BACKGROUND ART A bicycle is constructed, as well known, by a characteristic that a front wheel as a steering wheel and a back wheel as a driving wheel are disposed by one straight line in front and back sides of a frame and the bicycle is progressed forward according that a rider pedals the pedal interlocked with the back wheel so that the back wheel may be rotated.

In such bicycle, a power transmission device is provided to transfer power generated in the pedal till the back wheel, and this power transmission device is composed of a driving sprocket wheel installed in one side of the pedal, a driven sprocket wheel having a smaller diameter than the driving sprocket wheel and set in the back wheel as the driving wheel, and a chain for connecting the driving sprocket wheel and the driven sprocket wheel. In such construction, when the rider pedals, the driving sprocket wheel installed in one body with this pedal rotates, simultaneously, the back wheel connected to the driven sprocket wheel also rotates, to thereby make the bicycle advanced.

Meantime, the power transmission device using such sprocket and chain has a complicated structure and a large occupation area in the bicycle, and also causes problems that the ends of the rider's garments get caught between the driving sprocket wheel and the chain or are soiled. Particularly, in a case of installing a multistage type speed change gear in the driven sprocket wheel, it may be frequently caused a problem that the chain is escaped from the sprocket wheel in the midst of a speed change.

Considering such problem, recently, it was developed, then is being used a chainless type power transmission device which includes in a frame, a first bevel gear for changing a rotating force of a pedal axis to a right angle direction, a driving axis for transferring a driving force of the first bevel gear till a back wheel, and a second bevel gear for transferring the rotating force of the driving axis to a hub of the back wheel, to thus transfer power of a pedal till the back wheel.

Such chainless type power transmission device has advantages such as a simple structure and a small occupation area, and especially has an advantage of perfectly transferring the power generated from the pedal till the back wheel, etc.

Meanwhile, such chainless type power transmission device has much merits in comparison with a chain type power transmission gear but has a difficulty in its separation and combination. That is, the frame of the bicycle is formed in one body with a sub frame in which the first bevel gear, the second bevel gear and the driving axis may be set, and the sub frame has an installment of the first bevel gear, the second bevel gear and the driving

axis in the inside thereof. In a case of repairing the bicycle, therefore, there is the difficulty that the sub frame should be disassembled and also the first and second bevel gears and the driving axis should be separated.

In order to settle such problems, this inventor had developed the power transmission device easy to separate and assemble it from/with the frame, which was disclosed under the Utility Model Registration Application Opening No. 97-51617. Herewith, it has a separate construction for housings wrapping around the first bevel gear, the second bevel gear and the driving axis, and these respective housings are assembled one another and make them fixed to the frame by using bolts and nuts so that their assembly and disassembly with/from the frame may be easy thereby.

Such chainless type power transmission device with advanced structure became easy in the assembly and disassembly thereof comparatively with the conventional one, however, there is still an inconvenience that numerous bolts and nuts used to fasten the housings and the frame must be loosened one by one when separating, and must be fastened one by one when assembling.

Therefore, this device was more developed by a hard work and test of this inventor, to gain an inventive power transmission device of a chainless type bicycle more easy in its assembly and disassembly therewith/from, to be described in the following.

DISCLOSURE OF THE INVENTION Accordingly, the present invention is directed to a power

transmission device of a chainless type bicycle that substantially obviate one or more of the limitations and disadvantages of the related art.

A primary object of the present invention is to provide a power transmission device of a chainless type bicycle easy in its assembly and disassembly with/from a frame.

To achieve these and other advantages, and in accordance with the purpose of the present invention, in a bicycle to transfer power of a pedal set in a head of a frame to a back wheel, the power transmission device of the chainless type bicycle comprises a first housing having a loosing preventing nut 26 screw-combined with an end portion of an inner circumference face thereof, an extension part inserted into the head of the frame, and a ring nut fastened to the loosing preventing nut projected from one side of the head; a pedal axis which is inserted into one side of the first housing through an interposition of a bearing and whose one end is supported by a first housing cover screw-combined with the first housing; a first bevel gear installed in the first housing, for changing a rotating force of the pedal axis to a right angle direction; a driving axis interlocked with the first bevel gear, for transferring power thereof to the back wheel; an axis cover wrapping around an outer face of the driving axis; a second bevel gear for changing a rotating force of the driving axis to the right angle direction and transferring it to the back wheel; a second housing which wraps around the second bevel gear, is fixed to the frame and has a cut section based on a shape opened in the back side, the cut section having a formation of a fixing flute into which a hub axis of the back wheel is inserted; and a second

housing cover which covers the cut section of the second housing and whose one side is inserted in the hub axis then fixed by a fixing nut.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and features of the instant invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which: Fig. 1 is a side view of a bicycle in which a power transmission device of a chainless type bicycle is installed, in accordance with the present invention; Fig. 2 depicts a disassembly perspective view showing the construction for a power transmission device of a chainless type bicycle in the present invention; and Fig. 3 illustrates a longitudinally sectional view showing a combination state of Fig. 2 in the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawing.

In accordance with the present invention, Fig. 1 is a side view of a bicycle having a power transmission device of a chainless type bicycle installed therein, Fig. 2 depicts a perspective view showing the construction for the power transmission device of the chainless type bicycle, and Fig. 3

is a sectional view showing a combination state of Fig. 2. As shown in Fig. 1, a bicycle roughly provides an inverted triangle frame 1. In front and back sides of this frame 1, a front fork 3 and a back fork 5 are formed respectively, and in the front fork 3 and the back fork 5, a front wheel 7 as a steering wheel and a back wheel 8 as a driving wheel are individually set so as to be rotatable. In a lower part of the frame 1, a pedal 9 and a power transmission device 10 for transferring power of the pedal 9 to the back wheel are installed.

As shown in Fig. 2, the power transmission device 10 is largely composed of a pedal axis 30 rotated by the pedal 9, a first bevel gear 40 for changing a rotating force of the pedal axis 30 to a right angle direction, a driving axis 50 for transferring the power of the first bevel gear 40 till the back wheel, a second bevel gear 60 for changing the rotating force of the driving axis 50 to the right angle direction and transferring it to the back wheel, and housings which wrap around the pedal axis 30, the first bevel gear 40, the driving axis 50 and the second bevel gear 60, wherein the housing fixes them to the frame 1 of the bicycle.

Describing in detail, the power transmission device 10 provides a first housing 20. The first housing 20 fixes the pedal axis 30 to the frame 1 so as to be rotatable and wraps around the first bevel gear 40 for its protection, and also has an operational space 22 formed in the inside thereof.

In its one side, an extension part 23 inserted into a head la of the frame 1 is formed, and in its another side, an installment hole 24 is formed in a roughly right angle against the operational space 22. A female screw part 25

is further formed on an inner face girth of the extension part 23.

Such first housing 20 is set so that the extension part 23 thereof penetrates through the head la of the frame 1, and in another side of the head la a loosing preventing nut 25 is screw-combined with the female screw part 25 of the extension part 23. A ring nut 27 is screw-combined with an external face of the loosing preventing nut 26. As shown in Fig. 3, this ring nut 27 is supported by a side face of the head la of the frame 1 and is simultaneously fastened to the loosing preventing nut 26. In other words, the more the ring nut 27 is tightened, the more the ring nut 27 pulls the first housing 20 towards an inner side of the head la. Therefore, the first housing 20 is closely to the frame 1.

In the first housing 20, the pedal axis 30 is set so as to be rotatable.

This pedal axis 30 is rotated by the pedal 9 and is thus inserted into the first housing by interposing a bearing 32 in one side of the first housing 20 so that an end part of the pedal axis 30 is projected to an outer side of the head la. In an opened one side of the first housing 20 having an insertion of the pedal axis 30, a first housing cover 28 for preventing the pedal axis 30 from being escaped and for supporting the pedal axis 30 is screw-combined therewith through an interposition of the bearing 32. In such state, the first housing 20 is fixed to the head la of the frame 1 through the loosing preventing nut 26 and the ring nut 27, and the pedal axis 30 is fixed to the first housing 20 by the first housing cover 28, thereby the pedal axis 30 can be rotatably fixed within the first housing 20 without any other motion.

Like this, in comparison with a conventional technique in which a

plural number of bolts and nuts should be loosened one by one, the inventive first housing 20 provides a convenience to easily execute a repair and examination thereof since the pedal axis 30 can be simply separated from the frame 1 just by separating the first housing cover 28 from the first housing 20 then disassembling only the ring nut 27 from the loosing preventing nut 26.

While, a driving axis 50 for transferring a rotating force of the pedal axis 30 to the back wheel is installed so as to be rotatable in the first housing 20. That is, a connection aperture 29 having a penetration hole 29a is screw-combined with the installment hole 24 of the first housing 20, and an axis cover 52 of a hollow hole based on a given length is screw-combined with the penetration hole 29a of the connection aperture 29. In the inside of the axis cover 52, the driving axis 50 is set along the axis cover 52. Herewith, the connection aperture is provided to connect the axis cover 52 to the first housing 20, and the axis cover 52 is constructed so as to wrap around an external face of the driving axis 50, to thus protect the driving axis 50 from an impact of the outside. The axis cover 52 must be formed, more largely than a diameter of the driving axis 50 so that a rotation of the driving axis 50 is not influenced.

In such construction, that is, the driving axis 50 is disposed inside the axis cover 52 and under this state, the driving axis 50 is also set in the first housing 20.

With reference to Fig. 3, the driving axis 50 piercing through the connection aperture 29 and installed in the first housing 20 is formed so that

one end thereof is placed in a roughly right angle against the pedal axis 30, and the first bevel gear 40 for transferring the rotating force of the pedal axis 30 to the driving axis 50 in a right angle direction is set in the pedal axis 30 and the driving axis 50.

In other words, onto an outer circumference of the pedal axis, a driving gear 42 of the first bevel gear 40 rotating equally to the pedal axis 30 is fixed, and in one end of the driving axis 50 disposed in the right angle against the pedal axis 30, a driven gear 44 tooth-combined with the driving gear 42 is fixed thereto. At this time, a bearing 46 is interposed in an outer face of the driven gear 44 connected to one end of the driving axis 50, to smooth a rotation of the driving axis 50.

Therefore, the rotating force of the pedal axis 30 rotated by the pedal 9 is transferred to the driving gear 42, and the rotating force transferred to the driving gear 42 is changed to a right angle direction by the driven gear 44 tooth-combined with the driving gear 42, then is transferred to the driving axis 50.

Meantime, in another side of the driving axis 50 disposed lengthily towards the back wheel 8 under a state of its installment in the axis cover 52, the second bevel gear 60 for also direction-changing the rotating force of the driving axis 50 and transferring it to the back wheel 8 as the driving wheel is set. This second bevel gear 60 is fixed to the back fork 5 of the frame 1 under its installing state in the inside of a specific second housing 70.

Describing it, the second housing 70 includes a first space part 72

and a second space part 73 which are connected through each other as shown in Fig. 3. In the first space part 72 and the second space part 73, the driving gear 62 and the driven gear 64 of the second bevel gear 60 are installed, and in its one side a cut section 70a is formed. This cut section 70a makes one side of the first space part 72 opened, to thereby provide an easy assembly and disassembly of a hub axis 8b of the back wheel 8 with/from the second housing. One side of the cut section 70a has a formation of a fixing flute 72a having a given depth, and the hub axis 8b of the back wheel 8 is inserted into this fixing flute 72a then fixed thereto.

Meantime, the hub axis 8b of the back wheel 8 is inserted into the second housing 70, traversing the first space part 72, and is then inserted in the fixing flute 72a, and in the cut section 70a opened from the first space part 72, a second housing cover 75 is set. This second housing cover 75 seals up the first space part 72 and simultaneously fixes the hub axis 8b to the second housing 70.

That is to say, the second housing cover 75 is matched to the cut section 70a of the first space part 72 to seal up the first space part 72, and in one side of the second housing cover 75, an extension plate 75a for covering the fixing flute 72a of the second housing 70 is formed. This extension plate 75a is provided with a fastening hole 75b corresponding to the fixing flute 72a of the second housing 70, and the hub axis 8b passed through the fixing flute 72a is penetrated through this fastening hole 75b.

Also, a fixing nut 76 is fastened to the hub axis 8b penetrated through the fastening hole 75b and projected to one side thereof.

Thus, the hub axis 8b passes through the fixing flute 72a of the second housing 70 and the fastening hole 75b of the second housing cover 75, then an end of the hub axis 8b is fastened by the fixing nut 76 therein, whereby the back wheel 8 and the second housing 70 are assembled closely each other. In addition, when loosening only the fixing nut 76 fastened to one end of the hub axis 8b, the hub axis 8b is escaped from the fixing flute 72a of the second housing 70, simultaneously, is separated from the second housing through the cut section 70a. According to that, the back wheel 8 and the power transmission device 10 can get its separation and assembly easily.

A fastening plate 70b is also formed in an upper part direction from one side of the fastening plate 70b, wherein the fastening plate 70b is fastened to the back fork 5 of the frame 1 through a use of a bolt. Namely, the hub 8a of the back wheel 8 and the second housing 70 are assembled with each other, and under this state, the fastening plate 70b is fixed to the back fork 5, thereby the back wheel 8, the second housing 70 and the frame 1 can be assembled closely one another.

While, such second housing 70 described above is connected to the driving axis 50, and the second bevel gear 60 to change the rotating force of the driving axis 50 to a right angle direction is installed inside the second housing 70.

Namely, the second space part 73 of the second housing 70 has an installment of a connection aperture 77 having a penetration hole 77a, and the axis cover 52 of a hollow state is screw-combined with the penetration

hole 77a of the connection aperture 77. At this time, the driving axis 50 set in the inside of the axis cover 52 naturally passes through the connection aperture 77 and is disposed in the second space part 73 of the second housing 70, and herewith, a bearing 54 is interposed between the driving axis 50 and the connection aperture 77 to smooth a rotation of the driving axis 50.

As shown in Figs. 2 and 3, further, an extension axis 8c is formed, extended from one side of the hub 8a of the back wheel 8, wherein the extension axis 8c is rotated in one body with the hub 8a and is disposed in the first space part 72 of the second housing 70 as shown in Fig. 3. It is noted for reference that the extension axis 8c is constructed separately from the hub axis 8b and the hub 8a is installed so as to be rotatable through an interposition of a bearing.

Also, one end of the driving axis 50 installed in the second space part 73 of the second housing 70 roughly forms a right angle state against the extension axis 8c of the hub 8a disposed in the first space part 72. In end parts of the extension axis 8c and the driving axis 50, it is set the second bevel gear 60 to change the rotating force of the driving axis 50 to a right angle direction and transfer it to the hub 8a.

Describing in detail, the driving gear 62 of the second bevel gear 60 rotating equally to the driving axis 50 is fixed onto an outer circumference of the driving axis 50 disposed in the second space part 73 of the second housing 70, and the driven gear 64 tooth-combined with the driving gear 62 is fixed to the extension axis 8c of the hub 8a disposed in a right angle

against the driving axis 50. Thus the driving axis 50 which received the rotating force of the pedal axis 30, transfers the rotating force to the driving gear 62, and the rotating force transferred to the driving gear 62 is directionally changed to a right angle direction by the driven gear 64 tooth-combined with the driving gear 62 then is transferred to the hub 8a of the back wheel 8.

While, in such construction the rotation force of the pedal 9 is directionally changed, passing through the pedal axis 30 and the first bevel gear 40, then is transferred to the driving axis 50. The rotating force transferred to the driving axis 50 is also changed in a power direction, passing through the second bevel gear 60, then is transferred to the hub 8a.

In addition, the power transmission device 10 is constructed so as to be simply separated from the frame 1, that is, under a state that the power transmission device 10 is fixed to the frame 1, the first housing 20 can be easily disassembled from the frame 1, only if the ring nut 27 fastened to the loosing preventing nut 26 and provided to be supported by the head la of the frame 1 is separated therefrom. Further, only if the fixing nut 76 fastened to one end of the hub axis 8b and a bolt of the fastening plate 76b are loosened, the second housing 70 can be also separated from the back fork 5 of the frame 1. Accordingly, the power transmission device 10 is easily separated from the frame 1 just by a simple manipulation, which makes several kinds of abnormalities occurring in the power transmission device 10 to be simply checked and repaired.

Meantime, such power transmission device 10 disassembled can be

again assembled by a reverse order against its separation.

Although the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. It can be, for example, changeable a shape and structure of the respective constructive elements presented in the preferred embodiment of the present invention through other embodiments of the invention.

INDUSTRIAL APPLICABILITY As afore-mentioned, in accordance with the present invention, not only the power transmission device of the chainless type bicycle perfectly transfers a driving force generated in a pedal till a back wheel, but also its separation and assembly are easily gotten by the construction thereof, and it has an additional advantage of executing a repair and examination simply.