WO2007055495A1

WO2007055495A1 - Stepless variable transmission

Info

Publication number: WO2007055495A1
Application number: PCT/KR2006/004553
Authority: WO
Inventors: Sun Chung Kim
Original assignee: Sun Chung Kim
Priority date: 2005-11-08
Filing date: 2006-11-03
Publication date: 2007-05-18
Also published as: KR100678329B1

Abstract

The invention is a stepless variable transmission in which a clutch function and a con figuration of limiting or controlling transmitting torque are integrally equipped. The invention comprises a housing (42), a fixed shaft, a rotating cylinder (46) which is of a cylindrical form, disposed on the same axial line as that of the fixed shaft (44), and connected to a driving unit to then be rotationally driven; a pair of ring shaped first and second outer laces (52) and (54) and a pair of ring shaped first and second inner laces (56) and (58), a plurality of balls (66) which are inserted in the space portion of the ring shape which is formed by the inner concave groove (64) and the outer concave groove (60), an output shaft (68) which is disposed on the same axial line as that of the fixed shaft (44), and at one side of which a plurality of power transfer arms (70) extended between the balls (66), a frictional force control unit (74), and a variable speed change control unit (100).

Description

STEPLESS VARIABLE TRANSMISSION

Technical Field

[1] TECHNICAL HELD

[2] The present invention relates to a stepless variable transmission, and more particularly to, a stepless variable transmission of a new configuration in which a clutch function and a configuration of limiting or controlling transmitting torque are integrally equipped.

[3]

[4] BACKGROUND ART

[5] In general, a stepless variable transmission converts a variable speed change gear ratio sequentially. In this way, the transmission shock can be removed and the power loss can be minimized. The same applicant as that of this application developed a stepless variable transmission of a new structure suitable for an electric motor and obtained Korean Patent Registration No. 0503712.

[6] As shown in FTG. 1, the stepless variable transmission is integrated with an electric motor. The electric motor includes a stator 4 arranged in the inner circumference of a housing 2, and a rotor 6 and an output shaft 8 which are disposed in the stator 4. The stepless variable transmission includes: a pair of outer laces 12 each having a concave inner diameter portion 10 of a predetermined radius, which are mounted to the rotor 6 and which are faced to each other along the inner side of one end thereof; a pair of inner laces 18 each having a concave inner diameter portion 16 of a predetermined radius, which are disposed in the inner sides of the outer laces 12 and mounted to a fixed frame 14 of the electric motor and which are faced to the inner diameter portions 10 of the outer laces 12 along the outer side of one end thereof; a plurality of steel balls 20 which are inserted into a ring-doughnut shaped space portion made of the four inner diameter portions 10 and 16, and are friction-touched with the inner diameter portions 10 and 16 to thus perform a planetary motion; a power transmission member 24 whose one side is mounted to the output shaft 8 of the electric motor and to the other side of which a plurality of rotating vanes 22 disposed between the steel balls 20 in the ring doughnut shaped space portion are mounted; and a contact position change unit 26 adjusting the interval of the pair of the inner laces 18 and thus changing the contact position between the steel balls 20 and the laces 12 and 18.

[7] Here, elastic members 28 are equipped in the outer laces 12, and thus the steel balls

20 contact strongly closely to the inner diameter portions 10 and 16 of the respective laces 12 and 18. If the outer laces 12 are rotated with the rotor 6, the steel balls 20 perform the planetary motion, along the inner diameter portions 16 of the inner laces 18. In addition, the power transmission member 24 is rotated by the steel balls 20, and the output shaft 8 connected to the power transmission member 24 is rotated. If the interval between the inner laces 18 is adjusted by the contact position change unit 26, a location where the boundary surface of the steel balls 20 contacts the inner diameter portions 10 and 16 formed in the inner and outer laces 12 and 18 is changed, to thereby perform a stepless variable speed change.

[8] However, the stepless variable transmission has no configuration of preventing that the excessive load from being applied to the electric motor. Therefore, the excessive load is applied to the output shaft 8. As a result, the electric motor spends the excessive electric power unreasonably in order to overcome the excessive load, and thus the energy loss is not only increased but also the electric motor may be damaged. Particularly, when a resistance of a preset value or greater occurs in a machine tool, an apparatus in which a driving shaft automatically rotates idly is used. When the stepless variable transmission is applied to the machine tool, there is a problem that a separate apparatus in which the driving shaft automatically slips as described above, has to be included therein.

[9] Moreover, the configuration of the stepless variable transmission is used in a general internal combustion engine. However, the internal combustion engine is necessarily equipped with a clutch blocking the power as necessary. Therefore, there is a problem that since a clutch has to be included in the output shaft 8 of the stepless variable transmission, the size and weight of a product may not be only increased, but also the power loss may occur by the rotating inertia of the clutch.

[10]

[11] DISCLOSURE OF THE INVENTION

[12] To solve the above problems of the conventional stepless variable transmission, it is an object of the present invention to provide a stepless variable transmission being capable of both limiting and controlling transmitting torque, to thereby reduce size and weight as well as prevent a driving unit from being damaged by excessive loads applied to the driving unit.

[13] To accomplish the above object of the present invention, according to an aspect of the present invention, there is provided a stepless variable transmission comprising:

[14] a housing 42;

[15] a fixed shaft 44 fixed to the inner portion of the housing 42;

[16] a rotating cylinder 46 which is of a cylindrical form, disposed on the same axial line as that of the fixed shaft 44, and connected to a driving unit to then be rotationally driven;

[17] a pair of ring shaped first and second outer laces 52 and 54 which are accessibly spaced from the inner circumference of the rotating cylinder 46, to thus rotate with the rotating cylinder 46, and along the respective inner circumferences of which a mutually facing arc-shaped outer concave groove 60 is formed at a mutually adjacent side;

[18] a pair of ring shaped first and second inner laces 56 and 58 having the external diameters smaller than the inner diameters of the outer laces 52 and 54, which are accessibly spaced from the circumference of the fixed shaft 44, and along the respective outer circumferences of which an inner concave groove 64 corresponding to the outer concave groove 60 is formed at a mutually adjacent side;

[19] a plurality of balls 66 which are inserted in the space portion of the ring shape which is formed by the inner concave groove 64 and the outer concave groove 60, and whose circumferences frictionally contact the respective surfaces of the concave grooves 60 and 64, so as to perform the planetary motion along the inner concave groove 64 in the inner laces 56 and 58, at the time of rotation of the outer laces 52 and 54;

[20] an output shaft 68 which is disposed on the same axial line as that of the fixed shaft

44, and at one side of which a plurality of power transfer arms 70 extended between the balls 66 and contacting the sides of the balls 66 are provided so as to rotate by the planetary motion of the balls 66;

[21] a frictional force control unit 74 which is connected with one of the inner laces 56 and 58 and the outer laces 52 and 54 and which is elastically pressed so as to be mutually close to each other and control a pressing force to control a frictional force between the concave grooves 60 and 64 and the balls 66 in the respective laces 52, 54, 56 and 58; and

[22] a variable speed change control unit 100 which is connected to the other of the inner laces 56 and 58 and the outer laces 52 and 54 and changes the contact position between the balls 66 and the laces 52, 54, 56 and 58 so as to change the speed change ratio by adjusting the interval between the laces 52, 54, 56 and 58.

[23] According to another aspect of the present invention, there is also provided a stepless variable transmission wherein the second outer lace 54 is combined in order to be moved forward and backward in the longitudinal direction of the rotating cylinder 46 in the inner circumference of the rotating cylinder 46, and wherein the frictional force control unit 74 comprises:

[24] an elastic member 76 which is provided at the side of the second outer lace 54 and elastically presses the second outer lace 54 toward the first outer lace 52;

[25] a supporting member 78 which is screw-connected with the inner circumference of the rotating cylinder 46 and installed to support the elastic member 76; and

[26] a rotation driving unit 79 which is connected to the supporting member 78 and rotates the supporting member 78, [27] whereby if the rotation driving unit 79 makes the supporting member 78 rotate, the supporting member 78 is moved forward and backward to thus control pressure which the elastic member 76 presses the second outer lace 54, and thereby control the factional force between the balls 66 and the respective laces 52, 54, 56 and 58.

[28] According to still another aspect of the present invention, there is also provided a stepless variable transmission wherein the rotation driving unit 79 which is connected to the supporting member 78 to rotate the supporting member 78, and which further comprises:

[29] a frictional force control shaft 84 whose end is extended to the outer side of the rotating cylinder 46;

[30] a pair of frictional force control wheels 86 which are located at the outer side of the rotating cylinder 46 and connected with the frictional force control shaft 84; and

[31] a friction ring 90 formed of a ring shape, and in the inner circumference of which a friction groove 88 in which the frictional force control wheel 86 is inserted is formed in a concave shape, and which is mounted in the inner circumference of the housing 42 so as to move back and forth in the axial direction of the rotating cylinder 46, and

[32] wherein the friction ring 90 is made to move back and forth so that the frictional force control wheel 86 selectively contacts in both side walls 89 of the friction groove 88 so as to rotate forward and backward, to thereby make the frictional force control shaft 84 and the supporting member 78 rotate.

[33] According to yet another aspect of the present invention, there is also provided a stepless variable transmission wherein traction oil is filled in the internal space of the rotating cylinder 46, and a pair of oil paths 110 and 112 are formed in the fixed shaft 44 and the second inner lace 58 so as to communicate from the internal space of the rotating cylinder 46, and

[34] wherein the traction oil is injected through one oil path 110 and the traction oil is ejected via the other oil path 112, so that the traction oil can be replaced and the balls 66 and the laces 52, 54, 56 and 58 can be cooled.

[35]

[36] BRIEF DESCRIPTION OF THE DRAWINGS

[37] The above and other objects and advantages of the present invention will become more apparent by describing the preferred embodiments thereof in detail with reference to the accompanying drawings in which:

[38] FIG. 1 is a side sectional view which shows a conventional stepless variable transmission;

[39] FIG. 2 is a side sectional view which shows a stepless variable transmission according to the present invention;

[40] FIG. 3 is a cross-sectional view which shows a stepless variable transmission according to the present invention;

[41] FlG. 4 is a cross-sectional view which shows a frictional force controlling unit according to the present invention;

[42] FIGS. 5 A and 5B are referenced views which show operating states of a frictional force controlling wheel according to the present invention;

[43] FlG. 6 is a referenced view which shows a variable speed shaft and a variable speed lever according to the present invention;

[44] FIGS. 7 A and 7B are referenced views which show referenced views for explaining a variable speed change variable speed change ratio according to the present invention; and

[45] FlG. 8 is a referenced view which shows a stepless variable transmission according to another preferred embodiment according to the present invention.

[46]

[47] BEST MODE FOR CARRYING OUT THE INVENTION

[48] Hereinbelow, a stepless variable transmission according to the present invention will be described with reference to the accompanying drawings.

[49] FIGS. 2 to 7 show a stepless variable transmission according to the present invention, respectively. The stepless variable transmission includes a fixed shaft 44 and a rotating cylinder 46 which are equipped in a housing 42 of a cylindrical shape. The fixed shaft 44 and the rotating cylinder 46 are positioned on the central axis of the housing 42. A gear 48 is formed in the circumferential surface of the rotating cylinder 46. A driving gear 50 of a drive unit (not shown) is engaged with the gear 48 and is rotated with the drive unit. Here, the drive unit can be implemented in various forms such as an electric motor or an internal combustion engine.

[50] In the inner circumference of the rotating cylinder 46 are mounted the first and second ring shaped outer laces 52 and 54 so as to be mutually close to and spaced from each other. The first and second ring shaped inner laces 56 and 58 are mounted on the fixed shaft 44, so as to be mutually close to and spaced from each other, in which the external diameters of the first and second ring shaped inner laces 56 and 58 are smaller than the inner diameters of the first and second outer laces 52 and 54. A mutually facing arc-shaped outer concave groove 60 is formed along the inner circumferences of the adjacent sides of the first and second outer laces 52 and 54, respectively. The first and second outer laces 52 and 54 are spline combined with the inner circumference of the rotating cylinder 46 and is rotated with the rotating cylinder 46. Here, the first outer lace 52 is fixed so as not move by a projected wall 62 formed in the inner circumference of the rotating cylinder 46, and the second outer lace 54 is moved forward and backward in the longitudinal direction of the rotating cylinder 46. In the first and second inner laces 56 and 58, the inner concave groove 64 corresponding to the outer concave groove 60 is formed along the adjacent side on the outer circumference thereof. The first inner lace 56 is spline combined with the fixed shaft 44, and the second inner lace 58 is screw-connected with the first inner lace 56. Accordingly, if the second inner lace 58 is made to rotate, the first and second inner laces 56 and 58 are mutually close to or spaced from each other.

[51] A plurality of balls 66 are inserted in the space portion of the ring shape which is formed by the concave grooves 60 and 64 in the outer laces 52 and 54 and the inner laces 56 and 58. The balls 66 are made of steel balls whose intensity and hardness are high, and whose circumferences frictionally contact the respective surfaces of the concave grooves 60 and 64, so as to perform the planetary motion along the inner concave groove 64 in the inner laces 56 and 58, at the time of rotation of the outer laces 52 and 54.

[52] An output shaft 68 is disposed on the same axial line as that of the fixed shaft 44, and at one side of which a plurality of power transfer arms 70 extended between the balls 66 are disposed. As shown in FlG. 3, the power transfer arms 70 are extended between the balls 66 from the disc shaped base end 68a of the output shaft 68. At the ends of the power transfer arms 70 are rollers 72 which roll-contact the sides of the balls 66. Thus, if the rotating cylinder 46 and the outer laces 52 and 54 rotate with the drive unit, the balls 66 perform the planetary motion along the inner concave groove 64 in the inner laces 56 and 58. The power transfer arms 70 and the output shaft 68 rotate with the balls 66.

[53] A frictional force control unit 74 which control a pressing force to control a frictional force between the concave grooves 60 and 64 and the balls 66 in the respective laces 52, 54, 56 and 58, is provided in the outer laces 52 and 54. The frictional force control unit 74 includes: an elastic member 76 which is provided at the side of the second outer lace 54 and elastically presss the second outer lace 54 toward the first outer lace 52; a supporting member 78 which is screw-connected with the inner circumference of the rotating cylinder 46 to support the elastic member 76; and a rotation driving unit 79 which is connected to the supporting member 78 and rotates the supporting member 78.

[54] The elastic member 76 is formed of a disc-shaped spring whose central portion is protruded to one side, that is, several dish-shaped springs overlapped over each other to give a stronger elasticity. The elastic member 76 presses the side of the second outer lace 54, so as to closely contact the first outer lace 52. As described above, when the second outer lace 54 is strongly pressed toward the first outer lace 52, the balls 66 inserted into the outer concave groove 60 in the outer laces 52 and 54 are pushed toward the inner laces 56 and 58, and thus the balls 66 strongly closely contact the concave grooves 60 and 64 in the respective laces 52, 54, 56 and 58, to thereby increase a factional force.

[55] The supporting member 78 includes a disc portion 80 which makes the elastic member 76 closely contact the supporting member 78, and whose outer circumference is screw-connected with the inner circumference of the rotating cylinder 46. If the supporting member 78 is made to rotate, the supporting member 78 moves back and forth in the longitudinal direction of the rotating cylinder 46, to thus press the elastic member 76. Accordingly, the force which the elastic member 76 presss the second outer lace 54 can be controlled. Thus, when the supporting member 78 is rotated so that the supporting member 78 can move back and forth, the force which the elastic member 76 presss the second outer lace 54 is controlled and thus the frictional force between the balls 66 and the respective laces 52, 54, 56 and 58. In addition, when the supporting member 78 further moves backward, the frictional force between the balls 66 and the respective laces 52, 54, 56 and 58 is removed to thus perform a clutch function which cuts off power.

[56] Here, one side of the supporting member 78 is provided an extension pipe 82 which is connected to the outer portion of the fixed shaft 44 and connected with the rotating drive unit 79. As shown in FlG. 4, the rotation driving unit 79 includes: a frictional force control shaft 84 which is connected with the extension pipe 82; a pair of frictional force control wheels 86 which are located at the outer side of the rotating cylinder 46 and connected with the frictional force control shaft 84; and a friction ring 90 formed of a ring shape, and in the inner circumference of which a friction groove 88 in which the frictional force control wheel 86 is inserted is formed in a concave shape, and which is mounted in the inner circumference of the housing 42 so as to move back and forth in the axial direction of the rotating cylinder 46.

[57] The frictional force control shaft 84 is connected to the extension pipe 82 via a worm 92 and a worm wheel 94, and is installed at right angle with the central axis direction of the rotating cylinder 46. Both ends of the frictional force control shaft 84 are extended to the outer side while passing through both sides of the rotating cylinder 46. The frictional force control wheel 86 is mounted on either side of the diameter direction of the rotating cylinder 46, and is connected through a reduction gear 96 mounted on the outer circumference of the rotating cylinder 46 to the frictional force control shaft 84. The friction ring 90 is spline combined with the inner circumference of the housing 42, and is moved forward and backward not rotated by a control unit (not shown) along the inner circumference of the housing 42.

[58] As shown in FIGS. 5 A and 5B, if the friction ring 90 is moved back and forth at the state where the frictional force control wheel 86 is rotated with the rotating cylinder 46, both side walls 89 of the friction groove 88 in the friction ring 90 contacts frictionally with the frictional force control wheel 86. Accordingly, the frictional force control wheel 86 rotates in the forward or backward direction. Here, the control unit for make the friction ring 90 move back and forth is formed in various forms. It is preferable that the control unit is configured to include an arm extended to the outside of the housing 42 at one side of the control unit, so as to move back and forth in the outside of the housing 42. Therefore, when the friction ring 90 is moved back and forth, the frictional force control wheel 86 is rotated. Accordingly, the frictional force control shaft 84 and the supporting member 78 connected to the frictional force control wheel 86 are rotated, and thus the supporting member 78 can be moved back and forth. The pressure in which the elastic member 76 supported by the supporting member 78 presses the second outer lace 54 can be controlled. In FlG. 4, a reference number 98 denotes a reverse gear portion which is equipped in one side of the frictional force control shaft 84 and reverses the rotational direction of the frictional force control shaft 84. That is, a pair of the frictional force control wheels 86 contact both side walls 89 of the friction ring 90 simultaneously and rotate in the mutually opposing directions. Therefore, the reverse gear portion 98 reverses the rotational direction of one of the frictional force control wheels 86 so that the frictional force control shaft 84 can be smoothly rotated.

[59] As shown in FlG. 2, the variable speed change control unit 100 includes the connection pipe 102 which is inserted rotatably between the fixed shaft 44 and the extension pipe 82 of the supporting member 78 and connected to the second inner lace 58, and a variable speed change axis 104 which is connected with the connection pipe 102 in a worm gear coupling manner with a worm. As shown in FlG. 6, a lever 103 or a drive motor is connected to the end of the variable speed change axis 104. If the variable speed change axis 104 is rotated by the lever 103 or the drive motor, the connection pipe 102 and the second inner lace 58 which is connected to the connection pipe 102 are rotated. As shown in the FIGS. 7 A and 7B, the gap between the first inner lace 56 and the second inner lace 58 becomes narrow, the contact positions between the balls 66 and the laces 52, 54, 56 and 58 are changed to P3 and P4 from Pl and P2 and thus a variable speed change ratio is controlled. The configuration of the variable speed change control unit 100 is identical with the contact position change unit equipped in the conventional stepless variable transmission.

[60] Moreover, traction oil is filled in the internal space of the rotating cylinder 46, to coat the contact surfaces between the balls 66 and the laces 52, 54, 56 and 58. Accordingly, a sufficient frictional force is exerted and the power transmission is authentically guaranteed. Moreover, in the fixed shaft 44 and the second inner lace 58 are formed a pair of oil paths 110 and 112 which communicate from the internal space of the rotating cylinder 46. The traction oil is injected through one oil path 110 and the traction oil is ejected via the other oil path 112, so that the traction oil can be replaced and simultaneously the balls 66 and the laces 52, 54, 56 and 58 can be cooled.

[61] The above-described stepless variable transmission can control the frictional force between the concave grooves 60 and 64 and the balls 66 in the respective laces 52, 54, 56 and 58 by using the frictional force control unit 74. The above-described stepless variable transmission can completely pull back the supporting member 78 as necessary, and can control the frictional force between the concave grooves 60 and 64 and the balls 66 in the laces 52, 54, 56 and 58 to become zero. Accordingly, the stepless variable transmission according to the present invention can cut off power using only the internal configuration without using a separate clutch unit. Therefore, the present invention has the advantages that the size and weight can be reduced in comparison with the conventional transmission using a separative clutch unit, and the power loss by the clutch can be prevented.

[62] Moreover, the frictional force control unit 74 is used to properly control the frictional force between the concave grooves 60 and 64 and the balls 66 in the laces 52, 54, 56 and 58. As a result, a torque limit can be freely established. Accordingly, when the excessive resistance or load is applied to the output shaft 68, the balls 66 slip in the concave grooves 60 and 64 of the laces to thereby perform a function of a torque limiter which does not deliver the excessive resistance to the drive unit. Accordingly, the present invention has the advantage of preventing the malfunction from happening from the excessive resistance applied to the drive unit. When an electric motor is used as the drive unit, excessive loads are prevented from being applied to the electric motor and accordingly the excessive power which is consumed in the electric motor is prevented from exhausting. Moreover, when the excessive load equal to or larger than a predetermined load which has been established by the frictional force control unit 74 is applied to the drive unit, the balls 66 are automatically slipped. Therefore, when the stepless variable transmission is applied to a machine tool, the driving shaft can be automatically slipped in the case that the load which is a predetermined load which is set up without using a separate apparatus is applied to the drive unit. Therefore, the present invention has the advantage that the structure of the stepless variable transmission becomes very simple.

[63] Moreover, the present invention can control the pressure of the elastic member 76 by rotating the supporting member 78 to thus press the second outer lace 54. Therefore, the present invention has the advantage that the structure of the stepless variable transmission is very simple and the reliability thereof is high. Particularly, the rotation driving 79 connected to the supporting member 78 has the advantage that since the frictional force control wheel 86 has a friction with the friction ring 90 and thus the supporting member 78 is rotated, a separate drive unit is unnecessary and the structure of the stepless variable transmission is simple. There is also little concern of the malfunction. Moreover, since the traction oil is supplied or ejected through the oil paths 110 and 112, the traction oil can be easily replaced. In addition, at the same time, the balls 66 and the laces 52, 54, 56 and 58 can be cooled. Therefore, the power loss due to the physical property change of the traction oil is prevented. Simultaneously, the present invention has the advantage of cooling the balls 66 and the laces 52, 54, 56 and 58 without using a separate cooler.

[64] In the embodiment of the present invention, only one drive unit is connected to the rotating cylinder 46. However, several drive units can be connected to the rotating cylinder 46, or it is possible to alter the portion in which the drive unit is connected. Moreover, a pair of the frictional force control wheels 86 have been connected to the frictional force control shaft 84, to thus adjust a balance of the frictional force control shaft 84. However, a frictional force control wheel 86 is connected to only one side of the frictional force control shaft 84 according to necessity, and a separate weight is provided in the other side thereof, to take measures to fit the right and left balance of the frictional force control shaft 84. In addition, according to a need, the separate reverse gear part 98 is not used and the number of the reduction gears are varied, to thereby mutually reverse the rotational direction of the frictional force control wheel 86.

[65] FlG. 8 is a reference view showing a stepless variable transmission according to another preferred embodiment of the present invention, which exemplifies a model which is integrally connected with an electric motor having a stator 106 which is equipped in the inner circumference of a housing 42 and a rotor 108 arranged inside the stator 4. Here, the housing 42 of the invention uses the housing of the electric motor, and rotating cylinder 46 is connected to the rotor 6 so that the rotating cylinder 46 is driven by the rotor 108. As described above, size and weight of a product can be reduced in comparison with the conventional product having a separate drive unit.

[66]

[67] THE EFFECT OF THE INVENTION

[68] As described above, according to the present invention, the frictional force between the balls 66 and the laces 52, 54, 56 and 58 can be controlled using the frictional force control unit 74. Thus, the configuration of limiting or controlling the transmitting torque is integrally equipped in the stepless variable transmission to thereby reduce size and weight. In addition, the new stepless variable transmission prevents the drive unit from being damaged by the excessive loads applied to the drive unit.

[69] However, the protective scope of the present invention is not defined within the detailed description thereof but is defined by the claims to be described later and the technical spirit of the present invention.

Claims

[1] A stepless variable transmission comprising: a housing 42; a fixed shaft 44 fixed to the inner portion of the housing 42; a rotating cylinder 46 which is of a cylindrical form, disposed on the same axial line as that of the fixed shaft 44, and connected to a driving unit to then be ro- tationally driven; a pair of ring shaped first and second outer laces 52 and 54 which are accessibly spaced from the inner circumference of the rotating cylinder 46, to thus rotate with the rotating cylinder 46, and along the respective inner circumferences of which a mutually facing arc-shaped outer concave groove 60 is formed at a mutually adjacent side; a pair of ring shaped first and second inner laces 56 and 58 having the external diameters smaller than the inner diameters of the outer laces 52 and 54, which are accessibly spaced from the circumference of the fixed shaft 44, and along the respective outer circumferences of which an inner concave groove 64 corresponding to the outer concave groove 60 is formed at a mutually adjacent side; a plurality of balls 66 which are inserted in the space portion of the ring shape which is formed by the inner concave groove 64 and the outer concave groove 60, and whose circumferences frictionally contact the respective surfaces of the concave grooves 60 and 64, so as to perform the planetary motion along the inner concave groove 64 in the inner laces 56 and 58, at the time of rotation of the outer laces 52 and 54; an output shaft 68 which is disposed on the same axial line as that of the fixed shaft 44, and at one side of which a plurality of power transfer arms 70 extended between the balls 66 and contacting the sides of the balls 66 are provided so as to rotate by the planetary motion of the balls 66; a frictional force control unit 74 which is connected with one of the inner laces 56 and 58 and the outer laces 52 and 54 and which is elastically pressed so as to be mutually close to each other and control a pressing force to control a frictional force between the concave grooves 60 and 64 and the balls 66 in the respective laces 52, 54, 56 and 58; and a variable speed change control unit 100 which is connected to the other of the inner laces 56 and 58 and the outer laces 52 and 54 and changes the contact position between the balls 66 and the laces 52, 54, 56 and 58 so as to change the speed change ratio by adjusting the interval between the laces 52, 54, 56 and 58.

[2] A stepless variable transmission of claim 1, wherein the second outer lace 54 is combined in order to be moved forward and backward in the longitudinal direction of the rotating cylinder 46 in the inner circumference of the rotating cylinder 46, and wherein the frictional force control unit 74 comprises: an elastic member 76 which is provided at the side of the second outer lace 54 and elastically presses the second outer lace 54 toward the first outer lace 52; a supporting member 78 which is screw-connected with the inner circumference of the rotating cylinder 46 and installed to support the elastic member 76; and a rotation driving unit 79 which is connected to the supporting member 78 and rotates the supporting member 78, whereby if the rotation driving unit 79 makes the supporting member 78 rotate, the supporting member 78 is moved forward and backward to thus control pressure which the elastic member 76 presses the second outer lace 54, and thereby control the frictional force between the balls 66 and the respective laces 52, 54, 56 and 58.

[3] A stepless variable transmission of claim 2, wherein the rotation driving unit 79 which is connected to the supporting member 78 to rotate the supporting member 78, and which further comprises: a frictional force control shaft 84 whose end is extended to the outer side of the rotating cylinder 46; a pair of frictional force control wheels 86 which are located at the outer side of the rotating cylinder 46 and connected with the frictional force control shaft 84; and a friction ring 90 formed of a ring shape, and in the inner circumference of which a friction groove 88 in which the frictional force control wheel 86 is inserted is formed in a concave shape, and which is mounted in the inner circumference of the housing 42 so as to move back and forth in the axial direction of the rotating cylinder 46, and wherein the friction ring 90 is made to move back and forth so that the frictional force control wheel 86 selectively contacts in both side walls 89 of the friction groove 88 so as to rotate forward and backward, to thereby make the frictional force control shaft 84 and the supporting member 78 rotate.

[4] A stepless variable transmission of claim 1, wherein traction oil is filled in the internal space of the rotating cylinder 46, and a pair of oil paths 110 and 112 are formed in the fixed shaft 44 and the second inner lace 58 so as to communicate from the internal space of the rotating cylinder 46, and wherein the traction oil is injected through one oil path 110 and the traction oil is ejected via the other oil path 112, so that the traction oil can be replaced and the balls 66 and the laces 52, 54, 56 and 58 can be cooled.