JPH07117779A - Bicycle having electric motor - Google Patents

Abstract

PURPOSE:To restrain vibration and enhance silence while reducing the cost. CONSTITUTION:In a bicycle having an electric motor constituted in such a way that a manpower driving system 8 and an electric driving system 9 are arranged in parallel with each other, and output of the electric driving system 9 is controlled according to a change in driving force by manpower, a planetary friction type speed reducer is interposed in a motive power transmitting passage to a driving crank shaft of the manpower driving system 8 from an electric motor 9 as the electric driving system. Vibration or a noise produced by the planetary friction type speed reducer when electric driving force is added to the manpower driving force, is reduced more sharply than when a planetary gear type speed reducer is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bicycle equipped with an electric motor, the driving force of which is assisted by an electric motor, and more particularly to improvement of a reduction gear on the output side of the electric motor.

[0002]

2. Description of the Related Art As a conventional bicycle with an electric motor, there is one disclosed in Japanese Patent Laid-Open No. 5-58379.

In this bicycle with an electric motor, a planetary gear type speed reducer is used as a speed reducer installed in a power transmission path from an electric motor as an electric drive system to a drive shaft of a human power drive system.

[0004]

In the conventional bicycle with an electric motor as described above, a planetary gear type speed reducer is provided in a power transmission path from an electric motor as an electric drive system to a drive shaft of a human power drive system. Although this electric motor is used at a high speed because a small one is used in order to reduce the weight, vibration and noise from the planetary gear type speed reducer tend to be large in that case. Becomes For this planetary gear type speed reducer, if the precision of meshing between the gears is managed with high accuracy, the generation of vibration and noise can be suppressed to some extent, but the cost increase associated with gear processing is extremely large. There is little effect of suppressing the generation of vibration and noise, and there is room for improvement.

In view of such circumstances, it is an object of the present invention to suppress vibration and improve quietness while suppressing costs.

[0006]

SUMMARY OF THE INVENTION The present invention provides a bicycle with an electric motor in which a human-powered drive system and an electric drive system are provided in parallel, and the output of the electric drive system is controlled in response to changes in the drive force due to human power. A planetary friction reduction gear is installed in a power transmission path from an electric motor as the electric drive system to a drive shaft of the human power drive system.

[0007]

According to the above construction, since the planetary friction type speed reducer is used, the vibration and noise generated by the planetary friction type speed reducer when the electric driving force is added to the human-powered driving force are generated by the planetary gear type. It is significantly lower than when using a speed reducer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 is a side view of a bicycle equipped with an electric motor, FIG. 2 is a schematic configuration diagram of main parts of the bicycle, and FIG.
4 is an enlarged view of the vicinity of the electric motor of the bicycle, and FIG. 4 is a graph showing vibration characteristics of the electric drive system of the bicycle.

In this embodiment, a shaft-drive type electric motor-equipped bicycle is taken as an example. In the figure, 1 is a front wheel, 2 is a rear wheel, 3 is a main frame, 4 is a front fork, and 5 are two pairs. Is a rear stay, 6 is a handle, 7 is a saddle, and 8 is a pair of two crank pedals.

The mainframe 3 includes an electric motor 9 as an electric drive system, a controller 10 for controlling the electric motor 9, and a rechargeable battery 11 such as a lead-acid battery for powering the electric motor 9 and the controller 10. , And the power unit 20 are attached.

The power unit 20 selects one of the human-powered driving force from the crank pedal 8 and the combined force of the human-powered driving force and the electric driving force from the electric motor 9 for the axle 12 of the rear wheel 2. It is intended to be transmitted. Specifically, the power unit 20 includes a crankshaft 21 having crank pedals 8 attached to both ends thereof, as shown in FIG.
A cylindrical shaft-shaped resultant shaft 22 rotatably attached to the outer periphery of the crankshaft 21, a large bevel gear 23 integrally attached to one end of the resultant shaft 22, and an electric motor that meshes with the large bevel gear 23. 9, a small bevel gear 24 integrally coupled to the output shaft 13 of the gear 9 via a planetary friction reducer 30 described later, and a bevel gear mechanism 25 provided on the outer periphery of the resultant shaft 22.
And a drive shaft 26 that is inserted into one of the rear stays 5 and has one end meshed with the bevel gear mechanism 25 and the other end meshed with the bevel gear mechanism 14 provided on the rear wheel axle 12.
And a one-way clutch 27 that is mounted on the crankshaft 21.
The sun gear is integrally connected to the crank shaft 21, the carrier shaft is integrally connected to the outer ring of the one-way clutch 27, and the ring gear is connected to the large bevel gear 23. Unit case 2
9 and 9. Further, in the power unit 20, a torque detecting means 15 for detecting a torque corresponding to a stepping force on the crank pedal 8 by a reaction force applied to a crank shaft 21 provided with a sun gear of a planetary gear type speed increaser 28.
Is provided, and the detection output from the torque detecting means 15 is given to the controller 10. Controller 1
0 controls whether or not the electric driving force of the electric motor 9 is added to the human-powered driving force based on the detection output from the torque detection means 15 and the ratio thereof.

As shown in FIG. 3, the planetary friction reducer 30 described above uses the output shaft 13 of the electric motor 9 as the sun shaft, and a fixed ring 31 fixed to the electric motor 9 via bolts. And a plurality of planet rollers 32 which are interposed between the fixed wheel 31 and the output shaft 13 of the electric motor 9 in a pressure contact state and revolve while revolving, and the planet rollers 32 are rotatable at equal intervals around the circumference. And a carrier 33 to which the shaft 24A of the small bevel gear 24 of the power unit 20 is coupled and which is held. The carrier 33 includes a plurality of pins 34 that are inserted into the planetary rollers 32 via needle rollers (not shown), and a bottomed cylindrical tube shaft 35 to which the pins 34 are fixed. The inner hole portion of the cylinder shaft 35 communicates with the pin hole, so that the pin 34 can be easily attached. A one-way clutch device 40 is provided in the inner hole portion of the cylindrical shaft 35 to facilitate insertion of the shaft 24A of the small bevel gear 24 of the power unit 20, and rotation of the small bevel gear 24 with respect to the shaft 24A is performed. A ball 41 serving as a thrust bearing for reducing resistance and a friction plate 42 for wear prevention are provided. The one-way clutch device 4 described above
0 is a roller-type one-way clutch 44 and two cage-and-roller bearings 4 inside the shell-shaped outer ring 43.
It is a configuration that accommodates 5, 45. This shell-shaped outer ring 43
Although its outer circumference is cylindrical, although not shown in the drawing, a cam surface that is recessed radially outward is provided at several circumferential positions in the central portion where the roller type one-way clutch 44 is present on the inner circumference. In the circumference, both axial end portions where the bearing 45 exists are cylindrical. The bearings 45 on both sides in the axial direction of the roller type one-way clutch 44 are connected to the shaft 2 of the small bevel gear 24.
The state of engagement with 4A is set to loose fit, and therefore, when the roller type one-way clutch 44 is in the free state, the bearings 45 on both sides support the shaft 24A.

Next, the operation of the bicycle with the electric motor of this embodiment will be described. When the crank pedal 8 is rotationally operated, power is transmitted to the large bevel gear 23 via the crankshaft 21, the one-way clutch 27, and the planetary gear type speed increaser 28, and at the same time, the resultant shaft 22, the bevel gear mechanism. It is transmitted to the drive shaft 26 via 25, and the axle 12 of the rear wheel 2 is rotationally driven via the bevel gear mechanism 14. However, even if the rotation operation of the crank pedal 8 is interrupted, the rotational power from the axle 12 of the rear wheel 2 to the crankshaft 21 is interrupted by the one-way clutch 27.

By the way, when the controller 10 determines that it is necessary to add the electric driving force of the electric motor 9 to the human driving force based on the detection output from the torque detecting means 15 while the crank pedal 8 is rotating, The addition ratio is also determined, and the electric motor 9 is driven as necessary.
At this time, the rotational power of the electric motor 9 is transmitted through the planetary friction reduction gear 30, the small bevel gear 24, and the large bevel gear 23 to the resultant shaft 2.
2 is transmitted to the drive shaft 26 from the resultant shaft 22 via the bevel gear mechanism 25, and the axle 12 of the rear wheel 2 is rotationally driven via the bevel gear mechanism 14. Therefore, the axle 12 of the rear wheel 2 is driven by adding the electric driving force of the electric motor 9 as necessary to the rotational power of the crank pedal 8.

As shown in the graph of FIG. 4, the vibration of the planetary friction type speed reducer 30 when the power from the electric motor 9 is applied is greatly reduced as compared with the conventional planetary gear type speed reducer. It is confirmed to do. The input torque to the planetary friction reducer 30 at this time is 1.5 N · m.

The present invention is not limited to the above embodiment. For example, instead of the drive shaft 26, a chain drive system may be used in which a sprocket is fixed to the resultant shaft 22 of the power unit 20 and a chain is used.

[0017]

According to the present invention, since the speed reducer provided on the output side of the electric motor is a planetary friction type speed reducer,
The vibration and noise generated by the planetary friction type speed reducer when the electric driving force is added to the human-powered driving force are significantly reduced compared to the case where the planetary gear type speed reducer is used. It will be possible to provide a quiet bicycle with an electric motor. And, the vibration suppressing effect and the quietness maintaining effect of the planetary friction reducer are far superior to the case where the gear machining accuracy of the planetary gear reducer is made highly accurate, and the planetary friction reducer is Since it can be mass-produced, it can be said that it is cheaper than a highly accurate planetary gear type speed reducer.

[Brief description of drawings]

FIG. 1 is a side view of a bicycle with an electric motor according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a main part of the bicycle.

FIG. 3 is an enlarged view around the electric motor of the bicycle.

FIG. 4 is a graph showing vibration characteristics of the electric drive system of the bicycle.

[Explanation of symbols]

 8 crank pedal 9 electric motor 20 power unit 21 crankshaft 30 planetary friction reducer

[Procedure amendment]

[Submission date] October 21, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (1)

[Claims] 1. A bicycle with an electric motor, wherein a human-powered drive system and an electric drive system are provided in parallel, and the output of the electric drive system is controlled in response to changes in the drive force due to human power. A bicycle with an electric motor, characterized in that a planetary friction reduction gear is interposed in a power transmission path from the electric motor to the drive shaft of the human power drive system.