JPH08297059A - Torque detector for bicycle - Google Patents

Abstract

PURPOSE: To reduce the size and weight of torque detector while enhancing the durability thereof by disposing a magnetostrictive torque detector within the hanger of a bicycle. CONSTITUTION: A hollow tubular drive shell 17 is fitted over a crankshaft within the hanger 4 of a bicycle. The drive shell 17 is projected outward the hanger 4 on the front sprocket 7 side thereof and the front sprocket 7 is secured to the projecting part. The drive shell 17 is coupled, at the other end thereof, with a crankshaft 5 through a spline and the intermediate drum part thereof is coated with a magnetic material 22. A coil unit 23 wrapping the magnetic material 22 is secured to the hanger 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a device for detecting a driving torque of a bicycle which uses an electric motor as auxiliary power.

[0002]

2. Description of the Related Art Bicycles using an electric motor as auxiliary power are
Since the auxiliary power is output according to the driving torque, a driving torque detecting device is required. As this torque detection device, a device that is mechanically detected by a device incorporated in the crankshaft portion of a bicycle and a device that detects torque by the tension of a drive chain are known as conventional devices.

[0003]

However, the conventional torque detecting device incorporated in the crankshaft portion described above has a large number of parts and needs strength because it has a mechanical structure, and also has a drive unit and a torque detecting portion. However, since the device is large, the size of the device is large, and there is a problem in that the degree of freedom in design is reduced due to restrictions on the layout of the bicycle.

Further, since this conventional device has a complicated structure, it has a large mechanical loss and there is a relief when a pedaling force is applied, so that there is a problem that a direct feeling cannot be obtained.

Further, in the device for detecting the torque by the tension of the drive chain, when the wheels are assembled to the vehicle body, the detected value of the torque is likely to vary depending on the tension of the chain, so that the torque detection becomes inaccurate. There was a problem.

[0006]

In order to solve the above problems, according to the present invention, a hollow cylindrical drive shell is fitted to a crankshaft in a bicycle hanger, and the front sprocket side of the drive shell is placed on the hanger. Of the front sprocket to the outside of the
The other end of this drive shell is connected to the crankshaft, a magnetic material is applied to the middle body of this drive shell, and a coil unit that encloses this magnetic material is fixed to the hanger to provide a bicycle torque. Configure a detection device.

Further, a large number of grooves oblique to the axis of the crankshaft may be provided in the magnetic material adhered to the intermediate body of the drive shell of the bicycle torque detecting device of the first invention. .

The other end of the drive shell of the bicycle torque detecting device according to the first aspect of the invention may be spline-fitted to the crankshaft.

[0009]

According to the present invention, as described above, the magnetostrictive torque detecting device is used instead of the mechanical torque detecting. Therefore, the mechanical loss is reduced and the responsiveness of the torque detecting is improved.
A direct feeling can be obtained. Further, since the device of the present invention has a simple structure with a small number of parts, according to the present invention, it is possible to provide a compact torque detection device which is lightweight and has excellent durability.

Further, if a large number of grooves oblique to the axis of the crankshaft are distributed in the magnetic material adhered to the intermediate body of the drive shell, the magnetic material is generated by the torque acting on the crankshaft. The sensitivity of the applied tension can be increased and the torque detection accuracy can be improved.

When the other end of the drive shell is spline-fitted to the crankshaft, the spline can comfortably absorb axial strain due to twisting of the crankshaft.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, 1 (see FIG. 1) is a front wheel of a bicycle, 2 is a rear wheel, 3
Is a vehicle body (frame), 4 is a hanger of the vehicle body 3, 5 is a crankshaft, 6 is a crank arm, 7 is a front sprocket driven by the crankshaft 5, 8 is a rear axle, and 9 is after being fitted to the rear axle 8. Sprocket, 10 is front sprocket 7
A chain extending around the rear sprocket 9, 11 a drive motor for the auxiliary electric device, 12 a battery as a power source for the auxiliary electric device, and 13 a controller thereof.

In the present embodiment, as shown in detail in FIG. 2, a hollow cylindrical coil sleeve 14 located from the left side to the middle portion of the hanger 4 in FIG. 2 is inserted and fixed in the hanger 4. A ball bearing 16 interposed between the crankshaft 5 and a left one 15 screwed into the coil sleeve 14 is supported.

Further, a spline shaft portion 5a is formed in the hanger 4 adjacent to the ball bearing 16 of the crankshaft 5, and a spline hole portion 17a fitted with the shaft portion 5a.
2, a hollow cylindrical drive shell 17 having a left end portion in FIG. 2 is loosely fitted to the crankshaft 5, and the drive shell 17
2 is inserted between the right half of FIG. 2 and the crankshaft 5 to fill the gap. Reference numeral 19 is a retaining ring provided on the crankshaft 5 so as to be joined to the outer end surface of the sleeve 18.

A bearing protrusion 17b (see FIG. 3) is formed on the outer peripheral portion of the drive shell 17 on the right side in FIG.
The right one 21 supporting the ball bearing 20 supported on the protrusion 17b is screwed to the right side of the hanger 4 to rotatably support the crankshaft 5 and the drive shell 17. Then, the front sprocket 7 is screwed and fixed to the screw portion 17c provided on the projecting portion of the drive shell 17 projecting outward from the hanger 4.

Further, as shown in FIGS. 2 and 3, a magnetic material 22 such as an iron-based amorphous alloy is adhered to the intermediate body of the drive shell 17, and a coil unit enclosing the magnetic material 22 is provided. 23 is provided on the inner circumference of the coil sleeve 14. The coil unit 23 is formed of two layers, a detection coil 23a and an exciting coil 23b. Reference numeral 24 is a lead wire connected to the coil unit 23, and 25 is a lead hole for the lead wire 24 provided in the coil sleeve 14 and the hanger 4.

Further, as shown in FIG. 3, the magnetic material 22 adhered to the intermediate body of the drive shell 17 is provided with a large number of grooves 22a oblique to the axis of the crankshaft 5 so as to be distributed. It is preferable to divide the magnetic material 22 into strips having an appropriate width. This improves the torque detection accuracy.

Next, the operation of the device of the present invention constructed as described above will be explained. When the pedal of the crank arm 6 is depressed and the front sprocket 7 rotates, the rear wheel 2 rotates via the chain 10 and the rear sprocket 9, and the bicycle travels. The bicycle torque detection device of the present invention detects the torque acting on the crankshaft 5 from the crank arm 6 during traveling of the bicycle.

That is, when the rotation is transmitted from the crank arm 6 to the crankshaft 5, the rotation is transmitted from the spline shaft portion 5a of the crankshaft 5 to the drive shell 17 and the front sprocket 7 through the spline hole portion 17a.
That is, in this case, the torsion force corresponding to the magnitude of the torque acts on the drive shell 17. And drive shell 17
When a torsional force is applied to the magnetic material 22, the magnetic material 22 adhered to the body of the drive shell 17 generates a strain corresponding to the magnitude of the torque.

When the magnetic material 22 is distorted, the magnetic permeability of the magnetic material 22 changes in accordance with the distortion, and the exciting coil 23b which encloses the magnetic material 22 includes several coils from the amplifier connected to the lead wire 24. Since it is excited at 10 KHz, the voltage of the detection coil 23a changes due to the change of magnetic permeability. This change can be taken out via the lead wire 24 and the drive motor 11 can be controlled via the controller 13.

[0021]

As described above, according to the present invention, the magnetostrictive torque detecting device is used instead of the mechanical torque detecting. Therefore, the mechanical loss is reduced, the responsiveness of the torque detecting is improved, and the direct feedback is improved. The ring is obtained. Further, since the device of the present invention has a simple structure with a small number of parts, according to the present invention, there is an effect that it is possible to provide a compact torque detection device which is lightweight and has excellent durability.

If a large number of grooves 22a oblique to the axis of the crankshaft 5 are provided in the magnetic material 22 adhered to the middle portion of the drive shell 17, the crankshaft 5
It is possible to enhance the sensitivity of the tension generated in the magnetic material 22 by the torque that acts on the torque and improve the torque detection accuracy.

Further, when the other end of the drive shell 17 is spline-fitted to the crankshaft 5, the effect that the axial strain due to the twist of the crankshaft 5 can be absorbed by the spline without difficulty is obtained. To be

[Brief description of drawings]

FIG. 1 is a side view of a bicycle equipped with the device of the present invention.

2 is a cross-sectional view of the hanger portion of FIG.

FIG. 3 is a side view of a crankshaft.

[Explanation of symbols]

 1 front wheel 2 rear wheel 3 vehicle body (frame) 4 hanger 5 crankshaft 5a spline shaft 6 crank arm 7 front sprocket 8 rear axle 9 rear sprocket 10 chain 11 drive motor 12 battery 13 controller 14 coil sleeve 15 left one 16 ball bearing 17 Drive Shell 17a Spline Hole 17b Bearing Protrusion 17c Screw Part 18 Sleeve 19 Retaining Ring 20 Ball Bearing 21 Right One 22 Magnetic Material 22a Groove 23 Coil Unit 23a Detection Coil 23b Excitation Coil 24 Lead Wire 25 Drawout Hole

Front page continued (72) Inventor Toshiharu Furukawa 3-1-1 Nakatsuma, Ageo City, Saitama Prefecture Bridgestone Cycle Co., Ltd.

Claims (3)

[Claims] 1. A hollow cylindrical drive shell is fitted to a crankshaft in a bicycle hanger, a front sprocket side of the drive shell is projected to the outside of the hanger, and the front sprocket is fixed to the projected portion. , The other end of this drive shell is connected to the crank shaft, the magnetic material is applied to the middle body of this drive shell, and the coil unit that encloses this magnetic material is fixed to the hanger. A characteristic torque detection device for bicycles. 2. The magnetic material adhered to the middle body of the drive shell of the bicycle torque detection device according to claim 1,
A torque detecting device for a bicycle, characterized in that a number of grooves oblique to the axis of the crankshaft are distributed. 3. The bicycle torque detecting device according to claim 1, wherein the other end of the drive shell of the bicycle torque detecting device is spline-fitted to a crankshaft.