JPH11129974A - Drive unit of motor-assisted bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the drive unit of a motor-assisted bicycle having a little power loss. SOLUTION: In the drive unit of a motor assisted bicycle in which torque from a cylindrical sun roller shaft 35 coaxially arranged on the outer circumference of a crankshaft 19 is added to the crankshaft 19 while being reduced in speed by a planetary roller speed reducer 40 and a two step reduction gear mechanism 50, by providing ball bearings 21, 22 between the crankshaft 19 and the sun roller shaft 35 so as to support the sun roller shaft 35 with the crankshaft 19, the diameter of the bearing supporting the run roller shaft 35 of the highest rotating speed can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive unit for an electric bicycle, and more particularly to a drive unit of a cylindrical output shaft disposed coaxially around a crankshaft while applying a rotational force to the crankshaft while reducing the rotational force. It is effective if applied to the case.

[0002]

2. Description of the Related Art FIG. 4 shows the overall structure of an electric bicycle. As shown in FIG. 4, the electric bicycle 10 has a drive unit 100 attached to a crank hub portion of a frame 11. The drive unit 100 includes a drive-side chain sprocket 1 connected to a pedal crank 16 having a pedal.
5 is connected. A chain 18 is stretched between the chain sprocket 15 and a driven-side chain sprocket 17 attached to the shaft of the rear wheel 14 via a one-way clutch. That is, the human power through the pedal of the pedal crank 16 or the electric power of the drive unit 100 is transmitted from the chain sprocket 15 on the drive side to the chain sprocket 17 on the driven side via the chain 18 to rotate the rear wheel 14. is there. In FIG. 4, 12 is a steering wheel, 13 is a front wheel, 77 is a rechargeable battery, and 78 is a controller.

Here, the internal structure of the drive unit 100 will be described with reference to FIG. As shown in FIG. 5, the motor 31 is disposed in a space surrounded by a motor casing 39a and a middle wall 39b. The stator 32 of the motor 31 is fixed inside the motor casing 39a, and is wound with an exciting coil. The rotor 34 of the motor 31 is provided with a plurality of permanent magnets 33 which are equally arranged on the inner circumference. That is, the motor 31
Has a structure of an induction motor, in which the rotation speed can be controlled by frequency control by an inverter, and the torque can be controlled by current control.

A hollow (cylindrical) sun roller shaft (output shaft) 35 that protrudes from the middle wall 39b toward the speed reduction mechanism and forms a sun roller is fixed to the rotor 34. The outer peripheral surface of the sun roller shaft 35 is supported by a motor casing 39 a via a bearing 36 on the motor side shaft end, and the outer peripheral roller side is supported by a middle wall 39 b via a bearing 38.

The speed reduction mechanism casing 41 has one end integrally connected to the motor casing 39a with the middle wall 39b interposed therebetween and the other end integrally connected to the casing lid 52, thereby forming a closed power mechanism casing. ing. The sun roller shaft 35 is provided in the reduction mechanism casing 41.
An inner roller 43 is fixedly positioned by a plurality of pins 46 so as to be coaxial with the inner roller 43. A plurality of planetary rollers 42 are in contact with the inner roller 43. These planetary rollers 4
Numerals 2 are rotatably supported by planetary roller shafts 44 arranged at equal intervals in a circumferential direction on a planetary roller carrier 45. Such planetary roller 42, inner roller 43, planetary roller shaft 44, planetary roller carrier 45
The planetary roller speed reducer 40 is constituted by such means.

The planetary roller carrier 45 has a hollow output shaft rotatably supported by a crankshaft 19 via a bearing, and a pinion 45a formed on the outer peripheral surface. The motor 31 side (one end side) of the crankshaft 19 is
It is supported by a motor casing 39a via a bearing 37. The pinion 45a meshes with a large gear 53 supported on a gear shaft 54 via a bearing and a first one-way clutch 55. That is, the large gear 53 transmits only the power from the motor 31 to the gear shaft 54.

[0007] The gear shaft 54 has an integral gear 54a, a reduction gear casing 41 and a casing lid 5.
2 is rotatably supported via a bearing. Gear 54
The first gear 56 at the last stage, which is coaxial with the crankshaft 19, is meshed with a. Such a pinion 45
a, a large gear 53, gears 54a and 56, etc., constitute a two-stage gear reduction mechanism 50.

The gear 56 is supported on the casing lid 52 via a bearing 49 and is supported on the other end of the crankshaft 19 via a bearing 48. The drive sprocket 15 is fixed to the gear 56. The second gear 57 is rotatably supported on the crankshaft 19 via a bearing, and has the same meshing pitch diameter as the gear 56. The rotation of the crankshaft 19 is transmitted to the gear 57 by a second one-way clutch 58. The one-way clutch 58 is connected to the crankshaft 1 by the pedal crank 16.
The direction of the claw is set so that the claw can engage when the force applied to 9 is input in the forward direction.

As described above, the drive unit 100 includes the motor 31 having the output shaft (sun roller shaft 35) coaxial with the crankshaft 19 of the pedal crank 16, and the planetary shaft having the output shaft of the motor 31 as the sun roller shaft. Roller reducer 4
0, a pinion 45a formed on the hollow output shaft of the planetary roller carrier 45 of the planetary roller reducer 40 and supported by the crankshaft 19 via a bearing;
a, a two-stage gear reduction mechanism 50 composed of a combination of a large gear 53, and gears 54a, 56; a first one-way clutch 55 interposed in a power transmission path of the two-stage gear reduction mechanism 50; It is provided on the gear 56 of the two-stage gear reduction mechanism 50 and is supported by the drive-side chain sprocket 15 and the crankshaft 19 of the pedal crank 16 via bearings.
Is transmitted to the crankshaft 19 while the rotational force from the output shaft (the sun roller shaft 35) of the motor 31 is reduced.

In FIG. 5, reference numeral 59 denotes a compression spring, 60 denotes an angular displacement mechanism, 61 denotes an angular displacement detecting mechanism, 69 denotes a projecting member, and 89 denotes a rotation speed sensor.

[0011]

In the electric bicycle 10 provided with such a drive unit 100, the operation by the pedal crank 16 is performed in the same manner as in a normal bicycle, since the power is mainly driven by human power from the pedal crank 16. You need to be able to do it with a sense. Therefore, it is necessary to make the drive unit 100 as efficient as possible, that is, to reduce power loss.

In such a drive unit 100,
The places where the power loss is greatest are the bearings 36 and 38 that support the sun roller shaft 35 with the largest number of revolutions. Therefore, if the loss at the bearings 36 and 38 is reduced,
Efficiency can be greatly improved.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a drive unit for an electric bicycle according to the present invention provides a driving force of a cylindrical output shaft disposed coaxially around an outer periphery of a crankshaft. In a drive unit for an electric bicycle that is added to the crankshaft while decelerating, a bearing is provided between the crankshaft and the output shaft so that the output shaft is supported by the crankshaft. I do.

In the above-described drive unit for an electric bicycle, the bearing is a pair of ball bearings that support one end and the other end of the output shaft.

In the above-described drive unit for an electric bicycle, the bearing is a ball bearing that supports one end of the output shaft and a needle roller bearing that supports the other end of the output shaft.

In the above-described drive unit for an electric bicycle, the bearing is a ball bearing that supports one end of the output shaft.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a drive unit for an electric bicycle according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing the internal structure.

As shown in FIG. 1, the motor 31 is disposed in a space surrounded by a motor casing 39a and a middle wall 39b. The stator 32 of the motor 31 is fixed inside the motor casing 39a, and is wound with an exciting coil. The rotor 34 of the motor 31
A plurality of equally spaced permanent magnets 33 are attached to the inner circumference. That is, the motor 31 has the structure of an induction motor, and can control the rotation speed by the frequency control by the inverter and the torque by the current control.

A hollow (cylindrical) sun roller shaft (output shaft) 35 that protrudes from the middle wall 39b toward the speed reduction mechanism and forms a sun roller is fixed to the rotor 34. The sun roller shaft 35 has a motor-side shaft end (one end side) of the inner peripheral surface of the hollow portion supported by the crankshaft 19 via the ball bearing 21, and a roller side (the other end side) of the inner peripheral surface of the hollow portion. ) Are supported on the crankshaft 19 via ball bearings 22.

The reduction mechanism casing 41 has one end integrally connected to the motor casing 39a with the middle wall 39b interposed therebetween, and the other end integrally connected to the casing lid 52, thereby forming a closed power mechanism casing. ing. The sun roller shaft 35 is provided in the reduction mechanism casing 41.
An inner roller 43 is fixedly positioned by a plurality of pins 46 so as to be coaxial with the inner roller 43. A plurality of planetary rollers 42 are in contact with the inner roller 43. These planetary rollers 4
Numerals 2 are rotatably supported by planetary roller shafts 44 arranged at equal intervals in a circumferential direction on a planetary roller carrier 45. Such planetary roller 42, inner roller 43, planetary roller shaft 44, planetary roller carrier 45
The planetary roller speed reducer 40 is constituted by such means.

The planetary roller carrier 45 has a hollow output shaft rotatably supported by a crankshaft 19 via a bearing and a pinion 45a formed on the outer peripheral surface. The motor 31 side (one end side) of the crankshaft 19 is
It is supported by a motor casing 39a via a bearing 37. The pinion 45a meshes with a large gear 53 supported on a gear shaft 54 via a bearing and a first one-way clutch 55. That is, the large gear 53 transmits only the power from the motor 31 to the gear shaft 54.

The gear 56 is supported by the casing lid 52 via a bearing 49 and is supported by the other end of the crankshaft 19 via a bearing 48. The drive sprocket 15 is fixed to the gear 56. The second gear 57 is rotatably supported on the crankshaft 19 via a bearing, and has the same meshing pitch diameter as the gear 56. The rotation of the crankshaft 19 is transmitted to the gear 57 by a second one-way clutch 58. The one-way clutch 58 is connected to the crankshaft 1 by the pedal crank 16.
The direction of the claw is set so that the claw can engage when the force applied to 9 is input in the forward direction.

As described above, the drive unit 1 has a motor 31 having an output shaft (sun roller shaft 35) coaxial with the crankshaft 19 of the pedal crank 16, and a planet having the output shaft of the motor 31 as a sun roller shaft. A roller reducer 40,
The planetary roller reducer 40 includes a pinion 45a formed on the hollow output shaft of the planetary roller carrier 45 and supported on the crankshaft 19 via a bearing, and a combination of the pinion 45a, the large gear 53, and the gears 54a and 56. Two-stage gear reduction mechanism 50, and a first one-way clutch 55 interposed in the power transmission path of the two-stage gear reduction mechanism 50
And a drive-side chain sprocket 15 and a pedal crank 16 provided on a gear 56 of the two-stage gear reduction mechanism 50.
And a second one-way clutch 58 which is supported by the crankshaft 19 via a bearing and transmits the rotation of the crankshaft 19 to the chain sprocket 15, from the output shaft (sun roller shaft 35) of the motor 31. The rotational force can be applied to the crankshaft 19 while being reduced.

In FIG. 1, 59 is a compression spring, 60 is an angular displacement mechanism, 61 is an angular displacement detecting mechanism, 69 is a projecting member, and 89 is a rotation speed sensor.

Here, the relationship among the friction torque M, which leads to power loss of the bearing, the friction coefficient μ, the bearing load P, and the bearing diameter d is shown in the following equation (1).

[0026]

M = μP (d / 2) (1)

That is, as can be seen from the above equation (1),
Even if the friction coefficient μ and the bearing load P are the same, by reducing the bearing diameter d, the friction torque M can be reduced and the power loss of the bearing can be reduced.

Therefore, the sun roller shaft 35 having the largest number of rotations is supported by the crankshaft 19 via the ball bearings 21 and 22 from the inner peripheral side of the shaft inside the hollow, so that the driving unit 100 as described above is provided. The bearing diameter d of the bearing that supports the sun roller shaft 35 can be smaller than when the sun roller shaft 35 is supported by the bearings 36 and 38 from the outer peripheral side.

Therefore, according to such a drive unit 1, the friction torque M can be made smaller than in the case of the drive unit 100 described above, and the power loss of the bearing can be reduced. Can be planned.

Further, since the bearing supporting portion of the motor casing 39a can be reduced, the weight can be reduced, and the sun roller shaft 35 can be moved from the inner peripheral side of the hollow inner shaft via the ball bearings 21 and 22. Since the support is made by the crankshaft 19, the movement of the sun roller shaft 35 in the axial direction can be reliably prevented.

A second embodiment of the drive unit for an electric bicycle according to the present invention will be described with reference to FIG. In addition,
FIG. 2 is a sectional view showing the internal structure. However,
The same members as those in the first embodiment described above are denoted by the same reference numerals as those used in the description of the first embodiment, and the description thereof is omitted.

As shown in FIG. 2, the sun roller shaft 35 is
The motor-side shaft end (one end side) of the inner peripheral surface of the hollow portion is supported by the crankshaft 19 via a ball bearing 21, and the roller side (other end side) of the inner peripheral surface of the hollow portion is a needle roller bearing. It is supported by the crankshaft 19 via 23. In the needle roller bearing 23, a needle roller 23 b is provided between an outer ring 23 a formed on a hollow inner peripheral surface of the sun roller shaft 35 and an outer peripheral surface of the crankshaft 19.

That is, a needle roller bearing 23 is used in place of the ball bearing 22 used in the first embodiment described above. For this reason, the bearing diameter d of the portion can be further reduced as compared with the case where the ball bearing 22 is used.

Therefore, according to such a drive unit 2, the same effect as that of the drive unit 1 described above can be obtained, and the friction torque M can be further reduced as compared with the drive unit 1 described above. Therefore, the power loss of the bearing can be further reduced.

A third embodiment of the drive unit for an electric bicycle according to the present invention will be described with reference to FIG. In addition,
FIG. 3 is a sectional view showing the internal structure. However, the same members as those in the first and second embodiments described above are denoted by the same reference numerals as those used in the description of the first and second embodiments, and the description thereof is omitted. I do.

As shown in FIG. 3, the sun roller shaft 35 is
The motor-side shaft end (one end) of the inner peripheral surface of the hollow portion is supported by the crankshaft 19 via a ball bearing 21, while the roller side (the other end) is supported by the planetary rollers 42.

That is, by supporting the roller side of the sun roller shaft 35 with the planetary roller 42 meshing with the sun roller shaft 35, the ball bearing 22 used in the first embodiment described above is omitted. Therefore, it is possible to reduce the places where power loss occurs.

Therefore, according to such a drive unit 3, not only the same effects as those of the drive unit 1 described above can be obtained, but also a portion where power loss occurs more than in the drive units 1 and 2 described above. Since the number is small, the efficiency can be further improved.

[0039]

The drive unit for an electric bicycle according to the present invention is an electric bicycle in which the rotational force of a cylindrical output shaft disposed coaxially around the crankshaft is added to the crankshaft while reducing the rotational force. In the bicycle drive unit, since a bearing is provided between the crankshaft and the output shaft so as to support the output shaft with the crankshaft, it is possible to reduce the bearing diameter of the bearing that supports the output shaft. As a result, the friction torque can be reduced, the power loss of the bearing can be reduced, and higher efficiency can be achieved.

If the bearing is a pair of ball bearings that support one end and the other end of the output shaft, the output shaft can be reliably prevented from moving in the axial direction.

If the bearing is a ball bearing that supports one end of the output shaft and a needle roller bearing that supports the other end of the output shaft, the bearing diameter at the other end is further reduced. Therefore, the friction torque can be further reduced, the power loss of the bearing can be further reduced, and the efficiency can be further improved.

If the bearing is a ball bearing that supports one end of the output shaft, the number of places where power loss occurs can be reduced, so that higher efficiency can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an internal structure of a first embodiment of a drive unit for an electric bicycle according to the present invention.

FIG. 2 is a sectional view showing the internal structure of a second embodiment of the drive unit for the electric bicycle according to the present invention.

FIG. 3 is a sectional view illustrating an internal structure of a third embodiment of the drive unit for the electric bicycle according to the present invention.

FIG. 4 is an explanatory diagram of a schematic configuration of the electric bicycle.

FIG. 5 is a cross-sectional view illustrating an internal structure of a conventional drive unit of the electric bicycle.

[Explanation of symbols]

 1, 2, 3 Drive unit 10 Electric bicycle 11 Frame 12 Handle 13 Front wheel 14 Rear wheel 15 Chain sprocket 16 Pedal crank 17 Chain sprocket 18 Chain 19 Crankshaft 21,22 Ball bearing 23 Needle roller bearing 23a Outer ring 23b Needle roller 31 Motor 32 Stator 33 Permanent magnet 34 Rotor 35 Sun roller shaft 37 Bearing 39a Motor casing 39b Middle wall 40 Planetary roller reducer 41 Reduction mechanism casing 42 Planetary roller 43 Inner roller 44 Planetary roller shaft 45 Planetary roller shaft 45a Pinion 46 Pin 50 Two-stage Gear reduction mechanism 52 Casing lid 53 Large gear 54 Gear shaft 54a Gear 55 One-way clutch 56 First gear 57 Second gear 58 One-way clutch

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masashi Hirabayashi 1 Nagoya Research Center, Nagoya-shi, Aichi

Claims (4)

[Claims] 1. A drive unit for an electric bicycle, wherein a rotational force of a cylindrical output shaft disposed coaxially around a crankshaft is added to the crankshaft while reducing the rotational force. A drive unit for an electric bicycle, wherein a bearing is provided between the crankshaft and the output shaft so as to support the output shaft. 2. The drive unit for an electric bicycle according to claim 1, wherein the bearing is a pair of ball bearings respectively supporting one end and the other end of the output shaft. 3. The electric bicycle according to claim 1, wherein the bearing is a ball bearing that supports one end of the output shaft and a needle roller bearing that supports the other end of the output shaft. Drive unit. 4. The drive unit according to claim 1, wherein the bearing is a ball bearing that supports one end of the output shaft.