JP2000142539A - Canti-lever drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily install a transmission of relay type free from any interference with legs by employing a versatile change-gear hub. SOLUTION: In a cantilever drive unit of a bicycle in which a rear frame 2 having a drive system to a front frame 1 is pivotably supported in an oscillating manner, a change-gear hub 9 is installed between a crankshaft 4 (a crank sprocket 6) and a rear wheel hub (to be connected to a free wheel sprocket 12), and the crankshaft 4 and the change-gear hub 9, and the change- gear hub 9 and the rear wheel hub (the free wheel sprocket 12) are connected to each other through power transmission members 7, 11, respectively. The cantilever drive unit is provided with a rear frame 2 having the drive system which is easy in attachment/detachment to/from the front frame 1 during the assembly, etc., and also easy in maintenance and inspection through disassembly. A bicycle with a built-in change-gear can be provided at a low cost only by fitting the versatile change-gear hub 9 on the market on an intermediate part of the rear frame 2 without changing any part of the crank sprocket part or the rear wheel hub part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cantilever drive unit for a bicycle in which a rear frame having a driving system with respect to a front frame is pivotally supported.

[0002]

2. Description of the Related Art Various types of transmissions have been proposed for bicycles so that the pedal can be driven lightly according to the running speed. On the other hand, in order to simplify the configuration of the drive system, a cantilever drive unit that pivotally supports a rear frame having a drive system with respect to a front frame as shown in FIG. 9 has been proposed. In this apparatus, a rear frame 32 having a driving system is connected to a front
The drive unit has a cantilever drive unit that is pivotally supported by the drive shaft. A drive shaft is provided inside the rear frame 32, and the drive force of the crankshaft 34, which is rotationally driven by the depression of the pedal 35, is provided. The power is transmitted to the rear wheel hub 36. Reference numeral 37 denotes a shock absorber interposed between the front frame 31 and the rear frame 32. As a bicycle transmission, a transmission in which a multi-stage sprocket or an internal transmission is disposed on a crankshaft or a rear wheel hub is widely used. However, in these transmissions, the crankshaft and the rear wheel hub have a specific structure as a transmission, and therefore, need to be configured in a dedicated design shape. Therefore, there has been proposed an apparatus in which the transmission is installed with the crankshaft and the rear wheel hub kept in a versatile ordinary shape and form.

As examples of such a device, Japanese Patent Application Laid-Open No. 8-3321989 shown in FIG.
-278668. In the former first conventional example, the rotational driving force of the pedal 45 is supported from the chain wheel 46 to an appropriate portion of the frame.
The power is transmitted to a relay section including a small-diameter relay gear 48 and a large-diameter relay gear 49 fixed coaxially with the small-diameter relay gear 48. In addition, a small-diameter relay gear 48, a chain wheel 46
It includes a drive relay chain 47 looped between them, a large-diameter relay gear 49, and a transmission relay chain 44 looped between the rear chain gears 43, and the relay portion is formed from a group of gears having different diameters. The speed change means is configured to be able to freely set acceleration / deceleration.

[0004] The second conventional example is a pedal 5
The transmission system from the crankshaft, which is rotationally driven by the treading of step 5, to the output shaft 53 on which the drive wheel is mounted, includes a fixed pulley piece fixed to the shaft, a movable pulley piece movable at least in the axial direction with respect to the shaft, and It has a set of pulleys having at least one speed change pulley 56, 58 comprising means for moving the movable pulley piece, and a continuously variable transmission mechanism 59 comprising a belt 57 wound around the pulley. Reference numeral 60 denotes an output sprocket of the continuously variable transmission mechanism 59, and reference numeral 54 denotes a drive chain wound between the output sprocket 54 and the output shaft 53.

[0005]

However, in the conventional relay-type transmission configured as described above, the relay portion that constitutes the transmission is installed at a substantially central portion of the vertical pipe, so that the traveling speed is reduced. When the pedal is depressed during the operation, there is a risk that the chain, the belt, and the transmission may come into contact with the legs. On the other hand, a cantilever drive unit that pivotally supports a rear frame having a drive system with respect to the front frame so as to swing freely, usually constitutes a substantially linear rear frame, so that the relay as described above is used. It is difficult to apply a transmission of this type, and it has therefore been necessary to not install a transmission in such a cantilevered drive unit or to design a specially dedicated transmission.

Accordingly, the present invention solves the problems of the conventional cantilever drive unit and the relay type transmission, and
An object of the present invention is to provide a cantilevered drive unit that can easily install a relay type transmission that does not interfere with the legs by adopting a versatile transmission hub.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a cantilever drive unit for a bicycle in which a rear frame having a drive system with respect to a front frame is swingably supported. A transmission hub is installed between the transmission shaft and the transmission shaft, and between the crankshaft and the transmission hub and between the transmission hub and the rear wheel hub are connected by a power transmission member. Further, the present invention is characterized in that a shock absorber is provided between the front frame and the rear frame.
Further, the present invention is characterized in that a tensioner for absorbing a slack of the power transmission member is provided. Further, the present invention is characterized in that the periphery of the rear frame is covered with a cover body, and these are used as means for solving the problem.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a first embodiment of a cantilever drive unit according to the present invention. FIG. 1A is an overall side view of a bicycle, and FIG. 1B is an enlarged side view of the cantilever drive unit. 2, FIG. 2 is a plan view, a side view and a bottom view of the drive unit, FIG. 3 is a partial sectional view of a transmission hub portion, and FIG. 4 is a partial sectional view of a rear wheel hub portion. As shown in FIG. 1 (A), the cantilever drive unit of the present invention includes, for example, a front frame 1 in which a steering mechanism is pivotally supported at a front end and a saddle is attached to a rear upper end to form an integrated panel. On the other hand, it is pivotally supported at its lower end by a pivot shaft 3. The rear frame 2 constituting the cantilever drive unit is formed in a substantially linear shape, its front end is supported by the pivot shaft 3, and a buffer 13 of an appropriate type is interposed between the rear frame 2 and the lower portion of the front frame 1. Is done.

The cantilever drive unit of the present invention comprises a crankshaft 4 located near the front end of the rear frame 2 and driven to rotate by the pedal 5 and a rear wheel hub located at the rear end of the rear frame 2. 19 (FIG. 4), a transmission hub 9 is installed between the crankshaft 4 and the transmission hub 9 (between the crank sprocket 6 and the transmission input sprocket 8) and the transmission hub. 9
And the rear wheel hub 19 (between the shift output sprocket 10 and the freewheel sprocket 12) are connected by a power transmission member such as the first chain 7 and the second chain 11. Note that, if structural restrictions are allowed, another appropriate power transmission member may be used instead of the chain. In the present embodiment, as shown in FIG. 2, rear frame 2 is disposed on the center line of the vehicle body and surrounds transmission hub 9 (FIG. 2B) and is provided with rear frame front portion 2A. And a rear frame rear portion 2B which is deviated from the vehicle body center line from the rear end side of the front portion 2A and extends rearward (FIG. 2 (A)). These rear frames 2 are formed in a rectangular cross section by hollow steel or the like.

As shown in FIG. 2 (B), the transmission hub 9 is attached to the front portion 2A of the rear frame by using a gate-shaped transmission hub mounting bracket 16 or the like. As shown in FIG. 3, a transmission hub mounting bracket 1 on which a commercially available general-purpose four-speed transmission type transmission hub 9 is supported.
6 is fixed to the front portion 2A of the rear frame by an appropriate mounting tool such as a mounting bolt 17. The speed change hub mounting bracket 16 is mounted so as to be adjustable in position relative to the rear frame front portion 2A, and applies tension of the first chain 7 between the crank sprocket 6 and the speed change input sprocket 8 to the first chain tensioner 14 (FIG. 1B). )) To adjust the tension of the second chain 11 between the transmission output sprocket 10 and the freewheel sprocket 12 to the second chain tensioner 1.
5 (FIG. 2 (B)).

As shown in FIG. 4, the freewheel sprocket 12 arranged at the rear end of the rear frame 2 is supported by a bearing bracket 18 attached to the side of the rear frame 2 so as to be pivotally supported. You. Thereafter, the support to the frame 2 is provided by the penetration of the rear wheel shaft 22 into the rear end of the rear frame 2 where rotational driving force is transmitted only from the freewheel sprocket 12 in the driving direction. The rear wheel axle 22 is connected to a rear wheel hub 19 distributed on the vehicle center line on the opposite side of the freewheel sprocket 12, and the rear wheel is supported by the rear frame 2 in a cantilever manner. Therefore, the attachment and detachment of the rear wheel from the rear frame 2 is easy. A brake drum 20 is fixed to a side surface of the rear wheel hub 19, and a brake shoe 21 is fixed to a side of the rear frame 2. The brake shoe 21 is divided in the circumferential direction, and when expanded in the radial direction, slides on the inner circumferential surface of the brake drum 20 to brake the rear wheels.

With such a configuration, even if the cantilever drive unit has a rear frame having a drive system that can be easily attached to and detached from the front frame 1 at the time of assembling and the like, the crank sprocket portion and the rear wheel hub portion have no structure. By simply attaching a commercially available universal transmission hub to the middle portion of the rear frame without making any changes, a bicycle with a built-in transmission can be configured, and the cost is low. And
Since the crank sprocket, the transmission hub, and the rear wheel hub can be arranged on the substantially linear rear frame, a power transmission member such as a chain stretched between them can be accommodated in the shortest length. . In addition, since the transmission hub can be stored substantially within the width of the rear frame, the transmission hub does not interfere with the leg for stepping on the pedal.

FIGS. 5 and 6 show a second embodiment of the cantilever drive unit of the present invention. As shown in FIG. 5A, the basic structure is substantially the same as that of the first embodiment. In this embodiment, the rear frame 2 is supported by the lower end of the front frame 1 and the rear frame 2 is integrally formed by aluminum die casting or the like.
And a rear frame rear portion 2B. As shown in FIG. 6, a commercially-available speed change hub 9 is inserted into a substantially cylindrical hollow portion of the rear portion of the front portion 2 </ b> A of the rear frame. It is attached to the rear frame 2 by a pair of transmission hub attachment brackets 16A and 16B fixed to the side surface.

Another feature of the present embodiment is that when the periphery of the rear frame is covered with a cover (not shown),
As shown in FIG. 5 (B), which is constructed in the same manner as that of the above-described first embodiment so as to be maintenance-free and does not require maintenance / inspection, the space between the crank sprocket 6 and the transmission input sprocket 8 is provided. The first tensioner and the second tensioners 23 and 24 are respectively placed at appropriate positions on the rear frame 2 so as to constantly absorb the slack of the tension of the second chain 11 between the first chain 7 and the transmission output sprocket 10 and the freewheel sprocket 12. Support it,
It is in elastic contact with the outer periphery of the first chain 7 and the second chain 11. Note that reference numeral 25 in FIG.
The shifting hub 9 is operated by operating tools installed on a handlebar or the like.
2 shows a speed change wire for controlling the speed change of the vehicle.

With this configuration, the present embodiment has the same effects as those of the first embodiment, and furthermore, the transmission hub is made of a shell-shaped casing made of a light metal alloy such as aluminum. By being stored in the housing, the appearance is simple, the mechanical parts are not conscious, the rigidity is high, and the weight is low. In addition, a tensioner is installed around the outer periphery of the power transmission member, such as the chain, to constantly absorb the chain tension, so there is no need for maintenance and inspection as it is maintenance-free, and a cover body is provided around the drive system installed on the rear frame. To improve the appearance.

The embodiments of the present invention have been described above. However, the shapes and materials of the front and rear frames, the form of supporting the rear frame to the front frame, the type of the shock absorber and the interposition of the shock absorber are within the scope of the present invention. Form, type of crank sprocket and installation on the frame afterwards, type of transmission hub and installation on the frame afterwards, type of freewheel sprocket and rear wheel hub and their installation on the rear frame, power of chain, etc. The type of the transmission member, the type and the mounting form of the fastener, the type of the tensioner and the installation form thereof can be appropriately selected.

[0017]

As described above, according to the present invention, in a cantilever drive unit for a bicycle in which a rear frame having a drive system with respect to a front frame is swingably supported, a crankshaft and a rear wheel are provided. By installing a transmission hub between the hub and the crankshaft and the transmission hub and between the transmission hub and the rear wheel hub by a power transmission member, it can be attached to and detached from the front frame during assembly. Even a cantilevered drive unit having a rear frame with a drive system that is easy and easy to disassemble and maintain, even if the rear frame has no change to the crank sprocket or rear wheel hub, A bicycle with a built-in transmission can be constructed at a low cost simply by attaching a commercially available transmission hub to the intermediate portion. Since the crank sprocket, the transmission hub, and the rear wheel hub can be arranged on the substantially straight rear frame, the power transmission member such as a chain stretched between them is stored in the shortest length. In addition to the above, since the speed can be increased in two stages from the crank sprocket to the transmission hub and from the transmission hub to the rear wheel hub, the gear plate for shifting can be reduced. In addition, since the transmission hub can be stored substantially within the width of the rear frame, the transmission hub does not interfere with the legs for stepping on the pedal.

When a tensioner for absorbing the slack of the power transmission member is installed, the slack of the power transmission member, such as a chain, is always absorbed and maintenance-free, so that there is no need for maintenance and inspection. The periphery of the installed drive system is covered with a cover body, so that the appearance can be further improved. As described above, according to the present invention, there is provided a cantilever drive unit that can easily install a relay-type transmission that does not interfere with the legs by employing a versatile transmission hub.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a cantilever drive unit of the present invention, and FIG. 1 (A) is an overall side view of a bicycle, and FIG.
(B) is an enlarged side view of the cantilever drive unit.

FIG. 2 shows the first embodiment of the cantilever drive unit of the present invention, and is a plan view, a side view, and a bottom view of the drive unit.

FIG. 3 shows a first embodiment of the cantilever drive unit of the present invention, and is a partial cross-sectional view of a transmission hub.

FIG. 4 shows the first embodiment of the cantilever drive unit of the present invention, and is a partial cross-sectional view of a rear wheel hub.

5A and 5B show a cantilever drive unit according to a second embodiment of the present invention. FIG. 5A is an overall side view of the bicycle, and FIG.
(B) is an enlarged side view of the cantilever drive unit.

FIG. 6 shows a cantilevered drive unit according to a second embodiment of the present invention, and is a side view and a partially sectional bottom view of the drive unit.

FIG. 7 is an overall side view of a bicycle showing a first conventional example of a relay type transmission.

FIG. 8 is a side view of a main part of a bicycle showing a second conventional example of a relay type transmission.

FIG. 9 is an overall side view of the cantilever drive unit.

[Explanation of symbols]

 Reference Signs List 1 front frame 2 rear frame 3 pivot shaft 4 crankshaft 5 pedal 6 crank sprocket 7 first chain (power transmission member) 8 speed change input sprocket 9 speed change hub 10 speed change output sprocket 11 second chain (power transmission member) 12 freewheel sprocket DESCRIPTION OF SYMBOLS 13 Shock absorber 14 1st chain tensioner 15 2nd chain tensioner 16 Speed change hub mounting bracket 17 Mounting bolt 18 Bearing bracket 19 Rear wheel hub 20 Brake drum 21 Brake shoe 22 Rear wheel axle 23 1st tensioner 24 2nd tensioner 25 Speed change wire

Claims (4)

[Claims] 1. A cantilever drive unit for a bicycle in which a rear frame having a drive system is swingably supported with respect to a front frame, wherein a speed change hub is installed between a crankshaft and a rear wheel hub. A cantilever drive unit wherein a power transmission member connects the crankshaft and the transmission hub and the transmission hub and the rear wheel hub. 2. The cantilever drive unit according to claim 1, wherein a shock absorber is provided between the front frame and the rear frame. 3. The cantilever drive unit according to claim 1, further comprising a tensioner for absorbing a slack of the power transmission member. 4. The cantilever drive unit according to claim 3, wherein a periphery of the rear frame is covered with a cover body.