Planetary gear train of automatic transmission for vehicle

The present disclosure relates to an automatic transmission for a vehicle. More particularly, the present disclosure relates to a planetary gear train of an automatic transmission for a vehicle that improves power delivery performance and fuel economy.

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

Recently, increase of oil price has drawn the attention of the auto industry to develop a vehicle having high fuel efficiency.

As one approach, research for an automatic transmission has been made to provide better drivability and less fuel consumption by achieving more speed stages.

However, in the automatic transmission, as the number of speed stages increase, the number of internal components (particularly, planetary gear sets) increase, and as a result, a lengh of the transmission increases. Therefore, mountability, production cost, weight and power delivery efficiency may be deteriorated, in particular, in a case of a front wheel drive vehicle where an engine is laterally mounted.

Accordingly, development of a planetary gear train that improves efficiency with a small number of components may be provided in order to increase a fuel economy enhancement effect through the multiple speed stages.

In this aspect, in recent years, 8-speed automatic transmissions tend to be implemented and the research and development of a planetary gear train capable of implementing more speed stages has also been actively conducted.

However, a conventional 8-speed automatic transmission typically includes three to four planetary gear sets and five to six control elements (frictional elements). In this case, since the length of the automatic transmission increases, mountability in a front wheel drive vehicle may be deteriorated.

Recently, one planetary gear set is disposed above another planetary gear set, but structures of automatic transmissions to which parallel planetary gear sets is applied are very limited.

In another way, dog clutches instead of control elements of wet-type are used. However, shift feel can be undermined.

In addition, since a conventional 8-speed automatic transmission has gear ratio span of 6.5-7.5, we have discovered that improvement of power performance and fuel economy may be minimal.

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 achieving at least ten forward speed stages and one reverse speed stage by disposing four planetary gear sets separately on an input shaft and an output shaft disposed in parallel to each other and apart from each other and combining the four planetary gear sets with two external gears and seven control elements. Therefore, power delivery performance and fuel consumption may be improved due to multiple speed stages, and mountability may be improved by shortening a length of the automatic transmission.

Another form of the present disclosure provides a planetary gear train of an automatic transmission for a vehicle having further advantages of setting optimal gear ratios by freely changing teeth numbers of external gears. Therefore, power delivery performance and fuel consumption may further improved.

A planetary gear train of an automatic transmission for a vehicle according to an exemplary form of the present disclosure may include: a first planetary gear set including first, second, and third rotation elements; a second planetary gear set including fourth, fifth, and sixth rotation elements; a third planetary gear set including seventh, eighth, and ninth rotation elements; a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements; an input shaft, the first, second, and third planetary gear sets being disposed at a radial outer of the input shaft; an output shaft disposed in parallel to the input shaft, the fourth planetary gear set being disposed at a radial outer of the outer shaft; a first shaft directly connected to the first rotation element; a second shaft directly connecting the second rotation element to the fourth rotation element and being connected to the input shaft; a third shaft directly connected to the third rotation element; a fourth shaft directly connected to the fifth rotation element; a fifth shaft directly connecting the sixth rotation element to the eighth rotation element; a sixth shaft directly connected to the seventh rotation element; a seventh shaft directly connected to the ninth rotation element; an eighth shaft directly connected to the tenth rotation element, the eighth shaft connected to one of the third and seventh shafts through a first transfer gear; a ninth shaft directly connected to the eleventh rotation element and the output shaft; and a tenth shaft directly connected to the twelfth rotation element, the tenth shaft connected to the other of the third and seventh shafts through a second transfer gear.

The first shaft may be selectively connected to a transmission housing, the fourth shaft may be selectively connected to the third shaft, the fifth shaft may be selectively connected to the transmission housing, the sixth shaft may be selectively connected to the first shaft or the second shaft, and the seventh shaft may be selectively connected to the fourth shaft.

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

In some aspects, the eighth shaft may be connected to the third shaft through the second transfer gear, the tenth shaft may be connected to the seventh shaft through the first transfer gear, and the seventh and tenth shafts may be selectively connected to the transmission housing.

In one aspect, the planetary gear train may further include: a first clutch disposed between the second shaft and the sixth shaft; a second clutch disposed between the third shaft and the fourth shaft; a third clutch disposed between the fourth shaft and the seventh shaft; a fourth clutch disposed between the first shaft and the sixth shaft; a first brake disposed between the fifth shaft and the transmission housing; a second brake disposed between the seventh shaft and the transmission housing; and a third brake disposed between the first shaft and the transmission housing.

In another aspect, the planetary gear train may further include: a first clutch disposed between the second shaft and the sixth shaft; a second clutch disposed between the third shaft and the fourth shaft; a third clutch disposed between the fourth shaft and the seventh shaft; a fourth clutch disposed between the first shaft and the sixth shaft; a first brake disposed between the fifth shaft and the transmission housing; a second brake disposed between the tenth shaft and the transmission housing; and a third brake disposed between the first shaft and the transmission housing.

In some aspects, the eighth shaft may be connected to the seventh shaft through the first transfer gear, the seventh and eighth shafts may be selectively connected to the transmission housing, and the tenth shaft may be connected to the third shaft through the second transfer gear.

In one aspect, the planetary gear train may further include: a first clutch disposed between the second shaft and the sixth shaft; a second clutch disposed between the third shaft and the fourth shaft; a third clutch disposed between the fourth shaft and the seventh shaft; a fourth clutch disposed between the first shaft and the sixth shaft; a first brake disposed between the fifth shaft and the transmission housing; a second brake disposed between the seventh shaft and the transmission housing; and a third brake disposed between the first shaft and the transmission housing.

In another aspect, the planetary gear train may further include: a first clutch disposed between the second shaft and the sixth shaft; a second clutch disposed between the third shaft and the fourth shaft; a third clutch disposed between the fourth shaft and the seventh shaft; a fourth clutch disposed between the first shaft and the sixth shaft; a first brake disposed between the fifth shaft and the transmission housing; a second brake disposed between the eighth shaft and the transmission housing; a third brake disposed between the first shaft and the transmission housing.

A planetary gear train of an automatic transmission for a vehicle according to another exemplary form of the present disclosure may include: a first planetary gear set including first, second, and third rotation elements; a second planetary gear set including fourth, fifth, and sixth rotation elements; a third planetary gear set including seventh, eighth, and ninth rotation elements; a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements; an input shaft, the first, second, and third planetary gear sets being disposed at a radial outer of the input shaft; and an output shaft disposed in parallel to the input shaft, the fourth planetary gear set being disposed at a radial outer of the outer shaft, wherein the first rotation element is selectively connected to a transmission housing, the second rotation element is directly connected to the fourth rotation element and the input shaft, the sixth rotation element is directly connected to the eighth rotation element and is selectively connected to the transmission housing, the eleventh rotation element is directly connected to the output shaft, the third rotation element is connected to one of the tenth rotation element and the twelfth rotation element, and the ninth rotation element is connected to the other of the tenth rotation element and the twelfth rotation element and is selectively connected to the transmission housing.

The fourth rotation element may be selectively connected to the seventh rotation element, the third rotation element may be selectively connected to the fifth rotation element, the fifth rotation element may be selectively connected to the ninth rotation element, and the first rotation element may be selectively connected to the seventh rotation element.

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

In some aspects, the ninth rotation element may be connected to the twelfth rotation element through a first transfer gear, and the third rotation element may be connected to the tenth rotation element through a second transfer gear.

In one aspect, the planetary gear train may further include: a first clutch selectively connecting the fourth rotation element to the seventh rotation element; a second clutch selectively connecting the third rotation element to the fifth rotation element; a third clutch selectively connecting the fifth rotation element to the ninth rotation element; a fourth clutch selectively connecting the first rotation element to the seventh rotation element; a first brake selectively connecting the eighth rotation element to the transmission housing; a second brake selectively connecting the ninth rotation element to the transmission housing; and a third brake selectively connecting the first rotation element to the transmission housing.

In another aspect, the planetary gear train may further include: a first clutch selectively connecting the fourth rotation element to the seventh rotation element; a second clutch selectively connecting the third rotation element to the fifth rotation element; a third clutch selectively connecting the fifth rotation element to the ninth rotation element; a fourth clutch selectively connecting the first rotation element to the seventh rotation element; a first brake selectively connecting the eighth rotation element to the transmission housing; a second brake selectively connecting the twelfth rotation element to the transmission housing; and a third brake selectively connecting the first rotation element to the transmission housing.

In some aspects, the ninth rotation element may be connected to the tenth rotation element through a first transfer gear, and the third rotation element may be connected to the twelfth rotation element through a second transfer gear.

In one aspect, the planetary gear train may further include: a first clutch selectively connecting the fourth rotation element to the seventh rotation element; a second clutch selectively connecting the third rotation element to the fifth rotation element; a third clutch selectively connecting the fifth rotation element to the ninth rotation element; a fourth clutch selectively connecting the first rotation element to the seventh rotation element; a first brake selectively connecting the eighth rotation element to the transmission housing; a second brake selectively connecting the ninth rotation element to the transmission housing; and a third brake selectively connecting the first rotation element to the transmission housing.

In another aspect, the planetary gear train may further include: a first clutch selectively connecting the fourth rotation element to the seventh rotation element; a second clutch selectively connecting the third rotation element to the fifth rotation element; a third clutch selectively connecting the fifth rotation element to the ninth rotation element; a fourth clutch selectively connecting the first rotation element to the seventh rotation element; a first brake selectively connecting the eighth rotation element to the transmission housing; a second brake selectively connecting the tenth rotation element to the transmission housing; and a third brake selectively connecting the first rotation element to the transmission housing.

According to the exemplary forms of the present disclosure, a length of the automatic transmission may be shortened and mountability may be improved by disposing four planetary gear sets on the input shaft and the output shaft disposed in parallel with each other and apart from each other.

Since two transfer gears in addition to the planetary gear sets are used according to the exemplary forms of the present disclosure, optimal gear ratios may be set. Therefore, gear ratios may be changed according to demanded performance condition, starting performance may be improved, and a starting clutch instead of a conventional torque converter may be used.

The planetary gear train according to the exemplary forms of the present disclosure can secure gear ratio span greater than approximately 9.0 as well as achieve at least ten forward speed stages and one reverse speed stage. Therefore, driving efficiency of the engine may be improved.

In addition, since linearity of step ratios can be secured due to multiple speed stages, drivability such as acceleration before and after shift, continuous and smooth engine speed changes, and so on may be improved.

Other effects obtainable or predictable from an exemplary form of the present disclosure will be explicitly or implicitly described in a DETAILED DESCRIPTION section.

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 of a planetary gear train according to the first exemplary form of the present disclosure;

FIG. 2 is one example of an operation chart of control elements at each speed stage in the planetary gear train according to the first exemplary form of the present disclosure;

FIG. 3 is another example of an operation chart of control elements at each speed stage in the planetary gear train according to the first exemplary form of the present disclosure;

FIG. 4 is a schematic diagram of a planetary gear train according to a second exemplary form of the present disclosure;

FIG. 5 is a schematic diagram of a planetary gear train according to a third exemplary form of the present disclosure; and

FIG. 6 is a schematic diagram of a planetary gear train according to a fourth exemplary 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.

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

As those skilled in the art would realize, the described forms may be modified in various different ways, all without departing from the spirit or scope of the present disclosure.

Parts which are not related with the description are omitted for clearly describing the exemplary forms of the present disclosure.

In the following description, dividing names of components into first, second, and the like is to divide the names because the names of the components are the same as each other and an order thereof is not particularly limited.

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

Referring to FIG. 1 , a planetary gear train includes: an input shaft IS; an output shaft OS; first, second, third, and fourth planetary gear sets (PG 1 , PG 2 , PG 3 , and PG 4 ); two transfer gears (TF 1 and TF 2 ); and control elements including four clutches (C 1 , C 2 , C 3 , and C 4 ) and three brakes (B 1 , B 2 , and B 3 ).

The input shaft IS is an input member receiving torque from a crankshaft of an engine, after being torque-converted through a torque converter.

The output shaft OS is an output member, which is disposed in parallel with and apart from the input shaft IS, and transmits driving torque to a driving wheel through a differential apparatus.

The first, second, and third planetary gear set PG 1 , PG 2 , and PG 3 are disposed at a radial outer of the input shaft IS and embody a main shifting portion. The fourth planetary gear set PG 4 is disposed at a radial outer of the output shaft OS disposed in parallel with and apart from the input shaft IS and embodies an auxiliary shifting portion.

The first planetary gear set PG 1 is a single pinion planetary gear set and includes a first sun gear S 1 , a first planet carrier PC 1 rotatably supporting a first pinion P 1 that is externally meshed with the first sun gear S 1 , and a first ring gear R 1 that is internally meshed with the first pinion P 1 respectively as first, second, and third rotation elements N 1 , N 2 , and N 3 .

The second planetary gear set PG 2 is a single pinion planetary gear set and includes a second sun gear S 2 , a second planet carrier PC 2 rotatably supporting a second pinion P 2 that is externally meshed with the second sun gear S 2 , and a second ring gear R 2 that is internally meshed with the second pinion P 2 respectively as fourth, fifth, and sixth rotation elements N 4 , N 5 , and N 6 .

The third planetary gear set PG 3 is a single pinion planetary gear set and includes a third sun gear S 3 , a third planet carrier PC 3 rotatably supporting a third pinion P 3 that is externally meshed with the third sun gear S 3 , and a third ring gear R 3 that is internally meshed with the third pinion P 3 respectively as seventh, eighth, and ninth rotation elements N 7 , N 8 , and N 9 .

The fourth planetary gear set PG 4 is a single pinion planetary gear set and includes a fourth sun gear S 4 , a fourth planet carrier PC 4 rotatably supporting a fourth pinion P 4 that is externally meshed with the fourth sun gear S 4 , and a fourth ring gear R 4 that is internally meshed with the fourth pinion P 4 respectively as tenth, eleventh, and twelfth rotation elements N 10 , N 11 , and N 12 .

The second rotation element N 2 is directly connected with the fourth rotation element N 4 and the sixth rotation element N 6 is directly connected with the eighth rotation element N 8 such that the first, second, and third planetary gear sets PG 1 , PG 2 , and PG 3 include seven shafts TM 1 to TM 7 .

The rotation elements of the fourth planetary gear set PG 4 operate independently from each other and embody three shafts TM 8 to TM 10 .

The ten shafts TM 1 to TM 10 will be described in detail.

The first shaft TM 1 is directly connected to the first rotation element N 1 (first sun gear S 1 ) and is selectively connected to the transmission housing H so as to be operated as a selective fixed element.

The second shaft TM 2 directly connects the second rotation element N 2 (first planet carrier PC 1 ) to the fourth rotation element N 4 (second sun gear S 2 ), and is connected to the input shaft IS.

The third shaft TM 3 is directly connected to the third rotation element N 3 (first ring gear R 1 ).

The fourth shaft TM 4 is directly connected to the fifth rotation element N 5 (second planet carrier PC 2 ) and is selectively connected to the third shaft TM 3 .

The fifth shaft TM 5 directly connects the sixth rotation element N 6 (second ring gear R 2 ) to the eighth rotation element N 8 (third planet carrier PC 3 ), and is selectively connected to the transmission housing H so as to be operated as a selective fixed element.

The sixth shaft TM 6 is directly connected to the seventh rotation element N 7 (third sun gear S 3 ) and is selectively connected to the first shaft TM 1 or the second shaft TM 2 .

The seventh shaft TM 7 is directly connected to the ninth rotation element N 9 (third ring gear R 3 ), is selectively connected to the fourth shaft TM 4 , and is selectively connected with the transmission housing H so as to be operated as a selective fixed element.

The eighth shaft TM 8 is directly connected to the tenth rotation element N 10 (fourth sun gear S 4 ) and is connected to the third shaft TM 3 through an external gear.

The ninth shaft TM 9 is directly connected to the eleventh rotation element N 11 (fourth planet carrier PC 4 ) and is also directly connected to the output shaft OS so as to be continuously operated as an output element.

The tenth shaft TM 9 is directly connected to the twelfth rotation element N 12 (fourth ring gear R 4 ) and is connected to the seventh shaft TM 7 through another external gear.

The two transfer gears (i.e., TF 1 and TF 2 ) transmit torque changed by the first, second, and third planetary gear sets PG 1 , PG 2 , and PG 3 forming the main shifting portion to the fourth planetary gear set PG 4 forming the auxiliary shifting portion as an inverse rotation speed according to gear ratios of the two transfer gears TF 1 and TF 2 .

The first transfer gear TF 1 includes a first transfer drive gear TF 1 a directly connected with the seventh shaft TM 7 and a first transfer driven gear TF 1 b directly connected with the tenth shaft TM 10 . Therefore, the first transfer gear TF 1 connects the seventh shaft TM 7 with the tenth shaft TM 10 . The seventh shaft TM 7 and the tenth shaft TM 10 connected by the first transfer gear TF 1 rotate in opposite directions with each other.

The second transfer gear TF 2 includes a second transfer drive gear TF 2 a directly connected with the third shaft TM 3 and a second transfer driven gear TF 2 b directly connected with the eighth shaft TM 8 . Therefore, the second transfer gear TF 2 connects the third shaft TM 3 with the eighth shaft TM 8 . The third shaft TM 3 and the eighth shaft TM 8 connected by the second transfer gear TF 2 rotate in opposite directions to each other.

The gear ratios of the first and second transfer gears TF 1 and TF 2 can be set according to gear ratios demanded at each speed stages.

Arrangement of the control elements including the four clutches C 1 , C 2 , C 3 , and C 4 and the three brakes B 1 , B 2 , and B 3 will be described in detail.

The first clutch C 1 is disposed between the second shaft TM 2 and the sixth shaft TM 6 and selectively connects the second shaft TM 2 with the sixth shaft TM 6 .

The second clutch C 2 is disposed between the third shaft TM 3 and the fourth shaft TM 4 and selectively connects the third shaft TM 3 with the fourth shaft TM 4 .

The third clutch C 3 is disposed between the fourth shaft TM 4 and the seventh shaft TM 7 and selectively connects the fourth shaft TM 4 with the seventh shaft TM 7 .

The fourth clutch C 4 is disposed between the first shaft TM 1 and the sixth shaft TM 6 and selectively connects the first shaft TM 1 with the sixth shaft TM 6 .

The first brake B 1 is disposed between the fifth shaft TM 5 and the transmission housing H and selectively connects the fifth shaft TM 5 with the transmission housing H to be operated as the selective fixed element.

The second brake B 2 is disposed between the seventh shaft TM 7 and the transmission housing H and selectively connects the seventh shaft TM 7 with the transmission housing H to be operated as the selective fixed element.

The third brake B 3 is disposed between the first shaft TM 1 and the transmission housing H and selectively connects the first shaft TM 1 with the transmission housing H to be operated as the selective fixed element.

The control elements including the first, second, third, and fourth clutches C 1 , C 2 , C 3 , and C 4 and the first, second, and third brakes B 1 , B 2 , and B 3 may be multi-plates friction elements of wet type that are operated by hydraulic pressure.

FIG. 2 is one example of an operation chart of control elements at each speed stage in the planetary gear train according to the first exemplary form of the present disclosure.

As shown in FIG. 2 , three control elements among the first, second, third, and fourth clutches C 1 , C 2 , C 3 , and C 4 and the first, second, and third brakes B 1 , B 2 , and B 3 are operated at each speed stage in the planetary gear train according to the first exemplary form of the present disclosure.

First Forward Speed Stage:

The first and second clutches C 1 and C 2 and the second brake B 2 are operated at a first forward speed stage D 1 .

In a state that the second shaft TM 2 is connected with the sixth shaft TM 6 by operation of the first clutch C 1 and the third shaft TM 3 is connected with the fourth shaft TM 4 by operation of the second clutch C 2 , torque of the input shaft IS is input into the second shaft TM 2 . In addition, the seventh shaft TM 7 is operated as the fixed element by operation of the second brake B 2 . Therefore, the torque of the input shaft IS is shifted into the first forward speed stage, and the first forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Second Forward Speed Stage:

The second and fourth clutches C 2 and C 4 and the second brake B 2 are operated at a second forward speed stage D 2 .

In a state that the third shaft TM 3 is connected with the fourth shaft TM 4 by operation of the second clutch C 2 and the first shaft TM 1 is connected with the sixth shaft TM 6 by operation of the fourth clutch C 4 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the seventh shaft TM 7 is operated as the fixed element by operation of the second brake B 2 . Therefore, the torque of the input shaft IS is shifted into the second forward speed stage, and the second forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Third Forward Speed Stage:

The first and fourth clutches C 1 and C 4 and the second brake B 2 are operated at a third forward speed stage D 3 .

In a state that the second shaft TM 2 is connected with the sixth shaft TM 6 by operation of the first clutch C 1 and the first shaft TM 1 is connected with the sixth shaft TM 6 by operation of the fourth clutch C 4 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the seventh shaft TM 7 is operated as the fixed element by operation of the second brake B 2 . Therefore, the torque of the input shaft IS is shifted into the third forward speed stage, and the third forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Fourth Forward Speed Stage:

The fourth clutch C 4 and the second and third brakes B 2 and B 3 are operated at a fourth forward speed stage D 4 .

In a state that the first shaft TM 1 is connected with the sixth shaft TM 6 by operation of the fourth clutch C 4 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the seventh shaft TM 7 and the first shaft TM 1 are operated as the fixed elements by operation of the second and third brakes B 2 and B 3 . Therefore, the torque of the input shaft IS is shifted into the fourth forward speed stage, and the fourth forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Fifth Forward Speed Stage:

The third and fourth clutches C 3 and C 4 and the second brake B 2 are operated at a fifth forward speed stage D 5 .

In a state that the fourth shaft TM 4 is connected with the seventh shaft TM 7 by operation of the third clutch C 3 and the first shaft TM 1 is connected with the sixth shaft TM 6 by operation of the fourth clutch C 4 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the seventh shaft TM 7 is operated as the fixed element by operation of the second brake B 2 . Therefore, the torque of the input shaft IS is shifted into the fifth forward speed stage, and the fifth forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Sixth Forward Speed Stage:

The third and fourth clutches C 3 and C 4 and the third brake B 3 are operated at a sixth forward speed stage D 6 .

In a state that the fourth shaft TM 4 is connected with the seventh shaft TM 7 by operation of the third clutch C 3 and the first shaft TM 1 is connected with the sixth shaft TM 6 by operation of the fourth clutch C 4 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the first shaft TM 1 is operated as the fixed element by operation of the third brake B 3 . Therefore, the torque of the input shaft IS is shifted into the sixth forward speed stage, and the sixth forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Seventh Forward Speed Stage:

The first, third, and fourth clutches C 1 , C 3 , and C 4 are operated at a seventh forward speed stage D 7 .

In a state that the second shaft TM 2 is connected with the sixth shaft TM 6 by operation of the first clutch C 1 , the fourth shaft TM 4 is connected with the seventh shaft TM 7 by operation of the third clutch C 3 , and the first shaft TM 1 is connected with the sixth shaft TM 6 by operation of the fourth clutch C 4 , the torque of the input shaft IS is input into the second shaft TM 2 . Therefore, the torque of the input shaft IS is output through the output shaft OS connected with the ninth shaft TM 9 without rotation speed being changed.

Eighth Forward Speed Stage:

The first and third clutches C 1 and C 3 and the third brake B 3 are operated at an eighth forward speed stage D 8 .

In a state that the second shaft TM 2 is connected with the sixth shaft TM 6 by operation of the first clutch C 1 and the fourth shaft TM 4 is connected with the seventh shaft TM 7 by operation of the third clutch C 3 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the first shaft TM 1 is operated as the fixed element by operation of the third brake B 3 . Therefore, the torque of the input shaft IS is shifted into the eighth forward speed stage, and the eighth forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Ninth Forward Speed Stage:

The second and third clutches C 2 and C 3 and the third brake B 3 are operated at a ninth forward speed stage D 9 .

In a state that the third shaft TM 3 is connected with the fourth shaft TM 4 by operation of the second clutch C 2 and the fourth shaft TM 4 is connected with the seventh shaft TM 7 by operation of the third clutch C 3 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the first shaft TM 1 is operated as the fixed element by operation of the third brake B 3 . Therefore, the torque of the input shaft IS is shifted into the ninth forward speed stage, and the ninth forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Tenth Forward Speed Stage:

The first and second clutches C 1 and C 2 and the third brake B 3 are operated at a tenth forward speed stage D 10 .

In a state that the second shaft TM 2 is connected with the sixth shaft TM 6 by operation of the first clutch C 1 and the third shaft TM 3 is connected with the fourth shaft TM 4 by operation of the second clutch C 2 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the first shaft TM 1 is operated as the fixed element by operation of the third brake B 3 . Therefore, the torque of the input shaft IS is shifted into the tenth forward speed stage, and the tenth forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

Reverse Speed Stage:

The first and second clutches C 1 and C 2 and the first brake B 1 are operated at a reverse speed stage REV.

In a state that the second shaft TM 2 is connected with the sixth shaft TM 6 by operation of the first clutch C 1 and the third shaft TM 3 is connected with the fourth shaft TM 4 by operation of the second clutch C 2 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the fifth shaft TM 5 is operated as the fixed element by operation of the first brake B 1 . Therefore, the torque of the input shaft IS is shifted into the reverse speed stage, and the reverse speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

The gear ratios at each speed stage illustrated in FIG. 2 are calculated by assuming that a gear ratio of first ring gear R 1 /first sun gear S 1 is approximately 2.59, a gear ratio of second ring gear R 2 /second sun gear S 2 is approximately 3.81, a gear ratio of third ring gear R 3 /third sun gear S 3 is approximately 1.95, gear ratio of fourth ring gear R 4 /fourth sun gear S 4 is approximately 1.89, a gear ratio of first transfer driven gear TF 1 b /first transfer drive gear TFla is approximately 2.04, and a gear ratio of second transfer driven gear TF 2 b /second transfer drive gear TF 2 a is approximately 1.92.

FIG. 3 is another example of an operation chart of control elements at each speed stage in the planetary gear train according to the first exemplary form of the present disclosure.

Referring to FIG. 3 , the planetary gear train can achieve one reverse speed stage and eleven forward speed stages by operating three control elements among the first, second, third, and fourth clutches C 1 , C 2 , C 3 , and C 4 and the first, second, and third brake B 1 , B 2 , and B 3 .

That is, the planetary gear train according to the first exemplary form of the present disclosure can further achieve an eleventh forward speed stage D 11 by operating the second and fourth clutches C 2 and C 4 and the third brake B 3 in addition to the ten forward speed stages illustrated in FIG. 2 .

Since shifting processes from the first forward speed stage D 1 to the tenth forward speed stage D 10 are the same as the above-described shifting processes, detailed description thereof will be omitted.

As shown in FIG. 3 , the second and fourth clutches C 2 and C 4 and the third brake B 3 are operated at the eleventh forward speed stage D 11 .

In a state that the third shaft TM 3 is connected with the fourth shaft TM 4 by operation of the second clutch C 2 and the first shaft TM 1 is connected with the sixth shaft TM 6 by operation of the fourth clutch C 4 , the torque of the input shaft IS is input into the second shaft TM 2 . In addition, the first shaft TM 1 is operated as the fixed element by operation of the third brake B 3 . Therefore, the torque of the input shaft IS is shifted into the eleventh forward speed stage, and the eleventh forward speed stage is output through the output shaft OS connected with the ninth shaft TM 9 .

The gear ratios at each speed stage illustrated in FIG. 3 are calculated by assuming that a gear ratio of first ring gear R 1 /first sun gear S 1 is approximately 2.70, a gear ratio of second ring gear R 2 /second sun gear S 2 is approximately 3.81, a gear ratio of third ring gear R 3 /third sun gear S 3 is approximately 1.87, a gear ratio of fourth ring gear R 4 /fourth sun gear S 4 is approximately 1.63, a gear ratio of first transfer driven gear TF 1 b /first transfer drive gear TF 1 a is approximately 2.04, and a gear ratio of second transfer driven gear TF 2 b /second transfer drive gear TF 2 a is approximately 1.92.

FIG. 4 is a schematic diagram of a planetary gear train according to the second exemplary form of the present disclosure.

The second brake B 2 is disposed between the seventh shaft TM 7 and the transmission housing H in the planetary gear train according to the first exemplary form of the present disclosure, but as shown in FIG. 4 , the second brake B 2 is disposed between the tenth shaft TM 10 and the transmission housing H in the planetary gear train according to the second exemplary form of the present disclosure.

The seventh shaft TM 7 and the tenth shaft TM 10 connected thereto through the first transfer gear TF 1 are operated as the fixed elements when the second brake B 2 operates in the planetary gear train according to the first exemplary form, but the tenth shaft TM 10 and the seventh shaft TM 7 connected thereto through the first transfer gear TF 1 are operated as the fixed elements when the second brake B 2 operates in the planetary gear train according to the second exemplary form.

Since operation and shifting processes of the second exemplary form are the same as those of the first exemplary form except a position of the second brake B 2 , detailed description thereof will be omitted.

FIG. 5 is a schematic diagram of a planetary gear train according to the third exemplary form of the present disclosure.

The seventh shaft TM 7 is connected with the tenth shaft TM 10 through the first transfer gear TF 1 and the third shaft TM 3 is connected with the eighth shaft TM 8 through the second transfer gear TF 2 in the planetary gear train according to the first exemplary form of the present disclosure, but as shown in FIG. 5 , the seventh shaft TM 7 is connected with the eighth shaft TM 8 through the first transfer gear TF 1 and the third shaft TM 3 is connected with the tenth shaft TM 10 through the second transfer gear TF 2 according to the third exemplary form.

Compared with the first exemplary form, rotation speed output through the seventh shaft TM 7 and the third shaft TM 3 is changed according to the third exemplary form, but operation and shifting processes of the third exemplary form are the same as those of the first exemplary form. Therefore, detailed description thereof will be omitted.

FIG. 6 is a schematic diagram of a planetary gear train according to the fourth exemplary form of the present disclosure.

The second brake B 2 is disposed between the seventh shaft TM 7 and the transmission housing H in the planetary gear train according to the third exemplary form of the present disclosure, but as shown in FIG. 6 , the second brake B 2 is disposed between the eighth shaft TM 8 and the transmission housing H in the planetary gear train according to the fourth exemplary form.

The seventh shaft TM 7 and the eighth shaft TM 8 connected thereto through the first transfer gear TF 1 are operated as the fixed elements when the second brake B 2 operates in the planetary gear train according to the third exemplary form, but the eighth shaft TM 10 and the seventh shaft TM 7 connected thereto through the first transfer gear TF 1 are operated as the fixed elements when the second brake B 2 operates in the planetary gear train according to the fourth exemplary form.

Since operation and shifting processes of the fourth exemplary form are the same as those of the third exemplary form except a position of the second brake B 2 , detailed description thereof will be omitted.

The planetary gear train according to the exemplary forms of the present disclosure can achieve at least ten forward speed stages and one reverse speed stage by disposing the four planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 separately on the input shaft and the output shaft disposed in parallel with and apart from each other, and combining the four planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 with the two transfer gears TF 1 and TF 2 , the four clutches C 1 , C 2 , C 3 , and C 4 , and the three brakes B 1 , B 2 , and B 3 . Therefore, power delivery performance and fuel consumption may be improved, and mountability may be improved by shortening a length of the automatic transmission.

Since teeth numbers of the two transfer gears can be freely changed in the planetary gear train according to the exemplary forms of the present disclosure, optimal gear ratios may be set. Therefore, gear ratios may be changed according to demanded performance condition, starting performance may be improved, and a starting clutch instead of a conventional torque converter may be used.

The planetary gear train according to the exemplary forms of the present disclosure can secure gear ratio span greater than approximately 9.0 as well as achieve at least ten forward speed stages and one reverse speed stage. Therefore, driving efficiency of the engine may be improved.

In addition, since linearity of step ratios can be secured due to multiple speed stages, drivability such as acceleration before and after shift, rhythmical engine speed, and so on may be improved.

While this present disclosure has been described in connection with what is presently considered to be practical exemplary 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.