WO2002057651A2

WO2002057651A2 - Continuously variable transmission having high transmission efficiency and durability

Info

Publication number: WO2002057651A2
Application number: PCT/KR2002/000093
Authority: WO
Inventors: Hyuk Choul Sin
Original assignee: Oh, Hyo Keun
Priority date: 2001-01-19
Filing date: 2002-01-19
Publication date: 2002-07-25
Also published as: WO2002057651A3; AU2002225501A1; KR20020062068A

Abstract

A continuously variable transmission (CVT apparatus adopting a sun gar input-carrier output type. The CVT apparatus includes a torque converter for changing a rotational force and a rotational speed transmitted to a turbine according to a load to generate a second power; a transmission system for generating a transmission output by decelerating the number of revolutions of planetary gears generated in correspondence to a second rotational speed into the number of rotations of planetary gears in proportion with a rotational speed difference, for a carrier supporting the planetary gears, in the case that the rotational speed difference between first and second rotational speeds is generated; and a mode selection system for setting the CVT apparatus to one of drive modes.

Description

CONTINUOUSLY VARIABLE TRANSMISSION HAVING HIGH TRANSMISSION EFFICIENCY AND DURABILITY

Technical Field The present invention relates to a continuously variable transmission apparatus and method, and more particularly, to a continuously variable transmission apparatus andmethod for controlling the number of revolution of a planetary gear in a transmission system employing a sun gear input-carrier output type by generating a difference between revolutional speeds of a pump and a turbine in a torque converter according to a running state of a vehicle, in order to perform a continuously variable transmission and have a structure combined with a very simplemode selection system, to thereby enhance a silence and a high transmission efficiency and having an excellent durability.

Background Art

In general, a driving force of a vehicle varies greatly according to a vehicle weight, a road condition and a running speed. Accordingly, a transmission apparatus for properly changing a driving force of an engine according to an external situation is installed in a vehicle.

The vehicle transmission apparatus is installed between an engine and a driving shaft, to transfer a driving force of the engine to driving wheels. The transmission apparatus is classified into a manual transmission apparatus with which a driver selects a transmission stage at his or her will, an automatic transmission apparatus for performing an automatic transmission according to a running condition of a vehicle, and a continuously variable transmission apparatus for performing a continuously variable transmission without having a particular transmission region between respective transmission stages.

Amanual transmission apparatus among the transmission apparatuses includes a transmission lever for receiving a driver's manipulation force. The transmission lever manipulates a number of shift rails installed in a transmission gear box and operates a number of gears through a sleeve connected to a shift fork, in order to vary the transmission. During transmission, a clutch should be trod to cut off power transferred from the engine.

The manual transmission apparatus has advantages such as a simple structure, an excellent durability, a high transmission efficiency, and a large transmission capacity. However, the manual transmission apparatus has problems that a driver should manipulate transmission stages directly according to a vehicle running speed andmuch noise and tremble occurs. Thus, in the case of drivers who are not accustomed to driving and are not good at a transmission manipulation, a variety of accidents may be induced. Even skilled drivers may feel fatigue earlier for a long-time driving.

Meanwhile, an automatic transmission apparatus can obtain a constant gear ratio between an input element and an output element of power if one element of planetary gear devices such as a sun gear, a carrier and a ring gear is fixed with a multi-plate clutch and a handbrake which control the planetary gear device. Also, if two elements are fixed to each other among the planetary gear devices, the two elements are integrally rotated. Also, if any of them are not fixed, the automatic transmission apparatus is set a neutral state where power is not transmitted.

Thus, the automatic transmission apparatus has no manual-type clutch manipulation mechanism, to thereby perform an automatic transmission bymeans of an accelerating pedal and a brake pedal, without secession of gears . However, a hydraulic and electronic control mechanism for fixing and controlling the planetary gears with the multi-plate clutch and the band brake is very complicated and has a low durability, in particular, has a high production cost and a low transmission efficiency . Also, the automatic transmission apparatus undergoes a transmission impact according to a difference between transmission ratios of respective transmission stages when a speed of the vehicle shifts up or down.

Further, since the conventional manual and automatic transmission apparatuses are fixed and operated into predetermined gear ratios, it is difficult to maintain an optimal output power and an optimal combustion ratio. Accordingly, a multi-stage transmission unit has been developed. However, since the weight and cost of the multi-stage transmission unit increases, the multi-stage transmission unit is confronted with a limit.

Also, a general continuously variable transmission apparatus has been developed for the purpose of saving a cost and improving a combustion ratio as well as removing a transmission impact which are drawbacks of an automatic transmission apparatus.

A conventional continuously variable transmission apparatus uses a belt/pulley type method using a displacement in a diameter of each of pulleys mounted at an input shaft and an output shaft. However, a combustion ratio is worse in either a low or high speed, and thus a large amount of an exhaust gas is generated. Also, since a durability is lowered, noise/vibration is generated and a slip phenomenon occurs according to a use of a power transmission belt, the continuously variable transmission apparatus is difficult to be applied to a large-sized vehicle or a special purpose vehicle .

Also, a toroidal type continuously variable transmission apparatus has an excellent transmission efficiency, but has a weak durability, a complicated structure and a high production cost.

Meanwhile, a continuously variable transmission apparatus disclosed in Korean Patent Publication No.97-8224 uses a first output of a torque converted in a torque converter and a second output of an engine as a second input of a simple planetary gear device and uses a planetary carrier as an output. Accordingly, a vehicle speed is proportionally increased and decreased according to a difference between the number of rotations of the first output and that of the second output. However, the prior art patent transmits power of an engine and varies a vehicle speed, using two power transmission shafts of a main shaft and a sub-shaft which are separated asymmetrically. As a result, the whole structure of the transmission apparatus becomes large and complicated, which causes a power transmission/a transmission efficiency and durability to be lowered.

Meanwhile, a continuously variable transmission apparatus was proposed in Korean Patent Laid-open Publication No . 98-87621, in order to make use of advantages ofagear-type continuously variable transmission apparatus , and remove disadvantages thereof, by analyzing the advantages and disadvantages of the gear-type continuously variable transmission apparatus by the same applicant.

The transmission system in the automatic transmission apparatus adopts a sun gear input-fixing bar output type. The prior art technology controls the number of revolution of a planetary gear according to a difference between the revolutional speeds of a pump and a turbine in a torque converter based on a running state of a vehicle and then controls a transmission ratio via a fixing bar. However, the prior art technology proposed a theoretical technique which can be used for only a forward run, since a variable transmission output is generated with an output gear integrated with a fixing bar by use of only a sun gear input-fixing bar output type, and did not propose a configuration of selecting one of a forward drive, reverse drive and neutral mode necessary for functioning as a continuously variable transmission apparatus.

In addition, a vehicle transmission apparatus requires a broad transmission width. However, the prior art technology can extend a transmission widthwith a gear ratio. In this case, since a rotational speed of a worm gear is increased, a worm gear having a frictional coefficient has a disadvantageous point.

Also, since the prior art technology uses a fixing bar to support the whole transmission apparatus, a durability is somewhat lowered.

Accordingly, the applicant has solved the problems of the prior art, and researched a perfect continuously variable transmission apparatus to obtain the present invention.

Disclosure of the Invention

To solve the above problems, it is an object of the present invention to provide a continuously variable transmission apparatus and method having a very simple mode selection system for selecting a running mode in a continuously variable transmission apparatus including a transmission control system, and a transmission system adopting a sun gear input-carrier output type, to thereby perfectly and efficiently select one of forward drive, reverse drive, and neutral modes.

It is another object ofthe present invention to provide a continuously variable transmission apparatus and method having a very simple transmission system for controlling the number of revolutions of a planetary gear with a worm gear, to thereby control a transmission ratio continuously, in a transmission system adopting a sun gear input-carrier output type based on a difference between the rotational speeds of a pump and a turbine in a torque converter which is generated according to a running state of a vehicle, to thereby have a cost competitive power and an excellent productivity. It is still another object of the present invention to provide a continuously variable transmission apparatus of a symmetrical structure, employing a gear coupling method of a silence, a durability and an excellent transmission efficiency, since a continuous gear ratio variable transmission is performed at the state where gears are tooth-engaged with one another.

It is yet another object of the present invention to provide a continuously variable transmission method for controlling the number of revolutions and the number of rotations of a planetary gear by a two-line power transmission having a main power transmission line for converting power of an engine into a torque via a torque converter and inputting the torque converted result to a linear in order to revolve a planetary gear and a power transmission control line for inputting the power of the engine to an input bevel gear in order to rotate a worm wheel which is spline connected with a planetary gear through an output bevel gear and a worm gear in the direction opposedto the revolution direction of the planetary gear.

It is a further object of the present invention to provide a continuously variable transmission apparatus in which a transmission control system where a torque conversion is performed for transmission control, a transmission system for performing a transmission according to a converted torque, and a mode selection system for selecting a running mode need a minimal electronic control, to thereby shorten a development period and perform an easy repairing and maintenance.

To accomplish the above object of the present invention, there is provided a continuously variable transmission apparatus comprising: a torque converter for changing a rotational force and a rotational speed transmitted to a turbine according to a load applied to an output of the turbine when a first power generated from an engine is input, to thereby generate a second power via a first power transmission line; a transmission system of a sun gear input-carrier output type, for generating a transmission output obtained by decelerating the number of revolutions of a planetary gear generated in correspondence to a second rotational speed into the number of rotations of the planetary gear in proportion with a rotational speed difference, for a carrier supporting the planetary gear, in the case that the rotational speed difference between a first rotational speed and the second rotational speed is generated, in response to the first power input at the first rotational speed via a second power transmission line installed in the same axis as that of the first power transmission line, and the second power input at the second rotational speed to a sun gear revolving the planetary gear via the first power transmission line; and a mode selection system installed in the second power transmission line between the torque converter and the transmission system, for setting the continuously variable transmission apparatus to one of a forward drive mode, a reverse drive mode and a neutral mode. The transmission system comprises: a sun gear integrally formed at a leading end of the second power transmission line, to which the second power is applied; a first bevel gear integrally formed at a leading end of the first power transmission line, to which the first power is applied; a second bevel gear tooth-engaged perpendicularly with the first bevel gear; a worm gear support shaft whose both ends are rotatably supported, to the middle portion of which the second bevel gear is integrally formed; first and second worm gears which are integrally formed in both ends of the worm gear support shaft, respectively, and rotate in the same direction as that of the first power since spirals are formed respectively therein in the directions opposing each other; a carrier on the cover of which the leading end of the secondpower transmission line is rotatably supported, in which both ends of the worm gear support shaft is rotatably supported on opposing side walls of a cup-shaped carrier body coupled to the cover; first and second worm wheels rotatably installed on the bottom of the carrier, respectively, and diagonally tooth-engaged with the first and second worm gears, respectively, to thus rotate in the direction opposing that of the first power; first and second planetary gears which are coupled to the inner circumferential portions of the first and second worm wheels , respectively, and thus rotate integrally with the worm wheels, and whose inner sides are tooth-engaged with the sun gear and parts of outer sides protrude externally through a pair of windows open to both side walls of the carrier body; and an output shaft integrally formed on the carrier, from which a variable transmission output is obtained.

Also, the transmission system comprises: a main power transmission line for transmitting the second power to the sun gear via the second power transmission line and thus revolving the first and second planetary gears; and a power transmission control line for transmitting a first power to the first bevel gear via the first power transmission line, and thus rotating in the direction opposing those of the revolution directions of the first and second planetary gears spline coupled with the worm wheels via the second bevel gear, the worm gear support shaft, the first and second worm gears and the first and second worm wheels, in which the number of revolutions and the number of rotations of the first and second planetary gears are controlled, to thereby perform a continuous gear transmission with a result that the variable transmission output is transmitted to the output shaft via the carrier.

Also, the mode selection system comprises : a brake unit which is installed on the second power transmission line between the torque converter and the transmission system, for fixing the sun gear selectively according to a selected mode; and a clutch unit which is inserted on the second power transmission line between the torque converter and the transmission system, to thus prevent a power from being transmitted to the sun gear selectively according to a selected mode.

According to another aspect of the present invention, there is provided a continuously variable transmission apparatus comprising: a torque converter for changing a rotational force and a rotational speed transmitted to a turbine according to a load- applied to an output when a first power generated from an engine is input, to thereby generate a second power via a first power transmission line; a transmission system of a sun gear input-carrier output type, for generating a transmission output obtained by decelerating the number of revolutions of a planetary gear generated in correspondence to a second rotational speed into the number of rotations of the planetary gear in proportion with a rotational speed difference, for a carrier supporting the planetary gear, in the case that the rotational speed difference between a first rotational speed and the second rotational speed is generated, in response to the first power input at the first rotational speed via a second power transmission line installed in the same axis as that of the first power transmission line, and the second power input at the second rotational speed to a sun gear revolving the planetary gear via the first power transmission line; and a mode selection system installed in the rear end of the transmission system, for setting the continuously variable transmission apparatus to one of a forward drive mode, a reverse drive mode and a neutral mode, wherein a torque conversion and a gear variable transmission are performed until a load applied to the output of the transmission system and the rotational force transmitted to the output end are in equilibrium, between the torque converter and the transmission system.

According to still another aspect of the present invention, there is also provided a continuously variable transmission method for use in a continuously variable transmission apparatus having a torque converter, and a transmission system adopting a sun gear input-carrier output type, for converting a power output from an engine into a continuously variable transmission output according to a load applied to an output and generating the continuously variable transmission output, the continuously variable transmission method comprising the steps of: setting the continuously variable transmission apparatus to one of a forward drive mode, a reverse drive mode and a neutral mode; changing a rotational force and a rotational speed of a turbine according to a load applied to the turbine when a first power generated from the engine is input to a pump impeller in the torque converter to thereby generate a second power via a first power transmission line; transmitting both the first power via the second power transmission line inserted in the same axis as that of the first power transmission line and the second power via the first power transmission line from the torque converter, to the transmission system; transmitting the second power to a sun gear of a transmission system via the second power transmission line to thereby revolve first and second planetary gears; transmitting the first power to a first bevel gear via the second power transmission line to thereby rotate the first and second planetary gears in the direction opposing the revolutional direction via a second bevel gear, a worm gear support shaft, first and second worm gears, and first and second worm wheels; and decelerating the number of rotations from the number of revolutions applied to the first and second planetary gears, for generating a variable transmission output via a carrier, wherein a torque conversion is accomplished between the torque converter and the transmission system until a load applied to the output of the transmission system and the rotational force transmitted to the output end are in equilibrium, in which the rotational force of the output of the transmission system for keeping the balance between the load and the rotational force is determined as a value obtained by multiplying an increased rotational force of the transmission system by an increased rotational force of the torque converter.

As described above, the present invention adds a mode selection system of a very simple structure, for determining a running mode to the continuously variable transmission apparatus including a transmission control system and a transmission system, to thereby efficiently perform selection of one of a forward drive mode, a reverse drive mode and a neutral mode.

The present invention realizes a continuously variable transmission system having a very simple transmission system for controlling the number of revolutions of a planetary gear with a worm gear, to thereby control a transmission ratio continuously, by a sun gear input-carrier output type based on a difference between the rotational speeds of a pump and a turbine in a torque converter which is generated according to a running state of a vehicle, to thereby have a cost competitive power, accomplish a symmetrical structure, and control a transmission ratio continuously at the state where gears are tooth-engaged, and to thereby provide a silence, a durability and an excellent transmission efficiency.

The present invention also requires each system to have a minimal electronic control , to thereby shorten a development period and perform an easy repairing and maintenance.

Brief Description of the Drawings

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

FIG. 1 is a schematic view showing a continuously variable transmission method according to a first embodiment of the present invention, in which a mode selection system is coupled between a transmission control system and a transmission system;

FIG. 2 is a sectional view of an actual transmission system cut along a line A-A of FIG. 1;

FIG. 3 is a perspective view showing the transmission system of FIG. 2;

FIG. 4 is an exploded perspective view of FIG. 3; and

FIGs. 5 through 8 schematically show a respective continuously variable transmission apparatus according to second through fifth embodiments of the present invention, in which a mode selection system is coupled between a transmission control system and a transmission system.

Best Mode for Carrying out the Invention

A continuously variable transmission apparatus which is obtained by connecting a transmission control system and a transmission system according to a preferred embodiment of the present invention will be described below in more detail with reference to the accompanying drawings . A continuously variable transmission apparatus according to the present invention includes a transmission control system 100, a transmission system 300 and a mode selection system, on a large-scale basis.

First, referring to FIGs. 1 through 4, a continuously variable transmission apparatus according to a first embodiment of the present invention will be described. For convenience of explanation, a connection structure of the transmission control system 100 and the transmission system 300 except for a mode selection system 640 will be first described.

The transmission control system 100 is an application of a torque converter used in a general automatic transmission apparatus for torque conversion. A conventional torque converter transmits a power generated by an engine to a transmission system via a torque converter.

However, the transmission control system 100 according to the present invention includes a first power transmission line via which a first power generated by the engine directly to the transmission system 300, that is, an input shaft 302, and a second power transmission line for transmitting a second power to the transmission system 300 torque converted via a torque converter 100a being the transmission control system 100, that is, a control shaft 110.

That is, as shown in FIG. 1, the torque converter 100a used as the transmission control system 100 is integrally formed by means of spline-connection to a pump housing 102 where an input shaft 302 via which a first power of an engine is input is integrally formed with a pump propeller 104. A turbine 106 is installed at a position opposing the pump propeller 104, and a stator 108 is positioned between the pump impeller 104 and the turbine 106. A hollow fixed shaft 112 is installed at the inner side of the stator 108, and a one-direction clutch 114 is installed between the fixed shaft 112 and the stator 108 so that the stator 108 is prevented from being reversely rotated and kept rotating only in one direction. Also, the hollow fixed shaft 112 is inserted into a hollow control shaft 110 coaxially and fixed to a housing. An input shaft 302 is rotatably installed in the control shaft 110 coaxially. One end of the control shaft 110 is integrally formed by a spline-connection with the turbine 106, and the other end thereof is integrally formed with a sun gear 318 of the transmission system 300. A lock-up clutch 116 for enhancing an efficiency by integrating the pump housing 102 and the control shaft 110 during high speed rotation is installed between the pump housing 102 and the control shaft 110.

Meanwhile, in the case of the transmission system 300 in the present invention as shown in FIGs. 1 and 2, a spline 302a which is integrally connected with the pump housing 102 is formed in the outer circumferential portion in the middle of the input shaft 302 via which the first power of the engine is input and an input bevel gear 304 is integrally formed in the leading end of the input shaft 302.

Also, a spline 110a which is spline-connected with the turbine 106 is formed in the rear end of the control shaft 110 which is connected to the outer circumferential portion of the input shaft 302. The sun gear 318 is integrally formed in the leading end of the control shaft 110. The middle portion of the control shaft 110 is rotatably supported in the middle of a disc-shaped carrier cover 312a, and the carrier cover 312a is fixed to a carrier body 312b by use of a fixing bolt 312c. Thus, the carrier cover 312a and the carrier body 312b play a role of a housing for stably supporting various gears forming the transmission system 300 to be described later, to thereby greatly enhance a durability and a reliability of a continuously variable transmission apparatus. Also, internally generated noise is suppressed at maximum from being transmitted externally.

The input bevel gear 304 is tooth-engaged with an output bevel gear 306 perpendicularly with the input bevel gear 304. The output bevel gear 306 is integrally formed in the substantial middle portion of a worm gear support shaft 308.

Also, a first idle bevel gear 322 is installed in the worm gear support shaft 308 so that the first idle bevel gear 322 opposes the output bevel gear 306 and freely rotates. The upper portion of the first idle bevel gear 322 is tooth-engaged perpendicularly with the input bevel gear 304. Further, a second idle bevel gear 324 is freely rotatably installed on a support shaft 326 on the center of the carrier 312 opposing the input bevel gear 304. The output bevel gear 306 and the first idle bevel gear 322 are tooth-engaged with the second idle bevel gear 324.

As a result, the four bevel gears 304, 306, 322 and 324 are tooth-engaged and rotated in the same symmetric form as a differential device of a vehicle when viewed from both sides of the bevel gears. Accordingly, although the power applied via the input bevel gear 304 is transmitted to the other gear only via the output bevel gear 306, a rotational balance can be maintained and thus a distorted wear due to transmission of the distorted force can be prevented from occurring and a power transmission efficiency can be prevented from being lowered on a long-term basis.

A pair of worm gears 310 and 310 ' where spirals are formed in the direction opposing each other are integrally formed in both ends of the worm gear support shaft 308. As shown in FIGs. 2 and 4, both ends of the worm gear support shaft 308 are freely rotatably fixed to both side walls opposing a cup-shaped carrier body 312b of the carrier 312. Also, worm wheels 314 and 314' are tooth-engaged diagonally with the pair of worm gears 310 and 310', respectively. Inner circumferential spline connections 314a and 314a ' of the worm wheels 314 and 314 ' are integrally formed in spline connection with outer circumferential spline connections 316 and 316a' of the planetary gears 316 and 316 ' . Respective central throughholes 316b and 316b' of the planetary gears 316 and 316' rotating integrally together with the worm wheels 314 and 314' are rotatably coupled with a pair of support shafts 314b and 314b' protruding from the bottom of the carrier body 312b on the center of the worm wheels 314 and 314' . In this case, it is possible to fabricate the worm wheels 314 and 314 ' and the planetary gears 316 and 316' in integral form, other than a spline connection method. Also, the other spline connections employed in the present invention can be replaced by other known connection methods. The inner portions of the pair of planetary gears 316 and 316' is tooth-engaged with the sun gear 318. The outer portions of the pair of planetary gears 316 and 316' protrude partially externally through windows 312d and 312d' open to both side walls of the carrier body 312b. A variable transmission output is obtained from an output shaft 330 integrally formed with the carrier 312.

A variable' transmission operation of the continuously variable transmission apparatus having the above-described structure according to the present invention and a power transmission process therefor will be described below in detail .

(Low-speed start state) First, a case that a vehicle is in a low-speed state will be described. When a first power of an engine is gradually input into a continuously variable transmission apparatus having a transmission control system 100 and a transmission system 300 via an input shaft 302, the power is transmitted to the input bevel gear 304 and the pump impeller 104 of the torque converter 100a. Thus, the bevel gear 304 and the pump impeller 104 rotate in the same direction as that of the input shaft 302, for example, counterclockwise. The first power transmitted to the pump impeller 104 is transmitted to the turbine 106. The sun gear 318 is rotated by the control shaft 110 integrally formed with the turbine

106 in the same direction as that of the input shaft 302.

Thus, both the first and second planetary gears 316 and 316' tooth-engaged with sun gear 318 revolve in the direction opposing the rotational direction of the input shaft 302, that is, clockwise.

Here, the pair of worm wheels 314 and 314' integrally formed with the planetary gears 316 and 316 ' are tooth-engaged with the respective worm gears 310 and 310' . Thus, the worm wheels 314 and 314 ' are fixed so as not to rotate . In general, a worm gear cannot transmit power reversely, and thus cannot rotate by the wormwheels. As a result, the whole transmission system 300 integrally rotates in the same direction as that of the input shaft 302.

However, when a load for making a vehicle start is applied to the output shaft 330 integrally formed with the carrier 312 supporting the planetary gears 316 and 316' , the turbine 106 rotates more slowly than the rotational speed input to the pump impeller 104 of the torque converter 100a to thus transmit the torque converted second power to the sun gear 318.

Meanwhile, the first power of the engine is transmitted to the input bevel gear 304 via the input shaft 302, the power is transmitted to the output bevel gear 306 which is tooth-engaged with the input bevel gear 304 to thereby perform a function of controlling a transmission ratio of the transmission system 300 and the worm gear support shaft 308 integrally formed with the output bevel gear 306. When viewed from the upper portions of FIGs . 1 and 2 , the worm gear support shaft 308 rotates counterclockwise. As a result, the worm gears 310 and 310 ' integrally formed with the worm gear support shaft 308 also rotate counterclockwise due to a difference between the rotational speeds of the pump impeller 104 and the turbine 106 in the torque converter 100a.

Therefore, the worm wheels 314 and 314' tooth-engaged with the worm gears 310 and 310' and integrally formed with the planetary gears 316 and 316' rotate slowly clockwise, respectively. As a result, the carrier 312 supporting the planetary gears 316 and 316' is decelerated by a clockwise rotational speed of the planetary gears 316 and 316' at a counterclockwise revolutional speed of the planetary gears 316 and 316' corresponding to the rotational speed of the sun gear 318, and simultaneously rotates in the rotational direction of the input shaft 302, that is, counterclockwise, with a rotational force increased by torque conversion.

By the way, if a rotational force transmitted to the turbine is increased according to the characteristic of the torque converter 100a, the rotational speed of the turbine 106 is decelerated and the increased rotational force transmitted from the turbine 106 is transmitted to the output shaft 330 via the transmission system 300. In this case, when a load applied to the turbine 106 is greater than the rotational force transmitted to the turbine 106, the vehicle is in a stop state, and the load applied to the turbine 106 and the rotational force transmitted to the turbine 106 are in equilibrium, to then drive the output shaft 330.

Here, if the first power of the engine input to the torque converter 100a, that is, the rotational speed and force is continuously increased or the load of the turbine 106 is decreased otherwise, the rotational force transmitted to the turbine 106 is greater than the load applied to the turbine 106, to make the vehicle start at low speed. (Accelerating state from lower speed to higher speed)

Here, a continuously variable transmission process from a lower stage to a higher stage will be described. If the rotational speed and force of the engine is further increased, the difference between the rotational speeds of the pump impeller 104 and the turbine 106 in the torque converter 100a is further greater. The rotational force transmittedto the turbine 106 is increasedand the rotational force transmitted to the turbine 106 is greater than the load applied to the turbine. In this case, the rotational speed of the turbine 106 increases, until the rotational force transmitted from the pump impeller 104 to the turbine 106 is in equilibrium with the load applied to the turbine 106, to thus perform an acceleration.

Thus, the difference between the rotational speeds of the pump impeller 104 and the turbine 106 is gradually decreased, which is transmitted into the rotational speed difference between the input bevel gear 304 and the sun gear 318. The worm gears 310 and 310' integrally formed with the output bevel gear 306 are decelerated counterclockwise and rotated on its axis, by the decreaseddifference between the rotational speeds . That is, if the rotational speed difference between the input bevel gear 304 and the sun gear 318 is continuously decreased due to an increase in the rotational speed of the turbine 106, the clockwise rotational speeds of the wormwheels 314 and 314 ' and the planetary gears 316 and 316 ' tooth-engaged with the worm gears 310 and 310' as well as the worm gears

310 and 310' are sequentially decreased and the gear ratio is continuously varied from a lower stage to a higher stage.

Here, in the case that the magnitude of the load applied to the turbine 106 is smaller than or same as the rotational force transmitted to the turbine, the rotational speed of the turbine 106 becomes identical with the rotational speed of the pump impeller 104. Accordingly, the worm gears 310 and 310' are not rotated on their axes, and the whole transmission control system 100 is integrated to thus rotate counterclockwise so that the rotational force of the turbine 106 becomes that of the output shaft 330. This state is called a high-speed state.

In this case, it is preferable that a high-speed state is detected from a control apparatus (not shown) , to then make the lock-up clutch 116 installed between the pump housing 102 and the control shaft 110 operate. Accordingly, the pump housing 102 and the control shaft 110 are integrated, that is, directly connected, to thereby enhance an efficiency of power transmission.

(Decelerating state from higher speed to lower speed) For example, if a load applied to the output shaft 330 increases as if a vehicle rises up a heel, the rotational speed of the turbine 106 is decelerated and the rotational force transmitted from the pump impeller 104 to the turbine 106 increases. Thus, the rotational speed difference between the pump impeller 104 and the turbine 106 increases to make the worm gears 310 and 310* rotate counterclockwise with an accelerating speed.

Thus, the planetary gears 316 and 316' integrally formed with the worm wheels 314 and 314' rotate in the direction opposing that of the input shaft 302 on its axis with an accelerating speed, to make the gear ratio change from higher stage to lower stage. A magnitude of the load applied to the turbine 106 is reducedandis in equilibriumwith the rotational force transmitted to the turbine 106 to then drive the output shaft 330.

As described above, the gear variable transmission of the transmission system 300 is accomplished in the direction where the load applied to the output shaft 330 is in equilibrium with the rotational force transmitted to the output shaft 330. The equilibrium rotational force for keeping in equilibrium with the load is determined by the following equation (1). ER = IRtb X IRvts ...(1)

Here, ER denotes an equilibrium rotational force, IRtb denotes a rotational force increasing in a turbine, and IRvts denotes a rotational force increasing in a transmission system. Thus, the continuouslyvariable transmission according to the present invention drives the output shaft with a large rotational force at low speed, to thereby enhance an accelerating performance and an efficiency.

As described above, when the power of the engine is input in the present invention, torque conversion is performed in the torque converter 100a, and simultaneously a variable control of the turbine rotational speed is performed in inversely proportion with the torque conversion.

Thereafter, a variable transmission gear ratio is continuously changed in a manner that a rotational speed in the direction opposing the revolutional direction of the planetary gear is controlled according to a difference between the rotational speeds of the turbine applied to the transmission system 300 and the pump impeller, that is, an input shaft/input bevel gear, to thereby variably control the rotational speed of the output shaft and the corresponding torque. Thus, a control is performedbetween the transmission control system 100. including the torque converter and the transmission system 300 so that the load applied to the output shaft 330 (turbine) and the rotational force transmitted to the output shaft 330 (turbine) are in equilibrium.

First Embodiment

First, a mode selection system 640 in a continuously variable transmission apparatus according to a first embodiment shown in FIG. 1 will be described. The continuously variable transmission apparatus according to the first embodiment includes a mode selection system 640 between a transmission control system 100 and a transmission system 300. That is, in the first embodiment, a band brake or a multi-plate brake 604 for preventing a sun gear 318 from rotating (that is, for fixing a sun gear) is coupled with a control shaft 110 between the transmission control system 100 and the transmission system 300, and simultaneously as an example, a multi-plate clutch 605 is installed in the middle so that power transmission is controlled via the control shaft 110 between the transmission control system 100 and the transmission system 300. In this case, the brake and the clutch are not limited to the above-described examples, but may be extended to the others which can perform similar functions to those of the brake and the clutch.

In the case that a current drive mode is a forward drive mode D in the first embodiment, the band brake 604 is set as an off-state, and the multi-plate clutch 605 is set as an on-state. In the case that a current drive mode is a reverse drive mode R in the first embodiment, the band brake 604 is set as an on-state, and the multi-plate clutch 605 is set as an off-state. In the case of the neutral mode (N) , both the band brake 604 and the multi-plate clutch 605 are set as an off-state, respectively.

First, in the case that a user manipulates the mode selection system 640 to set a current drivemode as the forward drive mode D, power is transmitted to the sun gear 318 via the control shaft 110. Since the sun gear 318 is in the rotatable state, the forward running is accomplished in the same operation as that of the above-described basic configuration, the detailed description of which will be omitted.

In the case that a current drive mode is set as a reverse drive mode R, the multi-plate clutch 605 is in an off-state. Accordingly, power is not transmitted to the sun gear 318, and the sun gear 318 is in a fixed state by the band brake 604.

In this case, the power transmission from the input shaft 302 to the sun gear 318 via the torque converter 100a is not accomplished. However, only the power transmission is accomplished via the input shaft 302, the input bevel gear 304, the output bevel gear 306, the worm gear support shaft 308, the worm gears 310 and 310', the worm wheels 314 and 314', the planetary gears 316 and 316', the carrier 312 and the output shaft 330.

By the way, since the planetary gears 316 and 316' do not transmit power to the fixed sun gear 318 tooth-engaged with the planetary gears 316 and 316', the carrier 312 tooth-engaged with the planetary gears 316 and 316' also rotates clockwise . Accordingly, the rotational output of the direction opposing the rotational direction of the input shaft

302 is obtained at the output shaft 330, to thereby accomplish a reverse drive. In the case that a current drive mode is set as a neutral mode N, the band brake 604 and the multi-plate clutch 605 are in an off-state, respectively. Accordingly, the power transmission is not accomplished from the torque converter

100a to the sun gear 318. The sun gear 318 is in a freely rotatable state.

In the neutral mode, the power transmission is not made from the input shaft 302 to the sun gear 318 via the torque converter 100a. However, only the power transmission is accomplished via the input shaft 302, the input bevel gear 304, the output bevel gear 306, the worm gear support shaft 308, the worm gears 310 and 310', the worm wheels 314 and 314', and the planetary gears 316 and 316'. By the way, the planetary gears 316 and 316' do not transmit power to the carrier 312 to which a load is applied since the sun gear 318 tooth-engaged with the planetary gears 316 and 316' is in an idle state. The power transmission is accomplished to the sun gear 318, to thereby perform an idling. Thus, the vehicle keeps a stop state since the power is not transmitted to the output shaft 330.

In this case, it is preferable that an engine control unit judges whether a current drive mode is a neutral mode to thereby efficiently deceleration-control an engine output .

As described above, the continuously variable transmission apparatus according to the first embodiment of the present invention is very simple, and has an extremely simple mode selection structure, to thereby perform an efficient selection of one of a forward drive mode, a reverse drive mode and a neutral mode.

Second through Fifth Embodiments

Meanwhile, a continuously variable transmission apparatus according to each of second through fifth embodiments of the present invention illustrates an example where each of mode selection systems 600-630 is coupled with an output shaft 330 in a transmission system 300, as shown in FIGs. 5 through 8. In a continuously variable transmission apparatus according to a second embodiment shown in FIG. 5, an output sun gear 601 in a mode selection system 600 is integrally formed with an output shaft 330 in the transmission system 300. An output single-type planetary gear 602 and an output ring gear 603 are tooth-engaged with the outer side of the output sun gear 601, and the output ring gear 603 is integrally formed with the output shaft 330.

In this case, a band brake or a multi-plate brake 604b is connected to a carrier 607 supporting the output single-type planetary gear 602 for mode selection, and a multi-plate clutch 605b is installed between the output ring gear 603 and the output shaft 330.

The mode selection system 600 of the second embodiment is configured by use of a pair of single-pinion type planetary gear sets.

In a continuously variable transmission apparatus according to a third embodiment shown in FIG. 6, an output ring gear 603 in a mode selection system 610 is integrally formed with an output shaft 330 in the transmission system 300. An output single-type planetary gear 602 and an output sun gear 601 are tooth-engaged with the inner side of the output ring gear 603, andamulti-plate clutch 605c is connected between the output ring gear 603 and the output sun gear 601. The output single-type planetary gear 602 is freely rotatably supported in a carrier 607a. A band brake 604c is connected to the carrier 607a. An output is generated from the output sun gear 601.

The mode selection system 610 of the third embodiment is configured by use of a pair of single-pinion type planetary gear sets .

In a continuously variable transmission apparatus according to a fourth embodiment shown in FIG. 7, an output ring gear 603 in a mode selection system 620 is integrally formed with an output shaft 330 in the transmission system 300. Output double-type planetary gears 606a and 606b and an output sun gear 601 are sequentially tooth-engaged with the inner side of the output ring gear 603, and a multi-plate clutch 605d is connected between the output ring gear 603 and the output sun gear 601. A band brake 604d is connected to the output sun gear 601. An output is generated to an output double-type planetary gear carrier 607b freely rotatably supporting the output double-type planetary gears 606a and 606b. The mode selection system 620 of the fourth embodiment isconfiguredbyuseofapairof double-pinion type planetary gear sets.

In a continuously variable transmission apparatus according to a fifth embodiment shown in FIG. 8, an output sun gear 601 in a mode selection system 630 is connected to an output shaft 330 in the transmission system 300. A multi-plate clutch 605e is connected between the output shaft 330 and the output ring gear 603. Output double-type planetary gears 606a and 606b and an output sun gear 601 are tooth-engaged with the inner side of the output ring gear 603. A-band brake 604e is connected to the output ring gear 603. An output is generated to an output double-type planetary gear carrier 607c freely rotatably supporting the output double-type planetary gears 606a and 606b.

The mode selection system 630 of the fifth embodiment is configured by useofapairof double-pinion type planetary gear sets.

The mode selection systems 600-630 of the second through fifth embodiments operate in the substantially same manner as that of the first embodiment. That is, in the case that a current drive mode is a forward drive mode D, the band brakes 604b-604e are set as an off-state, respectively and the multi-plate clutches 605b-605e are set as an on-state, respectively. In the case that a current drive mode is a reverse drive mode R, the band brakes 604b-604e are set as an on-state, respectively and the multi-plate clutches 605b-605e are set as an off-state, respectively. In the case of the neutral mode (N) , all of the band brakes 604b-604e and the multi-plate clutches 605b-605earesetas an off-state, respectively.

First, in the case that the mode selection system 600 of the second embodiment shown in FIG. 5 is set as the forward drive mode D, that is, if both the sun gear 601 and the ring gear 603 are fixed by the multi-plate clutch 605, the whole mode selection system 600 is integrated to rotate in the. same direction as that of the sun gear 601. As a result, an output is input to the output sun gear 601 and thereafter is generated from the ring gear 603 via the multi-plate clutch 605b. In the case that a current drive mode is set as a reverse drive mode R, by releasing the multi-plate clutch 605 and manipulating the bandbrake 604, if a counterclockwise output of the transmission system 300 is input to the output sun gear 601, a clockwise output is generated from the planetary gear 602 and the ring gear 603 since the carrier 607 is fixed, to thereby accomplish a reverse drive.

In the case that a current drive mode is set as a neutral mode N, by releasing both the band brake 604 and the multi-plate clutch 605, an output transmitted to the output sun gear 601 is not sufficiently transmitted to the output ring gear 603 to which a load is applied, to thereby make a vehicle maintain a stop state.

Here, if two elements of the planetary gears are fixed to each other in the case of a forward drive mode, the whole portions are integrally rotate, which is not limited to the above-described embodiments.

In the case that the mode selection system 610 of the third embodiment shown in FIG. 6 is set as the forward drive mode D, that is, if both the sun gear 601 and the ring gear 603 are fixed by the multi-plate clutch 605c, the whole mode selection system 600 is integrated to rotate in the same direction as that of the ring gear 603. As a result, an output is input to the output ring gear 603 and thereafter is generated from the sun gear 601 via the multi-plate clutch 605c.

Also, in the case that a current drive mode is set as a reverse drive mode R fixing a carrier 607a, by releasing the multi-plate clutch 605c and manipulating the band brake 604c, if a counterclockwise output of the transmission system 300 is input to the ring gear 603, the planetary gear 602 also rotates counterclockwise on its axis, and the ring gear 603 generates a clockwise output to thereby accomplish a reverse drive.

As described above, a reverse drive output which is accelerated reversely is generated from the sun gear 601 via the planetary gear 602 from the ring gear 603 in the third embodiment, which is appropriate for a special-purpose vehicle requiring a fast reverse drive.

In the case that a current drive mode is set as a neutral mode N, by releasing both the band brake 604c and the multi-plate clutch 605c, an output transmitted to the ring gear 603 is not sufficiently transmitted to the sun gear 601 to which a load is applied, to thereby make a vehicle maintain a stop state.

Here, if two elements of the planetary gears are fixed to each other in the case of a forward drive mode, the whole portions integrally rotate, which is not limited to the above-described embodiments, but has many possible variations .

In the case that the mode selection system 620 of the fourth embodiment shown in FIG. 7 is set as the forward drive mode D, that is, if both the sun gear 601 and the ring gear 603 are fixed by the multi-plate clutch 605d, the whole mode selection system 620 integrally rotate in the same direction as that of the ring gear 603, to thereby rotate the sun gear 601 and the carrier 607c. As a result, an output is input to the output ring gear 603 and thereafter is generated from the sun gear 601 via the multi-plate clutch 605d.

Also, in the case that a current drive mode is set as a reverse drive mode R fixing the sun gear 601, by releasing the multi-plate clutch 605d and manipulating the band brake 604d, if a counterclockwise output of the transmission system 300 is input to the ring gear 603, the planetary gear 606a rotates clockwise and the planetary gear 606b rotates counterclockwise, since the sun gear 601 is fixed, and thus the carrier 607b generates a clockwise output to thereby accomplish a reverse drive. In the case that a current drive mode is set as a neutral mode N, by releasing both the band brake 604d and the multi-plate clutch 605d, an output transmitted to the ring gear 603 makes the planetary gears 606a and 606b and the sun gear 601 idly rotate, with a result that the carrier 607b to which a load is applied does not rotate, to thereby make a vehicle maintain a stop state.

Here, if two elements of the planetary gears are fixed to each other in the case of a forward drive mode, the whole portions integrally rotate, which is not limited to the above-described embodiments.

In the case that the mode selection system 620 of the fifth embodiment shown in FIG. 8 is set as the forward drive mode D, that is, if both the sun gear 601 and the ring gear 603 are fixed by the multi-plate clutch 605e, the whole mode selection system 630 integrally rotate in the same direction as that of the ring gear 603 and the sun gear 601, to thereby rotate the carrier 607c in the same direction. As a result, an output is generated from the carrier 607c.

Also, in the case that a current drive mode is set as a reverse drive mode R fixing the ring gear 603, by releasing the multi-plate clutch 605e and manipulating the band brake 604e, if a counterclockwise output of the transmission system 300 is input to the sun gear 601, the planetary gear 606a rotates clockwise and the planetary gear 606b does not rotate counterclockwise by the fixed ring gear 603. Thus the carrier 607c generates a clockwise output to thereby accomplish a reverse drive.

In the case that a current drive mode is set as a neutral mode N, by releasing both the band brake 604e and the multi-plate clutch 605e, an output transmitted to the sun gear 601 makes the planetary gears 606a and 606b idly rotate, with a result that the carrier 607c to which a load is applied does not rotate, to thereby make a vehicle maintain a stop state .

As described above, the present invention can realize a continuously variable transmission apparatus including a mode selection system 600, 610, 620 or 630 made of an appropriate combination of a planetary gear 601, 602, 603, 606a, 606b, 607a, 607b or 607c, a multi-plate clutch 605b, 605c, 605d or 605e and a band brake 604b, 604c, 604d or 604e to an output from a transmission system 300, to thereby efficiently accomplish selection of a forward drive mode, a reverse drive mode and a neutral mode.

Further, the continuously variable transmission apparatus according to the present invention is not limited to the above-described embodiments without departing from the basic spirit of the present invention, but can be used in combination with the other kinds of mode selection systems .

Also, the above-described embodiments have been described with respect to the cases that the structures appropriate for a rear-wheel drive have been used in the continuously variable transmission apparatus of the present invention. For example, it is apparent to one skilled in the art that a variety of mode selection systems can be combined between the transmission control system 100 and the transmission system 300, respectively. It is also apparent to a person who has an ordinary skill in the art that the present invention can be modified into a front-wheel drive type continuously variable transmission apparatus by connecting a variable transmission output gear connected to the mode selection system with a front-wheel axle shaft via an idle gear and a differential ring gear. Meanwhile, a continuously variable transmission apparatus according to the present invention can respond to a variation of a load quickly even at the state where all gears are connected with one another, to thereby perform a high efficiency variable transmission conveniently and comfortably even in a slope or steep road as well as at a usual running mode.

The present invention realizes a continuously variable transmission apparatus having a very simple transmission system for controlling the number of revolutions of a planetary gear with a worm gear, to thereby control a transmission ratio continuously, in a transmission system of a sun gear input-carrier output type based on a difference between the rotational speeds of a pump and a turbine in a torque converter, and to thereby have a cost competitive power and an excellent productivity.

A transmission system according to the present invention has a carrier having a cylindrical vessel structure made of a cup-shaped carrier body and a disc-shaped carrier cover, in which a control shaft and an output shaft are integrally formed, to thereby stably support various gears accommodated therein, and suppress internally generated noise from being discharged externally at minimum, which can therefore enhance a reliability and a durability of the continuously variable transmission apparatus.

The present invention provides a continuously variable transmission apparatus having a main power transmission line and a power transmission control line of a symmetrical structure, and whose whole structure is symmetric, which accomplishes a smooth power transmission to thereby enhance a silence, a durability and a transmission efficiency.

Industrial Applicability

As described above, the present invention does not need a separate control device for variable transmission, which provides the following advantages.

The present invention has a simple structure, and provides an inexpensive product since the number of components is reduced by 30% in comparison with the conventional case. The present invention is convenient to be used even for an unskilled person for driving, and can respond to a variation of a load even at the state where all gears are tooth-engaged with one another. The present invention can accomplish a continuously variable transmission, to thereby enhance a silence, an efficiency and a durability of a product. As described above, the present invention has been described with respect to the particularly preferred embodiments, but the present invention is not limited in the above-described embodiments. It is apparent to one who has an ordinary skill in the art that there are many variations and modifications within the scope of the appended claims with departing off from the spirit of the present invention.

Claims

What is claimed is :

1. A continuously variable transmission apparatus comprising: a torque converter for changing a rotational force and a rotational speed transmitted to a turbine according to a load applied to an output of the turbine when a first power generated from an engine is input, to thereby generate a second power via a first power transmission line; a transmission systemof a sun gear input-carrier output type, for generating a transmission output obtained by decelerating the number of revolutions of a planetary gear generated in correspondence to a second rotational speed into the number of rotations of the planetary gear in proportion with a rotational speed difference, for a carrier supporting the planetary gear, in the case that the rotational speed difference between a first rotational speed and the second rotational speed is generated, in response to the first power input at the first rotational speed via a second power transmission line installed in the same axis as that of the first power transmission line, and the second power input at the second rotational speed to a sun gear revolving the planetary gear via the first power transmission line; and a mode selection system installed in the second power transmission line between the torque converter and the transmission system, for setting the continuously variable transmission apparatus to one of a forward drive mode, a reverse drive mode and a neutral mode.

2. The continuously variable transmission apparatus of claim 1, wherein said transmission system comprises: a sun gear integrally formed at a leading end of the second power transmission line, to which the second power is applied; a first bevel gear integrally' formed at a leading end of the first power transmission line, to which the first power is applied; a second bevel gear tooth-engaged perpendicularly with the first bevel gear; a worm gear support shaft whose both ends are rotatably supported, to the middle portion of which the second bevel gear is integrally formed; first and second worm gears which are integrally formed in both ends of the worm gear support shaft, respectively, and rotate in the same direction as that of the first power since spirals are formed respectively therein in the directions opposing each other; a carrier on the cover of which the leading end of the second power transmission line is rotatably supported, in which both ends of the worm gear support shaft is rotatably supported on opposing side walls of a cup-shaped carrier body coupled to the cover; first and second worm wheels rotatably installed on the bottom of the carrier, respectively, and diagonally tooth-engaged with the first and second worm gears, respectively, to thus rotate in the direction opposing that of the first power; first and second planetary gears which are coupled to the inner circumferential portions of the first and second worm wheels, respectively, and thus rotate integrally with the worm wheels, and whose inner sides are tooth-engaged with the sun gear and parts of outer sides protrude externally through a pair of windows open to both side walls of the carrier body; and an output shaft integrally formed on the carrier, from which a variable transmission output is obtained.

3. The continuously variable transmission apparatus of claim 2, wherein a torque conversion and a gear variable transmission are accomplished between the torque converter and the transmission system until a load applied tothe output of the transmission system and the rotational force transmitted to the output end are in equilibrium, in which the rotational force of the output of the transmission system for keeping the balance between the load and the rotational force is determined as a value obtained by multiplying an increased rotational force . of the transmission system by an increased rotational force of the torque converter.

4. The continuously variable transmission apparatus of claim 1, further comprising a lock-up clutch installed between a pump impeller housing and the first power transmission line at the time of rotating at high speed in which the first and second rotational speeds are same, for integrating the pump impeller housing and the first power transmission line, in which case the transmission apparatus generates the output of the transmission apparatus at the same speed as the rotational speed of the turbine.

5. The continuously variable transmission apparatus of claim 2, wherein said transmission system increases the rotational speed of the transmission output in proportion with the rotational speed difference in the case that the second rotational speed is smaller than the first rotational speed, and a gear transmission ratio is continuously changed so that the rotational force of the transmission output is reduced.

6. The continuously variable transmission apparatus of claim 2, wherein said transmission system comprises: a main power transmission line for transmitting the second power to the sun gear via the second power transmission line and thus revolving the first and second planetary gears; and a power transmission control line for transmitting a first power to the first bevel gear via the first power transmission line, and thus rotating in the direction opposing those of the revolution directions of the first and secondplanetary gears spline coupled with the wormwheels via the second bevel gear, the worm gear support shaft, the first and second worm gears and the first and second worm wheels, wherein the number of revolutions and the number of rotations of the first and second planetary gears are controlled, to thereby perform a continuous gear transmission with a result that the variable transmission output is transmitted to the output shaft via the carrier.

7. The continuously variable transmission apparatus of claim 2, wherein if a load applied to the output of the transmission system is increased in the present invention, a rotational speed of the turbine is decelerated and a rotational force transmitted from the pump impeller to the turbine is increased, and thus a difference between the rotational speeds of the pump impeller and the turbine is increased, to thereby rotate the first and second worm gears at an increasing speed in the same direction as that of the first power, and the first and second planetary gears rotate at an increasing speed in the direction opposing that of the first power to thereby continuously change a gear ratio from a higher stage to a lower stage.

8. The continuously variable transmission apparatus of claim2, wherein as the rotational speed and the rotational force of the engine increase, a difference between the rotational speeds of the pump impeller and the turbine furthermore increases, and when the rotational force transmitted to the turbine becomes larger than the load applied to the turbine in accordance with a result that the rotational force transmitted to the turbine increases, the rotational speed of the turbine increases until the rotational force transmitted from the pump impeller to the turbine is in equilibrium with respect to the load applied to the turbine, and wherein if a difference between the rotational speeds of the first bevel gear and the sun gear continuously decreases in accordance with a result that the rotational speed of the turbine increases, the rotational speeds in the directions opposing the revolutional directions of the first and second planetary gears are also sequentially decelerated via the second bevel gear, the first and second worm gears, and the first and second worm wheels, to thereby change a gear ratio from a lower stage to a higher stage continuously.

9. The continuously variable transmission apparatus of claim 2, further comprising: a first idle bevel gear perpendicularly tooth-engaged with the first bevel gear in the worm gear support shaft and idly rotatably installed opposing the second bevel gear; and a second idle bevel gear tooth-engaged with the second bevel gear and the first idle bevel gear on the center of the carrier opposing the first bevel gear and idly rotatably installed, wherein the first and second bevel gears and the first and second idle bevel gears are tooth-engaged with each other in a symmetric form.

10. The continuously variable transmission apparatus of claim 1, wherein said mode selection system comprises: a brake unit which is installed on the second power transmission line between the torque converter and the transmission system, for fixing the sun gear selectively according to a selected mode; and a clutch unit which is inserted on the second power transmission line between the torque converter and the transmission system, to thus prevent a power from being transmitted to the sun gear selectively according to a selected mode.

11. A continuously variable transmission apparatus comprising : a torque converter for changing a rotational force and a rotational speed transmitted to a turbine according to a load applied to an output when a first power generated from an engine is input, to thereby generate a second power via a first power transmission line; a transmission systemof a sun gear input-carrier output type, for generating a transmission output obtained by decelerating the number of revolutions of a planetary gear generated in correspondence to a second rotational speed into the number of rotations of the planetary gear in proportion with a rotational speed difference, for a carrier supporting the planetary gear, in the case that the rotational speed difference between a first rotational speed and the second rotational speed is generated, in response to the first power input at the first rotational speed via a second power transmission line installed in the same axis as that of the first power transmission line, and the second power input at the second rotational speed to a sun gear revolving the planetary gear via the first power transmission line; and a mode selection system installed in the rear end of the transmission system, for setting the continuously variable transmission apparatus to one of a forward drive mode, a reverse drive mode and a neutral mode, wherein a torque conversion and a gear variable transmission are performed until a load applied to the output of the transmission system and the rotational force transmitted to the output end are in equilibrium, between the torque converter and the transmission system.

12. The continuously variable transmission apparatus of claim 11, wherein in said mode selection system, an output sun gear is integrally formed with the output shaft of the transmission system, an output single-type planetary gear and an output ring gear are tooth-engaged with the outer portion of the output sun gear, respectively, the output ring gear is integrally formed with the output shaft, a brake unit is coupled to a carrier rotatably supporting the output single-type planetary gear for mode selection and a clutch unit is installed between the output ring gear and the output shaft .

13. The continuously variable transmission apparatus of claim 11, wherein in said mode selection system, an output ring gear is integrally formed with the output shaft of the transmission system, an output single-type planetary gear and an output sun gear are tooth-engaged with the inner portion of the output ring gear, a clutch unit is installed between the output ring gear and the output sun gear, the output single-type planetary gear is rotatably supported in the carrier, a brake unit is coupled to a carrier, and an output is generated from the output sun gear.

14. The continuously variable transmission apparatus of claim 11, wherein in said mode selection system, an output ring gear is integrally formed with the output shaft of the transmission system, an output double-type planetary gear and an output sun gear are tooth-engaged with the inner portion of the output ring gear, a clutch unit is installed between the output sun gear and the output ring gear, a brake unit is coupled to the output sun gear, and an output is generated from the output double-type planetary gear carrier rotatably supporting the output double-type planetary gear.

15. The continuously variable transmission apparatus of claim 11, wherein in said mode selection system, an output sun gear is integrally formed with the output shaft of the transmission system, a clutch unit is installed between the output shaft and the output ring gear, an output double-type planetary gear and an output sun gear are sequentially tooth-engaged with the inner portion of the output ring gear, a brake unit is coupled to the output ring gear, an output is generated from an output from an output double-type planetary gear carrier rotatably supporting the output double-type planetary gear.

16. A continuously variable transmission method for use in a continuously variable transmission apparatus having a torque converter, and a transmission system adopting a sun gear input-carrier output type, for converting a power output from an engine into a continuously variable transmission output according to a load applied to an output and generating the continuously variable transmission output, the continuously variable transmission method comprising the steps of: setting the continuously variable transmission apparatus to one of a forward drive mode, a reverse drive mode and a neutral mode; changing a rotational force and a rotational speed of a turbine according to a load applied to the turbine when a first power generated from the engine is input to a pump impeller in the torque converter to thereby generate a second power via a first power transmission line; transmitting both the first power via the second power transmission line inserted in the same axis as that of the first power transmission line and the second power via the first power transmission line from the torque converter, to the transmission system; transmitting the second power to a sun gear of a transmission system via the second power transmission line to thereby revolve first and second planetary gears; transmitting the first power to a first bevel gear via the second power transmission line to thereby rotate the first and second planetary gears in the direction opposing the revolutional direction via a second bevel gear, a worm gear support shaft, first and second worm gears, and first and second worm wheels; and decelerating the number of rotations from the number of revolutions applied to the first and second planetary gears, for generating a variable transmission output via a carrier, wherein a torque conversion is accomplished between the torque converter and the transmission system until a load applied to the output of the transmission system and the rotational force transmitted to the output end are in equilibrium, and wherein the rotational force of the output of the transmission system for keeping the balance between the load and the rotational force is determined as a value obtained by multiplying an increased rotational force of the transmission system by an increased rotational force of the torque converter.