Planetary gear train of automatic transmission for vehicles

This application claims priority to and the benefit of Korean Patent Application No. 10-2016-0117353, filed on Sep. 12, 2016, the entire contents of which are incorporated herein by reference.

The present disclosure relates to a planetary gear train of an automatic transmission for vehicles, and more particularly, to a planetary gear train of an automatic transmission for vehicles capable of improving power transfer performance and fuel efficiency.

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

In an automatic transmission field, a research for an increase of the number of shift-stages is generally performed for a technology for improving fuel efficiency of a vehicle and maximizing drivability, and a recent increase in oil price causes unlimited competition for the improvement of the fuel efficiency.

As a result, in the case of an engine, a research capable of reducing weight and improving fuel efficiency by down-sizing the engine has been conducted, and in the case of an automatic transmission, a research capable of simultaneously securing drivability and fuel efficiency competitiveness by the increase of the number of shift-stages of the automatic transmission has been conducted.

However, as the number of shift-stages of the automatic transmission is increased, the number of internal parts, particularly, the number of planetary gear sets is increased, which increases an entire length of the transmission, thereby causing mountability, production cost, weight, transfer efficiency, etc., to be deteriorated.

In this aspect, the automatic transmission is configured to implement a shift of 8-speed or more and is mounted in the vehicle, and a research and development into a planetary gear train capable of implementing a shift-stage of 8-speed or more has been continuously desired.

However, a general automatic transmission of 8-speed or more generally includes 3 to 4 planetary gear sets and 5 to 7 control elements (friction elements), and in this case, since the entire length is increased, mountability may be deteriorated.

Accordingly, in order to increase the number of shift-stages of the automatic transmission, a double row structure in which the planetary gear set is disposed on the planetary gear set is recently adopted, or a dog clutch instead of a wet control element is recently applied, but in this case, we have discovered that there is a problem that an applicable structure is limited, and deterioration of shift sensitivity is involved due to the application of the dog clutch.

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 vehicles having advantages of improving power transfer performance and fuel efficiency according to an increase of shift-stages by implementing a shift-stage of an advance 10-speed and a reverse 1-speed by reduced components and improving drive silence of a vehicle by using an operating point in a low revolution per minute (RPM) region of an engine.

An example form of the present disclosure provides a planetary gear train of an automatic transmission for vehicles including: an input shaft configured to receive power from an engine; an output shaft configured to output shifted power; 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; a first shaft configured to be connected to the first rotation element; a second shaft configured to be connected to the second rotation element; a third shaft configured to be connected to the third rotation element, the twelfth rotation element and the input shaft; a fourth shaft configured to be connected to the fourth rotation element and selectively connected to the first shaft; a fifth shaft configured to be connected to the fifth element and the tenth rotation element; a sixth shaft configured to be connected to the sixth rotation element and the seventh rotation element, and selectively connected to the first shaft; a seventh shaft configured to be connected to the eighth rotation element, the eleventh rotation element and the output shaft; and an eighth shaft configured to be connected to the ninth rotation element and selectively connected to the second shaft and the third shaft, respectively.

The second shaft and the fourth shaft may be each selectively connected to a transmission housing.

The first, second, and third rotation elements of the first planetary gear set may be a first sun gear, a first planetary 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 planetary 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 planetary 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 planetary carrier, and a fourth ring gear, respectively.

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

The planetary gear train may further include: a first clutch configured to selectively connect the third shaft and the eighth shaft to each other; a second clutch configured to selectively connect the first shaft and the fourth shaft to each other; a third clutch configured to selectively connect the first shaft and the sixth shaft to each other; a fourth clutch configured to selectively connect the second shaft and the eighth shaft to each other; a first brake configured to selectively connect the second shaft and the transmission housing to each other; and a second brake configured to selectively connect the fourth shaft and the transmission housing to each other.

In one form of the present disclosure, the planetary gear train may implement the shift-stage of advance ten speeds and one reverse speed by combining four planetary gear sets formed of simple planetary gear sets with six control elements.

Further, the planetary gear train may implement the shift-stage suitable for the revolution per minute (RPM) of the engine by increasing the number of shift-stages of the automatic transmission, and may particularly improve drive silence of the vehicle by using the operating point in the low RPM region of the engine.

Further, the planetary gear train may increase driving efficiency of the engine by increasing the number of shift-stages of the automatic transmission, and improve power delivery performance and fuel efficiency.

Other effects that may be obtained or predicted from the exemplary forms of the present disclosure will be explicitly or implicitly disclosed in the following detailed description.

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 configuration diagram of a planetary gear train in one exemplary form of the present disclosure; and

FIG. 2 is an operation table for each of shift-stages of a control element used for the planetary gear train in one 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.

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

In the following detailed description, classifying names of the configurations into first, second, and the like, is to classify the configurations because the configurations have the same relationship, and the present disclosure is not necessarily limited to the above-mentioned order in the following detailed description.

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

Referring to FIG. 1 , the planetary gear train includes: first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 disposed on the same shaft line; an input shaft IS; an output shaft OS; eight shafts TM 1 to TM 8 connected to the respective rotational elements of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 ; four clutches C 1 to C 4 and two brakes B 1 and B 2 which are control elements; and a transmission housing H.

In addition, rotation power from an engine which is input from the input shaft IS is shifted by a mutual complementing operation between the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , and is then output through the output shaft OS.

Here, the respective planetary gear sets are disposed in order of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 from an engine side.

The input shaft IS is an input member, and rotation power from a crack shaft of the engine may be input to the input shaft after a torque thereof is converted by a torque converter.

The output shaft OS is an output member, and is disposed on the same shaft line as the input shaft IS to transfer shifted driving force to a driving shaft through a differential apparatus (not shown).

The first planetary gear set PG 1 , which is a single pinion planetary gear set, 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 , rotatably and revolvably supporting a plurality of first pinion gears P 1 externally engaged with the first sun gear S 1 ; and a first ring gear R 1 which is a third rotation element N 3 , internally engaged with the plurality of first pinion gears P 1 to be power-connected to the first sun gear S 1 .

The second planetary gear set PG 2 , which is a single pinion planetary gear set, includes: a second sun gear S 2 which is a fourth rotation element N 4 ; a second planetary carrier PC 1 which is a fifth rotation element N 5 , rotatably and revolvably supporting a plurality of second pinion gears P 2 externally engaged with the second sun gear S 2 ; and a second ring gear R 2 which is a sixth rotation element N 6 , internally engaged with the plurality of second pinion gears P 2 to be power-connected to the second sun gear S 2 .

The third planetary gear set PG 3 , which is a single pinion planetary gear set, 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 , rotatably and revolvably supporting a plurality of third pinion gears P 3 externally engaged with the third sun gear S 3 ; and a third ring gear R 3 which is a ninth rotation element N 9 , internally engaged with the plurality of third pinion gears P 3 to be power-connected to the third sun gear S 3 .

The fourth planetary gear set PG 4 , which is a single pinion planetary gear set, 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 , rotatably and revolvably supporting a plurality of fourth pinion gears P 4 externally engaged with the fourth sun gear S 4 ; and a fourth ring gear R 4 which is a twelfth rotation element N 12 , internally engaged with the plurality of fourth pinion gears P 4 to be power-connected to the fourth sun gear S 4 .

Here, in the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , the third rotation element N 3 is directly connected to the twelfth rotation element N 12 , the fifth rotation element N 5 is directly connected to the tenth rotation element N 10 , the sixth rotation element N 6 is directly connected to the seventh rotation element N 7 , and the eighth rotation element N 8 is directly connected to the eleventh rotation element N 11 , such that the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 are operated through the eight shafts TM 1 to TM 8 .

Configurations of the eight shafts TM 1 to TM 8 will be described in detail below.

However, the eight shafts TM 1 to TM 8 may be rotation members transferring power while being rotated together with rotation elements of the planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , directly or selectively, and may be rotation members selectively connecting the rotation elements to the transmission housing H, or be fixed members directly connecting the rotation elements to the transmission housing H to be fixed to the transmission housing H.

The first shaft TM 1 is directly connected to the first rotation element N 1 (the first sun gear S 1 ).

The second shaft TM 2 is directly connected to the second rotation element N 2 (the first planetary carrier PC 1 ), and is selectively connected to the transmission housing H to thereby be operated as a selective fixed element.

The third shaft TM 3 is directly connected to the third rotation element N 3 (the first ring gear R 2 ) and the twelfth rotation element N 12 (the fourth ring gear R 4 ), and is directly connected to the input shaft IS to thereby be always operated as an input element.

The fourth shaft TM 4 is directly connected to the fourth rotation element N 4 (the second sun gear S 2 ), is selectively connected to the first shaft TM 1 , and is selectively connected to the transmission housing H to thereby be operated as a selective fixed element.

The fifth shaft TM 5 is directly connected to the fifth rotation element N 5 (the second planetary carrier PC 2 ) and the tenth rotation element N 10 (the fourth sun gear S 4 ).

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

The seventh shaft TM 7 is directly connected to the eighth rotation element N 8 (the third planetary carrier PC 3 ) and the eleventh rotation element N 11 (the fourth planetary carrier PC 4 ), and is directly connected to the output shaft OS to thereby be always operated as an output element.

The eighth shaft TM 8 is directly connected to the ninth rotation element N 9 (the third ring gear R 3 ), and is selectively connected to the second shaft TM 2 and the third shaft TM 3 , respectively.

In addition, four clutches C 1 to C 4 are disposed at portions of shafts including the input shaft IS and the output shaft OS selectively connected to each other, among the eight shafts TM 1 to TM 8 .

In addition, two brakes B 1 and B 2 are disposed at portions of shafts selectively connected to the transmission housing H, among the eight shafts TM 1 to TM 8 .

Disposed positions of the four clutches C 1 to C 4 , and the two brakes B 1 and B 2 will be described below.

A first clutch C 1 is disposed between the third shaft TM 3 and the eighth shaft TM 8 to thereby selectively connect the third shaft TM 3 and the eighth shaft TM 8 to each other to transfer power.

A second clutch C 2 is disposed between the first shaft TM 1 and the fourth shaft TM 4 to thereby selectively connect the first shaft TM 1 and the fourth shaft TM 4 to each other to transfer power.

A third clutch C 3 is disposed between the first shaft TM 1 and the sixth shaft TM 6 to thereby selectively connect the first shaft TM 1 and the sixth shaft TM 6 to each other to transfer power.

A fourth clutch C 4 is disposed between the second shaft TM 2 and the eighth shaft TM 8 to thereby selectively connect the second shaft TM 2 and the eighth shaft TM 8 to each other to transfer power.

A first brake B 1 is disposed between the second shaft TM 2 and the transmission housing H to thereby selectively connect the second shaft TM 2 to the transmission housing H to be fixed to the transmission housing H.

A second brake B 2 is disposed between the fourth shaft TM 4 and the transmission housing H to thereby selectively connect the fourth shaft TM 4 to the transmission housing H to be fixed to the transmission housing H.

In the above-mentioned description, the respective control elements including the first, second, third, and fourth clutches C 1 , C 2 , C 3 , and C 4 , and the first and second brakes B 1 and B 2 , which are hydraulic friction coupling units operated by hydraulic pressure supplied from a hydraulic controller, mainly uses wet multi-plate hydraulic friction coupling units, but may include coupling units which may be operated in response to an electrical signal supplied from an electronic control apparatus such as a dog clutch, an electronic clutch, a differential clutch, or the like.

FIG. 2 is an operation table for each of shift-stages of a control element which is used for the planetary gear train in one exemplary form of the present disclosure.

Referring to FIG. 2 , in the respective shift-stages of the planetary gear train, while three control elements among the clutches (i.e., the first, second, third, and fourth clutches C 1 to C 4 ) and the brakes (i.e., first and second brakes B 1 and B 2 ), which are the control elements, are operated, shifts of a reverse 1-speed and forward 10 speeds (i.e., advance 10 speeds D 1 to D 10 ) are performed. A shift operation will be described below.

In an advance 1-speed shift stage (D 1 ), the first and third clutches C 1 and C 3 , and the first brake B 1 are simultaneously operated.

Accordingly, in a state in which the third shaft TM 3 is connected to the eighth shaft TM 8 by an operation of the first clutch C 1 , and the first shaft TM 1 is connected to the sixth shaft TM 6 by an operation of the third clutch C 3 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 1-speed by a mutual compensating operation of the respective shafts while the second shaft TM 2 is operated as the fixed element by an operation of the first brake B 1 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 2-speed shift stage (D 2 ), the second and third clutches C 2 and C 3 , and the first brake B 1 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the fourth shaft TM 4 by an operation of the second clutch C 2 , and the first shaft TM 1 is connected to the sixth shaft TM 6 by the operation of the third clutch C 3 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 2-speed by a mutual compensating operation of the respective shafts while the second shaft TM 2 is operated as the fixed element by an operation of the first brake B 1 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 3-speed shift stage (D 3 ), the third clutch C 3 , and the first and second brakes B 1 and B 2 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the sixth shaft TM 6 by the operation of the third clutch C 3 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 3-speed by a mutual compensating operation of the respective shafts while the second shaft TM 2 and the fourth shaft TM 4 are operated as the fixed elements by operations of the first and second brakes B 1 and B 2 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 4-speed shift stage (D 4 ), the second and third clutches C 2 and C 3 , and the second brake B 2 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the fourth shaft TM 4 by an operation of the second clutch C 2 , and the first shaft TM 1 is connected to the sixth shaft TM 6 by the operation of the third clutch C 3 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 4-speed by a mutual compensating operation of the respective shafts while the fourth shaft TM 4 is operated as the fixed element by an operation of the second brake B 2 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 5-speed shift stage (D 5 ), the first and third clutches C 1 and C 3 , and the second brake B 2 are simultaneously operated.

Accordingly, in a state in which the third shaft TM 3 is connected to the eighth shaft TM 8 by an operation of the first clutch C 1 , and the first shaft TM 1 is connected to the sixth shaft TM 6 by an operation of the third clutch C 3 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 5-speed by a mutual compensating operation of the respective shafts while the fourth shaft TM 4 is operated as the fixed element by an operation of the second brake B 2 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 6-speed shift stage (D 6 ), the third and fourth clutches C 3 and C 4 , and the second brake B 2 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the sixth shaft SM 6 by an operation of the third clutch C 3 , and the second shaft TM 2 is connected to the eighth shaft TM 8 by an operation of the fourth clutch C 4 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 6-speed by a mutual compensating operation of the respective shafts while the fourth shaft TM 4 is operated as the fixed element by an operation of the second brake B 2 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 7-speed shift stage (D 7 ), the second, third, and fourth clutches C 2 , C 3 , and C 4 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the fourth shaft SM 4 by an operation of the second clutch C 2 , the first shaft TM 1 is connected to the sixth shaft TM 6 by an operation of the third clutch C 3 , and the second shaft TM 2 is connected to the eighth shaft TM 8 by an operation of the fourth clutch C 4 , rotation power of the input shaft IS is input to the third shaft TM 3 .

Therefore, the shift-stage is shifted to an advance 7-speed that outputs an input as it is while the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 are integrally rotated, such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 8-speed shift stage (D 8 ), the second and fourth clutches C 2 and C 4 , and the second brake B 2 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the fourth shaft TM 4 by an operation of the second clutch C 2 , and the second shaft TM 2 is connected to the eighth shaft TM 8 by an operation of the fourth clutch C 4 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 8-speed, which is an over-drive state, by a mutual compensating operation of the respective shafts while the fourth shaft TM 4 is operated as the fixed element by an operation of the second brake B 2 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 9-speed shift stage (D 9 ), the second and fourth clutches C 2 and C 4 and the first brake B 1 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the fourth shaft TM 4 by an operation of the second clutch C 2 , and the second shaft TM 2 is connected to the eighth shaft TM 8 by an operation of the fourth clutch C 4 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 9-speed, which is an over-drive state, by a mutual compensating operation of the respective shafts while the second shaft TM 2 is operated as the fixed element by an operation of the first brake B 1 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In an advance 10-speed shift stage (D 10 ), the fourth clutch C 4 , and the first and second brakes B 1 and B 2 are simultaneously operated.

Accordingly, in a state in which the second shaft TM 2 is connected to the eighth shaft TM 8 by the operation of the fourth clutch C 4 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to an advance 10-speed, which is the highest shift-stage, by a mutual compensating operation of the respective shafts while the second shaft TM 2 and the fourth shaft TM 4 are operated as the fixed elements by operations of the first and second brakes B 1 and B 2 , such that the rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

In a reverse shift-stage REV, the third and fourth clutches C 3 and C 4 , and the first brake B 1 are simultaneously operated.

Accordingly, in a state in which the first shaft TM 1 is connected to the sixth shaft SM 6 by an operation of the third clutch C 3 , and the second shaft TM 2 is connected to the eighth shaft TM 8 by an operation of the fourth clutch C 4 , rotation power of the input shaft IS is input to the third shaft TM 3 .

In addition, the shift-stage is shifted to a reverse 1-speed by a mutual compensating operation of the respective shafts while the second shaft TM 2 is operated as the fixed element by an operation of the first brake B 1 , such that the reverse rotation power is output through the output shaft OS connected to the seventh shaft TM 7 .

As described above, the planetary gear train may implement a shift stage of the advance 10 speeds and the reverse 1 speed with the fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 by the operation control of the fourth clutches C 1 , C 2 , C 3 , and C 4 , and the two brakes B 1 and B 2 .

Further, the planetary gear train may implement the shift-stage suitable for the revolution per minute (RPM) of the engine by increasing the number of shift-stages of the automatic transmission, and may particularly improve drive silence of the vehicle by using the operating point in the low RPM region of the engine.

Further, the planetary gear train of the present disclosure may increase driving efficiency of the engine by increasing the number of shift-stages of the automatic transmission, and improve power delivery performance and fuel efficiency.

Hereinabove, although the present disclosure has been described in detail with reference to the exemplary form of the present disclosure, it is to be understood by those skilled in the art that the present disclosure may be variously modified and altered without departing from the scope and spirit of the present disclosure.

B 1 , B 2 . . . first, second brakes

C 1 , C 2 , C 3 , C 4 . . . first, second, third, fourth clutches

PG 1 , PG 2 , PG 3 , PG 4 . . . first, second, third, fourth planetary gear sets

S 1 , S 2 , S 3 , S 4 . . . first, second, third, fourth sun gears

PC 1 , PC 2 , PC 3 , PC 4 . . . first, second, third, fourth planetary carriers

R 1 , R 2 , R 3 , R 4 . . . first, second, third, fourth ring gears

IS . . . input shaft

OS . . . output shaft

TM 1 , TM 2 , TM 3 , TM 4 , TM 5 , TM 6 , TM 7 , TM 8 . . . first, second, third, fourth, fifth, sixth, seventh, eighth shafts