primary coil 81 Secondary coil 82 Variable resistor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-107268 (JP, A) JP-A-6-156361 (JP, A) JP-A-57-74285 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B62M 23/02 G01L 5/13 G01L 5/22

Claims (4)

(57) [Claims] 1. A human-powered drive unit that intervenes an elastic body between a pedal and a wheel to rotate the wheel through the elastic body by the pedaling force of the pedal, and an electric drive unit that rotates the wheel by driving an electric motor. A torque detection unit that detects expansion and contraction of the elastic body, a control unit that drives and controls the electric motor based on the detection of the torque detection unit, and a board that includes the electric drive unit, the torque detection unit, and the control unit. -Shaped casing, the plate-shaped casing is divided into a fixed-side casing that fixes the electric drive unit and the control unit, and a rotating-side casing that rotates together with the wheels, and the torque detection unit, A coil provided on the fixed side casing,
An electric bicycle, which is provided in the vicinity of the coil of the rotation side casing and is formed of a magnetic material that moves by expansion and contraction of the elastic body. 2. The magnetic material has a first rotating plate which is cylindrical and has notches at equal intervals and which rotates together with the rotating side casing, and notches at equal intervals as the notches of the first rotating plate. 2. The electric bicycle according to claim 1, further comprising: a second rotary plate which rotates coaxially with the first rotary plate together with the rotary casing and moves in a rotational direction by expansion and contraction of the elastic body. . 3. The magnetic material includes a disk-shaped first rotating plate that has notches at equal intervals and that rotates together with the rotating side casing, and notches at equal intervals as the notches of the first rotating plate. 2. The electric motor according to claim 1, further comprising: a second rotary plate that rotates coaxially with the first rotary plate together with the rotary casing and that moves in a rotational direction by expansion and contraction of the elastic body. bicycle. 4. A human-powered drive unit that rotates an elastic body between a pedal and a wheel and that rotates the wheel through the elastic body by the pedaling force of the pedal, and an electric drive unit that rotates the wheel by driving an electric motor. A torque detection unit that detects expansion and contraction of the elastic body, a control unit that drives and controls the electric motor based on the detection of the torque detection unit, and a board that includes the electric drive unit, the torque detection unit, and the control unit. -Shaped casing, the plate-shaped casing is divided into a fixed-side casing that fixes the electric drive unit and the control unit, and a rotating-side casing that rotates together with the wheels, and the torque detection unit, A primary coil provided in the stationary casing, a secondary coil provided facing the primary coil of the rotating casing, and a variable resistor whose value changes as the elastic body expands and contracts. An electric bicycle, wherein the electric coil is connected to the secondary coil.