JP2007205396A - Torque transmission structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planetary gear mechanism having a large reduction ratio in a non-complicated structure. <P>SOLUTION: A sun gear 2 having outward teeth 8 is provided on a rotating shaft 1 on the input side so as to be integrally rotatable. An external gear 6 having inward teeth 14 is provided on the outer diameter side of the sun gear 2 so as to be rotatable relative to the rotating shaft 1. A plurality of planetary gears 10, 15 are arranged between the sun gear 2 and the external gear 6 in radial parallel to gear each other, and the planetary gears 10, 15 only permit rotation instead of revolution. A ring gear 4 having inward teeth 9 and outward teeth 13 is laid between the plurality of planetary gears 10, 15 so as to be rotatable relative to the rotating shaft 1 and the external gear 6. Thereby, the rotation of the sun gear 2 can be transmitted to the external gear 6 via the planetary gears 10, 15 and the ring gear 4. Thus, the diameter of the external gear can be larger than the diameter of the sun gear and the sun gear be driven via the planetary gears which do not permit revolution, resulting in the non-complicated structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a torque transmission structure that transmits torque applied to a pedal of a bicycle to a traveling device.

  The torque transmission structure used in the conventional bicycle is provided on the axle of the rear wheel via a chain that meshes with the sprocket by rotating the sprocket integrally around the crankshaft when the bicycle driver steps on the pedal with his foot. It is a mechanism that drives a wheel by rotating a slightly small sprocket.

  The pedaling force acting on the pedal is transmitted as a larger rotational force to the center crankshaft if the crank length of the pedal is increased. On the other hand, if the radius of the sprocket that rotates integrally with the crankshaft is reduced, the rotational force generates a larger torque (driving force) in the tangential direction of the outer periphery of the sprocket, and drives the chain with a strong force. To get.

In this torque transmission structure, there is a limit to increasing the length of the crank, so that it is necessary to increase the reduction ratio as described above in order to ensure a large torque without extending the crank. In order to increase the reduction ratio, the ratio of the number of teeth, that is, the number of teeth on the driving side (input side) gear is reduced, and the number of teeth on the driven side (output side) is increased. However, reducing the number of teeth is limited by problems such as meshing with the chain, and increasing the number of teeth is also limited due to space limitations.
Further, when the reduction ratio of the gear is increased to increase the reduction ratio, there is a problem that the transmission structure is enlarged.
Therefore, a torque transmission structure using a planetary gear mechanism is employed.

In general, the planetary gear mechanism is composed of the elements of rotation of the sun gear, revolution (rotation) of the planetary gear, and rotation of the outer ring gear. The number of teeth of the sun gear is a, the number of teeth of the planetary gear is b, If the number of gear teeth (number of internal teeth) is c, the reduction ratio (output / input) is said to be as follows. That is,
(1) When the sun gear is fixed, the planetary gear is output (when a carrier that outputs the revolving motion of the planetary gear is provided), and the outer ring gear is input,
[Formula 1] (a + c) / c
(2) When the sun gear is input, the planetary gear is fixed (only rotation is allowed and not revolved), and the outer ring gear is output,
[Formula 2]-(c / a)
It becomes.
According to the above configuration, in any case, regardless of the number of teeth b of the planetary gear, there is an advantage that a large reduction ratio can be obtained with a small number of stages and a large torque can be transmitted. There is also an advantage that the input shaft and the output shaft can be arranged on the same axis.

The sprocket is provided on the outer periphery of the sun gear to be an output side and is rotatable without being fixed to the crankshaft. An outer ring gear having an internal gear is fixed, and an outer ring is interposed between the sun gear and the outer ring gear. Some planetary gears that mesh with the internal gear of the gear and the sun gear and revolve are provided on the input side (see, for example, Patent Document 1).
In addition, there is a type in which the planetary gear (2) can be revolved around the sun gear, and the outer ring gear having the inner teeth meshing with the planetary gear is rotated along with the revolution of the planetary gear (for example, patents) Reference 2).

JP-A-6-171574 (page 2, Fig. 2) Japanese Patent Laid-Open No. 4-85187

  However, according to Patent Document 1, since the planetary gear is set on the input side, the rotation shaft of the planetary gear is connected to the middle in the length direction of the crank. For this reason, the pedal force applied to the crank is not directly transmitted from the base portion of the crank to the crankshaft, but is transmitted to the rotating shaft of the planetary gear at the middle portion of the crank. Therefore, there is a problem that the effective length of the crank is shortened.

  According to Patent Document 2, in order to revolve the planetary gear around the fixed sun gear, a guide roller is provided inside the outer ring gear in addition to the sun gear and the planetary gear, and the sun gear, the planetary gear, Since a chain that meshes with the guide roller must be provided separately, the structure is complicated.

  Accordingly, an object of the present invention is to provide a planetary gear mechanism having a large reduction ratio without complicating the structure.

  In order to solve the above-described problems, the present invention provides a sun gear having outward teeth on a rotation shaft on the input side, and enables the sun gear to rotate integrally with the rotation shaft, and the outer diameter of the sun gear. An outer ring gear having inward teeth on the side is provided as an output side, and the outer ring gear is rotatable with respect to the rotating shaft, and the outward teeth of the sun gear and the inward teeth of the outer ring gear A plurality of planetary gears are arranged in parallel in the radial direction and meshed with each other, and each planetary gear is allowed to rotate only around the corresponding planetary support shaft and does not revolve. The rotation of the sun gear can be transmitted to the outer ring gear by the planetary gears.

Since the plurality of planetary gears are provided in parallel in the radial direction between the sun gear and the outer ring gear, the diameter of the outer ring gear can be made larger than the diameter of the sun gear. For this reason, it is easy to set the number of teeth on the input side and the number of teeth on the output side, and a large reduction ratio can be secured.
Moreover, since the space between the sun gear on the input side and the outer ring gear on the output side is driven via a planetary gear that does not allow revolution, the structure is not complicated and the size is not increased.
The number of planetary gears may be two, three, or more in parallel in the radial direction, and the number of gears parallel in the radial direction may be set freely. A plurality of planetary gear groups arranged in parallel in the radial direction may be arranged radially around the rotation axis (sun gear) on the input side. If a plurality of sets are arranged radially, rotation transmission from the sun gear to the outer ring gear is stabilized, which is preferable.

  In the above configuration, a ring gear having inward teeth and outward teeth is interposed between a plurality of planetary gears so that the ring gear is rotatable with respect to the rotating shaft and the outer ring gear. A configuration may be adopted in which the rotation of the planetary gear located on the inner diameter side can be transmitted to the planetary gear located on the outer diameter side by the ring gear.

Since each planetary gear has a relatively small diameter, care should be taken not to cause interference between adjacent gears, biting, excessive tooth wear, etc. when a plurality of consecutive planetary gears mesh with each other. However, as described above, if the rotation between adjacent planetary gears is transmitted via the ring gear, the outer diameter of the pitch circle between the meshing gears becomes relatively large, and the meshing The pressure angle generated at the mating portion is small.
For this reason, the occurrence of interference between gears, biting, excessive tooth wear, etc. is suppressed, and rotation transmission between the planetary gears is stabilized. As a result, rotation transmission from the sun gear to the outer ring gear is also achieved. Can be stable.

  Moreover, the torque transmission structure having the above-described configuration can be employed in a bicycle drive device. As its configuration, a crank extending in the radial direction is connected to the rotating shaft, the rotating shaft can be rotated by a circumferential force applied to the crank, an outward sprocket is provided on the outer ring gear, and the rotating shaft In this configuration, an outward sprocket is provided on a drive shaft provided separately, and a chain that meshes with both the sprockets is provided so that the rotation of the outer ring gear can be transmitted to the drive shaft by the chain.

  In this way, the occupant can rotate the crank by the stepping force and transmit the rotational force to the drive wheels with a large reduction ratio.

  Since the present invention is configured as described above, it can be a planetary gear mechanism having a large reduction ratio without complicating the structure.

  An embodiment will be described with reference to FIGS. This embodiment is a torque transmission device employed in the bicycle drive device shown in FIG.

  Both ends of the rotating shaft 1 are fitted into holes 31 a provided at the ends of the cranks 31, 31 to connect the rotating shaft 1 and both the cranks 31, 31, and the rotating shaft 1 is attached by the pedaling force applied to the crank 31. It can be rotated around its axis. The rotating shaft 1 is fitted in a hole 2a of a sun gear 2 having outward teeth 8 on the entire circumference, and is fixed via a keyway 33a and a key 33. The rotating shaft 1 and the sun gear 2 are connected to each other. It is attached so as to rotate together. The rotating shaft 1 is fitted in the fixed boss portion 34 and the hole 35 of the fixed base plate B.

  On the outer diameter side of the sun gear 2, an outer ring gear 6 having inward teeth 14 on the entire circumference is provided coaxially with the rotary shaft 1, and the outer ring gear 6 has a hole with respect to the rotary shaft 1. It is rotatably fixed via a bearing 32 provided in 6a. A sprocket 18 is attached to the outer periphery of the outer ring gear 6.

  Between the outward teeth 8 of the sun gear 2 and the inward teeth 14 of the outer ring gear 6, two planetary gears 10, 15 are arranged in parallel in the radial direction, and each planetary gear 10, 15 is arranged. The corresponding planetary support shafts 11 and 16 provided on the fixed base plate B are fitted in the holes 10a and 15a, and only the rotation around the planetary support shafts 11 and 16 is allowed, so that they do not revolve. ing. Three sets of planetary gears 10 and 15 (planetary gear group) arranged in parallel in the radial direction are arranged radially in the same direction around the rotary shaft 1 (sun gear 2) on the input side.

  A ring gear 4 having inward teeth 9 and outward teeth 13 on the entire circumference is interposed between the two planetary gears 10 and 15, and the ring gear 4 is provided in the hole 4a. The ring gear 4 is rotatable with respect to the rotating shaft 1 via a bearing 32, and the ring gear 4 is also rotatable with respect to the outer ring gear 6 so as to rotate separately.

  Each of the planetary gears 10 and 15 meshes with the teeth 8 of the sun gear 2 and the teeth 14 of the outer ring gear 6 that face each other, and the rotation of the planetary gear 10 positioned on the inner diameter side via the ring gear 4. Can be transmitted to the planetary gear 15 located on the outer diameter side, so that the rotation of the sun gear 2 can be transmitted to the outer ring gear 6 via the planetary gear 10, the ring gear 4, and the planetary gear 15. .

  The radius 3 of the sun gear 2 is set to 2 cm, and its teeth 8 are 6 mm pitch. The radii 12 and 17 of the planetary gears 10 and 15 are set to 1 cm, respectively, and their teeth are each 6 mm pitch. The inner radius 5 of the ring gear 4 is set to 4 cm, and the teeth 9 and 13 are each 6 mm pitch. The inner ring side radius 7 of the outer ring gear 6 is set to 6 cm, and the inward teeth 14 have a pitch of 6 mm. The outward teeth (sprockets) 18 of the outer ring gear 6 have a 12 mm pitch. In order to simplify the explanation, the thickness of the ring gear 4 is ignored here.

  Here, the radius is the radius of the reference pitch circle, and the reference pitch circle is a pair of gears that mesh with each other and a friction wheel (a component that transmits power by the frictional force between the outer circumferences of two discs. ) Is considered to correspond to the diameter of the friction wheel when the rotation ratio (reduction ratio, speed increase ratio) is made equal, but the radius and the number of teeth shown in this embodiment Since the numerical values of the tooth pitch indicate one embodiment, they are not limited to these numerical values.

  Further, as shown in FIG. 4, a drive shaft 23 that rotates integrally with the rear wheel of the bicycle is provided separately from the torque transmission structure (see FIG. 1) coaxially disposed around the rotation shaft 1. An outward sprocket 20 is attached to the drive shaft 23, and an annular chain C is engaged between the outward sprocket 18 provided on the outer ring gear 6 and the sprocket 20.

  With the above configuration, when the rotating shaft 1 is rotated by the circumferential force applied to the crank 31 and the outer ring gear 6 is rotated via the sun gear 2, the planetary gear 10, the ring gear 4, and the planetary gear 15, the chain With C, the rotation of the outer ring gear 6 is transmitted to the drive shaft 23.

The operation of the torque transmission structure will be described with reference to FIG.
(1) When the rotating shaft 1 of the crank 31 rotates and the sun gear 2 having a radius 3 of 2 cm rotates in the A direction indicated by the arrow (one rotation),
(2) The planetary gear 10 with a radius 12 of 1 cm located on the inner diameter side rotates in the direction of arrow B, and the ring gear 4 with a radius 5 of 4 cm rotates in the direction of arrow C (1/2 rotation). To do.
(3) With the rotation (1/2 rotation) of the ring gear 4, the outer diameter planetary gear 15 having a radius 17 of 1 cm rotates in the direction of arrow D, and the outer ring whose radius 7 on the inner diameter side is 6 cm. The gear 6 (chain wheel) rotates in the direction of arrow E (1/3 rotation).

That is, for example, if the sun gear 2 rotates three times, the outer ring gear 6 rotates one time, which indicates that the traveling speed is the same as that when a normal bicycle chain wheel rotates one time.
At this time, since the radius 3 of the sun gear 2 is 2 cm, the force generated in the sun gear 2 is 510 cm if the crank length is 17 cm and the leg force (pedal force) acting on the pedal is 30 kg. Since this is / 2 (kg), this 510/2 (kg) is transmitted to the outer ring gear 6. That is, the strong force generated in the teeth 8 of the sun gear 2 is transmitted as it is to the teeth 14 of the outer ring gear 6 to obtain a large reduction ratio.
On the other hand, when rotating a chain wheel of a normal bicycle, if the chain wheel has the same radius 7 as the outer ring gear 6, 510/6 (kg) of the same leg force (stepping force) is obtained. Since the force is transmitted to the chain wheel, the reduction gear ratio is relatively small.

As another embodiment, another torque transmission device may be interposed between the torque transmission device provided around the rotary shaft 1 and the drive shaft 23.
That is, the rotating shaft 1 of one torque transmission device is rotated by the circumferential force applied to the crank 31, and the outer ring gear 6 is rotated via the sun gear 2, the planetary gear 10, the ring gear 4, and the planetary gear 15. Then, the rotating shaft 1 ′ of another torque transmission device is rotated by the chain C. The rotating shaft 1 'is supported rotatably.
The sun gear 2 ′, the planetary gear 10 ′, and the ring having the same configuration as the sun gear 2, the planetary gear 10, the ring gear 4, the planetary gear 15, and the outer ring gear 6 are coaxially formed around the rotation shaft 1 ′. A gear 4 ′, a planetary gear 15 ′, and an outer ring gear 6 ′ are provided, and the rotation of the outer ring gear 6 ′ causes another chain C ′ (sun gear 2 ′, planetary gear 10 ′, ring gear 4 ′, planetary gear 15). ', Outer ring gear 6', and chain C 'are all not shown) and may be transmitted to the drive shaft 23.

  In any of the embodiments, the ring gear 4 or the ring gear 4 ′ is omitted as necessary, and the planetary gears 10 and 15 or the planetary gears 10 ′ and 15 ′ arranged in parallel in the radial direction are directly meshed with each other. A configuration can also be adopted.

Explanatory drawing which shows the structure of one Embodiment Cut side view of FIG. 1 is an exploded perspective view of FIG. Explanatory drawing which shows the Example which employ | adopted the torque transmission mechanism of FIG. 1 for the drive device of a bicycle.

Explanation of symbols

1 Rotating shaft (Crank rotating shaft)
2 Sun gear 3 Sun gear radius 4 Ring gear 5 Ring gear inner radius 6 Outer gear 7 Outer gear inner radius 8 Sun gear outward teeth 9 Ring gear inner teeth 10, 15 Planetary gear 11 , 16 Planetary support shafts 12, 17 Radius of the planetary gear 13 Outward teeth of the ring gear 14 Inward teeth of the outer ring gear 18 Outward teeth of the outer ring gear (sprocket)
20 sprockets 21 and 22 planetary gear teeth 23 drive shaft 30 pedal 31 crank 32 bearing 33 key 33a key groove 34 boss

Claims (3)

  A sun gear 2 having outward teeth 8 is provided on the rotary shaft 1 on the input side so that the sun gear 2 can be rotated integrally with the rotary shaft 1, and an inward tooth on the outer diameter side of the sun gear 2. The outer ring gear 6 having 14 is provided as an output side, and the outer ring gear 6 is rotatable with respect to the rotary shaft 1, and the outward teeth 8 of the sun gear 2 and the inward teeth of the outer ring gear 6 are provided. 14, a plurality of planetary gears 10 and 15 are arranged in parallel in the radial direction and meshed with each other, and the planetary gears 10 and 15 only rotate around the corresponding planetary support shafts 11 and 16. A torque transmission structure characterized in that the planetary gears 10 and 15 allow the rotation of the sun gear 2 to be transmitted to the outer ring gear 6 by allowing the planetary gears 10 and 15 to revolve.   A ring gear 4 having inward teeth 9 and outward teeth 13 is interposed between the plurality of planetary gears 10 and 15 so that the ring gear 4 is connected to the rotary shaft 1 and the outer ring gear 6. 2. The torque according to claim 1, wherein the torque is rotatable, and the ring gear 4 is capable of transmitting the rotation of the planetary gear 10 located on the inner diameter side to the planetary gear 15 located on the outer diameter side. Transmission structure.   A crank 31 extending in the radial direction is connected to the rotary shaft 1 so that the rotary shaft 1 can be rotated by a circumferential force applied to the crank 31, and an outward sprocket 18 is provided on the outer ring gear 6. A drive shaft 23 provided separately from the shaft 1 is provided with an outward sprocket 20, and a chain C meshing with both the sprockets 18, 20 is provided, and the rotation of the outer ring gear 6 is transmitted to the drive shaft 23 by the chain C. The torque transmission structure according to claim 1, wherein transmission is possible.

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