Background Art In a conventional lever-type transmission, since a driver manually changes speed using a shift lever, the transmission mechanism does not operates smoothly. Further, since other necessary mechanisms such as a clutch are required, the structure of the transmission complicated and thus costs for manufacture thereof are high.

In addition to the above problems, since the velocity ratios are defined into several steps, transfer of rotational force is required to be temporariiy discontinued. Also, the complicated transmission means increases the defect rate.

To overcome the above disadvantages, an automatic clutchless transmission using a fluid has been developed. However, the automatic clutchless transmission has problems of its own. First, there is a great loss in the engine output while climbing elevated slopes. The clutch less transmission is large and heavy increasing the total weight of a vehicle adopting the same, which has an adverse effect on fuel efficiency. Also, the structure of the clutch less transmission is complicated and the parts thereof are expensive.

Disclosure of the Invention To solve the above problems, it is a first object of the present invention to provide a step less transmission in which a temporary separation

of an engine from a transmission for changing speed, is not required.

It is a second object of the present invention to provide a stepless transmission capable of changing speeds and/or the direction of rotation with an odd- or even- number of rotating balls linearly assembled in a cylinder and a frictional force between a driving plate and a driven plate.

It is a third object of the present invention to provide a step less transmission that is lightweight and has a simple structure so that a loss in an engine output can be prevented.

To achieve the above objects there is provided a step less transmission comprising a driving axis receiving a rotational force from an engine or a motor, a first speed-changing portion for changing the rotational velocity of a driving plate combined to said driving axis, and a second speed-changing portion for providing a driving power of various rotation ratios to a driven axis by combining the rotation speed transferred from the first speed-changing portion with the rotation speed transferred from the driving axis.

The first speed-changing portion comprises a driving plate having a groove of which an arc-shaped profile is formed on the inner surface of the driving plate around the driving axis, in the first and second preferred embodiments, and spline-coupled to a driving plate confining groove formed on an appropriate position of the driving axis, a driven plate having the same groove as that of the driving plate and disposed to face the inner surface of the driving plate, a cylinder installed between the driving plate and the driven plate, rotating balls assembled together to stay together and rotate with friction inside the cylinder and roll on the surface of the groove formed on the inner surfaces of the respective driving plate and the driven plate, a coupling ring adjusting means for changing the rotation velocity of the driving axis by controlling the inclination or position of the cylinder with respect to the driving axis, an elastic supporting means, installed between the driving plate and a first fixed plate, which is fixed to the driving axis between the engine and the driving plate, for elastically supporting the driving plate, and a second fixed plate fixed to a driven axis contacting the outer surface of the

driven plate by means of bearings interposed therebetween.

In a first preferred embodiment, the elastic supporting means is a leaf spring, having one end contacting fixed plate and the other end contacting the side surface of a supporting plate which will be described later, for elastically supporting the driving plate. Also, the supporting plate is disposed in a circular indentation formed on the outer surface of the driving plate.

Here, the surface of the supporting plate does not contact the surface of the indentation so that a chamber is formed therebetween. The chamber is sealed by a seal ring interposed between the outer circumferential surface of the supporting plate and the inner circumferential surface of the indentation. An inlet for injecting oil for generating a hydraulic pressure is formed at the supporting plate so that oil can be supplied to the inside of the chamber from the outside. Since a seal member acting as a check valve for allowing a flow of oil in one direction is provided at the iniet, oil for generating a hydraulic pressure can be supplied from the outside. The oil together with the leaf spring supports by pressing the driving plate in the chamber.

In the second preferred embodiment, a coil spring is used as the elastic supporting means.

Also, in the first preferred embodiment, the coupling ring adjusting means comprises a cylinder coupling ring, a coupling ring adjustment nut coupled to the outer circumference of the cylinder coupling ring, a coupling ring adjustment screw screw-coupled to the coupling ring adjustment nut, an outside gear coupled to the inner circumferential surface of the cylinder coupling ring, and an inside gear of a cylindrical shape having a geared portion formed on its outer circumferential surface, centered about the driving axis by being supported by bearings with respect to the outer circumferential surface of the driving axis to face the outside gear. The outside gear and the inside gear are separated to face each other by a cylinder interposed therebetween. The cylinder has a cylinder rotation gear and a circular gear on its outer circumferential surface so as to be engaged with the outside gear and the inside gear, respectively.

Also, the coupling ring adjusting means according to the second preferred embodiment comprises a cylinder coupling ring, a coupling ring adjustment nut coupled to the outer circumference of the cylinder coupling ring, a coupling ring adjustment screw screw-coupled to the coupling ring adjustment nut, a connection pin coupling piece having a slot and extending from the inner circumferential surface toward the driving axis, and a connection pin inserting into the slot of the connection pin coupling piece to be capable of moving. The connection pin connects the connection pin coupling piece and a cylinder guide member formed on the outer circumferential surface of the cylinder.

A second speed-changing portion according to the first preferred embodiment comprises a sun gear fixed to the driving axis, a ring gear coupled to the driven plate of the first speed-changing portion to thereby rotate at varying speeds, and planetary pinion and planetary carrier for connecting the sun gear and the ring gear.

A second speed-changing portion according to the second preferred embodiment comprises a planetary gear portion for converting the speed of the driven plate of the first speed-changing portion, and a differential gear box for combining the rotational speed of the driving axis.

Hereinafter, the present invention will be explained in detail with reference to the attached drawings.

Brief Description of the Drawings FIG. 1 is a sectional view illustrating the cylinder of the first speed- changing portion, in a decelerating state, in the stepless transmission according to the present invention; FIG. 2 is a sectional view illustrating the cylinder of the first speed- changing portion, in an accelerating state, in the stepless transmission according to the present invention; FIG. 3 is a sectional view illustrating the supporting means of the driven plate and the second speed-changing portion according to the first preferred embodiment of the present invention;

FIG. 4 is a sectional view illustrating the supporting means of the driven plate and the second speed-changing portion according to the second preferred embodiment of the present invention; FIG. 5 is a partial sectional view illustrating the stepless transmission according to the first embodiment of the present invention; FIG. 6 is a partial sectional view illustrating the step less transmission according to the second preferred embodiment of the present invention; FIG. 7 is a sectional view illustrating the stepless transmission according to the first embodiment in which the cylinder coupling ring and the cylinder are assembled; FIG. 8 is a sectional view taken along line VIII-VIII of FIG. 7; FIG. 9 is a view for explaining the state in which the cylinder pivot axis connecting the cylinder and the cylinder casing and the leaf spring shown in FIG. 7 are assembled; FIG. 10 is a perspective view illustrating the double-sided cross gear; FIGS. 11 and 12 are views for explaining the rotation of the cylinder shown in FIG. 7 when the driving plate and the driven plate are rotated; FIG. 13 is a sectional view for explaining the state in which the cylinder and the cylinder coupling ring for adjusting the step less speed- changing range in the stepless transmission according to the second preferred embodiment of the present invention are connected; FIG. 14 is a sectional view illustrating the connection pin shown in FIG. 13 which is coupled to the connection pin coupling piece; FIG. 15 is a sectional view illustrating the cylinder of the first speed- changing portion, in an accelerating state, in the stepless transmission according to the third preferred embodiment of the present invention; FIG. 16 is a sectional view illustrating the cylinder of the first speed- changing portion, in a decelerating state, in the stepless transmission according to the third preferred embodiment of the present invention; FIG. 17 is a partial sectional view illustrating the stepless transmission according to the third preferred embodiment of the present invention; FIG. 18 is a partial sectional view illustrating the cylinder of the first

speed-changing portion, in a decelerating state, in the step less transmission according to the fourth preferred embodiment of the present invention; and FIG. 19 is a partial sectional view illustrating the cylinder of the first speed-changing portion, in an accelerating state, in the step less transmission according to the fourth preferred embodiment of the present invention Best mode for carrying out the Invention FIGS. 1 and 2 show the cylinder 8 of the first speed-changing portion of the stepless transmission in a decelerating state and in an accelerating state, respectively, according to the first and second preferred embodiments of the present invention.

As shown in the drawing, when the rotational velocity of the driven plate 9 is low or decreasing, one of the rotating balls 7 in the cylinder 8 which contacts the driving plate 4 approaches the driving axis 1 along the arc-shaped surface of the inner surface of the driving plate 4. Contrarily, when the rotational velocity of the driven plate 9 is high or increasing, the rotating ball contacting the driving plate 4 is separated far from the driving axis 1 by the coupling ring adjusting means. The coupling ring adjusting means is operated by a manipulation of a user using a common controlling device. When the cylinder 8 is horizontally positioned by the coupling ring adjustment screw 12 (see FIGS. 5 and 6) operated by the controlling device, the cylinder 8 is disposed parallel to the driving axis 1. Thus, the rotational velocity of the driving plate 4 is transferred to the driven plate 9 at a ratio of about 1:1. As a result, in FIGS. 1 and 2, the distance (Ra/2 and Ray2) between the left rotating ball contacting the driving plate 4 by the coupling ring adjusting means and the driving axis 1 and the distance (Rb/2 and Rb'/2) between the right rotating ball contacting the driven plate 9 and the driving axis 1 vary. Accordingly, it can be seen that the rotational velocity of the driven plate 9 is changed. Thus, according to the present invention, there is little loss in the output of an engine compared to the conventional automatic transmission using the frictional force of a fluid.

The output of an engine transmitted to the driving axis 1 is transmitted

to the driving plate 4 rotating with the driving axis 1 and is further transmitted to the driven plate 9 via the rotating balls 7 contacting and pressing the inner surface of the driving plate 4. The radius (R2/2) of each arc formed on the opposite surfaces of the driving plate 4 and the driven plate 9 equals the sum of the radii (R1/2) of the rotating balls 7 in the cylinder 8.

The rotational speed V7 of the rotating balls 7 is V4 (rotational velocity <BR> <BR> <BR> <BR> of the driven plate) x (RaIR1 or Ra'/Rl ) and the rotational velocity V9 of the driven plate 9 is V7 (rotational velocity of the rotating balls) x (R1/Rb or R,/Rb'). Consequently, the rotational velocity of the driven plate 9 varies according to a change in the angle of disposition of the cylinder 8 with respect to the driving axis 1 as the cylinder 8 having the rotating balls 7 moves along the arc surface, and the value thereof can be calculated by V4 x (Ra/Rb or Ra'/Rb') which is expressed in Equation (1) V7 = V4 x (Ra/R1 or Ra' IRI) V9 = V7 x (R1/Rb or R1/Rb') . (1) Vg = V4 X (RalRb or Ra'lRb') FIG. 3 shows the supporting means of the driven plate 109 and the second speed-changing portion 120 according to the first preferred embodiment of the present invention. As shown in the drawing, the second speed-changing portion 120 includes a sun gear 123 fixed to the driving axis 1, a ring gear 121 coupled to the driven plate 109 of the first speed-changing portion 110 and rotating at varying rotational velocities, and a planetary pinion 122 and a planetary carrier 124 for connecting the sun gear 123 and the ring gear 121.

The driven gear 109 transmits a rotational force received via the rotating balls 7 in the cylinder 8 to the ring gear 121 of the second speed- changing portion 120 connected to the driven plate 109. Then, the driven gear 109 combines the rotational velocity of the ring gear 121 with the rotational velocity of the sun gear 123 coupled to the driving axis 1 to rotate the planetary carrier 124 supporting the planetary pinion 122. The number of rotations of the planetary carrier 124, Nc, can be calculated by Equation (2).

NC = (Ns Zs +NRZR)/(Zs+ZR) (2)<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> Here, N and 4 are the number of rotations and the number of gears of the sun gear 123, respectively, and NR and 4 are the number of rotations and the number of gears of the ring gear, respectively.

FIG. 4 shows the supporting means of the driven plate 9 and the second speed-changing portion 120 according to the second preferred embodiment of the present invention. Referring to FIG. 4, the second speed-changing portion 120 of the second preferred embodiment includes a planetary gear portion 130 for changing the speed of the driven plate 9 of the first speed-changing portion and a differential gear box for combining the rotational velocity of the driving axis 1.

The rotational force of the driven plate 9 rotated by the rotational force received via the rotating balls 7 is transmitted to the planetary gear portion 130 and rotates a casing 20 having a differential gear and confining a speed converting gear axis 26. Then, the driven plate 9 rotates the driven axis 24 having the driven gear 23 as the speed-changing gear 21 rotates by the difference between the number of rotations of the driving gear 22 coupled to the driving axis 1 and the number of rotations of the differential gear casing 20. Since the driven gear 23 rotates at a speed equivalent to a value determined by deducting the number of rotations of the driving gear 22 from twice the rotational velocity of the casing 20 (refer to Equation (3)), the driven gear 23 reversely rotates when the number of rotations of the driving gear 22 is twice the number of rotations of the casing 20. Thus, the driven axis 24 connected to the driven gear 23 can move a vehicle in a backward direction.

V23 = 2 V20- (3) FIG. 5 shows an assembled stepless transmission according to the first preferred embodiment of the present invention. As shown in the

drawing, the coupling ring adjusting means includes a cylinder coupling ring 111, a coupling ring adjustment nut 11 coupled to the outer circumference of the cylinder coupling ring 111, a coupling ring adjustment screw 12 screw- coupled to the coupling ring adjustment nut 11, an outside gear 200 coupled to the inner circumferential surface of the cylinder coupling ring 111, and an inside gear 113 of a cylindrical shape having a geared portion formed on its outer circumferential surface, centered about the driving axis 1 by being supported by bearings 17 with respect to the outer circumferential surface of the driving axis 1 to face the outside gear 200. The outside gear 200 and the inside gear 113 are separated to face each other by a cylinder 8 interposed therebetween. The cylinder 8 has a cylinder rotation gear 312 and a circular gear 113a on its outer circumferential surface so as to be engaged with the outside gear 200 and the inside gear 113, respectively.

When the coupling ring adjustment screw 12 is rotated by a common controller manipulated by a driver, the cylinder coupling ring 111 moves forward and backward in the longitudinal direction of the driving axis 1 as indicated by arrow "b". Accordingly, the outside gear 200 formed on the inner circumferential surface of the cylinder coupling ring 111 pivots a double-sided cross gear 309 engaged with the outside gear 200 in a direction indicated by arrow "a" as the outside gear moves. Thus, the rotation ratio of the driivng plate 304 and the driven plate 109 are changed by changing the inclination of the cylinder 8. That is, the inside gear 113 supported by the bearings 17 and encompassing the driving axis 1 and the outside gear 200 provided on the inner circumferential surface of the cylinder coupling ring 111 are respectivley engaged with the double-sided cross gear 309 and the circular gear 11 3a provided on the upper and lower portions of the cylinder 8, respectively. Thus, when the cylinder coupling ring 111 is moved by the rotation of the coupling ring adjustment screw 12 in the directions indicated by "b", the double-side cross gear 309 and the circular gear 11 3a engaged with the outside gear 200 and the inside gear 113, respectivley, pivot in the directions indicated by arrow "a" so that the inclination of the cylinder 8 varies. Therefore, the speed of the driven plate

109 with respect to that of the driving plate 304 can be adjusted.

Also, as the driven plate 109 rotates, the ring gear 121 coupled to the driven plate 109 rotates and the sun gear 123 coupled to the driving axis 1 rotates according to the rotation of the driving axis. As mentioned above, the planetary pinion 122 is installed between the ring gear 121 and the sun gear 123 and the axis of the planetary pinion 122 is coupled to the planetary carrier 124 capable of rotating. The planetary carrier 124 is connected to the driven axis 24. Thus, by appropriately combining the speeds of the sun gear 123 and the ring gear 121, varying rotational velocities of the driven axis 24 can be obtained.

FIG. 6 shows an assembled stepless transmission according to the second preferred embodiment of the present invention. The coupling ring adjusting means according to the second embodiment includes a cylinder coupling ring 5, a coupling ring adjustment nut 11 coupled to the outer circumference of the cylinder coupling ring 5, a coupling ring adjustment screw 12 scew-coupled to the coupling ring adjustment nut 11, a connection pin coupling piece 25 having a slot and extending from the inner circumferential surface toward the driving axis 1, and a connection pin 6 inserting in the slot of the connection pin coupling piece 25 to be capable of moving. The connection pin 6 connects the connection pin coupling piece 25 and a cylinder guide member 37 formed on the outer circumferential surface of the cylinder 8 and moves in the connection pin coupling piece 25.

When the coupling ring adjustment screw 12 is rotated by a common controller manipulated by a vehicle operator, the cylinder coupling ring 5 moves forward and backward in the longitudinal direction of the diriving axis 1. Accordingly, as the connection pin 6 being inserted into the slot of the connection pin coupling piece 25 extending toward the driving axis 1 moves in the longitudinal direction of the connection pin coupling piece 25, the ratio of the rotational velocities between the driving plate 4 and the driven plate 9 varies by changing the angle of disposition of cylinder 8. Since the cylinder 8 pivots in the directions indicated by arrows "c" as the cylinder coupling ring 5 moves forward or backward, the contact position of the

rotating balls 7 with respect to the arc inner surfaces of the driving plate 4 and the driven plate 9 changes, thereby changing the speed.

A planetary carrier fixing means 14 is for fixing the planetary carrier 13. Thus, when a vehicle operator operates an accelerator of a vehicle or a braking means, the planetary carrier fixing means 14 fixes the planetary carrier 13 by a well-known controller so that the planetary pinion 15 rotates to transmit a rotational force received from the driven plate 9 to a ring gear 19. When the vehicle operator wants to stop the vehicle temporarily without completely stopping the engine of the vehicle, i.e., in an idle state, the planetary carrier 13 rotates in a state in which the planetary carrier fixing means 14 is maintained being separated by a predetermined distance from the planetary carrier 13. Accordingly, the planetary pinion 15 rotate idly so that the rotational force of the driven plate 9 is not transmitted to the ring gear 19. Thus, there is no rotational force transmitted to the driven axis 24 of the second speed-changing portion 120.

In the first and second preferred embodiments of the present invention, it is preferable that there are between 3-6 cylinders 8 and between 2-7 rotating balls 7 in each cylinder 8. The number of the rotating balls 7 becomes even- or odd-numbered to secure a smooth speed-chaning manipulation according to the shape of the driving plates 4 and 304 and the driven plates 9 and 109. Although the rotating balls 7 in the cylinder 8 are linearly arranged in the drawings, the present invention is not limited to the embodiments shown in the drawings. When the number of rotating balls 7 is odd-numbered, the rotational direction of the driven plates 9 and 109 is opposite to that of the driving plates 4 and 304.

FIGS. 7 through 12 show the first speed-changing portion according to the first preferred embodiment of the present invention.

As shown in FIG. 7, in the first speed-changing portion 110 of the present embodiment, the inside gear 113 is supported by the bearings 17 capable of moving freely on the outer circumferential surface of the driving axis 1 and the gear formed on the outer circumferential surface of the inside gear 113 is engaged with the circular gear 113a provided on the outer

circumferential surface of a cylinder casing 314. The geared portion of the circular gear 113a is a rounded surface having a bulged center portion. In the circular gear 113a shown in FIG. 7, the center point of the partially arc shaped gear 113a positioned at the center point of the cylinder 8. Thus, although the cylinder 8 and the cylinder casing 314 rotate in directions indicated by arrows "d", the gear engagement between the inside gear 113 and the circular gear 113a is stably maintained.

Also, a cylinder rotation gear 312 having teeth in a direction perpendicular to the teeth of the circular gear 11 3a is installed on the outer circumferential surface of the cylinder casing 314 disposed opposite the circular gear 11 3a with respect to the cylinder 8. The surface of the cylinder rotation gear 312 is a partial arc shape corresponding to a circle centered about the cylinder 8. The cylinder rotation gear 312 is engaged with the double-sided cross gear 309 and a slip prevention pin 310 for preventing the engaged gears from slipping is interposed between the cylinder rotation gear 312 and the double-sided cross gear 309.

The double-sided cross gear 309 is a gear having geared portions formed on the respective upper and lower surfaces of a rectangular planar member in which the directions of the upper gear teeth and the lower gear teeth are perpendicular to each other. Also, the lower geared surface of the double-sided cross gear 309 engaged with the cylinder rotation gear 312 is a partial arc shape centered about the driving axis 1. The upper geared surface is a round shape of a partial arc of an imaginary circle having a center at the center of the cylinder 8 like the above-described circular gear 113a.

A cylinder rotation prevention member 311 is provided on the inner circumferential surface of the cylinder coupling ring 111. The cylinder rotation prevention member 311 has an end portion extending toward the center of the cylinder coupling ring 111 to a predetermined length to prevent rotation of the cylinder casing 314 over a predetermined range. Also, reference numeral 315 indicates a cylinder pivot axis. A leaf spring 313 provides an elastic force so that the cylinder casing 413 can be elastically

coupled to the cylinder 8.

FIG. 8 is a sectional view taken along line VIII-VIII of FIG. 7. In the drawing, the upper surface of the double-sided cross gear 309 is engaged with the outside gear 200 and simultaneously the lower surface thereof is engaged with the cylinder rotation gear 312. Also, a slip prevention pin 310 is interposed between the cylinder rotation gear 312 and the double-sided cross gear 309.

FIG. 9 shows the cylinder pivot axis 315 and the leaf spring 313 coupled to the cylinder 8.

FIG. 10 shows the double-sided gear 309 in which the upper surface and the lower surface thereof are engaged with the outside gear 200 and the cylinder rotation gear 312, respectively.

FIG. 11 shows a state in which the center line "u" of the cylinder pivot axis315 forms a caster angle "0" with respect to a tangent line "v" at the tangent point at which the driving plate 304 or the driven plate 109 contacts the rotating balls 7 while the driving plate 304 and the driven plate 109 rotate in a direction indicated by arrow "e" to transmit a rotational force.

As shown in the drawing, when the driving plate 304 and the driven plate 109 rotate in a direction indicated by arrow "e", the rotating balls 7 being in a frictional contact with the plates receive pressure to rotate the cylinder 8 in a direction indicated by arrow "f" until stopped by the rotation prevention member 311. Thus, the angle "0" is formed with respect to a tangent line "v" at the tangent point at which the driving plate 304 or the driven plate 109 contacts the rotating balls 7 so that the leaf spring 313 confining the cylinder 8 shares the rotational force applied to the respective rotating balls 7. That is, most of the rotational force generated by the driving plate 304 is transmitted to the driven plate 109 through the rotating balls 7 and a part thereof is used as a force for maintaining the cylinder 8 by rotating the same by the angle "6" in the direction "f". Here, the rotating ball in the cylinder 8 rotating in contact with the driving plate 304 or the driven plate 109 located away from the driving axis 1 receives more pressure than the rotating ball in the cylinder 8 rotating in contact with the driving plate 304

or the driven plate 109 located closer to the driving axis 1 due to a difference in the angular velocity. Accordingly, as the cylinder 8 rotates by the operation of the caster of the cylinder pivot axis 315, the rotating ball is pulled toward the driving axis 1 so that the distances Ra, Ra', Rb and Rb' between the other opposite rotating balls (see FIGS. 1 and 2) becomes equal and the leaf spring 313 confining the cylinder 8 receives a greater pressure. Contrarily, since the rotating ball having shorter distances Ra, Ra', Rb and Rb' than the other rotating balls receives less pressure, the load of the rotational force to the leaf spring 313 decreases. Then, as the cylinder 8 rotates due to the above operation of the caster, the rotating ball is pushed away from the driving axis 1 and thus the distances Ra, Ra', Rb and Rb' between the other opposite rotating balls (see FIGS. 1 and 2) becomes equal.

FIG. 12 shows a state in which the center line "u" of the cylinder pivot axis 315 forms a caster angle "0" with respect to a tangent line "v" at the tangent point at which the driving plate 304 or the driven plate 109 contacts the rotating balls 7 while the driving plate 304 and the driven plate 109 rotate in a direction indicated by arrow "g". The operational principle is the same as the above descriptions with reference to FIG. 11.

FIG. 13 shows the cylinder 8 and the cylinder coupling ring 5 according to the second preferred embodiment of the present invention, and FIG. 14 shows the connection pin 6 inserted in the slot formed in the connection pin coupling piece 25. The same reference numerals indicate elements having the same functions.

FIGS. 15 and 16 show a third preferred embodiment of the present invention, in which FIG. 15 is for showing the position of the cylinder 8 in a high speed or accelerating state and FIG. 15 is for showing the position of the cylinder 8 in a low speed or decelerating state.

As shown in the drawings, in the stepless transmission according to the present embodiment, the driving plate 27 has a bulged portion different from the shapes of the first and second preferred embodiments. In this embodiment, the number of rotating balls 7 in the cylinder 8 is two.

FIG. 17 shows an assembled state of the stepless transmission according to the third preferred embodiment of the present invention. Here, the same reference numerals indicate the elements having the same functions.

As shown in the drawing, in the planetary gear 130 interacting with the first speed-changing portion 110, the ring gear fixing device 34 fixes the ring gear 19 and the planetary carrier 13 and the casing 20 of the second speed- changing portion 120 are fixed by a combining means 36 such as bolts, different from FIG. 4. The structure and operation of the second speed- changing portion 120 is the same as those of the second speed-changing portion of FIGS. 4 or 6. Here, the arrangement of the planetary gear 130 and the second speed-changing portion 120 can be positioned reversely, and In this case, the rotation direction of the driven plate 24 is reversed accordingly. Also, the rotational velocity can be changed by adjusting the combination of the number of gears of the planetary gear 130.

In the present embodiment shown in FIG. 17, the coupling ring adjusting means, different from the structure shown in FIG. 6, includes a cylinder adjustment rod 30 connected to the cylinder 8, an adjustment rod guide ring 29 for guiding the cylinder adjustment rod 30, an adjustment rod ring gear 31 engaged with a gear formed on the cylinder adjustment rod 30, an adjustment ring gear fixing device 32 for fixing the adjustment rod ring gear 31, and an adjustment gear 33 engaged with said adjustment rod ring gear 31. As in the above embodiments, when the adjustment rod ring gear 31 moves the cylinder adjustment rod 30 by a well-known controller by manipulation of an operator, the cylinder 8 moves in a space between a driving plate 27 and a driven plate 28 so that the rotational velocity of the driving plate 27 is transmitted to the driven plate 28.

FIGS. 18 and 19 show a fourth preferred embodiment of the present invention, in which FIG. 18 is for showing the position of the cylinder 8 in a high speed or accelerating state and FIG. 19 is for showing the position of the cylinder 8 in a low speed or decelerating state.

As shown in the drawings, in the present embodiment, a driving plate

47 has a cone shape and a driven plate 48 has an inner circumferential surface formed to be parallel to the outer circumferential surface of the driving plate 47 so that the cylinder 8 moves perpendicular to both the outer circumferential surface of the driving plate 47 and the inner circumferential surface of the driven plate 48. Also, the number of rotating balls 7 in the cylinder 8 is two or even-numbered. It is preferable that there are 3-6 cylinders 8.

The structures and operations of the planetary gear 130 and the second speed-changing portion 120 in the present embodiment are the same as those of the third embodiment. Also, the above Equations (1) through (3) can be applied to the present embodiment.

Industrial Applicabiiity As described above, according to the present invention, a speed change is possible without disengaging the engine and the transmission.

Also, the structure of the transmission is simplified, the transmission is light, and there is little loss in the engine output.