JPH0572318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a motorized bicycle having a bicycle-type body frame, and particularly to a power transmission device for driving a rear wheel.

[Technical background of the invention and its problems]

This type of motorized bicycle can be used in two ways: like a normal bicycle, it can be driven by pedal cranks with the feet, or it can be driven by engine power. If this driving force is transmitted to the engine power transmission system when the vehicle is running, problems such as increased pedal drive may occur.

Furthermore, the gear case located below the saddle supports not only the drive shaft artificially rotated by the pedal crank, but also various shafts such as the reduction gear shaft that transmits engine power to the drive sprocket. As a result, the bearing portion increases, so the rigidity and processing accuracy of the gear case must be increased, which results in the gear case itself becoming heavier and larger, and the structure becoming more complex, resulting in higher costs.

[Purpose of the invention]

The present invention was developed based on the above circumstances, and allows light pedal drive when riding as a normal bicycle.Moreover, even though the power transmission system has three axes, the gear case is not directly connected to the bicycle. The purpose of the present invention is to provide a power transmission device for a motorized bicycle, which only needs to be supported by the drive sprocket shaft, and which can realize not only a smaller and lighter gear case but also a simpler structure.

[Summary of the Invention] In order to achieve the above object, the power transmission device for a motorized bicycle according to the present invention includes a gear case body with one side open below the saddle, and a cap that covers the one side opening of the gear case body. A hollow drive sprocket shaft equipped with a drive sprocket is rotatably supported in the gear case main body of the gear case via a bearing, and a pedal crank is mounted inside the drive sprocket shaft. A drive shaft that is artificially rotationally driven by stepping on the sprocket shaft is inserted coaxially, and this drive shaft is rotatably supported on the inner circumferential surface of the drive sprocket shaft, and both ends of this drive shaft are The cap and gear case main body are passed through the side opposite to the cap and led out to the left and right sides of the gear case, and between the outer periphery of the drive shaft and the inner periphery of the drive sprocket shaft, a drive shaft is inserted from the drive shaft side. The first part allows power transmission only to the sprocket shaft.
A one-way clutch is interposed therebetween, and a reduction gear shaft is disposed coaxially around the outer periphery of the drive sprocket shaft, and the reduction gear shaft is rotatably driven by transmission of power from the prime mover. A second shaft is rotatably supported on the outer peripheral surface of the sprocket shaft, and between the inner periphery of the reduction gear shaft and the outer periphery of the drive sprocket shaft is a second shaft that allows power transmission only from the reduction gear shaft to the drive sprocket shaft. The present invention is characterized in that a one-way clutch is interposed, the bearing portion of the gear case is located at one location, and power is not transmitted to the prime mover side from the drive sprocket shaft during input from the pedal crank.

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in the drawings.

Reference numeral 1 in FIG. 2 is a bicycle-type body frame, and a front fork 4, which pivotally supports a front wheel 3, is pivotally supported on a head pipe 2 at the front end of the frame. A down tube 5 extending rearward and downward is connected to the head pipe 2, and a gear case 7 is bolted to the rear end of the down tube 5 via a battery box 6. The gear case 7 is located approximately in the center of the vehicle body.
A rear wheel 9 is supported between rear end portions of left and right rear arms 8, 8 extending rearward from the vehicle. Left and right backstays 10, 10 are led out obliquely forward from the rear ends of the rear arms 8, 8, and the upper ends of these backstays 10, 10 are attached to the gear case 7.
A saddle 12 is supported by a hollow cylindrical upper bracket 11 located substantially directly above the seat and attached to its upper end.

As shown in FIG. 1, the gear case 7 consists of a gear case body 13 and a cap 14 that covers one side opening 13a of the gear case body 13.
A hollow cylindrical drive sprocket shaft 16 is inserted coaxially in the left-right direction into a hollow boss portion 15 provided opposite to the opening 13a on one side of the gear case body 13. The drive sprocket shaft 16 has a large diameter portion 16a and a small diameter portion 16b, and the large diameter portion 16a is attached to the boss portion 15 with the bearing 1.
The small diameter portion 1 is rotatably supported via 7 and 17.
6b is located at one end on the opening 13a side. One end of the large diameter portion 16a passes through the side surface of the gear case body 13 opposite to the one side opening 13a and is led out to the side of the gear case 7. This large diameter portion 16
A drive sprocket 18 is fixed to the outer periphery of the lead-out portion a, and a chain 20 is wound between the drive sprocket 18 and a fleece sprocket 19 on the rear wheel 9 side.

A drive shaft 21 is inserted coaxially into the drive sprocket shaft 16 and rotatably supported via bearings 22 , 22 .
Both ends of the gear case 7 pass through the drive sprocket shaft 16 and the cap 14 and are led out to both left and right sides of the gear case 7, and pedals 24, 24 are attached to both ends via pedal cranks 23, 23. . A first one-way clutch 25 is interposed between the inner periphery of the large diameter portion 16a and the outer periphery of the drive shaft 21, which allows power to be transmitted only from the drive shaft 21 side to the drive sprocket shaft 16 side. Therefore, when the drive shaft 21 is rotationally driven by depressing the pedals 24, 24,
This rotation of the drive shaft 21 is controlled by the first one-way clutch 2.
5 and the drive sprocket shaft 16 to the drive sprocket 18, and from the drive sprocket 18 to the rear wheel 9 through the chain 20. Further, a hollow cylindrical reduction gear shaft 26 is coaxially mounted on the outer periphery of the small diameter portion 16b of the drive sprocket shaft 16, and is rotatably supported via a bearing 27. A reducing bevel gear 28 is integrally formed on the outer periphery of the reduction gear shaft 26, and a drive sprocket shaft is connected from the reduction gear shaft 26 side between the inner periphery of the reduction gear shaft 26 and the outer periphery of the small diameter portion 16b. A second one-way clutch 29 is interposed that allows power transmission only to the 16 side. Therefore, the drive sprocket shaft 16,
The three axes, the drive shaft 21 and the reduction gear shaft 26, are arranged coaxially with each other, and the drive shaft 21 and the reduction gear shaft 26 are not directly supported by the gear case body 13, but are supported by the drive sprocket shaft 16. It is being

When assembling these three shafts to the gear case 7, the drive shaft 21 is first installed inside the drive sprocket shaft 16, and then the drive sprocket shaft 16 is inserted through the opening 13a on one side of the gear case body 13. The reduction gear shaft 26 is inserted into the boss portion 15, and then the reduction gear shaft 26 is mounted on the outer periphery of the small diameter portion 16b of the drive sprocket shaft 16 through the opening 13a on one side. It is designed so that it can be done sequentially from one side.

Further, a power transmission shaft 31 is pivotally supported in a cylindrical portion 30 extending upward from the upper part of the gear case body 13 along a vertical direction perpendicular to the drive shaft 21.
This power transmission shaft 31 is interlocked with the drive sprocket shaft 16 through engagement between a reducing bevel gear 32 provided at its lower end and the reducing bevel gear 28 .

On the other hand, between the saddle 12 and the gear case 7, a forced air-cooled two-stroke engine 33 as a prime mover and a power transmission mechanism 34 for transmitting the engine power to the drive sprocket shaft 16 are sequentially arranged from above. The engine 33 includes a crankshaft 36 disposed vertically in a substantially cylindrical crankcase 35, and a flywheel magneto 37 and a centrifugal automatic clutch constituting the power transmission mechanism 34 at the lower end thereof. 38 and a planetary gear type reduction gear 39 are coaxially arranged in this order. These flywheel magnetos 3
7. The clutch 38 and the reduction gear 39 are surrounded by a hollow cylindrical casing 40 that is integrally connected to the crankcase 35, which allows the engine 33 and the power transmission mechanism 34 to form a substantially cylindrical structure. A power unit 41, which is integrally shaped, is constructed. The power unit 41 is constructed by inserting the upper end of the crankcase 35 into the upper bracket 11 and tightening bolts, and by tightening the lower end of the casing 40 to the upper surface of the cylindrical part 30. Due to this fixation, the crankcase 35 and the casing 40 have a function as a saddle tube that supports the saddle 12, and constitute a part of the vehicle body frame 1. Further, an output shaft 42 of the transmission 39 is led out from the lower end surface of the casing 40, and the leading end of the output shaft 42 is introduced into the cylindrical part 30 and is inserted through a square joint 43. It is connected to the power transmission shaft 31.

In addition, in the figure, numeral 44 is a cylinder, 45 is a carburetor, 46 is an air cleaner, 47 is a fuel tank, 4
8 is an exhaust pipe, 49 is a muffler, 50 is a starter motor for starting the engine, and 51 . . . is a battery as a power source for the starter motor 50, respectively.

According to this configuration, when riding the pedals 24, 24 as a normal bicycle, the rotational driving force transmitted to the drive shaft 21 through the pedal cranks 23, 23 is transmitted via the first one-way clutch 25. It is transmitted to the outer drive sprocket shaft 16, and from this drive sprocket shaft 16 via the drive sprocket 18, chain 20, and fleece sprocket 19 to the rear wheel 9. At this time, a reduction gear shaft 26 interlocked with the power transmission mechanism 34 is mounted on the drive sprocket shaft 16, and between these two shafts 6, 26, the reduction gear shaft 2
Since the second one-way clutch 29 that only allows power transmission from the 6 side is interposed, when rotational force is input from the drive sprocket shaft 16 side as described above, this second one-way clutch 29 is inserted. The directional clutch 29 idles and no power is transmitted to the reduction gear shaft 26. Therefore, when viewed from the drive sprocket shaft 16 side, the reduction gear shaft 2 has a predetermined speed increase ratio.
6 is no longer dragged and rotated, so there is an advantage that the pedal can be driven easily.

In addition, when traveling by engine power, the engine power transmitted from the output shaft 42 to the power transmission shaft 31 via the angle joint 43 is further decelerated by the meshing of the reducing bevel gear 32 and the reducing bevel gear 28. is transmitted to the reduction gear shaft 26, and
From there, it is transmitted to the drive sprocket shaft 16 via the second one-way clutch 29, and thereafter to the rear wheel 9 in the same manner as described above. In this case, the first one-way clutch 15 between the drive sprocket shaft 16 and the drive shaft 21 idles when rotational force is input from the drive sprocket shaft 16 side, causing the clutch to move toward the drive shaft 21 side. Since there is no power transmission,
The pedal cranks 23, 23 do not rotate, and the vehicle can run using the pedals 24, 24 instead of a footrest.

Moreover, according to the above configuration, the three axes of the drive sprocket shaft 16, the drive shaft 21, and the reduction gear shaft 26 are arranged coaxially, and the drive shaft 21 and the reduction gear shaft 26 are connected to the gear case body 13.
drive sprocket shaft 1 instead of cap 14
6, the gear case 7 only needs to directly receive one drive sprocket shaft 16. Therefore, even though the three shafts 16, 21, and 26 are housed in the gear case 7, the bearing part that requires rigidity and processing accuracy is only at one location in the boss part 15, which makes the structure simpler. It is possible to reduce the weight, and the number of processing parts can be reduced, making it possible to reduce costs.

Furthermore, in the case of this embodiment, the drive sprocket shaft 1
6 is pivotally supported by the boss portion 15 by its large diameter portion 16a, so the bearing area is increased, and therefore, shaft runout does not occur and it can be supported reliably. At the same time, since the reduction gear shaft 26 located at the outermost position among the three shafts is supported by the small diameter portion 16b of the drive sprocket shaft 16, the shaft diameter is of course reduced by that amount, and in turn, the reduction gear shaft 28
The diameter of the gear case 7 can also be reduced, which also contributes to making the gear case 7 smaller and lighter.

In addition, since the drive shaft 21, reduction gear shaft 26, and reducing bevel gear 28 are supported on the drive sprocket shaft 16 that is pivotally supported by the gear case body 13, the parts necessary for power transmission are moved near the center of the vehicle body. This allows the mass to be concentrated and improves steering stability.

〔Effect of the invention〕

According to the present invention described in detail above, when rotational force is transmitted from the drive sprocket shaft side as when riding as a normal bicycle, the second one-way clutch idles and is transferred to the reduction gear shaft. Since no power transmission is performed, the power transmission mechanism on the prime mover side is not dragged and rotated together, and therefore, the pedal can be driven lightly. Moreover, the three axes, the drive sprocket shaft, the drive shaft, and the reduction gear shaft, are arranged coaxially, and among these three axes, the drive shaft and the reduction gear shaft are located on the drive sprocket shaft rather than on the gear case body or cap. Since the gear case is supported in this way, only one drive sprocket shaft is required to be directly supported by the gear case. Therefore, even though three shafts are housed in the gear case, there is only one bearing part that requires rigidity and processing precision, which makes the structure simpler and the gear case lighter. This has the advantage of requiring fewer machining locations and reducing costs.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which FIG. 1 is a sectional view, FIG. 2 is a side view of a motorized bicycle, FIG. 3 is a partially sectional side view showing an enlarged middle part of FIG. 2, and FIG. FIG. 4 is a view taken from the direction of the line in FIG. 7... Gear case, 12... Saddle, 13...
Gear case body, 13a... One side opening, 14...
... Cap, 16 ... Drive sprocket shaft, 17
... Bearing, 18 ... Drive sprocket, 21 ...
Drive shaft, 23...Pedal crank, 25...1st
One-way clutch, 26... Reduction gear shaft, 29...
...second one-way clutch, 33...engine.

Claims (1)

[Claims] 1. A gear case including a gear case body with an opening on one side and a cap covering the opening on one side of the gear case body is arranged below the saddle, and a drive sprocket is attached to the gear case body of the gear case. A hollow drive sprocket shaft equipped with a shaft is rotatably supported via a bearing, and a drive shaft that is artificially rotated by depressing a pedal crank is coaxially inside this drive sprocket shaft. The drive shaft is rotatably supported on the inner circumferential surface of the drive sprocket shaft, and both ends of the drive shaft are inserted through the cap and the side surface of the gear case main body opposite to the cap to connect the gear case to the gear case. A first one-way clutch is inserted between the outer periphery of these drive shafts and the inner periphery of the drive sprocket shaft to allow only power transmission from the drive shaft side to the drive sprocket shaft. and a reduction gear shaft rotatably driven by power transmission from the prime mover is disposed coaxially around the outer periphery of the drive sprocket shaft, and the reduction gear shaft is arranged on the outer periphery of the drive sprocket shaft. A second one-way clutch is installed between the inner periphery of the reduction gear shaft and the outer periphery of the drive sprocket shaft to allow power to be transmitted only from the reduction gear shaft to the drive sprocket shaft. A power transmission device for a motorized bicycle, which is characterized by: