Planetary gear train of automatic transmission for vehicles

This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0049876, filed on Apr. 18, 2017, which is incorporated herein by reference in its entirety.

The present disclosure relates to a planetary gear train of an automatic transmission for a vehicle having advantages of improving power delivery performance and fuel consumption.

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

Generally, in automatic transmission field, achieving more shift stages is a technology for improving fuel consumption and driving efficiency and has been researched, and recent increases in oil prices are triggering hard competition in enhancing fuel consumption of a vehicle.

In this sense, research on an engine has been undertaken to achieve weight reduction and to enhance fuel consumption by so-called downsizing, and research on an automatic transmission has been performed to simultaneously provide better drivability and fuel consumption by achieving more shift stages.

In order to achieve more shift stages for an automatic transmission, the number of parts, particularly the number of planetary gear sets is typically increased. This negatively affects installability, production cost, weight, and power flow efficiency, and a total length of transmission.

The majority of general automatic transmissions having more than eight speeds also increase its total length, which has drawbacks of deteriorating installability.

As a result, plural rows structure which planetary gear sets are on planetary gear sets has been adopted, or a dog clutch is applied in place of wet control elements. However, in this case, applicable structure is restricted and shift feel is deteriorated by applying 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 in this country to a person of ordinary skill in the art.

The present disclosure has been made in an effort to provide a planetary gear train of an automatic transmission for a vehicle having advantages of obtaining shift-stages of the forward nine speeds and one reverse speed with reduced number of parts, improving power delivery performance and fuel consumption by multi-stages of an automatic transmission, and improving driving stability of a vehicle by utilizing a low rotation speed of an engine.

A planetary gear train according to an exemplary form of the present disclosure includes: an input shaft for receiving an engine torque; an output shaft for outputting a shifted torque; a first planetary gear set having first, second, and third rotational elements; a second planetary gear set having fourth, fifth, and sixth rotational elements; a third planetary gear set having seventh, eighth, and ninth rotational elements; a fourth planetary gear set having tenth, eleventh, and twelfth rotational elements; a first shaft connected with the first rotational element, and connected with the input shaft; a second shaft connected with the second rotational element and selectively connected with the first shaft; a third shaft connected with the third rotational element and the fifth rotational element; a fourth shaft connected with the fourth rotational element and fixed to a transmission housing; a fourth shaft connected with the fourth rotational element and fixed to a transmission housing; a sixth shaft connected with the seventh rotational element and the tenth rotational element and selectively connected with the second shaft and fifth shaft respectively; a seventh shaft connected with the eighth rotational element and the twelfth rotational element, and connected with the output shaft; an eighth shaft connected with the ninth rotational element; and a ninth shaft connected with the eleventh rotational element and selectively connected with the first shaft.

Further, the second and eighth shafts may be selectively connected with the transmission housing respectively.

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

Further, the planetary gear train may include a first clutch selectively connecting the first shaft and the second shaft; a second clutch selectively connecting the second shaft and the sixth shaft; a third clutch selectively connecting the fifth shaft and the sixth shaft; a fourth clutch selectively connecting the first shaft and the ninth shaft; a first brake selectively connecting the second shaft and the transmission housing; and a second brake selectively connecting the eighth shaft and the transmission housing.

A planetary gear train of an automatic transmission for a vehicle according to an exemplary form of the present disclosure, shift-stages of forward nine speeds and one reverse speed may be realized by combination of four planetary gear sets of simple planetary gear sets and six control elements.

Further, a planetary gear train according to an exemplary form of the present disclosure may realize shift stages appropriate for rotation speed of an engine due to multi-stages of an automatic transmission and improve driving stability of a vehicle by utilizing a low rotation speed of an engine.

Further, a planetary gear train according to an exemplary form of the present disclosure maximize engine driving efficiency by multi-stages of an automatic transmission, and may improve power delivery performance and fuel consumption.

Further, effects that can be obtained or expected from exemplary forms of the present disclosure are directly or suggestively described in the following detailed description. That is, various effects expected from exemplary forms of the present disclosure will be described 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 schematic diagram of a planetary gear train according to an exemplary form of the present disclosure; and

FIG. 2 is an operational chart for respective control elements at respective shift stages in a planetary gear train according to an 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.

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

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

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.

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

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

Referring to FIG. 1 , a planetary gear train includes: first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 arranged on a same axis, an input shaft IS, an output shaft OS, nine shafts TM 1 to TM 9 connected with 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 as control elements, and a transmission housing H.

Torque input from the input shaft IS is shifted by cooperative operation of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , and then output through the output shaft OS.

The simple planetary gear sets are arranged in the order of 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 the torque from a crankshaft of an engine, after being torque-converted through a torque converter, is input into the input shaft IS.

The output shaft OS is an output member, and being arranged on a same axis with the input shaft IS, delivers a shifted torque to a drive shaft through a differential apparatus which is not illustrated.

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 that supports a plurality of first pinion gear P 1 externally engaged with the first sun gear S 1 so that the first pinion gear P 1 may rotate and revolute, and a first ring gear R 1 internally engaged and torque-connected with a plurality of the first pinion gear P 1 . The first sun gear S 1 acts as a first rotational element N 1 , the first planet carrier PC 1 acts as a second rotational element N 2 , and the first ring gear R 1 acts as a third rotational element 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 that supports a plurality of second pinion gear P 2 externally engaged with the second sun gear S 2 so that the second pinion gear P 2 may rotate and revolute, and a second ring gear R 2 internally engaged and torque-connected with a plurality of the second pinion P 2 . The second sun gear S 2 acts as a fourth rotational element N 4 , the second planet carrier PC 2 acts as a fifth rotational element N 5 , and the second ring gear R 2 acts as a sixth rotational element 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 that supports a plurality of a third pinion gear P 3 externally engaged with the third sun gear S 3 so that the third pinion gear P 3 may rotate and revolute, and a third ring gear R 3 internally engaged and torque-connected with a plurality of the third pinion P 3 . The third sun gear S 3 acts as a seventh rotational element N 7 , the third planet carrier PC 3 acts as a eighth rotational element N 8 , and the third ring gear R 3 acts as a ninth rotational element 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 that supports a plurality of a fourth pinion gear P 4 externally engaged with the fourth sun gear S 4 so that the fourth pinion gear P 4 may rotate and revolute, and a fourth ring gear R 4 internally engaged and torque-connected with a plurality of the fourth pinion P 4 . The fourth sun gear S 4 acts as a tenth rotational element N 10 , the fourth planet carrier PC 4 acts as a eleventh rotational element N 11 , and the fourth ring gear R 4 acts as a twelfth rotational element N 12 .

In the arrangement of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , the third rotational element N 3 and the fifth rotational element N 5 are directly connected with each other, the seventh rotational element N 7 and the tenth rotational element N 10 are directly connected with each other, and the eighth rotational element N 8 and the twelfth rotational element N 12 are directly connected with each other by a corresponding shaft selected from the nine shafts TM 1 to TM 9 .

The nine shafts TM 1 to TM 9 are arranged as follows.

Each of the nine shafts TM 1 to TM 9 may be a rotational member that delivers torque and rotates with rotational element via directly or selectively interconnecting a plurality of the rotational elements of the rotational elements of the planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , and the nine shafts TM 1 to TM 9 may be a rotational member selectively connecting the rotational element with the transmission housing H, or be a fixed member directly connecting and fixing the rotational element(s) with the transmission housing H.

The first shaft TM 1 directly connects the first rotational element N 1 (the first sun gear S 1 ) and is directly connected with the input shaft IS, thereby always acting as an input element.

The second shaft TM 2 is connected, and preferably fixedly connected, with the second rotational element N 2 (the first planet carrier PC 1 ), selectively connected with the first shaft TM 1 , and selectively connected with the transmission housing H, thereby acting as a selective fixed element.

The third shaft TM 3 is connected, and preferably fixedly connected, with the third rotational element N 3 (the first ring gear R 1 ) and the fifth rotational element N 5 (the second planet carrier PC 2 ).

The fourth shaft TM 4 is connected, and preferably fixedly connected, with the fourth rotational element N 4 (the second sun gear S 2 ), and directly connected with the transmission housing H, thereby always acting as a fixed element.

The fifth shaft TM 5 is connected, and preferably fixedly connected, with the sixth rotational element N 6 (the second ring gear R 2 ).

The sixth shaft TM 6 is connected, and preferably fixedly connected, with the seventh rotational element N 7 (the third sun gear S 3 ) and the tenth rotational element N 10 (the fourth sun gear S 4 ) and selectively connected with the second shaft TM 2 and the fifth shaft TM 5 .

The seventh shaft TM 7 is connected, and preferably fixedly connected, with the eighth rotational element N 8 (the third planetary carrier PC 3 ) and the twelfth rotational element N 12 (the fourth ring gear R 4 ), and connected with the output shaft OS, thereby always acting as an output element.

The eighth shaft TM 8 is connected, and preferably fixedly connected, with the ninth rotational element N 9 (the third ring gear R 3 ), and selectively connected with the transmission housing H, thereby acting as a selective fixed element.

The ninth shaft TM 9 is connected, and preferably fixedly connected, with the eleventh rotational element N 11 (the fourth planetary carrier PC 4 ), and selectively connected with the first shaft TM 1 .

The nine shafts TM 1 to TM 9 , the input shaft IS, and the output shaft OS may be selectively interconnected with one another by control elements of four clutches C 1 , C 2 , C 3 and C 4 .

The shafts TM 1 to TM 9 may be selectively connected with the transmission housing H, by control elements of two brakes B 1 and B 2 .

The four clutches C 1 to C 4 and the two brakes B 1 and B 2 are arranged as follows.

The first clutch C 1 is arranged between the first shaft TM 1 and the second shaft TM 2 , so as to selectively connect the first shaft TM 1 and the second shaft TM 2 for power delivery.

The second clutch C 2 is arranged between the second shaft TM 2 and the sixth shaft TM 6 , so as to selectively connect the second shaft TM 2 and the sixth shaft TM 6 for power delivery.

The third clutch C 3 is arranged between the fifth shaft TM 5 and the sixth shaft TM 6 , so as to selectively connect the fifth shaft TM 5 and the sixth shaft TM 6 for power delivery.

The fourth clutch C 4 is arranged between the first shaft TM 1 and the ninth shaft TM 9 , so as to selectively connect the first shaft TM 1 and the ninth shaft TM 9 for power delivery.

The first brake B 1 is arranged between the second shaft TM 2 and the transmission housing H, such that the second shaft TM 2 may be selectively connected with the transmission housing H and act as a fixed element.

The second brake B 2 is arranged between the eighth shaft TM 3 and the transmission housing H, such that the eighth shaft TM 8 may be selectively connected with the transmission housing H and act as a fixed element.

The control elements of 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 may be realized as hydraulic pressure friction control elements that are frictionally engaged by hydraulic pressure supplied from a hydraulic pressure control devices. The control elements are primarily used as a wet multi-plate hydraulic pressure friction control element, but as control elements which may operate according to electric signal supplied from an electronic control devices such as a dog clutch, an electro-magnetic clutch, a magna clutch etc.

FIG. 2 is an operational chart for respective control elements at respective shift stages in a planetary gear train according to an exemplary form of the present disclosure.

Referring to FIG. 2 , a planetary gear train realizes forward nine speeds and one reverse speed 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 and second brakes B 1 and B 2 at respective shift-stages.

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

As a result, the second shaft TM 2 and the sixth shaft TM 6 are interconnected with each other by the operation of the second clutch C 2 , and the fifth shaft TM 5 and the sixth shaft TM 6 are interconnected with each other by the operation of the third clutch C 3 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Further, the eighth shaft TM 8 acts as a fixed element by the operation of the second brake B 2 , thereby realizing the forward first speed and outputting a shifted torque through the output shaft OS connected with the seventh shaft TM 7 .

In the forward second speed shift-stage D 2 , the first and second clutches C 1 and C 2 and the second brake B 2 are simultaneously operated.

As a result, the first shaft TM 1 and the second shaft TM 2 are interconnected with each other by the operation of the first clutch C 1 , and the second shaft TM 2 and the sixth shaft TM 6 are interconnected with each other by the operation of the second clutch C 2 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Further, the eighth shaft TM 8 acts as a fixed element by the operation of the second brake B 2 , thereby realizing the forward second speed and outputting a shifted torque through the output shaft OS connected with the seventh shaft TM 7 .

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

As a result, the first shaft TM 1 and the second shaft TM 2 are interconnected with each other by the operation of the first clutch C 1 , and the fifth shaft TM 5 and the sixth shaft TM 6 are interconnected with each other by the operation of the third clutch C 3 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Further, the eighth shaft TM 8 acts as a fixed element by the operation of the second brake B 2 , thereby realizing the forward third speed and outputting a shifted torque through the output shaft OS connected with the seventh shaft TM 7 .

In the forward fourth speed shift-stage D 4 , the first and fourth clutches C 1 and C 4 and the second brake B 2 are simultaneously operated.

As a result, the first shaft TM 1 and the second shaft TM 2 are interconnected with each other by the operation of the first clutch C 1 , and the sixth shaft TM 6 and the ninth shaft TM 9 are interconnected with each other by the operation of the fourth clutch C 4 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Further, the eighth shaft TM 8 acts as a fixed element by the operation of the second brake B 2 , thereby realizing the forward fourth speed and outputting a shifted torque through the output shaft OS connected with the seventh shaft TM 7 .

In the forward fifth speed shift-stage D 5 , the first, third, and fourth clutches C 1 , C 3 , and C 4 are simultaneously operated.

As a result, the first shaft TM 1 and the second shaft TM 2 are interconnected with each other by the operation of the first clutch C 1 , the fifth shaft TM 5 and the sixth shaft TM 6 are interconnected with each other by the operation of the third clutch C 3 , and the first shaft TM 1 and the ninth shaft TM 9 are interconnected with each other by the operation of the fourth clutch C 4 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Then, the forward fifth speed is realized and a shifted torque through the output shaft OS connected with the seventh shaft TM 7 is output.

In the forward sixth speed shift-stage D 6 , the first, second, and fourth clutches C 1 , C 2 , and C 4 are simultaneously operated.

As a result, the first shaft TM 1 and the second shaft TM 2 are interconnected with each other by the operation of the first clutch C 1 , the second shaft TM 2 and the sixth shaft TM 6 are interconnected with each other by the operation of the second clutch C 2 , and the first shaft TM 1 and the ninth shaft TM 9 are interconnected with each other by the operation of the fourth clutch C 4 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Then, the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 are integrally rotate, and a shifted torque of the input shaft IS is transmitted to a forward sixth speed to be output through the output shaft OS connected with the seventh shaft TM 7 .

In the forward sixth speed shift-stage D 7 , the second, third, and fourth clutches C 2 , C 3 , and C 4 are simultaneously operated.

As a result, the second shaft TM 2 and the sixth shaft TM 6 are interconnected with each other by the operation of the second clutch C 2 , the fifth shaft TM 5 and the sixth shaft TM 6 are interconnected with each other by the operation of the third clutch C 3 , and the first shaft TM 1 and the ninth shaft TM 9 are interconnected with each other by the operation of the fourth clutch C 4 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Then, the forward seventh speed is realized and a shifted torque through the output shaft OS connected with the seventh shaft TM 7 is output.

In the forward eighth speed shift-stage D 8 , the second and fourth clutches C 2 and C 4 and the first brake B 1 are simultaneously operated.

As a result, the second shaft TM 2 and the sixth shaft TM 6 are interconnected with each other by the operation of the second clutch C 2 , and the first shaft TM 1 and the ninth shaft TM 9 are interconnected with each other by the operation of the fourth clutch C 4 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Further, the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , thereby realizing the forward eighth speed and outputting a shifted torque through the output shaft OS connected with the seventh shaft TM 7 .

In the forward ninth speed shift-stage D 9 , the third and fourth clutches C 3 and C 4 and the first brake B 1 are simultaneously operated.

As a result, the fifth shaft TM 5 and the sixth shaft TM 6 are interconnected with each other by the operation of the third clutch C 3 , and the first shaft TM 1 and the ninth shaft TM 9 are interconnected with each other by the operation of the fourth clutch C 4 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Further, the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , thereby realizing the forward ninth speed and outputting a shifted torque through the output shaft OS connected with the seventh shaft TM 7 .

In the reverse speed REV, the third clutch C 3 , the first and second brakes B 1 and B 2 are simultaneously operated.

As a result, the fifth shaft TM 5 and the sixth shaft TM 6 are interconnected by the operation of the third clutch C 3 . In this state, torque of the Input shaft IS is input to the first shaft TM 1 .

Further, the second shaft TM 2 and the eighth shaft TM 8 act as fixed elements by the operation of the first brake B 1 and the second brake B 2 , thereby realizing the reverse speed and outputting a shifted torque through the output shaft OS connected with the seventh shaft TM 7 .

As described above, a planetary gear train according to an exemplary form of the present disclosure may realize forward nine speeds and a reverse first speed formed by operating four planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 by controlling the four clutches C 1 , C 2 , C 3 , and C 4 and the two brakes B 1 and B 2 .

In addition, a planetary gear train according to an exemplary form of the present disclosure may realize shift stages appropriate for rotation speed of an engine due to multi-stages of an automatic transmission and improve driving stability of a vehicle by utilizing a low rotation speed of an engine.

In addition, a planetary gear train according to an exemplary form of the present disclosure may increase engine driving efficiency by multi-stages of an automatic transmission, and may improve power delivery performance and fuel consumption.

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.

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

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

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

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

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

R 1 , R 2 , R 3 , R 4 . . . first, second, third, and 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 , TM 9 . . . first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth shafts