KR101416349B1 - Power train of automatic transmission - Google Patents

Abstract

A first planetary gear set including a first operating member fixedly connected to the transmission case, a second operating member, and a third operating member fixedly connected to the output shaft; A second planetary gear set including a fourth operating member fixedly connected to the input shaft, a fifth operating member selectively connected to the input shaft and selectively connected to the third operating member, and a sixth operating member; A seventh actuating member selectively connected to the transmission case and selectively connected to the fifth actuating member, an eighth actuating member fixedly connected to the second actuating member, and an eighth actuating member fixedly connected to the sixth actuating member, A third planetary gear set including a ninth actuating member selectively connected to the operating member and selectively connected to the transmission case; And a plurality of friction members selectively connecting the operation members of the first, second, and third planetary gear sets, the input shaft, the output shaft, and the transmission case.

Automatic transmission, power train, planetary gear set

Description

POWER TRAIN OF AUTOMATIC TRANSMISSION < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a powertrain of an automatic transmission, and more particularly, to a powertrain of an automatic transmission implementing three forward speeds and one reverse speed using three simple planetary gear sets and six friction elements.

The multi-speed shifting mechanism of the automatic transmission is usually implemented by a combination of a plurality of planetary gear sets. A powertrain in which a plurality of planetary gear sets are combined is used to receive torque from a torque converter included in the automatic transmission, To the output shaft.

However, the more transmission speeds that can be implemented in the transmission, the more appropriate transmission ratio can be designed, and a vehicle having superior power performance and fuel economy can be realized. Therefore, have.

In addition, even if the same number of gear stages are implemented, the durability, power transmission efficiency, and size of the power train are changed according to the combination of the planetary gear sets, thereby making it more robust, Efforts are constantly being made.

In particular, unlike the manual transmission in which the driver incurs an inconvenience that the shift must be frequently performed if the speed change stage is excessively large, the automatic transmission performs shifting by controlling the operation of the power train in accordance with the operation state, Efforts to find the configuration of a powertrain that implements a stage have even more value in an automatic transmission.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems associated with the development of an automatic transmission, and it is an object of the present invention to provide a planetary gear set having three forward planetary gear sets and six friction elements, Thereby providing a powertrain of the automatic transmission.

To achieve these and other advantages and in accordance with the purpose of the present invention, a powertrain of an automatic transmission includes a first operating member fixedly connected to a transmission case, a second operating member, and a third operating member fixedly connected to the output shaft A first planetary gear set; A second operating gear set including a fourth operating member fixedly connected to the input shaft, a fifth operating member selectively connected to the input shaft and selectively connected to the third operating member, and a sixth operating member; A seventh actuating member selectively connected to the transmission case and selectively connected to the fifth actuating member, an eighth actuating member fixedly connected to the second actuating member, and an eighth actuating member fixedly connected to the sixth actuating member, A third planetary gear set including a ninth actuating member selectively connected to the operating member and selectively connected to the transmission case; And a plurality of friction members for selectively connecting the operation members of the first, second, and third planetary gear sets, the input shaft, the output shaft, and the transmission case.

The plurality of friction members include: a first clutch selectively connecting the input shaft and the fifth operating member; A second clutch for selectively connecting the third operating member and the fifth operating member; A third clutch that selectively connects the eighth operating member and the ninth operating member; A fourth clutch for selectively connecting the fifth operating member and the seventh operating member; A first brake selectively connecting the ninth operating member and the transmission case; And a second brake selectively connecting the seventh operation member and the transmission case

More specifically, the plurality of friction members include: a first clutch selectively connecting the input shaft and the second planetary carrier; A second clutch selectively connecting the first planetary carrier and the second planetary carrier; A third clutch selectively connecting the third ring gear and the third planetary carrier; A fourth clutch selectively connecting the second planetary carrier and the third sun gear; A first brake selectively connecting the third planetary carrier and the transmission case; And a second brake selectively connecting the third sun gear and the transmission case.

Wherein the first planetary gear set is a double pinion planetary gear set including a first sun gear, a first ring gear, and a first planetary carrier as operating members, the first sun gear serving as a first operating member, One ring gear acts as a second actuating member, and the first planetary carrier acts as a third actuating member.

Wherein the second planetary gear set is a single pinion planetary gear set including a second sun gear, a second planetary carrier, and a second ring gear as its operating members, the second sun gear serving as a fourth operating member, 2 planetary carrier acts as a fifth operating member, and the second ring gear acts as a sixth operating member.

Wherein the third planetary gear set is a double pinion planetary gear set including a third sun gear, a third ring gear, and a third planetary carrier as its operating members, the third sun gear acting as a seventh operating member, The third ring gear acts as an eighth operating member, and the third planetary carrier acts as a ninth operating member.

The fourth clutch and the first brake operate in forward speed 1, the second clutch and the first brake operate in forward speed 2, the second clutch and fourth clutch operate in forward speed 3, The third clutch and the second clutch operate in the fifth speed forward, the first clutch and the second clutch operate in the sixth forward speed, the first clutch and the second brake operate in the forward seventh speed, The first and third clutches or the first and fourth clutches operate, and in the reverse first speed, the fourth clutch and the second brake operate.

As described above, according to the powertrain of the automatic transmission according to the present invention, three forward planetary gear sets and six friction elements can be used to implement forward forward speed and reverse reverse speed.

In addition, since the engine is provided with a large number of gear stages, the power of the engine can be effectively utilized to improve the power transmission performance and reduce the fuel consumption.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1, the powertrain of the automatic transmission according to the embodiment of the present invention includes an input shaft 10, an output shaft 20, a transmission case 30, and first, second and third planetary gear sets PG1, PG2, PG3).

The input shaft 100 receives the power of an engine (not shown) through a torque converter (not shown).

The output shaft 20 outputs power from the power train.

The first planetary gear set PG1 is a double pinion planetary gear set including a first sun gear S1, a first ring gear R1 and a first planetary carrier PC1 as operating members thereof. The first planetary carrier PC1 is connected to the first sun gear S1 and the first pinion gear P1 that is gear-coupled to the first ring gear R1.

The second planetary gear set PG2 is a single pinion planetary gear set including the second sun gear S2, the second planetary carrier PC2, and the second ring gear R2 as operating members thereof. The second planetary carrier PC2 is connected to the second pinion gear P2 that is gear-coupled to the second sun gear S2 and the second ring gear R2.

The third planetary gear set PG3 is a double pinion planetary gear set including the third sun gear S3, the third ring gear R3, and the third planetary carrier PC3 as operating members thereof. The third planetary carrier PC3 is connected to the third sun gear S3 and the third pinion gear P3 which is gear-coupled to the third ring gear R3.

The first sun gear S1, the first ring gear R1 and the first planetary carrier PC1 are connected to the first, second and third actuating members N1 (first and second) of the powertrain of the automatic transmission according to the embodiment of the present invention, , N2, N3), respectively. The second sun gear S2, the second planetary carrier PC2 and the second ring gear R2 are connected to the fourth, fifth and sixth operating members N4 (N4, N6) of the powertrain of the automatic transmission according to the embodiment of the present invention, , N5, and N6, respectively. The third sun gear S3, the third ring gear R3 and the third planetary carrier PC3 are connected to the seventh, eighth and ninth operating members N7 of the powertrain of the automatic transmission according to the embodiment of the present invention, , N8, N9), respectively.

The fourth actuating member N4 is fixedly connected to the input shaft 10 and functions as an input member at all times. The third actuating member N3 is fixedly connected to the output shaft 20 and functions as an output member at all times. The first actuating member N1 is fixedly connected to the transmission case 30 and functions as a stop member at all times.

The second ring gear R2 is fixedly connected to the third planetary carrier PC3. The first ring gear R1 is fixedly connected to the third ring gear R3.

The powertrain of the automatic transmission according to the embodiment of the present invention uses six friction members.

The plurality of friction members include: a first clutch (C1) for selectively connecting the input shaft (10) and the fifth operating member (N5); A second clutch C2 selectively connecting the third actuating member N3 and the fifth actuating member N5; A third clutch C3 selectively connecting the eighth actuating member N8 and the ninth actuating member N9; A fourth clutch C4 selectively connecting the fifth actuating member N5 and the seventh actuating member N7; A first brake B1 for selectively connecting the ninth actuating member N9 to the transmission case 30; And a second brake B2 for selectively connecting the seventh actuating member N7 and the transmission case 30. [

More specifically, the first clutch C1 selectively connects the input shaft 10 and the second planetary carrier PC2. The second clutch C2 selectively connects the first planetary carrier PC1 and the second planetary carrier PC2. The third clutch C3 selectively connects the third ring gear R3 and the third planetary carrier PC3. The fourth clutch C4 selectively connects the second planetary carrier PC2 and the third sun gear S3. The first brake B1 selectively connects the third planetary carrier PC3 and the transmission case 30. [ The second brake B2 selectively connects the third sun gear S3 and the transmission case 30. [

As shown in FIG. 2, the automatic transmission according to the embodiment of the present invention implements a first forward speed and a reverse reverse speed, and two friction members are operated at each speed change stage.

That is, the fourth clutch C4 and the first brake B1 operate in the forward first speed (D1). And the second clutch C2 and the first brake B1 operate in the forward second speed (D2). In the forward third speed (D3), the second clutch C2 and the fourth clutch C4 operate. In the forward fourth speed (D4), the second clutch C2 and the third clutch C3 operate. In the forward fifth speed (D5), the second clutch C2 and the second brake B2 operate. In the forward sixth speed (D6), the first clutch C1 and the second clutch C2 operate. In the forward seventh speed (D7), the first clutch C1 and the second brake B2 operate. The first and third clutches C1 and C3 or the first and fourth clutches C1 and C4 operate in the forward eighth gear D8. That is, the same forward deceleration (D8) is implemented when the first clutch Cl and the third clutch C3 operate and when the first clutch C1 and the fourth clutch C4 operate. In the reverse first speed (Rev 1), the fourth clutch C4 and the second brake B2 operate.

Hereinafter, the formation of the forward 8-speed and the reverse 1-speed in the power train of the automatic transmission according to the embodiment of the present invention will be described in detail.

3 to 12, the fourth actuating member N4 which always acts as the input member always rotates at the rotational speed of the input shaft 10. [ Since the first actuating member N1 is fixedly connected to the transmission case 30, the first actuating member N1 is always stopped.

Since the second actuating member N2 and the eighth actuating member N8 are fixedly connected to each other, they rotate at the same speed at all times, and the sixth actuating member N6 and the ninth actuating member N9 are fixed So it always rotates at the same speed.

In this state, forward first to eighth speed and reverse speed are realized by selective operation of the first clutch C1 to the fourth clutch C4 and the first and second brakes B1 and B2. Will be described in detail.

[Advancing first gen]

In the forward first speed (D1), the fourth clutch C4 and the first brake B1 operate.

Since the first brake B1 is operated, the ninth actuating member N9 and the sixth actuating member N6 fixedly connected thereto stop. The fourth operating member N4 rotates at the same speed as the input shaft 10 and the sixth operating member N6 is stopped so that the speed diagram of the second planetary gear set PG2 is formed as shown in Figure 3 .

Since the fourth clutch C4 is operated, the seventh actuating member N7 rotates at the same speed as the fifth actuating member N5 of the second planetary gear set PG2. Therefore, the speed line diagram of the third planetary gear set PG3 is formed as shown in Fig.

Since the first actuating member N1 is always stopped and the second actuating member N2 rotates at the same speed as the eighth actuating member N8, the velocity diagram of the first planetary gear set PG1 is shown in Fig. 3 As shown in FIG. Therefore, the forward first speed D1 is outputted through the third operating member N3 as the output member.

[Advancing second gen]

And the second clutch C2 and the first brake B1 operate in the forward second speed (D2).

Since the first brake B1 is operated, the ninth actuating member N9 and the sixth actuating member N6 fixedly connected thereto stop. The fourth operating member N4 rotates at the same speed as the input shaft 10 and the sixth operating member N6 is stopped so that the speed line of the second planetary gear set PG2 is formed as shown in Figure 4 .

As the second clutch C2 is operated, the third actuating member N3 rotates at the same speed as the fifth actuating member N5.

Accordingly, the speed line diagram of the first planetary gear set PG1 is formed as shown in Fig. 4, and the forward second speed D2 is outputted through the third operation member N3 as the output member.

[Three steps forward]

In the forward third speed (D3), the second clutch C2 and the fourth clutch C4 operate.

As the second clutch C2 is operated, the third actuating member N3 rotates at the same speed as the fifth actuating member N5. Since the fourth clutch C4 is operated, the seventh actuating member N7 rotates at the same speed as the fifth actuating member N5 of the second planetary gear set PG2.

The fixedly connected second actuating member N2 and the eighth actuating member N8 rotate at the same speed and the fixedly connected sixth actuating member N6 and the ninth actuating member N9 rotate at the same speed.

The speed diagrams of the first, second and third planetary gear sets PG1, PG2 and PG3 are shown in Fig. 5 by the interaction of the first, second and third planetary gear sets PG1, PG2, And the forward third speed D3 is output through the third operation member N3 as the output member.

[Advance 4th gen]

In the forward fourth speed (D4), the second clutch C2 and the third clutch C3 operate.

The eighth operation member N8 and the ninth operation member N9 of the third planetary gear set PG3 are rotated at the same speed because the third clutch C3 is operated so that the third planetary gear set PG3 is rotated And rotates integrally.

The second actuating member N2 and the sixth actuating member N6 fixedly connected to the third planetary gear set PG3 rotate at the same speed as the third planetary gearset PG3.

As the second clutch C2 is operated, the third actuating member N3 rotates at the same speed as the fifth actuating member N5.

The speed diagrams of the first, second and third planetary gear sets PG1, PG2 and PG3 are shown in Fig. 6 by the interaction of the first, second and third planetary gear sets PG1, PG2, And the forward fourth gear D4 is output via the third actuating member N3 as the output member.

[Five steps forward]

In the forward fifth speed (D5), the second clutch C2 and the second brake B2 operate.

The seventh operation member N7 stops because the second brake B2 is operated. Since the second clutch is operated, the third actuating member N3 rotates at the same speed as the fifth actuating member N5.

The fixedly connected second actuating member N2 and the eighth actuating member N8 rotate at the same speed and the fixedly connected sixth actuating member N6 and the ninth actuating member N9 rotate at the same speed.

The speed diagrams of the first, second and third planetary gear sets PG1, PG2, PG3 are shown in Fig. 7 by the interaction of the first, second and third planetary gear sets PG1, PG2, And the forward fifth speed D5 is output via the third operation member N3 as the output member.

[6 steps forward]

In the forward sixth speed (D6), the first clutch C1 and the second clutch C2 operate.

Since the first clutch C1 is operated, the fifth operating member N5 rotates at the same speed as the fourth operating member N4. Therefore, the first planetary gear set PG1 rotates integrally with the rotation speed of the input shaft 10. [

As the second clutch C2 is operated, the third actuating member N3 rotates at the same speed as the fifth actuating member N5. That is, the third actuating member N3, which is the output member, rotates at the rotational speed of the input shaft 10 and outputs the forward sixth gear D6.

[Advancing seven genus]

In the forward seventh speed (D7), the first clutch C1 and the second brake B2 operate.

Since the first clutch C1 is operated, the fifth operating member N5 rotates at the same speed as the fourth operating member N4. Therefore, the first planetary gear set PG1 rotates integrally with the rotation speed of the input shaft 10. [

The seventh operation member N7 stops because the second brake B2 is operated. Since the ninth actuating member N9 is fixedly connected to the sixth actuating member N6, the ninth actuating member N9 rotates at the rotational speed of the input shaft 10. [ Therefore, the speed line of the third planetary gear set PG3 is formed as shown in Fig.

Since the first actuating member N1 is stopped and the second actuating member N2 is rotating at the same speed as the eighth actuating member N8, the velocity diagram of the first planetary gear set PG1 is shown in Fig. 9 .

Thus, the forward seventh speed D7 of the speed higher than the speed of the input shaft 10 is output through the third operating member N3 as the output member.

[Going forward 8]

The first and third clutches C1 and C3 or the first and fourth clutches C1 and C4 operate in the forward eighth gear D8. That is, the same forward deceleration (D8) is implemented when the first clutch Cl and the third clutch C3 operate and when the first clutch C1 and the fourth clutch C4 operate.

First, the case where the first clutch Cl and the fourth clutch C4 operate will be described.

Since the first clutch C1 is operated, the fifth operating member N5 rotates at the same speed as the fourth operating member N4. Therefore, the second planetary gear set PG2 rotates integrally with the rotation speed of the input shaft 10.

The seventh actuating member N7 rotates at the speed of the input shaft 10 and the ninth actuating member N9 fixedly connected to the sixth actuating member N6 is also engaged with the input shaft 10, . Therefore, the third planetary gear set PG3 rotates integrally with the rotation speed of the input shaft 10. [

Therefore, the speed diagram of the first planetary gear set PG1 is the same as that of the first planetary gear set PG1 shown in Fig. 10, since the second actuating member N2 rotates at the rotational speed of the input shaft 10 and the first actuating member N1 is stopped And the forward eighth gear D8 is output via the third actuating member N3 as the output member.

Next, the case where the first clutch Cl and the third clutch C3 operate will be described.

Since the first clutch C1 is operated, the fifth operating member N5 rotates at the same speed as the fourth operating member N4. Therefore, the first planetary gear set PG1 rotates integrally with the rotation speed of the input shaft 10. [ At this time, the ninth actuating member N9 fixedly connected to the sixth actuating member N6 also rotates at the rotational speed of the input shaft 10. [

The eighth actuating member N8 and the ninth actuating member N9 rotate at the same speed because the third clutch C3 is operated so that the third planetary gear set PG3 is integrally formed with the rotational speed of the input shaft 10 .

Therefore, the speed diagram of the first planetary gear set PG1 is the same as that of the first planetary gear set PG1 shown in Fig. 10, since the second actuating member N2 rotates at the rotational speed of the input shaft 10 and the first actuating member N1 is stopped And the forward eighth gear D8 is output via the third actuating member N3 as the output member.

That is, the second planetary gear set PG2 rotates integrally with the rotation speed of the input shaft 10 by the operation of the first clutch C1, so that the ninth operating member N9 is also rotated by the rotation of the input shaft 10 The third clutch C3 is operated or the fourth clutch C4 is operated or the third planetary gear set PG3 is rotated integrally with the rotational speed of the input shaft 10, The speed line is displayed.

[Backward speed]

In the reverse first speed (Rev 1), the fourth clutch C4 and the second brake B2 operate.

The seventh operation member N7 stops because the second brake B2 is operated. Since the fourth clutch C4 is operated, the fifth operating member N5 also stops. Therefore, the speed line diagram of the second planetary gear set PG2 is formed as shown in Fig.

The seventh operation member N7 stops and the ninth operation member N9 rotates at the same speed as the sixth operation member N6 so that the speed line diagram of the third planetary gear set PG3 is changed as shown in Fig. .

The speed diagram of the first planetary gear set PG1 is shown in Fig. 11 because the first actuating member N1 is always stopped and the second actuating member N2 is rotating at the same speed as the eighth actuating member N8 .

Therefore, the reverse first speed Rev1 is outputted through the third operating member N3 as the output member.

In Fig. 2, examples of possible speed ratios for the eight forward speeds and one reverse speed are described. In this example, the number of sun gear / ring gear teeth of the first planetary gear set PG1 is 10 and 22, the number of teeth of the sun gear / ring gear of the second planetary gear set PG2 is 10 and 23, respectively, And the number of sun gear / ring gear teeth of the set PG3 is 10 and 26, respectively.

However, the scope of protection of the present invention should not be construed as being limited thereto. By varying the number of sun gear / ring gear teeth of the first, second and third planetary gear sets PG1, PG2, and PG3, various other speed change ratios can be obtained.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And all changes to the scope that are deemed to be valid.

1 is a configuration diagram of a powertrain of an automatic transmission according to a first embodiment of the present invention.

2 is an operation table of the powertrain of the automatic transmission according to the first embodiment of the present invention.

3 is a speed diagram showing the rotational speeds of the respective operating members in the first forward speed of the power train of the automatic transmission according to the embodiments of the present invention.

4 is a speed diagram showing the rotational speeds of the respective operating members in the second forward speed of the power train of the automatic transmission according to the embodiment of the present invention.

5 is a speed diagram showing the rotational speeds of the respective operating members in the third forward speed of the power train of the automatic transmission according to the embodiment of the present invention.

6 is a speed diagram showing the rotational speeds of the respective operating members in the fourth forward speed of the power train of the automatic transmission according to the embodiment of the present invention.

7 is a speed diagram showing rotational speeds of respective operating members in five forward speeds of a power train of an automatic transmission according to an embodiment of the present invention.

8 is a speed line diagram showing rotational speeds of respective operating members in six forward speeds of a power train of an automatic transmission according to an embodiment of the present invention.

9 is a speed diagram showing the rotational speeds of the respective operating members in the forward seventh speed of the power train of the automatic transmission according to the embodiment of the present invention.

10 is a speed line diagram showing the rotational speeds of the respective operating members in the forward direction of the power train of the automatic transmission according to the embodiment of the present invention.

11 is a speed diagram showing the rotational speeds of the respective operating members in the first reverse speed of the power train of the automatic transmission according to the embodiment of the present invention.

Claims (9)

A first planetary gear set including a first operating member fixedly connected to the transmission case, a second operating member, and a third operating member fixedly connected to the output shaft; A second planetary gear set including a fourth operating member fixedly connected to the input shaft, a fifth operating member selectively connected to the input shaft and selectively connected to the third operating member, and a sixth operating member; A seventh actuating member selectively connected to the transmission case and selectively connected to the fifth actuating member, an eighth actuating member fixedly connected to the second actuating member, and an eighth actuating member fixedly connected to the sixth actuating member, A third planetary gear set including a ninth actuating member selectively connected to the operating member and selectively connected to the transmission case; And A plurality of friction members selectively connecting the operation members of the first, second and third planetary gear sets, the input shaft, the output shaft, and the transmission case; The powertrain of the automatic transmission. The method according to claim 1, Wherein the plurality of friction members A first clutch selectively connecting the input shaft and the fifth operating member; A second clutch for selectively connecting the third operating member and the fifth operating member; A third clutch that selectively connects the eighth operating member and the ninth operating member; A fourth clutch for selectively connecting the fifth operating member and the seventh operating member; A first brake selectively connecting the ninth operating member and the transmission case; And A second brake selectively connecting the seventh operation member and the transmission case; The powertrain of the automatic transmission. The method according to claim 1, Wherein the first planetary gear set is a double pinion planetary gear set including a first sun gear, a first ring gear, and a first planetary carrier as operating members thereof, Characterized in that the first sun gear acts as a first actuating member, the first ring gear acts as a second actuating member, and the first planetary carrier acts as a third actuating member . The method according to claim 1, The second planetary gear set is a single pinion planetary gear set including a second sun gear, a second planetary carrier, and a second ring gear as operating members thereof, Characterized in that the second sun gear acts as a fourth operating member, the second planetary carrier acts as a fifth operating member, and the second ring gear acts as a sixth operating member. . The method according to claim 1, The third planetary gear set is a double pinion planetary gear set including a third sun gear, a third ring gear, and a third planetary carrier as operating members thereof, The third sun gear acting as a seventh actuating member, the third ring gear acting as an eighth actuating member, and the third planetary carrier acting as a ninth actuating member. . 3. The method of claim 2, The fourth clutch and the first brake are actuated in forward 1 speed, The second clutch and the first brake are actuated in forward 2, In the third forward speed, the second clutch and the fourth clutch operate, The second clutch and the third clutch operate in forward speed 4, In the fifth forward speed, the second clutch and the second brake are actuated, In the sixth forward speed, the first clutch and the second clutch operate, The first clutch and the second brake are operated in forward speed 7, The first and third clutches or the first and fourth clutches operate in forward speed 8, And the fourth clutch and the second brake are actuated in reverse 1. The method according to claim 1, Wherein the first planetary gear set is a double pinion planetary gear set including a first sun gear, a first ring gear, and a first planetary carrier as operating members, the first sun gear serving as a first operating member, One ring gear acts as a second actuating member, and the first planetary carrier acts as a third actuating member; Wherein the second planetary gear set is a single pinion planetary gear set including a second sun gear, a second planetary carrier, and a second ring gear as its operating members, the second sun gear serving as a fourth operating member, 2 planetary carrier acts as a fifth operating member, and the second ring gear acts as a sixth operating member; Wherein the third planetary gear set is a double pinion planetary gear set including a third sun gear, a third ring gear, and a third planetary carrier as its operating members, the third sun gear acting as a seventh operating member, The third ring gear acting as an eighth operating member, and the third planetary carrier acting as a ninth operating member. 8. The method of claim 7, Wherein the plurality of friction members A first clutch selectively connecting the input shaft and the second planetary carrier; A second clutch selectively connecting the first planetary carrier and the second planetary carrier; A third clutch selectively connecting the third ring gear and the third planetary carrier; A fourth clutch selectively connecting the second planetary carrier and the third sun gear; A first brake selectively connecting the third planetary carrier and the transmission case; And A second brake selectively connecting the third sun gear and the transmission case; The powertrain of the automatic transmission. 9. The method of claim 8, The fourth clutch and the first brake are actuated in forward 1 speed, The second clutch and the first brake are actuated in forward 2, In the third forward speed, the second clutch and the fourth clutch operate, The second clutch and the third clutch operate in forward speed 4, In the fifth forward speed, the second clutch and the second brake are actuated, In the sixth forward speed, the first clutch and the second clutch operate, The first clutch and the second brake are operated in forward speed 7, The first and third clutches or the first and fourth clutches operate in forward speed 8, And the fourth clutch and the second brake are actuated in reverse 1.

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