Planetary gear train of automatic transmission for vehicles

This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0058304, filed on May 10, 2017, which is incorporated herein by reference in its entirety.

The present disclosure relates to a planetary gear train of an automatic transmission for vehicles that can improve a power delivery performance and fuel consumption and linearity of gear shifts stages.

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

In general, in an automatic transmission field, a research of a multistage of gear shifts has been performed to reduce fuel consumption and improve drivability of a vehicle.

The multistage of gear shift stages of such an automatic transmission is desired to increase a power performance and driving efficiency while downsizing an engine.

However, as a gear shift stage increases, the number of components of an automatic transmission increases and thus a mounting capability, a cost, a weight, and transfer efficiency are undermined.

Therefore, in order to increase a fuel efficiency through a multistage, a planetary gear train has been developed to enhance power efficiency with reduced components.

Nowadays, an 8-speed automatic transmission has been developed to implement gear shift stages of an 8-speed or more by utilizing a planetary gear train.

However, we have discovered that, in an 8-speed automatic transmission, because a shift span of a gear shift ratio (a factor for securing linearity of interstage ratios) is maintained in a level of 6.5-7.5, an enhancement effect of a power performance and fuel consumption with a downsized engine is below a desired level of efficiency.

Further, when a shift span rises to a level above 9.0, the 8-speed automatic transmission is disadvantage in securing linearity of the ratios between gear shift stages (i.e., interstage ratios).

The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

The present disclosure provides a planetary gear train of an automatic transmission for a vehicle having advantages of being capable of improving power delivery efficiency and fuel consumption by reducing a drag loss of a clutch and a brake by applying only six coupling elements instead of applying five planetary gear sets while implementing gear shift stages for ten forward speeds and one reverse speed.

The present disclosure has been made in an effort to further provide a planetary gear train of an automatic transmission for a vehicle having advantages of being capable of enhancing torque transfer efficiency and durability by decreasing torque allotment of each planetary gear set and each coupling element by applying a torque parallel method to an output side planetary gear set.

In addition, the present disclosure further provides a planetary gear train of an automatic transmission with an excellent linearity of interstage ratios by increasing flexibility of an output gear ratio by applying five planetary gear sets in order to implement gear shift stages for ten forward speeds and one reverse speed.

In one form of the present disclosure, a planetary gear train of an automatic transmission for a vehicle includes: an input shaft that receives power of an engine; an output shaft that outputs power; a first planetary gear set having first, second, and third rotation elements; a second planetary gear set having fourth, fifth, and sixth rotation elements; a third planetary gear set having seventh, eighth, and ninth rotation elements; a fourth planetary gear set having tenth, eleventh, and twelfth rotation elements; a fifth planetary gear set having thirteenth, fourteenth, and fifteenth rotation elements; a first shaft that is connected with the second rotation element and the input shaft; a second shaft that is connected with the fourteenth rotation element and the output shaft; a third shaft that is connected with the sixth rotation element and the thirteenth rotation element; a fourth shaft that is connected with the seventh rotation element and the fifteenth rotation element; a fifth shaft that is connected with the first rotation element, the fourth rotation element, and the twelfth rotation element; a sixth shaft that is connected with the third rotation element and the eleventh rotation element; a seventh shaft that is connected with the fifth rotation element and the eighth rotation element; an eighth shaft that is connected with the tenth rotation element; and a ninth shaft that is connected with the ninth rotation element.

The planetary gear train may include six coupling elements that selectively connect shafts selected from the nine shafts to each other or a corresponding shaft selected from the nine shafts to a transmission housing, and three coupling elements selected from the six elements are controlled to implement a forward speed stage or a reverse speed stage.

The six coupling elements may include: three clutches that connect two shafts of the nine shafts; and three brakes that selectively connect the transmission housing and the corresponding shaft that is not connected with the input shaft or the output shaft.

The six coupling elements may include: a first clutch that is disposed between the second shaft and the fifth shaft; a second clutch that is disposed between the sixth shaft and the seventh shaft; a third clutch that is disposed between the seventh shaft and the eighth shaft; a first brake that is disposed between the fourth the shaft and the transmission housing; a second brake that is disposed between the ninth shaft and the transmission housing; and a third brake that is disposed between the eighth shaft and the transmission housing.

The first, second, and third rotation elements may be respectively a first sun gear, a first planetary carrier, and a first ring gear, the fourth, fifth, and sixth rotation elements may be respectively a second sun gear, a second planetary carrier, and a second ring gear, the seventh, eighth, and ninth rotation elements may be respectively a third sun gear, a third planetary carrier, and a third ring gear, the tenth, eleventh, and twelfth rotation elements may be respectively a fourth sun gear, a fourth planetary carrier, and a fourth ring gear, and the thirteenth, fourteenth, and fifteenth rotation elements may be respectively a fifth sun gear, a fifth planetary carrier, and a fifth ring gear.

The first, second, third, fourth, and fifth planetary gear sets may be disposed in order of the fourth, first, second, third, and fifth planetary gear sets from an engine side and may be disposed in order of the fourth, first, third, fifth and second planetary gear sets from the engine side.

According to an exemplary form of the present disclosure, by combining five planetary gear sets that are formed with a simple planetary gear set with six coupling elements, ten forward speed gear shift stages and one reverse speed gear shift stage can be implemented.

Further, by securing a shift span of 9.8 or more, engine driving efficiency can be improved and linearity of gear shift stages (e.g., interstage ratios) can be secured and thus drivability (such as acceleration before and after gear shifts) and a sense of rhythm of an engine speed can be improved.

Further, while implementing gear shift stages for ten forward speeds and one reverse speed, by reducing a drag loss of a clutch and a brake by limiting application of a coupling element instead of applying five planetary gear sets, power delivery efficiency and fuel consumption can be improved.

Further, by uniformly distributing an allotment torque of each planetary gear set and each coupling element by applying a torque parallel method to an output side planetary gear set, torque transfer efficiency and durability can be enhanced.

Further, by increasing flexibility of an output gear ratio while applying five planetary gear sets, the planetary gear train provides excellent linearity of gear shift stages for ten forward speed and one reverse speed stages.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a planetary gear train according to a first exemplary form of the present disclosure;

FIG. 2 is a table illustrating operation of a gear shift stage by control elements applied to a planetary gear train according to a first exemplary form of the present disclosure; and

FIG. 3 is a schematic diagram illustrating a planetary gear train according to a second form of the present disclosure.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

Hereinafter, an exemplary form of the present disclosure will be described in detail with reference to the accompanying drawings.

The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the present disclosure.

In the following description, terms such as a first and a second used in names of constituent elements are used for distinguishing constituent elements having the same name and do not limit order thereof.

Further, as used herein, description of elements being “fixedly” connected or interconnected includes elements that are directly connected, i.e. one element directly connected to another element for rotation therewith.

FIG. 1 is a schematic diagram illustrating a planetary gear train in a first exemplary form of the present disclosure.

Referring to FIG. 1 , a planetary gear train includes: first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 that are disposed on the same shaft line; an input shaft IS; an output shaft OS; nine shafts TM 1 -TM 9 that connect each rotation element of the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 ; three clutches C 1 -C 3 , which are a coupling element; three brakes B 1 -B 3 ; and a transmission housing H.

Rotation power from an engine that is input to the input shaft IS is shifted by a mutual compensation operation of the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 to be output through the output shaft OS.

In a first exemplary form of the present disclosure, each planetary gear set is disposed in order of fourth, first, second, third, and fifth planetary gear sets PG 4 , PG 1 , PG 2 , PG 3 , and PG 5 from the engine side.

The input shaft IS is an input member, and rotation power from a crankshaft of the engine may convert a torque through a torque converter to be input.

The output shaft OS is an output member and may be disposed on the same shaft line as that of the input shaft IS to deliver a shifted driving torque to a drive shaft through a differential apparatus.

The first planetary gear set PG 1 is a single pinion planetary gear set and includes a first sun gear S 1 , which is a first rotation element N 1 , a first planetary carrier PC 1 , which is a second rotation element N 2 that supports to rotate and revolve a plurality of first pinion gears P 1 that are circumscribed engaged in a radial equal gap at the external circumference side of the first sun gear S 1 , and a first ring gear R 1 , which is a third rotation element N 3 that is inscribed engaged with the plurality of first pinion gears P 1 to be power connected with the first sun gear S 1 .

The second planetary gear set PG 2 is a single pinion planetary gear set and includes a second sun gear S 2 , which is a fourth rotation element N 4 , a second planetary carrier PC 2 , which is a fifth rotation element N 5 that supports to rotate and revolve a plurality of second pinion gears P 2 that are circumscribed engaged in a radial equal gap at the external circumference side of the second sun gear S 2 , and a second ring gear R 2 , which is a sixth rotation element N 6 that is inscribed engaged with the plurality of second pinion gears P 2 to be power connected with the second sun gear S 2 .

The third planetary gear set PG 3 is a single pinion planetary gear set and includes a third sun gear S 3 , which is a seventh rotation element N 7 , a third planetary carrier PC 3 , which is an eighth rotation element N 8 that supports to rotate and revolve a plurality of third pinion gears P 3 that are circumscribed engaged in a radial equal gap at the external circumference side of the third sun gear S 3 , and a third ring gear R 3 , which is a ninth rotation element N 9 that is inscribed engaged with the plurality of third pinion gears P 3 to be power connected with the third sun gear S 3 .

The fourth planetary gear set PG 4 is a single pinion planetary gear set and includes a fourth sun gear S 4 , which is a tenth rotation element N 10 , a fourth planetary carrier PC 4 , which is an eleventh rotation element N 11 that supports to rotate and revolve a plurality of fourth pinion gears P 4 that are circumscribed engaged in a radial equal gap at the external circumference side of the fourth sun gear S 4 , and a fourth ring gear R 4 , which is a twelfth rotation element N 12 that is inscribed engaged with the plurality of fourth pinion gears P 4 to be power connected with the fourth sun gear S 4 .

The fifth planetary gear set PG 5 is a single pinion planetary gear set and includes a fifth sun gear S 5 , which is a thirteenth rotation element N 13 , a fifth planetary carrier PC 5 , which is an fourteenth rotation element N 14 that supports to rotate and revolve a plurality of fifth pinion gears P 5 that are circumscribed engaged in a radial equal gap at the external circumference side of the fifth sun gear S 5 , and a fifth ring gear R 5 , which is a fifteenth rotation element N 15 that is inscribed engaged with the plurality of fifth pinion gears P 5 to be power connected with the fifth sun gear S 5 .

Here, because the first rotation element N 1 , the fourth rotation element N 4 , and the twelfth rotation element N 12 are directly connected to each other, the third rotation element N 3 and the eleventh rotation element N 11 are directly connected to each other, the fifth rotation element N 5 and the eighth rotation element N 8 are directly connected to each other, the sixth rotation element N 6 and the thirteenth rotation element N 13 are directly connected to each other, and the seventh rotation element N 7 and the fifteenth rotation element N 15 are directly connected to each other, the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 operate while having total nine shafts TM 1 -TM 9 .

A configuration of the nine shafts TM 1 -TM 9 is described in detail as follows.

The nine shafts TM 1 -TM 9 may be a rotation member that delivers power while rotating together with rotation elements of the planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 . The nine shafts may directly connect or selectively connect a plurality of rotation elements among the rotation elements of the planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 and may be a rotation member that selectively connects the rotation element to a transmission housing H or may be a fixing member that directly connects and fixes the rotation element to the transmission housing H.

The first shaft TM 1 is connected with the second rotation element (N 2 ; first planetary carrier PC 1 ) and is directly connected with the input shaft IS to always operate as an input element.

The second shaft TM 2 is connected, and preferably fixedly connected, with the fourteenth rotation element {N 14 : fifth planetary carrier PC 5 } and is directly connected with the output shaft OS to always operate as an output element.

The third shaft TM 3 is connected, and preferably fixedly connected, with the sixth rotation element {N 6 : second ring gear R 2 } and the thirteenth rotation element {N 13 ; fifth sun gear S 5 }.

The fourth shaft TM 4 is connected, and preferably fixedly connected, with the seventh rotation element {N 7 ; third sun gear S 3 } and the fifteenth rotation element {N 15 ; fifth ring gear R 5 }.

The fifth shaft TM 5 is connected, and preferably fixedly connected, with the first rotation element {N 1 ; first sun gear S 1 }, the fourth rotation element {N 4 ; second sun gear S 2 }, and the twelfth rotation element {N 12 ; fourth ring gear R 4 }.

The sixth shaft TM 6 is connected, and preferably fixedly connected, with the third rotation element {N 3 : first ring gear R 1 } and the eleventh rotation element {N 11 ; fourth planetary carrier PC 4 }.

The seventh shaft TM 7 is connected, and preferably fixedly connected, with the fifth rotation element {N 5 ; second planetary carrier PC 2 } and the eighth rotation element {N 8 ; third planetary carrier PC 3 }.

The eighth shaft TM 8 is connected, and preferably fixedly connected, with the tenth rotation element {N 10 : fourth sun gear S 4 }.

The ninth shaft TM 9 is connected, and preferably fixedly connected, with the ninth rotation element {N 9 ; third ring gear R 3 }.

Here, the second shaft TM 2 is selectively connected with the fifth shaft TM 5 to be power connected with the fifth shaft TM 5 , and the sixth shaft TM 6 and the eighth shaft TM 8 each are selectively connected with the seventh shaft TM 7 to be power connected with the seventh shaft TM 7 .

Further, the fourth shaft TM 4 , the ninth shaft TM 9 , and the eighth shaft TM 8 operate as a selective fixed element while being selectively connected with the transmission housing H.

Among the nine shafts TM 1 -TM 9 , in a portion including the input shaft IS and the output shaft OS and that mutually selectively connects shafts, clutches C 1 , C 2 , and C 3 , which are three coupling elements, are disposed.

Further, among the nine shafts TM 1 -TM 9 , in a portion in which the shaft and the transmission housing H are selectively connected, brakes B 1 , B 2 , and B 3 , which are three coupling elements, are disposed.

Here, the three clutches C 1 -C 3 and three brakes B 1 -B 3 , which are the six coupling elements, are described as follows.

The first clutch C 1 is disposed between the second shaft TM 2 and the fifth shaft TM 5 to selectively connect the second shaft TM 2 and the fifth shaft TM 5 , thereby delivering power.

The second clutch C 2 is disposed between the sixth shaft TM 6 and the seventh shaft TM 7 to selectively connect the sixth shaft TM 6 and the seventh shaft TM 7 , thereby delivering power.

The third clutch C 3 is disposed between the seventh shaft TM 7 and the eighth shaft TM 8 to selectively connect the seventh shaft TM 7 and the eighth shaft TM 8 , thereby delivering power.

The second brake B 1 is disposed between the fourth shaft TM 4 and the transmission housing H to selectively connect and fix the fourth shaft TM 4 to the transmission housing H.

The second brake B 2 is disposed between the ninth shaft TM 9 and the transmission housing H to selectively connect and fix the ninth shaft TM 9 to the transmission housing H.

The third brake B 3 is disposed between the eighth shaft TM 8 and the transmission housing H to selectively connect and fix the eighth shaft TM 8 to the transmission housing H.

Here, coupling elements that are formed with the first, second, and third clutches C 1 , C 2 , and C 3 and the first, second, and third brakes B 1 , B 2 , and B 3 may be formed with a multiplate type hydraulic friction coupling unit that operates by a hydraulic pressure that is supplied from a hydraulic control apparatus, and a wet multiplate type hydraulic friction coupling unit is generally used, but the coupling elements may be formed with a coupling unit that may be operated according to an electrical signal that is supplied from an electronic control apparatus such as a dog clutch, an electronic clutch, and a magnetic particle clutch.

FIG. 2 is a table illustrating operation of a gear shift stage by control elements applied to a planetary gear train according to a first exemplary form of the present disclosure.

Referring to FIG. 2 , in each gear shift stage of the planetary gear train according to a first exemplary form of the present disclosure, three elements operate among the first, second, and third clutches C 1 , C 2 , and C 3 and the first, second, and third brakes B 1 , B 2 , and B 3 , which are coupling elements, to provide ten forward speed stages and one reverse speed stage. the shifting process of the speed stages is described as follows.

In a forward one-speed gear shift stage D 1 , the second clutch C 2 and the first and third brakes B 1 and B 3 simultaneously operate.

Accordingly, in a state in which the sixth shaft TM 6 is connected with the seventh shaft TM 7 by an operation of the second clutch C 2 , an input to the first shaft TM 1 is performed.

In the input state, while the fourth and eighth shafts TM 4 and TM 8 operate as a fixed element by operation of the first and third brakes B 1 and B 3 , shifting to a forward one-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward two-speed gear shift stage D 2 , the second and third clutches C 2 and C 3 and the first brake B 1 simultaneously operate.

Accordingly, in a state in which the sixth shaft TM 6 is connected with the seventh shaft TM 7 by an operation of the second clutch C 2 and in which the seventh shaft TM 7 is connected with the eights shaft TM 8 by an operation of the third clutch C 3 , an input is performed to the first shaft TM 1 .

In the input state, while the fourth shaft TM 4 operates as a fixed element by operation of the first brake B 1 , shifting to a forward two-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward three-speed gear shift stage D 3 , the first and second clutches C 1 and C 2 and the first brake B 1 simultaneously operate.

Accordingly, in a state in which the second shaft TM 2 is connected with the fifth shaft TM 5 by an operation of the first clutch C 1 and in which the six shaft TM 6 is connected with the seventh shaft TM 7 by an operation of the second clutch C 2 , an input is performed to the first shaft TM 1 .

In the input state, while the fourth shaft TM 4 operates as a fixed element by operation of the first brake B 1 , shifting to a forward three-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward four-speed gear shift stage D 4 , the first and third clutches C 1 and C 3 and the first brake B 1 simultaneously operate.

Accordingly, in a state in which the second shaft TM 2 is connected with the fifth shaft TM 5 by operation of the first clutch C 1 and in which the seventh shaft TM 7 is connected with the eighth shaft TM 8 by operation of the third clutch C 3 , an input is performed to the first shaft TM 1 .

In the input state, while the fourth shaft TM 4 operates as a fixed element by operation of the first brake B 1 , shifting to a forward four-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward five-speed gear shift stage D 5 , the first, second, and third clutches C 1 , C 2 , and C 3 simultaneously operate.

Accordingly, in a state in which the second shaft TM 2 is connected with the fifth shaft TM 5 by operation of the first clutch C 1 and in which the sixth shaft TM 6 is connected with the seventh shaft TM 7 by operation of the second clutch C 2 and in which the seventh shaft TM 7 is connected with the eighth shaft TM 8 by operation of the third clutch C 3 , an input is performed to the first shaft TM 1 .

Therefore, the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 are integrally formed to be in a state of rotating in one, and when an input to the first shaft TM 1 is performed, shifting to a forward five-speed is performed in which an input becomes an output and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward six-speed gear shift stage D 6 , the first and third clutches C 1 and C 3 and the second brake B 2 simultaneously operate.

Accordingly, in a state in which the second shaft TM 2 is connected with the fifth shaft TM 5 by operation of the first clutch C 1 and in which the seventh shaft TM 7 is connected with the eighth shaft TM 8 by operation of the third clutch C 3 , an input is performed to the first shaft TM 1 .

In the input state, while the ninth shaft TM 9 operates as a fixed element by operation of the second brake B 2 , shifting to a forward six-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward seven-speed gear shift stage D 7 , the first clutch C 1 and the second and third brakes B 2 and B 3 simultaneously operate.

Accordingly, in a state in which the second shaft TM 2 is connected with the fifth shaft TM 5 by an operation of the first clutch C 1 , an input is performed to the first shaft TM 1 .

In the input state, while the ninth and eighth shafts TM 9 and TM 8 operate as a fixed element by operation of the second and third brakes B 2 and B 3 , shifting to a forward seven-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward eight-speed gear shift stage D 8 , the first and second clutches C 1 and C 2 and the second brake B 2 simultaneously operate.

Accordingly, in a state in which the second shaft TM 2 is connected with the fifth shaft TM 5 by operation of the first clutch C 1 and in which the sixth shaft TM 6 is connected with the seventh shaft TM 7 by operation of the second clutch C 2 , an input is performed to the first shaft TM 1 .

In the input state, while the ninth shaft TM 9 operates as a fixed element by operation of the second brake B 2 , shifting to a forward eight-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward nine-speed gear shift stage D 9 , the second clutch C 2 and the second and third brakes B 2 and B 3 simultaneously operate.

Accordingly, in a state in which the sixth shaft TM 6 is connected with the seventh shaft TM 7 by an operation of the second clutch C 2 , an input is performed to the first shaft TM 1 .

In the input state, while the ninth and eighth shafts TM 9 and TM 8 operate as a fixed element by operation of the second and third brakes B 2 and B 3 , shifting to a forward nine-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

In a forward ten-speed gear shift stage D 10 , the second and third clutches C 2 and C 3 and the second brake B 2 simultaneously operate.

Accordingly, in a state in which the sixth shaft TM 6 is connected with the seventh shaft TM 7 by operation of the second clutch C 2 and in which the seventh shaft TM 7 is connected with the eighth shaft TM 8 by operation of the third clutch C 3 , an input is performed to the first shaft TM 1 .

In the input state, while the ninth shaft TM 9 operates as a fixed element by operation of the second brake B 2 , shifting to a forward ten-speed is performed and thus an output is performed to the output shaft OS that is connected with the second shaft TM 2 .

Shifting to the reverse stage is performed according to three operation forms REV 1 , REV 2 , REV 3 .

In the REV 1 , the third clutch C 3 and the first and second brakes B 1 and B 2 simultaneously operate.

Accordingly, in a state in which the seventh shaft TM 7 is connected with the eighth shaft TM 8 by operation of the third clutch C 3 , an input is performed to the first shaft TM 1 .

In the input state, while the fourth and ninth shafts TM 4 and TM 9 operate as a fixed element by operation of the first and second brakes B 1 and B 2 , shifting to the reverse stage (i.e., REV 1 ) is performed and thus a reverse rotation is output to the output shaft OS that is connected with the second shaft TM 2 .

Further, in the REV 2 , the third clutch C 3 and the first and third brakes B 1 and B 3 simultaneously operate.

Accordingly, in a state in which the seventh shaft TM 7 is connected with the eighth shaft TM 8 by an operation of the third clutch C 3 , an input is performed to the first shaft TM 1 .

In the input state, while the fourth and eighth shafts TM 4 and TM 8 operate as a fixed element by operation of the first and third brakes B 1 and B 3 , shifting to the reverse stage (i.e., REV 2 ) is performed and thus a reverse rotation is output to the output shaft OS that is connected with the second shaft TM 2 .

Further, in the REV 3 , the first, second, and third brakes B 1 , B 2 , and B 3 simultaneously operate.

Accordingly, an input is performed to the first shaft TM 1 .

In the input state, while the fourth, ninth, and eighth shafts TM 4 , TM 9 , and TM 8 operate as a fixed element by operation of the first, second, and third brakes B 1 , B 2 , and B 3 , shifting to the reverse stage (i.e., REV 3 ) is performed and thus a reverse rotation is output to the output shaft OS that is connected with the second shaft TM 2 .

FIG. 3 is a schematic diagram illustrating a planetary gear train according to a second form of the present disclosure.

Referring to FIGS. 1 and 3 , in a planetary gear train according to a first exemplary form of the present disclosure, each planetary gear set is disposed in order of fourth, first, second, third, and fifth planetary gear sets PG 4 , PG 1 , PG 2 , PG 3 , and PG 5 from the engine side, but in a planetary gear train according to a second exemplary form of the present disclosure, each planetary gear set is disposed in order of fourth, first, third, fifth, and second planetary gear sets PG 4 , PG 1 , PG 3 , PG 5 , and PG 2 from the engine side and thus the planetary gear train according to the first exemplary form is different from the planetary gear train according to the second exemplary form.

The planetary gear train according to the second exemplary form is different only in a disposition configuration of the planetary gear sets from the planetary gear train according to the first exemplary form, but nine shafts TM 1 -TM 9 , which are major constituent elements, and entire connection relations of three clutches C 1 , C 2 , and C 3 and three brakes B 1 , B 2 , and B 3 , which are each coupling element, are the same, and thus operation and effect of an entire planetary gear train are the same.

The planetary gear train according to first and second exemplary forms of the present disclosure may realize a gear shift stages for ten forward speeds and one reverse speed by applying only six coupling elements that are formed with three clutches C 1 , C 2 , and C 3 and three brakes B 1 , B 2 , and B 3 instead of applying five planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 .

Further, because a shift span is secured to at least 9.8, engine driving efficiency can be improved, and by securing linearity of gear shift stages (i.e., interstage ratios) according to a multistage of high efficiency, drivability such as acceleration before and after shift and a sense of rhythm of an engine speed can be improved.

Further, even while implementing gear shift stages for ten forward speeds and one reverse speed, by reducing coupling elements such as a clutch and a brake which may cause a drag loss, power delivery efficiency and fuel consumption can be improved due to less drag loss.

Further, by uniformly distributing an allotment torque of each planetary gear set and each coupling element by applying a torque parallel method to an output side planetary gear set, torque transfer efficiency and durability can be improved.

Further, in order to implement gear shift stages for ten forward speeds and one reverse speed, five planetary gear sets are applied and thus flexibility of an output gear ratio can be increased and thus a planetary gear train of high efficiency having excellent linearity in an interstage ratio of a gear shift stage is provided.

While this present disclosure has been described in connection with what is presently considered to be practical example forms, it is to be understood that the present disclosure is not limited to the disclosed forms, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the present disclosure.