JP3201234B2 - Drive assist device for bicycle with drive assist force - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bicycle having a drive assist device having a built-in electric motor and a resultant device mounted on a body of a bicycle.
The present invention relates to a bicycle with a driving assist force that assists a pedal depression force by a driving assist force of the electric motor and facilitates climbing or traveling while receiving a headwind.

[0002]

2. Description of the Related Art A resultant force device incorporated in the above-mentioned drive assist device combines a pedal depression force of an occupant applied to a crankshaft and a drive assist force of an electric motor, and transmits the resultant force to drive wheels. Planetary gear devices and differential devices are widely used.

When the pedaling force and the driving assist force are combined by the resultant device, an assist ratio based on the driving assist force,
That is, the output of the electric motor is controlled so that the ratio between the pedal depression force and the driving assistance force is always constant, and preferably, the assist ratio is always 1: 1. It is necessary to keep the running feeling of the attached bicycle good. At this time, special care must be taken to ensure that the drive assist force does not exceed the pedal depression force in any case.

The conventional drive assist device detects pedal depression force by a dedicated detecting means (torque sensor or the like) and inputs a signal to a control device (small CPU or the like), and this control device adjusts the pedal depression force. Thus, the current flowing through the electric motor is controlled to set the assist ratio to 1: 1 or an arbitrary ratio.

[0005]

However, the accuracy of the detecting means for detecting the pedaling force, the output characteristics of the electric motor with respect to the current value, the friction loss of the resultant device, and the like are slightly different for each individual. If these small differences are accumulated, the assist ratio easily fluctuates.

Therefore, in order to accurately set the assist ratio to one to one or an arbitrary ratio, the accuracy of the pedal depression force detecting means, the output characteristics of the electric motor, the friction loss of the resultant device, and the like are strictly checked. In addition, it is necessary to perform an inspection step of checking the output of the electric motor again after assembling the entire drive assist device, thereby reducing the productivity of the drive assist device and greatly increasing the cost.

Further, even if the assist ratio is 1 to 1 under the condition that the battery is correctly charged at the time of a new vehicle, if the output of the electric motor is improved due to overcharging of the battery, When the friction loss of the resultant device is reduced and the output of the electric motor is relatively improved later, the assist ratio is not necessarily 1: 1 because the driving assist force may exceed the pedal depression force.

If the drive assist force exceeds the pedal depression force,
Not only does the running feeling of the bicycle with the driving assist force become unnatural, but also the occupant experiences unexpected acceleration force.To avoid this situation, the output of the electric motor is set to a small value in advance, and the battery is overcharged. It is necessary to prevent the driving assist force from exceeding the pedal depression force even when the friction loss of the resultant force device is reduced.

However, if the output of the electric motor is set to a small value in advance in case the battery is overcharged or the friction loss of the resultant device is reduced, when the battery is properly charged or the friction loss of the resultant device is reduced. At the time of a large new vehicle, the output of the electric motor becomes too low, so that the assist ratio cannot be maintained at 1: 1.
When the battery voltage is low, the output of the electric motor is further reduced, and the assist ratio is further reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an assist ratio by a driving assist force of an electric motor can be accurately controlled to 1: 1 or an arbitrary ratio. It is an object of the present invention to provide a drive assist device for a bicycle with a drive assist force capable of improving the performance and reducing the cost.

[0011]

In order to achieve the above object, a bicycle with a driving assisting force according to the present invention is provided with a resultant device for synthesizing a pedal depression force of an occupant and a driving assisting force of an electric motor around a crankshaft. A drive sprocket rotatably supported and wound around a drive chain is provided integrally with the rotation, and an output rotation member for transmitting a resultant force of a pedal depression force and a drive assist force to a drive wheel side via the drive chain; A resultant rotating member integrally and rotatably provided in the member via an axial moving means and movably in the axial direction, and transmitting a pedal depression force and a driving assistance force to the resultant rotation member, and simultaneously exerting a pedal depression force and a driving assistance force. Force generating means for applying two thrust component forces having a strength proportional to the axial direction of the crankshaft from both sides of the resultant rotating member, and a resultant rotating member A biasing means for maintaining the axial movement range at a neutral position, and a position sensor for detecting a moving direction and a moving amount from the neutral position of the resultant rotating member which moves in the axial direction by receiving the two thrust components. And the detection point of the position sensor is arranged at a point that is orthogonal to the tension side chain line of the drive chain and coincides with a reference plane passing through the center line of the crankshaft, and based on an input from the position sensor. The intensity difference between the two thrust components is detected, and this intensity difference is set to 0.
And a control device for controlling the output of the electric motor so as to obtain an arbitrary intensity difference.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a drive assist device mounted on a vehicle body frame of a bicycle with drive assist force and configured to assist a pedaling force of an occupant by a drive assist force of an electric motor provided therein. FIG. 2 is a longitudinal sectional view of the drive assist device taken along the line II-II in FIG. FIG. 3 is a right side view of the drive assist device.

A casing 2 forming an outer shell of the drive assist device 1 is made of, for example, an aluminum alloy. As shown in FIG. 1, a left case 2L located on the left side, a middle case 2M located in the center, and a right case 2M on the right side. The located light case 2R has a structure fixed by several bolts 3 penetrating in the vehicle width direction. FIG. 2 shows a state in which the left case 2L has been removed.

A crankshaft 4 extending in the vehicle width direction is rotatably supported at a rear portion of the casing 2. Cranks 5L and 5R are fixed to both ends of the crankshaft 4 protruding left and right from the casing 2 with bolts 6. Is done. Crankshaft 4
Is driven to rotate in the direction shown by arrow A when a pedal (not shown) provided at the distal end of each of the cranks 5L and 5R is depressed by the foot of the occupant.

On the other hand, an electric motor 7 is provided at a front portion in the casing 2. The electric motor 7 generates a driving assist force. The outer case 8 is fixed to the middle case 2M side by several bolts 9, and the main shaft 10 of the electric motor 7 is parallel to the crankshaft 4. . This spindle 10
Rotates in the direction indicated by arrow B.

A reduction gear train 12 is provided on the left side of the casing 2. The reduction gear train 12 is located on the left side of the primary drive gear 13, the primary drive gear 13 meshed with the primary drive gear 13, and the primary drive gear 13, which is provided integrally with the main shaft 10 of the electric motor 7. A secondary drive gear 16 that is rotatably integrated with the primary driven gear 14 only when the electric motor 7 is operated by the action of the one-way clutch 15, a secondary driven gear 17 that meshes with the secondary drive gear 16, and a right side of the secondary driven gear 17. It comprises a tertiary drive gear 18 provided integrally with the rotation, and a large-diameter tertiary driven gear 19 provided near the left end of the crankshaft 4 and meshing with the tertiary drive gear 18.

An intermediate device is provided at an intermediate portion of the crankshaft 4.
21 is mounted on the shaft. FIG. 4 is an enlarged longitudinal sectional view of the resultant device 21. The resultant device 21 is configured as follows, for example.

First, a substantially cylindrical pedal force transmitting member 22 is provided on the outer periphery of an intermediate portion of the crankshaft 4 with a pair of metal bearings 23,2.
It is rotatably supported via 4. The right end of the pedaling force transmitting member 22 has an enlarged diameter to form a clutch housing 25, in which a one-way clutch 26 is provided. The one-way clutch 26 transmits only the rotation of the crankshaft 4 in the direction A to the pedal depression force transmission member 22.
When the rotation speed of the rotation shaft 22 exceeds the rotation speed of the crankshaft 4, the clutch is disconnected.

A drive assisting force transmitting member 27 formed in the shape of a cup is rotatably mounted on the outer periphery of the left end portion of the pedal pressing force transmitting member 22 while the axial movement is restricted by a circlip 28. Have been. This driving assist force transmitting member
The tertiary driven gear 19 is rotatably connected to the left end of 27 by a spline connection or the like. For this reason, the rotation of the tertiary driven gear 19, that is, the rotation of the electric motor 7 in which the driving assist force is reduced, is directly used as the driving assist force transmitting member 27.
It is transmitted to.

On the other hand, near the right end of the crankshaft 4, an output rotary member 31 is rotatably supported by a bearing 32.
The output rotating member 31 is connected to an output housing located on the right side.
33, and an output sleeve 34 located on the left side. The joint flanges 35, 36 formed at the joint of the two parts 33, 34 are assembled by being fastened with six bolts 37. ing.

As shown in FIG. 2, the inner peripheral surface of the output sleeve 34 is provided with a plurality of inner peripheral spline grooves 38 extending in the axial direction. Output housing 33 and output sleeve
A ball stopper 41 made of a steel plate is sandwiched between the output sleeve 34 and a ball stopper 42 made of a steel plate is fixed to the left end of the output sleeve 34 using a circlip 43.

A resultant rotating member 45 is provided inside the output rotating member 31. This resultant force rotating member 45 is a member in which a donut disk-shaped resultant force flange 47 is integrally provided at the left end of a cylindrical resultant force sleeve 46 located inside the output sleeve 34, and further has an annular sensor on its left side. A ring 48 is provided integrally with the rotation. The pedal force transmitting member 22 is loosely inserted into the inner diameter of the resultant flange 47, and a sensor groove 49 is formed on the outer periphery of the sensor ring 48.

A plurality of outer peripheral spline grooves 51 extending in the axial direction are formed on the outer peripheral surface of the resultant sleeve 46, and a steel ball is provided between the outer peripheral spline groove 51 and the inner peripheral spline groove 38 of the output sleeve 34. The ball splines 53 are configured by arranging the 52. Both ends of the row of steel balls 52 are held by the ball stoppers 41, 42, thereby preventing the steel balls 52 from being pulled out of the spline grooves 38, 51 on the inner and outer circumferences. By the ball spline 53, the resultant rotating member 45 is integrally rotatable with the output rotating member 31, and is kept relatively movable in the axial direction. The ball spline 53 serves as the axial moving means described in the first aspect.

Further, the resultant flange 47 of the resultant rotating member 45
A torque cam 55 is provided between the power transmission member 22 and the clutch housing 25 of the pedal depression force transmission member 22, and a torque cam 56 is provided between the resultant flange 47 and the driving assist force transmission member 27. These torque cams 55 and 56 serve as a component force generating means according to the first aspect, and are provided on the inner peripheral side of the ball spline 53 described above.

As shown in FIG. 5, the right torque cam 55 is formed on the inclined cam-shaped inner cam 57 provided on the right side of the resultant flange 47, and is formed on the left side of the clutch housing 25 and meshes with the inner cam 57. And an outer cam 58. The left torque cam 56 includes a sloped cam-shaped inner cam 59 provided on the left side of the resultant flange 47 and an outer cam 60 formed at the right end of the driving assist force transmitting member 27 and meshing with the inner cam 59. It is configured.

The cam shapes of the left and right torque cams 55 and 56 are symmetric with respect to the resultant flange 47. The cam shape of the torque cam 55 on the right side is such that when the pedal pressing force transmitting member 22 rotates in the direction A due to the rotation of the crankshaft 4 (pedal pressing force), the pedal pressing force P is transmitted to the resultant force flange 47 as indicated by the vector. At the same time, a thrust component p having a strength proportional to the pedal depression force P is generated, and the resultant flange 47 is pressed to the left by the thrust component p.

On the other hand, the cam shape of the left torque cam 56 is
When the drive assist force transmitting member 27 receives the drive assist force of the electric motor 7 and rotates in the direction A, the drive assist force M is transmitted to the resultant flange 47 and, at the same time, a thrust having a strength proportional to the drive assist force M A thrust component m
As a result, the resultant flange 47 is pressed to the right.

Further, a pair of left and right coil springs 62, 63 are provided on the inner peripheral side of the torque cams 55, 56. These coil springs 62 and 63 are urging means according to the first aspect. Right coil spring 62
Is resiliently mounted between the resultant flange 47 and the clutch housing 25 of the pedal force transmitting member 22, and the left coil spring 63
Is elastically mounted between the resultant flange 47 and the driving assist force transmitting member 27. The shape dimensions and spring constants of the left and right coil springs 62 and 63 are set to be the same.

The pedaling force transmitting member 22 (the clutch housing 25) and the drive assisting force transmitting member 27 are immovable in the axial direction of the crankshaft 4, and the resultant flange 47 between them acts on the crankshaft 4 by the action of the ball spline 53. When the resultant flange 47 is pressed from both sides by two coil springs 62, 63 having an equal biasing force, the position C at which the lengths of the coil springs 62, 63 become equal is possible. With the bias of the coil springs 62 and 63 balanced,
The resultant flange 47 stops. This position C is the resultant rotating member
The neutral position 45 is set to be a middle point of a range in which the resultant rotating member 45 can move in the axial direction of the crankshaft 4 (movable range of the ball spline 53).

The output housing 33 of the output rotary member 31
A sprocket boss 64 is formed at the right end, and the sprocket boss 64 protrudes from the right side of the casing 2 to the outside. A drive sprocket 65 is integrally fixed to this portion by a connecting means such as a spline or a screw. ing. A drive chain 66 is wound between the drive sprocket 65 and a driven sprocket provided on the rear wheel (not shown) of the bicycle with a driving assist force.

On the other hand, a position sensor 67 is fixed to the rear portion of the bottom surface of the casing 2 with bolts 68. The position sensor 67 has a rotating arm 69 provided on the upper surface thereof. A miniature bearing 70 rotatably supported at the tip of the rotating arm 69 is provided with a sensor groove 49 of a sensor ring 48.
It is tightly and slidably fitted inside.

When the resultant rotation member 45 moves in the axial direction of the crankshaft 4, the sensor ring 48 also moves in the axial direction together with the resultant rotation member 45, so that the rotation arm 69 of the position sensor 67 rotates to rotate the resultant force. The direction and amount of movement of the member 45 from the neutral position C are detected.

Here, assuming a reference plane D passing through the center line of the crankshaft 4 perpendicularly to the tension side chain line 66a of the drive chain 66 as shown in FIG. Bearing 70
Are arranged at a point E corresponding to the reference plane D. The rotation arm 69 of the position sensor 67 is set so as to be perpendicular to the reference plane D when the resultant rotation member 45 is at the neutral position C. The reference plane D is the same as point E.
The position sensor 67 may be provided so that the miniature bearing 70 is arranged at the point F corresponding to the position.

The resultant device 21 is configured as described above, and the drive assist device 1 is provided with a control device 72 (not shown in drawings other than FIG. 6). As shown in FIG. 6, a position sensor 67 is electrically connected to the control device 72, and data of the moving direction and the moving amount of the resultant rotating member 45 measured by the position sensor 67 are transmitted to the control device 72.
72 is to be entered. The control device 72 is electrically connected to the electric motor 7, a battery unit 73 serving as a power source for the electric motor 7, a rotational speed sensor 74, and the like.

The rotation speed sensor 74 is a sensor fixed to the left side surface of the middle case 2M with a bolt 75 as shown in FIG. For example, a disk-shaped rotation sensor plate 76 is provided on the left side of the tertiary driven gear 19 so as to rotate integrally with the crankshaft 4.
The rotation speed sensor 74 reads the movement of the irregularities 77 provided at regular intervals on the outer periphery of the
Is detected, and the data is input to the control device 72.

Next, the operation of the thus configured drive assist device 1 will be described.

When the bicycle with the driving assist force runs, the crankshaft 4 rotates in the direction A by receiving the pedaling force of the occupant, and the rotation of the crankshaft 4 is transmitted via the one-way clutch 26 of the resultant device 21 to the pedaling force transmitting member 22. And the pedal effort transmitting member 22 rotates in the A direction. On the other hand, the electric motor 7
Is reduced by the reduction gear train 12 and transmitted to the driving assist force transmitting member 27, and the driving assist force transmitting member 27 also rotates in the A direction. The rotational force of the pedal depression force transmitting member 22 and the driving assist force transmitting member 27 is transmitted to the resultant force flange 47 of the resultant rotating member 45 via the torque cams 55 and 56, and the resultant rotating member 45 is output through the ball spline 53 to the output rotating member 31. Is rotated in the A direction.

The rotational force of the output rotary member 31 is a resultant force of the pedal depression force of the occupant and the driving assist force of the electric motor 7, and the resultant force is output from the drive sprocket 65, and is provided via the drive chain 66. It is output to the driving wheel (rear wheel) of the bicycle. For this reason, the pedaling force is assisted by the driving assisting force of the electric motor 7, and the bicycle with the driving assisting force can be easily run with a small pedaling force.

Each of the torque cams 55 and 56 is a pedal force transmitting member.
At the same time as transmitting the torque of the driving force transmitting member 22 and the driving force transmitting member 27 to the resultant force rotating member 45, two thrust components p, p having a strength proportional to the pedal depression force P and the driving force M as indicated by the vector in FIG. m is the resultant flange 47 of the resultant rotating member 45
The resultant flange 47 is pressed from both the left and right sides by the thrust components p and m.

When the ratio between the pedal depression force P and the driving assist force M, that is, the assist ratio is 1: 1, the strengths of the two thrust component forces p and m acting on both sides of the resultant flange 47 become equal. 4, 5 and 7 because they cancel each other out.
The position of the resultant rotation member 45 is maintained at the neutral position C as shown in FIG.

However, when the assist ratio is not 1 to 1, the strengths of the two thrust components p and m become uneven, and the resultant rotation member 45 is pressed against the stronger thrust component p or m. Then, it moves in the axial direction of the crankshaft 4.
For example, if the pedaling force P is greater than the driving assist force M,
Since the thrust component p of the pedal depressing force P becomes stronger than the thrust component m of the driving assist force M, the resultant rotation member 45 is pressed by the thrust component p, and as shown in FIG.
To the left.

When the driving assist force M is greater than the pedal depression force P, the thrust component m of the driving assistance force M becomes greater than the thrust component p of the pedal depression force P.
Numeral 45 is pushed by the thrust component m and moves rightward from the neutral position C as shown in FIG.

The neutral position C of the resultant rotating member 45
The direction and amount of movement from are read by the position sensor 67, and the data is input to the control device 72. The control device 72 performs the following based on the input from the position sensor 67:
The difference in the strength of the three thrust components p and m is detected, and this difference is
The output of the electric motor 7 is controlled so that That is,
As shown in FIG. 7A, when the resultant rotation member 45 moves to the left from the neutral position C, the output of the electric motor 7 is improved,
When the resultant rotation member 45 moves to the right from the neutral position C as shown in FIG. 7C, the output of the electric motor 7 is controlled to be reduced.

As a result, the resultant force device 21 is maintained in a state where the resultant force rotating member 45 is placed at the neutral position C as shown in FIG. 7B, and the assist ratio is always maintained at 1: 1. The assist ratio is not limited to one-to-one but can be set to an arbitrary ratio by causing the control device 72 to arbitrarily set the difference between the two thrust component forces p and m. For example, when the strength difference between the two thrust components p and m is set to 1: 0.5, the driving assist force M becomes half the pedaling force P.

The ratio of the intensity difference can be changed continuously during running. For example, when starting a bicycle with a driving assist force, the assist ratio is set to the maximum ratio of 1 to 1,
By lowering the assist ratio as the vehicle speed increases, the power consumption of the electric motor 7 can be significantly reduced while reducing the burden on human power, and the discharge distance of the battery unit 73 can be suppressed to greatly extend the traveling distance. it can.

Further, the control device 72 determines the vehicle speed from the rotation speed of the crankshaft 4 input from the rotation speed sensor 74. For example, when the vehicle speed exceeds a certain value, the electric motor 7
The power supply to the vehicle is reduced or set to zero so that the vehicle speed does not become excessive.

When the drive assist device 1 is configured as described above, the resultant force device 21 in which the pedal depression force and the drive assist force are combined.
Since the assist ratio is directly and mechanically detected in the part, the assist ratio can be accurately determined without error. For this reason, there is no need to once detect the pedaling force applied to the crankshaft 4 and control the output of the electric motor 7 in accordance therewith, which eliminates the need for a detecting means such as a torque sensor for detecting the pedaling force. Become.

Therefore, it is not necessary to consider the error of the pedal depression force detecting means, and the assist ratio is set to 1: 1 or an arbitrary ratio based on the net output of the electric motor 7. Variations in output characteristics, the state of charge of the battery unit 73, or changes in friction loss of the resultant device 21 before and after the running-in operation do not affect the assist ratio, and the assist ratio can be accurately and easily controlled. it can.

In addition, since only the intensity difference between the thrust component forces p and m, which is significantly smaller than the absolute values of the pedal depression force and the driving assist force, needs to be read by the position sensor 67, the reading error of the position sensor 67 can be greatly reduced. It is possible to make the assist ratio smaller, which also makes it easier to accurately control the assist ratio.

Then, as in the prior art, the output characteristics of the electric motor 7, the friction loss of the resultant device 21, etc. are strictly checked for all, the drive assist device 1 is assembled, and the output of the electric motor 7 is checked again. Since the steps can be omitted, the productivity of the drive assist device 1 can be dramatically improved and the cost can be reduced.

If, for example, a difference occurs in the operability of the left and right torque cams 55, 56 of the resultant device 21, or a difference occurs in the spring constants of the left and right coil springs 62, 63, the neutral of the resultant rotation member 45 will not occur. It is conceivable that the assist ratio changes due to a slight shift of the position C. In this case, the shifted neutral position C
Since the assist ratio can be accurately returned to 1: 1 only by resetting the neutral reading value of the position sensor 67 in accordance with the above, the maintenance performance is very good.

In the drive assist device 1, as described above, the miniature bearing 70, which is the detection point of the position sensor 67, is connected to the center line of the crankshaft 4 orthogonally to the tension side chain line 66a of the drive chain 66. Are arranged at the point E or the point F which coincides with the reference plane D passing through.

That is, since the drive sprocket 65 around which the drive chain 66 is wound is provided at the rightmost side of the resultant device 21, when the drive sprocket 65 is driven to rotate by the combined force of the pedal depression force and the drive assist force,
Due to the chain tension of the tension side chain line 66a, a moment is generated to rotate the resultant apparatus 21 clockwise in plan view. Therefore, the sensor ring 48 of the resultant device 21 is slightly inclined such that its front side (point G in FIG. 3) is rightward and its rear side (point H) is leftward.

Therefore, when the miniature bearing 70 of the position sensor 67 is disposed at the point G or H, the inclination of the sensor ring 48 due to the influence of the chain tension is completely sensed by the position sensor 67. The neutral position C of the resultant rotation member 45 shifts depending on the presence or absence of the tension, and the assist ratio becomes inaccurate.

However, since the sensor ring 48 is tilted about the points E and F crossed by the reference plane D, the points E and F
At the point F, the amount of movement of the sensor ring 48 to the left and right becomes zero. Therefore, if the miniature bearing 70 of the position sensor 67 is disposed at the point E or F as in this embodiment, the position sensor 67 does not sense the inclination of the sensor ring 48 due to the chain tension. The shift of the neutral position C is eliminated, and the assist ratio can be more accurately controlled.

In the present embodiment, the torque cams 55 and 56, which are the component force generating means of the resultant device 21, are configured as slide-type slope cams. However, the present invention is not limited to this. A torque cam may be configured such that an inner cam formed in a helical gear shape is engaged with an outer cam formed in a helical gear shape. Further, in this embodiment, the urging means of the resultant device 21 is the coil springs 62 and 63, but other types of springs may be used.

[0057]

As described above, the drive assist device for a bicycle with drive assist force according to the present invention rotates the resultant device for synthesizing the pedal depression force of the occupant and the drive assist force of the electric motor around the crankshaft. A drive sprocket that is freely rotatably supported and winds around the drive chain, is provided integrally with the rotation, and an output rotation member that transmits a resultant force of a pedal depression force and a drive assist force to the drive wheels via the drive chain;
The output rotary member is rotated integrally with the output rotary member via the axial moving means, and the resultant rotary member is provided so as to be movable in the axial direction. Component force generating means for applying two thrust component forces having a strength proportional to the driving assist force from both sides of the resultant rotating member along the axial direction of the crankshaft, and keeping the resultant rotating member at a neutral position in the axial movement range. A bias sensor, and a position sensor configured to detect a moving direction and a moving amount from a neutral position of the resultant rotating member that moves in the axial direction by receiving the two thrust components, and a detection point of the position sensor. At a point that is perpendicular to the tension side chain line of the drive chain and coincides with a reference plane passing through the center line of the crankshaft,
A control device is provided for detecting an intensity difference between the two thrust component forces based on an input from the position sensor, and controlling an output of the electric motor so as to make the intensity difference zero and an arbitrary intensity difference. It is assumed that.

With this configuration, the assist ratio is directly and mechanically detected in the resultant device, so that the assist ratio can be accurately determined without error, and the assist ratio is determined based on the net output of the electric motor. Since the ratio is set to one-to-one or an arbitrary ratio, variations in output characteristics of the electric motor, the state of charge of the battery unit, or changes in friction loss of the resultant device before and after the running-in operation affect the assist ratio. Without giving, the assist ratio can be controlled accurately and easily.

Further, since only the intensity difference between the two thrust component forces which are significantly smaller than the absolute values of the pedal depression force and the drive assist force need to be read by the position sensor, the reading error of the position sensor can be made very small. Can,
Thus, the assist ratio can be accurately controlled.

In addition, it is possible to omit the inspection step of strictly checking the output characteristics of the electric motor, friction loss of the resultant device, etc., and assembling the drive assist device, and then checking the output of the electric motor again. Therefore, it is possible to improve the productivity and reduce the cost of the drive assist device.

In addition, since the detection point of the position sensor is located at a point which is perpendicular to the tension side chain line of the drive chain and coincides with the reference plane passing through the center line of the crankshaft, the position of the resultant device by the chain tension is reduced. The slight inclination is not detected by the position sensor, and the assist ratio can be controlled more accurately.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a drive assist device.

FIG. 2 is a longitudinal sectional view of the drive assist device taken along line II-II of FIG.

FIG. 3 is a right side view of the drive assist device according to the embodiment of the present invention.

FIG. 4 is an enlarged vertical sectional view of the resultant device.

FIG. 5 is a partial sectional view showing a structure of a torque cam of the resultant device.

FIG. 6 is a block diagram showing a control system of the drive assist device.

FIGS. 7A and 7B are longitudinal sectional views showing an operation state of the resultant device; FIG. 7A shows a case where the pedal depression force is stronger than the driving assistance force; FIG. 7B shows a case where the pedal depression force is equal to the driving assistance force; C) shows the case where the driving assist force is stronger than the pedal depression force.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 drive assist device 4 crankshaft 7 electric motor 21 resultant device 31 output rotating member 45 resultant rotating member 53 ball spline 55,56 as axial moving means torque cam 62,63 coil spring as biasing means 65 Drive sprocket 66 Drive chain 66a Drive chain tension side chain line 67 Position sensor 70 Miniature bearing to be the detection point of position sensor 72 Controller C Neutral position of resultant rotating member D Crank perpendicular to drive chain tension side chain line Reference planes E and F passing through the center line of the axis Points corresponding to the reference plane D P Vector indicating the pedal depression force M Vector indicating the driving assistance force p Vector m indicating the thrust component having an intensity proportional to the pedal depression force m Drive assistance force A thrust component with strength proportional to Torr

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-2368 (JP, A) JP-A 8-295283 (JP, A) JP-A 7-40878 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B62M 23/02

Claims (1)

(57) [Claims] 1. A crankshaft 4 that is rotationally driven by a pedal depression force, an electric motor 7 that generates a driving assistance force, and a resultant device that combines the pedal depression force and the driving assistance force and outputs the resultant force to the driving wheel side. 21. In the drive assist device 1 for a bicycle with a drive assist force provided with the drive chain 21 described above, the resultant force device 21 is rotatably supported around the crankshaft 4 so that the drive chain
A drive sprocket 65 around which the drive sprocket 65 is rotatably provided, and an output rotary member 31 that transmits the resultant force of the pedal depression force and the drive assist force to the drive wheels via the drive chain 66; A resultant force rotating member 45, which is provided integrally and movably in the axial direction via a moving means (ball spline 53), transmits a pedal pressing force and a driving assist force to the resultant force rotating member 45, and at the same time, transmits a pedal pressing force P 2 having an intensity proportional to the driving assist force M
Component force generating means (torque cams 55 and 56) for applying two thrust component forces p and m from both sides of the resultant force rotating member 45 along the axial direction of the crankshaft 4, and the neutral position of the resultant force rotating member 45 in the axial movement range. C biasing means (coil spring 6
2,63) and a position sensor 67 for detecting the moving direction and the moving amount from the neutral position C of the resultant force rotating member 45 that moves in the axial direction by receiving the two thrust component forces p and m. The detection point (miniature bearing 70) of the position sensor 67 to the drive chain
Crankshaft 4 perpendicular to 66's tight side chain line 66a
At the point corresponding to the reference plane D passing through the center line, and detecting the intensity difference between the two thrust component forces p and m based on the input from the position sensor 67, and setting this intensity difference to 0 and any A drive assisting device 1 for a bicycle with a driving assisting force, comprising a control device 72 for controlling the output of the electric motor 7 so as to obtain a difference in intensity.