WO2006049366A1

WO2006049366A1 - Chainless power transmission

Info

Publication number: WO2006049366A1
Application number: PCT/KR2004/003210
Authority: WO
Inventors: Tae-Ho Maeng
Original assignee: Tae-Ho Maeng
Priority date: 2004-11-08
Filing date: 2004-12-08
Publication date: 2006-05-11

Abstract

A chainless transmission of the present invention comprises a roller gear including roller teeth, a disk having a plurality of roller-placing recesses for disposing the roller teeth on an outer periphery thereof, a shaft-coupling end member having a guide groove for coupling a shaft at the center of a stub extending by a predetermined length from the center of a lower surface of the disk, and a fixing means for rotatably fixing one end of each of the roller teeth to the disk; a crown gear having convex and concave surfaces that are formed through successive repetition of gear teeth and tooth indents to be engaged with the roller teeth of the roller gear and are formed as round surfaces; and a shaft device including a joint guide portion defining a groove with a certain depth and at least one chamfered section at the center of the shaft-coupling end member, a joint portion that is in the form of a spherical body inserted into the joint guide portion to restrictedly play in vertical and lateral directions and in an axial direction and has at least one chamfered section formed on an outer surface of the spherical body for achieving restricted rotation of the spherical body within the joint guide portion, a shaft with the joint portions formed integrally at both ends thereof, a ball bearing inserted into the joint guide portion to be in rolling contact with a front end of the joint portion of the shaft, and an elastic member inserted into the joint guide portion to elastically support and urge the ball bearing in one direction.

Description

CHAINLESS POWER TRANSMISSION

TECHNICAL FIELD The present invention relates to a chainless power transmission.

BACKGROUND ART

Fig. 1 is a perspective view schematically showing a configuration of a conventional chainless power transmission, and Fig. 2 is a plan view schematically showing an operating state of the conventional chainless power transmission.

A shown in the figures, the conventional power transmission mainly comprises a crown gear 10, a roller gear 20, and a shaft 30.

The crown gear 10 is constructed by forming a plurality of gear teeth 12 along an outer periphery of a disk 11 and tooth indents 13 with a predetermined curvature between adj acent gear teeth 12.

Roller teeth 25 which are engaged vertically with the gear teeth 12 of the crown gear 10 are arranged on the roller gear 20. Shaft pins 26 are passed through axial centers of the roller teeth 25 and upper and lower ends of each of the shaft pins are fixed to disks 21 so that the roller teeth can run idle. The conventional power transmission constructed as above is used in a chainless bicycle and the like. Pedals of the bicycle are coupled to the crown gear 10 to transmit power to the crown gear, so that the power is then transmitted to the roller gear 20 engaged with the crown gear 10.

The roller gear 20 is connected to one end of an additional shaft 30 to transmit the power to a rear axle 50.

At this time, an additional roller gear 20' coupled to the other end of the shaft 30 drives an additional crown gear 10' fitted around the rear axle 50 so that the power can be transmitted thereto.

Although not shown in the figures, the crown gear 10 and the roller gear 20 are fixed to a main body of the bicycle via a separate gearbox.

However, in the prior art descried above, there is a disadvantage in that the roller 20 and the shaft 30 play toward or away from a central portion of the crown gear 10 due to vibration generated in and an impact applied to the bicycle during the process of transmitting the power, as shown in Fig. 2.

Further, there is a problem in that a portion of any one of the disks 21 of the roller gear 20 engaged with the gear teeth 12 of the crown gear 10 interferes with the crown gear 10.

In addition, in the prior art, the roller gear 20 engaged with the crown gear 10 may play vertically and laterally due to vibration generated in and an impact applied to the bicycle. At this time, there is a problem in that since the roller teeth 25 engaged with the teeth recesses 13 are driven while playing vertically and laterally, outer sectional surfaces of the gear teeth 12 and the tooth indents 13 are rubbed against outer peripheral surfaces of the roller teeth 25, so that the two members are worn away or damaged.

These problems produce great loss of rotational power and frequently cause failures, resulting in degradation of the reliability of the product. Moreover, in the prior art, there is a problem in that a slip is produced during the process of transmitting power through the engagement between the gear teeth 12 of the crown gear 10 and the roller teeth 25 of the roller gear 20.

Furthermore, in the prior art, there is a problem in that since the roller teeth 25 of the roller gear 20 and the shaft pins 26 are manufactured separately from each other, the roller teeth 25 are distorted or the shaft pins 26 are bent due to pressure produced when the roller gear 20 is engaged with the crown gear 10, resulting in degradation of the reliability of the product.

Further, in the prior art, there is a problem in that once an impact is applied to the bicycle, such as by collision of a wheel of the bicycle against a projection on a road when a user rides the bicycle, the rear axle 50 and the shaft of the pedal 10 are instantaneously distorted.

Due to these problems, an impact is concentrated on a connected portion of the shaft 30 and the roller gear 20, or on engaged portions of the roller gear 20 and the crown gear 10. If such an impact is applied repeatedly and successively or an impact exceeding an allowable load is applied, the connected portion or the engaged portions are damaged momentarily. Consequently, in the prior art, there are problems in that the reliability of the product is deteriorated and consumers' inconvenience such as occurrence of repair expenses is caused. Therefore, there is a need for technical improvement in the conventional chainless power transmission.

DISCLOSURE OF INVENTION

TECHNICAL PROBLEM

An object of the present invention for solving the aforementioned problems is to minimize loss of power by preventing a roller gear from being rubbed against an inner surface of a crown gear when the roller gear engaged with the crown gear plays in an axial direction.

Another object of the present invention is to enable roller teeth of the roller gear to move along round surfaces of gear teeth of the crown gear without friction even when vertical and lateral distortion is caused in a state where the crown gear and the roller gear are engaged with each other.

A further object of the present invention is to construct a structure in which integral roller teeth are used in the roller gear and an upper disk of the roller gear can be detachably assembled to assembly/replace the roller teeth. A still further object of the present invention is to minimize loss of power by minimizing a slip between the gear teeth and the roller teeth.

A still further object of the present invention is to enable transmission of power by coupling a shaft to one side of the roller gear in a state where the shaft can play in vertical and lateral directions for the purpose of shock absorption.

TECHNICAL SOLUTION

According to the present invention for achieving the objects, there is provide a chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein the roller gear comprises roller teeth, a disk having a plurality of roller-placing recesses for disposing the roller teeth on an outer periphery thereof, a shaft-coupling end member having a guide groove for coupling a shaft at the center of a stub extending by a predetermined length from the center of a lower surface of the disk, and a fixing means for rotatably fixing one end of each of the roller teeth to the disk.

According to the present invention for achieving the objects, there is provide a chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein the crown gear has convex and concave surfaces that are formed through successive repetition of the gear teeth and the tooth indents and are formed as round surfaces.

According to the present invention for achieving the objects, there is provide a chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein the shaft device comprises a joint guide portion defining a groove with a certain depth and at least one chamfered section at the center of a shaft-coupling end member extending by a predetermined length from the center of a lower surface of the disk forming the roller gear thereon, a joint portion that is in the form of a spherical body inserted into the joint guide portion to restrictedly play in vertical and lateral directions and in an axial direction and has at least one chamfered section formed on an outer surface of the spherical body for achieving restricted rotation of the spherical body within the joint guide portion, a shaft with the joint portions formed integrally at both ends thereof, a ball bearing inserted into the joint guide portion to be in rolling contact with a front end of the joint portion of the shaft, and an elastic member inserted into the joint guide portion to elastically support and urge the ball bearing in one direction.

According to the present invention for achieving the objects, there is provide a chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein the roller gear comprises a lower disk with a plurality of roller-placing recesses on an outer periphery thereof, a shaft-coupling end member formed with a guide groove for use in coupling a shaft at the center of a stub extending by a certain length from the center of a lower surface of the lower disk, a disk- coupling end member with a coupling guide portion formed at the center of a stub extending by a certain height from the center of an upper surface of the lower disk such that a separate fastening member is inserted by a proper depth into and fastened to the coupling guide portion, an upper disk that has a protrusion portion formed at the center thereof for matching with the disk-coupling end member and also has a plurality of roller- placing recesses formed on an outer periphery thereof, and roller teeth each of which has a cylindrical body and upper and lower shaft projections formed integrally at the centers of upper and lower end surfaces of the cylindrical body to be coupled to the respective roller-placing recesses and of the upper and lower disks.

According to the present invention for achieving the objects, there is provide a chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein the crown gear has a slip-preventing portion expanding with a predetermined curvature at a distal end of each of the gear teeth. According to the present invention for achieving the objects, there is provide a chainless transmission, comprising a roller gear including roller teeth, a disk having a plurality of roller-placing recesses for disposing the roller teeth on an outer periphery thereof, a shaft-coupling end member having a guide groove for coupling a shaft at the center of a stub extending by a predetermined length from the center of a lower surface of the disk, and a fixing means for rotatably fixing one end of each of the roller teeth to the disk; a crown gear having convex and concave surfaces that are formed through successive repetition of gear teeth and tooth indents to be engaged with the roller teeth of the roller gear and are formed as round surfaces; and a shaft device including a joint guide portion defining a groove with a certain depth and at least one chamfered section at the center of the shaft-coupling end member, a joint portion that is in the form of a spherical body inserted into the joint guide portion to restrictedly play in vertical and lateral directions and in an axial direction and has at least one chamfered section formed on an outer surface of the spherical body for achieving restricted rotation of the spherical body within the joint guide portion, a shaft with the joint portions formed integrally at both ends thereof, a ball bearing inserted into the joint guide portion to be in rolling contact with a front end of the joint portion of the shaft, and an elastic member inserted into the joint guide portion to elastically support and urge the ball bearing in one direction.

According to the present invention for achieving the objects, there is provide a chainless transmission, comprising a roller gear including a lower disk with a plurality of roller-placing recesses on an outer periphery thereof, a shaft-coupling end member formed with a guide groove for use in coupling a shaft at the center of a stub extending by a certain length from the center of a lower surface of the lower disk, a disk-coupling end member with a coupling guide portion formed at the center of a stub extending by a certain height from the center of an upper surface of the lower disk such that a separate fastening member is inserted by a proper depth into and fastened to the coupling guide portion, an upper disk that has a protrusion portion formed at the center thereof for matching with the disk-coupling end member and also has a plurality of roller-placing recesses formed on an outer periphery thereof, and roller teeth each of which has a cylindrical body and upper and lower shaft projections formed integrally at the centers of upper and lower end surfaces of the cylindrical body to be coupled to the respective roller-placing recesses and of the upper and lower disks; a crown gear having a slip- preventing portion expanding with a predetermined curvature at a distal end of each of the gear teeth engaged with the roller teeth; and a shaft device including a joint guide portion defining a groove with a certain depth and at least one chamfered section at the center of the shaft-coupling end member, a joint portion that is in the form of a spherical body inserted into the joint guide portion to restrictedly play in vertical and lateral directions and in an axial direction and has at least one chamfered section formed on an outer surface of the spherical body for achieving restricted rotation of the spherical body within the joint guide portion, a shaft with the joint portions formed integrally at both ends thereof, a ball bearing inserted into the joint guide portion to be in rolling contact with a front end of the joint portion of the shaft, and an elastic member inserted into the joint guide portion to elastically support and urge the ball bearing in one direction.

ADVANTAGEOUS EFFECTS

According to the prevent invention, there are the following advantages: First, the present invention has an advantage in that loss of power is minimized by preventing the roller gear from being rubbed against an inner surface of the crown gear when the roller gear plays in an axial direction in a state where the roller gear is engaged with the crown gear.

Second, the present invention has an advantage in that the roller teeth can be moved along round surfaces of the gear teeth without friction even when vertical and lateral distortion is caused in a state where the crown gear and roller gear are engaged with each other, thereby preventing damage to the roller teeth and the gear teeth and maximizing the efficiency of transmission of power.

Third, the present invention has an advantage in that it is possible to construct a structure in which integral roller teeth are used in the roller gear and the upper disk of the roller gear can be detachably assembled to assembly/replace the roller teeth, thereby facilitating operations for assembly and replacement of the roller teeth.

Fourth, the present invention has an advantage in that a slip-preventing portion, which expands with a proper curvature, is formed at a distal end of each of the gear teeth, thereby minimizing a slip between the gear teeth and the roller teeth upon transmission of power and improving the efficiency of transmission of power. Fifth, the present invention has an advantage in that power can be transmitted by coupling the shaft to one side of the roller gear in a state where the shaft can play in vertical and lateral directions for the purpose of shock absorption, thereby improving the reliability of the product.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view schematically showing a configuration of a conventional chainless power transmission.

Fig. 2 is a plan view schematically showing an operating state of the conventional chainless power transmission.

Fig. 3 is an exploded perspective view showing a configuration of a power transmission according to a first embodiment of the present invention.

Fig. 4 is a plan view showing a state where a roller gear engaged with a crown gear in the first embodiment of the present invention plays in an axial direction. Fig. 5 is a partial enlarged perspective view showing a state where roller teeth of the roller gear engaged with gear teeth of the crown gear in the first embodiment of the present invention play in vertical and lateral directions.

Fig. 6 is an exploded perspective view showing an embodiment of a shaft device of the power transmission according to the present invention. Fig. 7 is a sectional view showing an assembled state of the shaft device of Fig. 6.

Figs. 8 to 10 are schematic perspective views showing embodiments of a power transmitting member that can be coupled to the shaft device of Fig. 6.

Fig. 1 1 is an exploded perspective view showing a configuration of a power transmission according to a second embodiment of the present invention. Fig. 12 is an exploded perspective view specifically showing a configuration of a roller gear in the second embodiment of the present invention.

Fig. 13 is a partially sectional view showing a coupled state of components of the power transmission according to the second embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 3 is an exploded perspective view showing a configuration of a power transmission according to a first embodiment of the present invention, Fig. 4 is a plan view showing a state where a roller gear engaged with a crown gear in the first embodiment of the present invention plays in an axial direction, and Fig. 5 is a partial enlarged perspective view showing a state where roller teeth of the roller gear engaged with gear teeth of the crown gear in the first embodiment of the present invention play in vertical and lateral directions.

As shown in these figures, a chainless power transmission according to the first embodiment of the present invention mainly comprises a crown gear 100, a roller gear 200 and a shaft device 300.

The crown gear 100 comprises a hollow tube 140 formed at the center of a disk 110 such that a shaft 270 for use in transmitting power is coupled thereto, a plurality of gear teeth 120 along an outer periphery of the disk, and tooth indents 130 with a predetermined curvature between adjacent gear teeth 120.

At this time, the crown gear 100 has convex and concave surfaces formed through successive repetition of the gear teeth 120 and the tooth indents 130. The convex and concave surfaces are formed as round surfaces 150 as shown in Fig. 5. Once the round surfaces 150 are formed as such, it is possible to prevent in advance a problem of the occurrence of friction between roller teeth 230 of the roller gear 200 and the crown gear 100 or a problem of abrasion of contact surfaces even though the roller teeth 230 of the roller gear 200 engaged with the gear teeth 120 and tooth indents 130 of the crown gear 100 play in vertical and lateral directions.

The roller gear 200 comprises the roller teeth 230, a disk 210 with a plurality of roller-placing recesses 211 for arrangement of the roller teeth 230 on an outer periphery thereof, a shaft-coupling end member 220 formed with a guide groove 221 for use in coupling the shaft 270 at the center of a stub extending by a certain length from the center of a lower surface of the disk 210, and fixing means 240 for rotatably fixing one ends of the roller teeth 230 to the disk 210. At this time, upon assembly of the roller teeth 230, one side of each of the roller teeth 230 is fixed to each of the plurality of roller-placing recesses 211 formed on the circumference of the disk 210 by means of the separate fixing means 240.

As for the fixing means 240, it is possible to use a shaft pin that has one end defining a step for preventing the roller teeth 230 from coming out and the other end inserted into each of the roller-placing recesses 21 1 of the disk 210. Further, the roller teeth 230 may be fixedly coupled directly to the roller-placing recesses 211 without using the separate fixing means 240.

With the fixation of only one side of each of the roller teeth 230 to the disk 210 of the roller gear 200 as described above, the roller gear can be prevented from being rubbed against the inner surface of the crown gear 100 even though the roller gear 200 plays toward the shaft of the crown gear 100 as shown in Fig. 4.

The shaft device 300 comprises a joint guide portion 330 defining a groove with a certain depth and at least one chamfered section 331 at the center of the shaft-coupling end member 220 of the roller gear 220; a joint portion 340 that is in the form of a spherical body 341 inserted into the joint guide portion 330 to restrictedly play in the vertical and lateral directions and in an axial direction and has at least one chamfered section 343 formed on an outer surface of the spherical body 341 for achieving restricted rotation of the spherical body within the joint guide portion 330; a shaft 350 with the joint portions 340 formed integrally at both ends thereof; a ball bearing 360 inserted into the joint guide portion 330 to be in rolling contact with a front end of the joint portion 340 of the shaft 350; and an elastic member 370 inserted into the joint guide portion 330 to elastically support and urge the ball bearing 360 in one direction.

Fig. 6 is an exploded perspective view showing an embodiment of the shaft device of the power transmission according to the present invention, and Fig. 7 is a sectional view showing an assembled state of the shaft device of Fig. 6. As shown in these figures, in the shaft device 300, a shaft-coupling end member

320 used for coupling of the shaft 350 is formed at one side of a separate disk 310, and an appropriate number of fastening portions 311 are formed on a periphery of the shaft- coupling end member 320, so that various types of power transmission members can be connected to the shaft device. Further, it is preferred that the joint guide portion 330 be formed as a hexagonal recess. Moreover, the joint portion 340 inserted into and coupled to the joint guide portion 330 has six chamfered portions 343 formed on the outer surface of the spherical body 341.

Figs. 8 to 10 are schematic perspective views showing embodiments of the power transmitting member that can be coupled to the shaft device of Fig. 6. As for the power transmitting member 380 capable of being coupled to the shaft device according to the embodiment of the present invention, as shown in these figures, it is possible to use a roller gear with a plurality of roller teeth, a crown gear with gear teeth formed perpendicularly to a peripheral portion of one side surface thereof, or a general circular gear. It will be apparent that in addition to the aforementioned types of gears, a variety of power transmitting members such as a belt pulley or an internal gear used for achieving special purposes may also be used.

The operation of the chainless power transmission according to the first embodiment of the present invention constructed as above will be described below. First, rotational power is transmitted from the crown gear 100 that has the hollow tube 140 formed at the center of the disk 110. The hollow tube 140 is connected to a power source such as pedals of a bicycle.

As the crown gear 100 is rotated with appropriate power, the roller gear 200 engaged therewith is rotated. The rotational power transmitted to the roller gear 200 is transmitted to another power transmission member such as a rear axle of the bicycle via the shaft device 300 coupled to the shaft-coupling end member 220.

At this time, since the elastic member 370 and the ball bearing 360 are sequentially inserted into the joint guide portion 330 formed in the shaft-coupling end member 220, and the joint portion 340 formed integrally with the shaft 350 is then inserted into the joint guide portion, the power is transmitted while the joint portion is in rolling contact with the ball bearing 360 and performs variable movement corresponding to vertical or lateral rock transmitted through the shaft 350.

That is, when the shaft 350 rocks in an axial direction, the shaft can be moved in a proper displacement range by a restoring force of the elastic member 370. Further, the shaft can comply with the vertical or lateral rock due to the spherical shape of a certain section of the joint portion 340.

To this end, it is preferred that the inner diameter of the recess of the joint guide portion 330 be slightly larger than the distance between the opposite chamfered sections

343 of the joint portion 340. The rotational power transmitted to the shaft 350 as described above is transmitted to another power transmitting member through another joint portion 340 formed integrally with the other end of the shaft 350.

The transmission of power caused by the chainless power transmission according to the first embodiment of the present invention as described above may be performed in reverse order.

Fig. 1 1 is an exploded perspective view showing a configuration of a power transmission according to a second embodiment of the present invention, Fig. 12 is an exploded perspective view specifically showing a configuration of a roller gear in the second embodiment of the present invention, and Fig. 13 is a partially sectional view showing a coupled state of components of the power transmission according to the second embodiment of the present invention.

As shown in these figures, a chainless power transmission according to the second embodiment of the present invention comprises a crown gear 400, a roller gear

500 and a shaft device 300. The crown gear 400 comprises a hollow tube 440 formed at the center of a disk

410, a plurality of gear teeth 420 along an outer periphery of the disk, and tooth indents

430 with a predetermined curvature between adjacent gear teeth 420.

At this time, each of the gear teeth 420 has a slip-preventing portion 450 formed with a proper curvature such that its distal end expands in the form of a mushroom. To increase an outer contact area between the slip-preventing portion 450 and each of roller teeth 550 of the roller gear 500 guided into each of the tooth indents 430, the slip-preventing portion is designed such that its curvature matches with the outer diameter of each of the roller teeth 550, thereby minimizing a slip phenomenon upon transmission of power. As shown in the Fig. 12, the roller gear 500 integrally comprises a lower disk 510 with a plurality of roller-placing recesses 511 on an outer periphery thereof, a shaft- coupling end member 520 formed with a guide groove 521 for use in coupling a shaft 570 at the center of a stub extending by a certain length from the center of a lower surface of the lower disk 510, and a disk-coupling end member 530 with a coupling guide portion

531 formed at the center of a stub extending by a certain height from the center of an upper surface of the lower disk 510 such that a separate fastening member S is inserted by a proper depth into and fastened to the coupling guide portion.

Further, the roller gear 500 comprises an upper disk 540 that has a protrusion portion 543 formed at the center thereof for matching with the disk-coupling end member

530 and also has a plurality of roller-placing recesses 541 formed on an outer periphery thereof; and roller teeth 550 each of which has a cylindrical body 551 and upper and lower shaft projections 553 formed integrally at the centers of upper and lower end surfaces of the cylindrical body to be coupled to the respective roller-placing recesses 541 and 51 1 of the upper and lower disks 540 and 510.

As for the assembly order of the roller gear 500, the roller teeth 550 are aligned in such a manner that the lower shaft projections 553 of the roller teeth 550 are matched with the respective roller-placing recesses 51 1 of the lower disk 510, and then, the upper disk 540 is coupled to the disk-coupling end member 530.

At this time, the protrusion portion 543 of the upper disk 540 is inserted into and guided in the coupling guide portion 531 of the disk-coupling end member 530, and the fastening member S is passed through and fastened to fastening holes 545 and 533 formed in the protrusion portion 543 and the coupling guide portion 531, respectively.

A bolt or nut may be used as the fastening member S. It is preferred that the fastening member be inserted into the coupling guide portion 531 not to be exposed to the outside. Since the upper disk 540 can be assembled and disassembled in the roller gear in the second embodiment of the present invention, there is an advantage in that the integral roller teeth 550 can be easily assembled or replaced.

The shaft device 300 comprises a joint guide portion 330 defining a groove with a certain depth and at least one chamfered section 331 at the center of the shaft-coupling - end member 520 of the roller gear 500; a joint portion 340 that is in the form of a spherical body 341 inserted into the joint guide portion 330 to restrictedly play in the vertical and lateral directions and in an axial direction and has at least one chamfered section 343 formed on an outer surface of the spherical body 341 for achieving restricted rotation of the spherical body within the joint guide portion 330; a shaft 350 with the joint portions 340 formed integrally at both ends thereof; a ball bearing 360 inserted into the joint guide portion 330 to be in rolling contact with a front end of the joint portion 340 of the shaft 350; and an elastic member 370 inserted into the joint guide portion 330 to elastically support and urge the ball bearing 360 in one direction.

The operation of the present invention constructed as above will be described below. First, rotational power is transmitted from the crown gear 400 that has the hollow tube 440 formed at the center of the disk 410. The hollow tube 440 is connected to a power source such as pedals of a bicycle.

As the crown gear 400 is rotated with appropriate power, the roller gear 500 engaged therewith is rotated. At this time, the gear teeth 420 of the crown gear 400 come into rolling contact with the roller teeth 550 of the roller gear 500, thereby preventing abrasion due to friction. The slip-preventing portion 450 formed at the distal end of each of the gear teeth 420 increases the area of contact with the outer peripheries of the roller teeth 550 guided in the tooth indents 430, thereby minimizing a slip upon transmission of power. That is, it is possible to maximize engagement of the roller teeth 550 with the tooth indents 430 of the gear teeth 420.

The rotational power transmitted to the roller gear 500 is transmitted to another power transmission member such as a rear axle of the bicycle via the shaft device 300 coupled to the shaft-coupling end member 520. At this time, since the elastic member 370 and the ball bearing 360 are sequentially inserted into the joint guide portion 330 formed in the shaft-coupling end member 520, and the joint portion 340 formed integrally with the shaft 350 is then inserted into the joint guide portion, the power is transmitted while the joint portion is in rolling contact with the ball bearing 360 and performs variable movement corresponding to vertical or lateral rock transmitted through the shaft 350.

To this end, it is preferred that the inner diameter of the recess of the joint guide portion 330 be slightly larger than the distance between the opposite chamfered sections 343 of the joint portion 340.

The rotational power transmitted to the shaft 350 as described above is transmitted to another power transmitting member through another joint portion 340 formed integrally with the other end of the shaft 350. The transmission of power caused by the chainless power transmission according to the second embodiment of the present invention as described above may be performed in reverse order.

It will be understood from the description of the present invention constructed as above that those skilled in the art can make various modifications and changes without departing from the technical spirit of the present invention.

Therefore, the scope of the present invention is not limited to the detailed description of the present invention but should be construed as being defined by the appended claims.

INDUSTRIAL APPLICABILITY

When the present invention is applied to the industry, there are advantages in that loss of power is minimized by preventing a roller gear from being rubbed against an inner surface of a crown gear, and roller teeth of the roller gear are moved along round surfaces of gear teeth of the crown gear without friction to prevent damage to the roller teeth and the gear teeth and to maximize the efficiency of transmission of power. Further, there are advantages in that assembly and replacement of the roller teeth can be easily performed, and the efficiency of transmission of power is improved by minimizing a slip between the gear teeth and the roller teeth upon transmission of power due to the formation of a slip-preventing portion expanding with a certain curvature at a distal end of each of the gear teeth. Moreover, there is an advantage in that the reliability of the product can be improved since the transmission of power is achieved by coupling a shaft to one side of the roller gear in a state where the shaft can play in vertical and lateral directions as well as in an axial direction.

Claims

1. A chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein: the roller gear comprises: roller teeth; a disk having a plurality of roller-placing recesses for disposing the roller teeth on an outer periphery thereof; a shaft-coupling end member having a guide groove for coupling a shaft at the center of a stub extending by a predetermined length from the center of a lower surface of the disk; and a fixing means for rotatably fixing one end of each of the roller teeth to the disk.

2. A chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein: the crown gear has convex and concave surfaces formed through successive repetition of the gear teeth and the tooth indents, the convex and concave surfaces being formed as round surfaces.

3. A chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein: the shaft device comprises: a joint guide portion defining a groove with a certain depth and at least one chamfered section at the center of a shaft-coupling end member extending by a predetermined length from the center of a lower surface of the disk forming the roller gear thereon; a joint portion that is in the form of a spherical body inserted into the joint guide portion to restrictedly play in vertical and lateral directions and in an axial direction and has at least one chamfered section formed on an outer surface of the spherical body for achieving restricted rotation of the spherical body within the joint guide portion; a shaft with the joint portions formed integrally at both ends thereof; a ball bearing inserted into the joint guide portion to be in rolling contact with a front end of the joint portion of the shaft; and an elastic member inserted into the joint guide portion to elastically support and urge the ball bearing in one direction.

4. A chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein: the roller gear comprises: a lower disk with a plurality of roller-placing recesses on an outer periphery thereof; a shaft-coupling end member formed with a guide groove for use in coupling a shaft at the center of a stub extending by a certain length from the center of a lower surface of the lower disk; a disk-coupling end member with a coupling guide portion formed at the center of a stub extending by a certain height from the center of an upper surface of the lower disk such that a separate fastening member is inserted by a proper depth into and fastened to the coupling guide portion; an upper disk that has a protrusion portion formed at the center thereof for matching with the disk-coupling end member and also has a plurality of roller-placing recesses formed on an outer periphery thereof; and roller teeth each of which has a cylindrical body and upper and lower shaft projections formed integrally at the centers of upper and lower end surfaces of the cylindrical body to be coupled to the respective roller-placing recesses and of the upper and lower disks.

5. A chainless power transmission including a crown gear having a plurality of gear teeth formed on an outer periphery of a disk and a plurality of tooth indents with a predetermined curvature between adjacent gear teeth, a roller gear having a plurality of roller teeth vertically engaged with the gear teeth of the crown gear and a disk with the roller teeth fixedly assembled thereto, and a shaft device coupled to the disk of the roller gear to transmit power for a long distance, wherein: the crown gear has a slip-preventing portion expanding with a predetermined curvature at a distal end of each of the gear teeth.

6. A chainless transmission, comprising: a roller gear including roller teeth, a disk having a plurality of roller-placing recesses for disposing the roller teeth on an outer periphery thereof, a shaft-coupling end member having a guide groove for coupling a shaft at the center of a stub extending by a predetermined length from the center of a lower surface of the disk, and a fixing means for rotatably fixing one end of each of the roller teeth to the disk; a crown gear having convex and concave surfaces formed through successive repetition of gear teeth and tooth indents to be engaged with the roller teeth of the roller gear, the convex and concave surfaces being formed as round surfaces; and a shaft device including a joint guide portion defining a groove with a certain depth and at least one chamfered section at the center of the shaft-coupling end member, a joint portion that is in the form of a spherical body inserted into the joint guide portion to restrictedly play in vertical and lateral directions and in an axial direction and has at least one chamfered section formed on an outer surface of the spherical body for achieving restricted rotation of the spherical body within the joint guide portion, a shaft with the joint portions formed integrally at both ends thereof, a ball bearing inserted into the joint guide portion to be in rolling contact with a front end of the joint portion of the shaft, and an elastic member inserted into the joint guide portion to elastically support and urge the ball bearing in one direction.

7. A chainless transmission, comprising: a roller gear including a lower disk with a plurality of roller-placing recesses on an outer periphery thereof, a shaft-coupling end member formed with a guide groove for use in coupling a shaft at the center of a stub extending by a certain length from the center of a lower surface of the lower disk, a disk-coupling end member with a coupling guide portion formed at the center of a stub extending by a certain height from the center of an upper surface of the lower disk such that a separate fastening member is inserted by a proper depth into and fastened to the coupling guide portion, an upper disk that has a protrusion portion formed at the center thereof for matching with the disk-coupling end member and also has a plurality of roller-placing recesses formed on an outer periphery thereof, and roller teeth each of which has a cylindrical body and upper and lower shaft projections formed integrally at the centers of upper and lower end surfaces of the cylindrical body to be coupled to the respective roller-placing recesses and of the upper and lower disks; a crown gear having a slip-preventing portion expanding with a predetermined curvature at a distal end of each of the gear teeth engaged with the roller teeth; and a shaft device including a joint guide portion defining a groove with a certain depth and at least one chamfered section at the center of the shaft-coupling end member, a joint portion that is in the form of a spherical body inserted into the joint guide portion to restrictedly play in vertical and lateral directions and in an axial direction and has at least one chamfered section formed on an outer surface of the spherical body for achieving restricted rotation of the spherical body within the joint guide portion, a shaft with the joint portions formed integrally at both ends thereof, a ball bearing inserted into the joint guide portion to be in rolling contact with a front end of the joint portion of the shaft, and an elastic member inserted into the joint guide portion to elastically support and urge the ball bearing in one direction.

8. The chainless power transmission as claimed in any one of claims 3, 6 or 7, wherein the joint guide portion of the shaft device is formed as a hexagonal groove.

9. The chainless power transmission as claimed in any one of Claims 3, 6 or 7, wherein the joint portion of the shaft device has six chamfered surfaces formed on an outer surface of the spherical body.