JP3155133B2 - Driving force assist device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force assisting device provided with a motor for a vehicle driven by human power and assisting human power.

[0002]

2. Description of the Related Art An example of this kind of driving force assisting device includes an example in which the output of an electric motor is controlled by detecting a load on a pedal side of a manual driving system (Japanese Patent Laid-Open No. 4-100790). Has a load detecting means for detecting a pedaling force on a drive shaft downstream of the pedal crankshaft, and further has a separate motor driving means downstream thereof.

[0003]

As described above, in the conventional driving force assisting device, since the load detecting means and the motor driving means are separately mounted on the vehicle, the number of components for mounting is large and the mounting work is troublesome. The vehicle speed or pedal crankshaft rotation
When controlling the motor by detecting
It is necessary to provide means, and the number of parts is further increased.
The attachment is also troublesome .

[0004] The present invention has been made in view of such a point, and an object thereof is to provide auxiliary power using pedaling force and vehicle speed.
Or with a system that can be controlled accurately by the pedal rotation speed
Despite this, the pedal depression force detection mechanism is combined with the assist unit.
By integrating it and using it as a vehicle speed sensor,
Simple appearance with a compact cyst unit
The present invention provides a driving force assisting device capable of:

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an assist motor arranged close to a pedal crankshaft, and supporting the pedal crankshaft to hold the assist motor. An assist unit, a pedal depression force detection mechanism that detects human power applied to the pedal crankshaft, a control device that controls the assist motor based on a pedal depression force detected by the pedal depression force detection mechanism and a rotation speed of the pedal crankshaft, A driving means provided on one side of an assist unit and a driving means for driving a driving wheel, wherein the assist motor is connected from the one side of the driving means and has a motor shaft behind the pedal crankshaft. The pedal depression force detection mechanism is provided so as to be oriented substantially horizontally, and the one-way A rotating member that will be journaled through the latch, the phase shift in the rotational direction relative to the rotation of said rotary member
The drive means, the displacement means being pivotally supported by the outer periphery of the rotating member and being displaced by a displacement amount corresponding to the phase shift, and the displacement means being integrally attached to the assist unit on the outer periphery of the displacement means. Mean displacement over time
And detecting means for detecting a and the detected driving force assisting device over time displacement information to detect the rotational speed of the pedal force applied to the pedal crank shaft and said pedal crank shaft by said detecting means .

[0006] While the control device can accurately control the auxiliary power based on the pedal depression force and the vehicle speed or the number of revolutions of the pedal, the pedal depression force detection mechanism includes a rotating member pivotally supported on the pedal crankshaft via a one-way clutch. Displacement means is supported on the outer periphery of the displacement means, detection means is attached to the periphery of the displacement means integrally with the assist unit, the rotating member and the displacement means are provided collectively around the pedal crank shaft, and the detection means Since it is located in the vicinity thereof and is advantageous in detection accuracy, the pedal depression force detection mechanism itself can be configured to be lightweight and compact. Such a pedal depression force detection mechanism contributes to the weight reduction and compactness of the assist unit. Also, the assist unit as a whole has an assist motor located close to the rear of the pedal crankshaft and oriented so that the motor shaft is oriented substantially horizontally, thereby achieving a low center of gravity and compactness, and connecting the assist motor to the drive means. Is also provided on one side of the assist unit, so that there is a high degree of freedom in arranging the adjacent pedaling force detecting mechanism, and by arranging it at an optimum position, it is possible to further promote compactness. Further, the drive means is a rotating member.
Phase shift in the rotational direction with respect to the rotation of
Position means is displaced by a displacement amount corresponding to the phase shift, and the detection means
Since the displacement of the displacement means is detected over time,
The pedaling force applied to the pedal crankshaft is detected from the displacement itself.
The rotation of the pedal crank can be obtained from the information on the displacement over time.
Number can be detected. Therefore , the pedal depression force detection mechanism detects not only the pedal depression force but also the crankshaft rotation speed without providing a mechanism for separately detecting the crankshaft rotation speed, thereby reducing the number of parts and facilitating assembly work.
The assist unit can be arranged compactly and have a simple appearance.

[0007]

[0008]

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention shown in FIGS. 1 to 9 will be described below. FIG. 1 is a side view of a motorcycle 1 using the driving force assist device of the present embodiment.

In the vehicle body frame, a main frame 3 extends substantially linearly obliquely downward from the head pipe 2 to a shaft supporting portion of the rear wheel 10, and a seat post 5 stands up from the middle of the main frame 3.

A front wheel 9 is rotatably supported at the lower end of a front fork 8 rotatably supported by the head pipe 2, and a rear wheel 10 is rotatably supported by an axle case 21 which is mounted on a rear end of the main frame 3 by mounting bolts 25. Have been. An upper portion of the front fork 8 is connected to a handle 11, and a seat 12 is provided at an upper end of the seat post 5.

A crankshaft case 14 is connected to a connection portion of the main frame 3 with the seat post 5 via a bracket 13.
A pedal arm 16 is attached to both ends of a crankshaft 15 protruding right and left from the crankshaft case 14 at right angles by fitting base ends thereof, and a pedal 17 protrudes from the distal end of the pedal arm 16 in the left-right direction. The whole has constituted the pedal crank.

A drive shaft 19 extends rearward from a gear case 18 behind the crankshaft case 14 through a cylindrical cover 20 and fits into an axle case 21 of the rear wheel 10. A motor 22 is provided between the pedal cranks along the gear case 18. A cavity is formed inside the main frame 3, and a battery 23 and a control unit 24 are built in the cavity.

The configuration of a human-powered drive system by the pedal 17 and a motor drive system by the motor 22 will be described with reference to FIGS. Bearing 15a in crankshaft case 14
The center boss 35 is rotatably fitted to the crankshaft 15 via a pole ratchet type one-way clutch 30 at the left and right center positions of the crankshaft 15 rotatably supported through the crankshaft 15.

The center boss 35 has a large-diameter disk portion 35b at the left end of a fitting cylindrical portion 35a rotatably fitted to the crankshaft 15, and a ratchet cylindrical portion 35c on the left side of the large-diameter disk portion 35b. On the right side, five recesses 35d for housing springs are formed at equal intervals.

A ratchet tooth 35e is formed on the inner peripheral surface of the ratchet cylindrical portion 35c, and a pole ratchet case 15b formed on the crankshaft 15 inside the ratchet tooth 35e.
As shown in FIG. 4, a ratchet pole 31 and a biasing means 32 for biasing the ratchet pole 31 are interposed therebetween.

In FIG. 4, when the crankshaft 15 is rotated counterclockwise (rotation of the pedal 17 in the forward direction), the ratchet pawl 31 engages with the ratchet teeth 35e to rotate the center boss 35 integrally in the same direction. But crankshaft 1
In the clockwise direction of 5, the ratchet pawl 31 is displaced inward against the urging means 32, gets over the ratchet teeth 35e and does not engage, the crankshaft 15 idles, and the driving force is transmitted to the center boss 35. Not done. The one-way clutch 30 as described above is configured.

On the other hand, the fitting cylindrical portion 35a of the center boss 35
A drive bevel gear 36 is provided on the outer periphery of the center boss 35.
The drive bevel gear 36 has teeth 36a formed on the peripheral edge of the drive bevel gear 36 toward the right side, and the disk portion of the drive bevel gear 36 has five recesses 35d of the center boss 35. In response to the above, five concave portions 36b for storing springs are formed.

As shown in FIG. 5, the concave portion 35d of the center boss 35 and the concave portion 36b of the drive bevel gear 36 are combined to form one cylindrical space, and the springs 37 are respectively interposed in the formed five spaces.

Therefore, the rotation of the center boss 35 is transmitted to the drive bevel gear 36 via the spring 37, and the spring 37 is elastically contracted in accordance with the load state of the center boss 35 and the drive bevel gear 36, so that the two rotate relatively. Dynamically displaces.

Ratchet cylindrical portion 35 of center boss 35
A plurality of projections 35f are formed on the outer peripheral surface of the outer peripheral surface of the ratchet c in the axial direction. A sensor ring 38, which is a cylindrical movable piece, is formed on the inner peripheral groove of the ratchet cylindrical portion 35c. The protrusions 35f on the center boss 35 side are engaged with each other so as to be slidable in the axial direction.

Therefore, the sensor ring 38 rotates integrally with the center boss 35 and can be displaced in the axial direction.

On the other hand, five protrusions 36c protrude in the left axial direction from a predetermined radial position of the disk portion of the drive bevel gear 36, and the sensor ring 38 is coaxially adjacent to the inside of the five protrusions 36c. ing.

As shown in FIG. 6, a grooved cam 36d is formed obliquely in the shape of a long hole on the protruding piece 36c. Is movably fitted to

Therefore, when there is a relative rotational displacement between the center boss 35 and the drive bevel gear 36, the pin 39 rotates integrally with the center boss 35, and is guided by the groove cam 36d to move in the axial direction to move the sensor ring 38. Is displaced in the axial direction.

FIGS. 2 and 6 show the case where there is no load on the pedal side by a solid line. The sensor ring 38 and the pin 39 are located at the rightmost end. When the center boss 35 compresses the spring 37 via 30 and precedes the drive bevel gear 36, the pin 39 precedes (relatively displaces to the left) the protruding piece 36c in FIG. , Ie, move to the left in the axial direction as shown by the phantom line in FIG. 6, and protrude the sensor ring 38 to the left as shown by the phantom line in FIG.

The larger the load on the pedal side, the more the center boss 3
5 tends to precede the drive bevel gear 36 more, so that the sensor ring 38 is increasingly displaced to the left.

The sensor ring 38 is connected to the center boss 35
A plurality of projections 38b each having a mountain-like tip formed on the left side from the fitting portion 38a to the ratchet cylindrical portion 35c are continuously annularly projected. As shown in FIG. 7, the plurality of protrusions 38b are spaced apart from each other by a predetermined distance, and the tips have a triangular shape.

In the sensor ring 38, the fitting portion 38a is thicker inward than the projection 38b.
A compression spring 41 is interposed between a disc-shaped holding member 40 integrally fitted with the compression spring 41. The compression spring 41 always urges the sensor ring 38 to the right to eliminate hysteresis due to the clearance between the pin 39 integrated with the sensor ring 38 and the groove cam 36d.

A Hall sensor 42 having a detection point 42a located at a predetermined axial position where the projection 38b of the sensor ring 38 is displaced is fixed to the front portion of the crankshaft case 14.

When the sensor ring 38 is located at the right end, the detection point 42a is located slightly to the left of the tip of the projection 38b. As the sensor ring 38 is displaced to the left, the triangular crest of the projection 38b is shifted toward the bottom. Relatively. Accordingly, the rate at which the hall sensor 42 detects the protrusion 38b of the rotating sensor ring 38 increases as the load on the pedal side increases and the sensor ring 38 is displaced to the left.

FIG. 8 shows a waveform of a voltage signal detected and output by the Hall sensor 42. As shown in FIG. 7, the output waveform of the Hall sensor 42 when the relative position of the detection point 42a of the Hall sensor 42 to the projection 38b of the sensor ring 38 is detected at each of the positions a, b, c, and d is shown in FIG.
Shows corresponding positions.

At the position a, the hall sensor 42 is
Since no b is detected, there is no high level portion indicating detection, and the ratio is 0%. At the position b where the sensor ring 38 is displaced to some extent, the tip of the projection 38b is detected and the ratio of the high level portion is detected. Is about 10%, and at the position c where the sensor ring 38 is displaced, the ratio is about 45%. The sensor ring 38 is displaced more than a certain degree and the detection point 42a of the Hall sensor 42 is located at the foot of the projection 38b. At the d position, the proportion of the high level portion is 90%.

This output signal is used as it is as a duty signal for controlling the motor 22.

Next, the drive transmission means downstream of the drive bevel gear 36 will be described. Drive bevel gear 3
A driven bevel gear 45 that meshes at right angles with 6 is supported by bearings 44 and fitted to the front end of the drive shaft 19.

As shown in FIG. 3, the drive shaft 19 is inserted into the axle case 21 through the inside of the cylindrical cover 20, and a bevel gear 46 is fitted to an end of the drive shaft 19. The bevel gear 46 is rotatably supported by a bearing 47. ing.

A rotating cylindrical shaft 49 rotatably supported by bearings 48 in the axle case 21 has a pivot 5 inside.
The bevel gear 52, which is penetrated by 0 and is supported via a needle bearing 51, is fitted to the rotating cylindrical shaft 49 and meshes with the bevel gear 46 fitted to the drive shaft 19.

A rotating cylindrical shaft 49 is provided on the right outside of the bevel gear 52.
The cover 48 is fitted over the bearing 48 for supporting the shaft 48, and a nut 54 is screwed into the right end thread portion of the pivot 50 projecting outward from the cover member 53 to prevent the bearing 48 from coming off. . The wheel hub 55 of the rear wheel 10 is fitted into a spline groove in the left half of the rotary cylindrical shaft 49 and is fixed by a nut 56. The rear wheel 10 is supported on the wheel hub 55 via spokes 57.

The rear portion of the main frame 3 is divided into left and right frames 3a and 3b. The right frame 3b is mounted on the axle case 21 by mounting bolts 25. The left frame 3a has a rear end 3c branched in a fork shape. Flange 50 formed on pivot 50 by fitting the left end of pivot 50
The rear end 3c of the frame 3a is sandwiched between the a and the nut 58 fitted to the left end thread portion of the pivot 50.

The above is the manual drive system. When the driver steps on the pedal 17 to rotate the crankshaft 15, the one-way clutch 30, the spring 37, and the bevel gears 36, 4
By rotating the drive shaft 19 via the wheel 5, the rotating cylindrical shaft 49 is rotated together with the rear wheel 10 via the bevel gears 46 and 52, and can be run as a bicycle.

At this time, when the load is large, such as when climbing a sloping road or at the start of traveling, the output waveform of the Hall sensor 42 has a high level portion at an increased rate. When the pedal is not depressed during running, the rotation of the rear wheel 10 is transmitted to the front bevel gear 45 and the center boss 35 via the drive shaft 19, but the one-way clutch 3
The value "0" is not transmitted to the crankshaft 15 and the pedal 17, and the vehicle can run with the same feeling as in normal bicycle running.

On the other hand, the Hall sensor 42 detects the rotation of the center boss 35 (that is, the rotation of the rear wheel 10), and the period in which the high level portion of the output waveform appears corresponds to the vehicle speed. The output waveform includes both the pedal load element and the vehicle speed element.

Next, a drive system by a motor 22 provided between the left and right pedal cranks behind the crankshaft 15 will be described. The gear case 18 includes the drive shaft 1
9 swells to the left from the portion that houses the upstream side, and the motor 22 is fitted into the swelling portion front opening from the front.

Accordingly, the driving force assisting mechanism is unitized together with the pedal depression force detecting mechanism. The motor 22 is located near the crankshaft 15, and its drive shaft projects rearward and is directed in a direction orthogonal to the crankshaft 15. The motor 22 itself fits compactly within the left and right widths of the crankshaft 15. ing.

A gear 60 is formed at the end of the drive shaft projecting rearward from the motor 22. A gear 61 meshes with the gear 60, and a gear 62a is formed on a rotary shaft 62 that integrally supports the gear 61. A gear 63 meshes with the gear 62a, and a gear 64a is formed on a rotating shaft 64 integrated with the gear 63, thereby forming a reduction gear group.

On the other hand, the gear 65 fitted to the drive shaft 19 via the one-way clutch 66 is
4 gear 64a.

Accordingly, when the motor 22 is driven, the gear 65 is reduced by the engagement of the reduction gear group to rotate the gear 65, and further transmitted to the drive shaft 19 via the one-way clutch 66 to assist the rotational drive of the rear wheel 10 by human power. can do.

The rotation of the rear wheel 10 is not transmitted to the gear 65 by the one-way clutch 66, and the reduction gear group and the motor 22 do not become a resistance during running or the like due to inertia.

The above-mentioned human assist control by the motor 22 is performed based on the output signal of the Hall sensor 42, and this motor drive circuit is shown in FIG.

The output of the Hall sensor 42 is input to the base terminal of a power transistor 71 whose emitter is grounded via an amplifier 70. The collector terminal of the power transistor 71 is connected to one terminal of the motor 22, and the other terminal is connected to the battery. 23.

The output waveform of the Hall sensor 42 is as shown in FIG.
Are conducted, and the output signal of the Hall sensor 42 controls the duty of the motor 22 as it is. Therefore, it is not necessary to separately provide an electrical chopping control circuit and the like.

The duty control of the motor 22 is such that as the load on the pedal side increases, the proportion of the high level portion of the Hall sensor 42 increases (the duty ratio increases), so that the power supply time to the motor 22 increases and the motor 22 , The driving force of the motor 22 is increased, the assistance by the motor 22 is increased, and the burden on the driver is reduced.

Further, in this embodiment, the motor 22 is disposed at a position where the driving force of the motor 22 is transmitted to the drive shaft 19 downstream of the driving transmission position by the spring 37, and self-feedback is possible. That is, when the motor output exceeds the human treading force, the motor 22 acts in a direction to return the relative displacement between the center boss 35 and the drive bevel gear 36, and as a result, the motor output is reduced.

On the other hand, the motor 22 is also controlled by the control unit 24. Although not shown, the vehicle speed is measured from the output signal of the hall sensor 42, and the motor 22 is controlled based on the vehicle speed. For example, when the vehicle speed is a low speed below a certain value and at a high speed above a certain value, the motor 22 is stopped to put a heavy load on the motor 22,
I try to avoid unnecessary operations.

In this embodiment, the vehicle speed detection used for such control can be simultaneously detected by a mechanism such as the sensor ring 38 and the hall sensor 42, so that there is no need to provide a separate vehicle speed detection device, the number of parts is reduced, and assembly is performed. The work can be simplified, the weight of the vehicle body can be reduced, and the cost can be reduced.

Drive bevel gear 3 as drive transmission member
6, a center boss 35 as a rotating member, a sensor ring 38 as a movable piece, a pin 39 as a displacement means, and a groove cam 36
Since the pedal depression force detection mechanism including the d and the hall sensor 42 serving as the detection means is included in the crankshaft case 14 which supports the crankshaft 15, the pedal depression force detection mechanism can be compactly arranged near the crankshaft 15 in a compact manner. A simple appearance can be secured. Further, a pedal depression force detection mechanism can be mounted without changing the crankshaft width of a normal bicycle or the like, so that the structure is highly versatile.

Since the motor 22 is provided integrally with the rear of the crankshaft case 14 within the left and right widths of the crankshaft 15, the pedal depression force detecting mechanism and the heavy load of the motor 22 are concentrated at a low position of the vehicle body near the crankshaft 15. As a result, the center of gravity can be reduced, and the crankshaft case 14 is provided in front of the motor 22 to protect the motor 22 against water splashing and flying stones from the front.

The projection 3 of the sensor ring 38 of this embodiment
8b, the tip portion has a triangular shape, and the ratio of the ridge portion changes linearly toward the tip, and the groove cam 36d for guiding the movement of the sensor ring 38 is a linear long hole. As shown by the solid line A, the output of the hall sensor 42 with respect to the pedaling force changes linearly.

Here, as shown in FIG. 11A, assuming that the tip of the projection of the sensor ring 138 has a shape Ia in which two sides of the triangular shape are bulged outward, the output characteristics of the Hall sensor 42 are as shown in FIG. As shown by a dashed-dotted line I in FIG. 10, an upwardly convex curve is shown, and the assisting force of the motor 22 can be increased while the pedal effort is small.

Conversely, as shown in FIG. 11 (2), if the shape of the tip of the projection of the sensor ring 238 is a shape IIa in which two sides of a triangle are depressed inward, the Hall sensor 42
10 shows a downwardly convex curve as shown by a two-dot chain line II in FIG. 10, and the greater the pedal effort, the greater the assisting force of the motor 22 can be applied.

By changing the shape of the tip of the projection of the center ring in this manner, the output characteristics of the Hall sensor 42 can be changed, and the manner in which the assisting force of the motor 22 acts can be easily changed.

Further, the projecting piece 36 of the drive bevel gear 36
The output characteristics of the Hall sensor 42 can also be changed by changing the shape of the groove cam 36d provided in c.

That is, in this embodiment, the groove cam 36d is
As shown in FIG. 10, the output characteristics of the Hall sensor 42 are also linear as shown by the solid line in FIG. In the same manner, the inclination direction is a downwardly convex curved shape 136d, so that the displacement of the sensor ring 38 is increased while the pedaling force is small, and the characteristic of the upwardly convex curve indicated by the dashed line I in FIG. Conversely, as shown in FIG. 12 (2), by forming the groove cam 236 into an upwardly convex curved shape 236d, the displacement of the sensor ring 38 increases as the treading force increases, and the two-dot chain line II in FIG. The characteristic of the downward convex curve shown can be obtained.

By changing the shape of the groove cam in this manner, the manner of operation of the assisting force of the motor 22 can be easily changed.

Although the above-described embodiment is a two-wheeled vehicle driven by a shaft driven by a drive shaft 19, the present invention is also applicable to a two-wheeled vehicle driven by a chain.

For example, the drive bevel gear 3 of the above embodiment
6 and the bevel gear 52 as a chain sprocket, a chain is bridged between the two, and a driving force from the motor 22 is transmitted to a sprocket meshing with the chain via a one-way clutch after deceleration. The mechanism for detecting the pedal load and the vehicle speed can be used as it is.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle to which a driving force assist device according to an embodiment of the present invention is applied.

FIG. 2 is a sectional view showing a configuration of a first half of a drive system.

FIG. 3 is a cross-sectional view illustrating a configuration of a rear half of a drive system.

FIG. 4 is a sectional view showing a ball ratchet type one-way clutch unit.

FIG. 5 is a cross-sectional view showing a drive transmission portion by a spring.

FIG. 6 is a view showing a groove cam and a pin provided on a projection of a bevel gear.

FIG. 7 is a diagram showing a shape of a tip of a projection of a sensor ring.

FIG. 8 is a diagram showing an output waveform of a Hall sensor.

FIG. 9 is a circuit diagram of a drive control system of the motor.

FIG. 10 is a diagram illustrating output characteristics of a hall sensor with respect to a pedal depression force.

FIG. 11 is a view showing a modification of the shape of the tip of the projection of the sensor ring.

FIG. 12 is a view showing a modification of the shape of the groove cam.

[Explanation of symbols]

1 ... two-wheeled vehicle, 2 ... head pipe, 3 ... main frame,
5 ... seat post, 8 ... front fork, 9 ... front wheel,
DESCRIPTION OF SYMBOLS 10 ... rear wheel, 13 ... bracket, 14 ... crankshaft case, 15 ... crankshaft, 16 ... pedal arm, 17 ... pedal, 18 ... gear case, 19 ... drive shaft, 2
0: cylindrical cover, 21: axle case, 22: motor, 2
DESCRIPTION OF SYMBOLS 3 ... Battery, 24 ... Control unit, 25 ... Mounting bolt, 30 ... One-way clutch, 31 ... Ratchet pole, 32 ... Urging means, 35 ... Center boss, 36
... Drive bevel gear, 37 ... Spring, 38 ... Sensor ring, 39 ... Pin, 40 ... Pressing bracket, 41 ... Compression spring, 42 ... Hall sensor, 44 ... Bearing, 45,46 ... Bevel gear, 47,48 ... Bearing, 49 ... Rotating cylindrical shaft, 50 ... pivot, 51 ... needle bearing, 52 ... bevel gear, 53 ... lid member, 54 ... nut, 55 ... wheel hub, 56 ... nut, 57 ... spoke, 58 ... nut, 60, 61 ... gear, 62 ... Rotating shaft, 63 ... Gear, 64 ... Rotating shaft, 65 ... Gear, 66 ... One-way clutch, 70 ... Amplifier, 71 ... Power transistor, 136 ... Groove cam, 138 ... Sensor ring, 2
36 ... groove cam, 238 ... sensor ring.

Continuation of the front page (56) References JP-A-4-244496 (JP, A) JP-A-3-150431 (JP, A) JP-A-57-74285 (JP, A) JP-A-6-247377 (JP) , A) JP-A-6-105413 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62M 23/02 G01L 3/02

Claims (1)

(57) [Claims] 1. An assist motor disposed close to a pedal crankshaft, an assist unit that supports the pedal crankshaft and holds the assist motor, and a pedal depression force detection mechanism that detects human power applied to the pedal crankshaft. A control device that controls the assist motor based on a pedal depression force detected by the pedal depression force detection mechanism and a rotation speed of the pedal crankshaft; and a drive unit provided on one side of the assist unit for driving a driving wheel. In the driving force assisting device, the assist motor is connected from the one side of the drive means and provided so as to direct a motor shaft substantially horizontally behind the pedal crankshaft. The pedal depression force detection mechanism includes the pedal. a rotating member that will be journaled through the one-way clutch to the crank shaft, rotation of said rotary member To allow the phase shift against the direction of rotation
The drive means connected to the rotary member, and a change in accordance with the phase shift supported by the outer periphery of the rotating member.
A displacement unit that is displaced by a displacement amount; and a detection unit that is integrally attached to the assist unit on the outer periphery of the displacement unit and that detects a displacement amount of the displacement unit over time. A driving force assisting device, wherein a pedaling force applied to the pedal crankshaft and a rotation speed of the pedal crankshaft are detected based on displacement information.