KR20090129815A - Power train of automatic transmission - Google Patents

Abstract

PURPOSE: A power train of an automatic transmission is provided to use selective operation of first to fourth clutches and first and second brakes, thereby realizing forward speeds 1 to 8 and backward speed 1. CONSTITUTION: A first planetary gear set(PG1) comprises a first operation member, a second operation member, and a third operation member. The first operation member is fixably connected to a transmission case. The third operation member is fixably connected to an output shaft. A third planetary gear set(PG3) comprises a seventh operation member, an eighth operation member, and a ninth operation member. The seventh operation member is selectively connected to the transmission case.

Description

POWER TRAIN OF AUTOMATIC TRANSMISSION}

The present invention relates to a power train of an automatic transmission, and more particularly, to a power train of an automatic transmission that implements eight forward speeds and one reverse speed by using three simple planetary gear sets and six friction elements.

In general, a multi-stage shifting mechanism of an automatic transmission is implemented by combining a plurality of planetary gearsets, and a power train in which the plurality of planetary gearsets is combined receives a torque from a torque converter included in the automatic transmission and shifts it. It will function to transfer to the output shaft.

However, the more transmission stages that can be implemented, the more appropriate transmission ratios can be designed, and the vehicle can be realized in terms of power performance and fuel efficiency. Therefore, automatic transmissions that implement more transmission stages are of interest for continuous research. have.

In addition, even if the same number of gear stages are implemented, the durability, power transmission efficiency, and size of the power train vary according to the combination method of the planetary gear set, so that a more robust, no power loss, and a more compact power train configuration Efforts are always underway to invent.

In particular, unlike manual transmissions in which the driver has to shift frequently if the shift stage is too large, the automatic transmission performs shifting by controlling the operation of the power train by the control unit according to the driving condition. Efforts to find the configuration of the power train that implements the stage become more important for automatic transmissions.

Therefore, the present invention is devised to meet the development of the automatic transmission as described above, the object of the present invention is to implement the eight forward speed and the first reverse speed by using three simple planetary gear set and six friction elements. It is to provide the power train of the automatic transmission.

The power train of the automatic transmission according to the embodiment of the present invention for achieving this object includes 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 first planetary gear set; 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 operating member selectively connected to the transmission case and selectively connected to the fifth operating member, an eighth operating member fixedly connected to the second operating member, and fixedly connected to the sixth operating member and A third planetary gear set including a ninth operating member selectively connected to an eight 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 plurality of friction members may include: a first clutch selectively connecting the input shaft and the fifth operation member; A second clutch for selectively connecting the third operating member and the fifth operating member; A third clutch for selectively connecting 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 for selectively connecting the ninth operating member and the transmission case; And a first brake for selectively connecting the seventh operation member and the transmission case.

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

The first planetary gear set is a double pinion planetary gear set including a first sun gear, a first ring gear, and a first planet carrier as its operating member, wherein the first sun gear acts as a first actuating member. The first ring gear acts as the second actuation member, and the first planet carrier acts as the third actuation member.

The second planetary gear set is a single pinion planetary gear set including a second sun gear, a second planet carrier, and a second ring gear as its operating member, wherein the second sun gear acts as a fourth operating member. The two planetary carriers may act as the fifth operating member, and the second ring gear may act as the sixth operating member.

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

The fourth clutch and the first brake operate at the forward 1 speed, the second clutch and the first brake operate at the forward 2 speed, the second clutch and the fourth clutch operate at the forward 3 speed, and the second clutch and the second clutch at the forward 4 speed. 3 clutch operates, 2nd clutch and 2nd brake operate at 5th forward, 1st clutch and 2nd clutch operate at 6th forward, 1st clutch and 2nd brake operate at 7th forward, 8 forward The first clutch, the third clutch or the first clutch and the fourth clutch operate in the inside, and the fourth clutch and the second brake operate in the reverse speed 1.

As described above, according to the power train of the automatic transmission according to the present invention, three forward planetary gear sets and six friction elements may be used to implement eight forward speeds and one reverse speed.

In addition, by providing a large number of gear stages it is possible to effectively use the power of the engine to improve the power transmission performance and reduce fuel economy.

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

As shown in FIG. 1, a power train of an automatic transmission according to an exemplary 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 power from 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 planet carrier PC1 as its operating member. The first sun gear S1 and the first pinion gear P1 gear-coupled to the first ring gear R1 are connected to the first planet carrier PC1 to rotate.

The second planetary gear set PG2 is a single pinion planetary gear set including a second sun gear S2, a second planet carrier PC2, and a second ring gear R2 as its operating member. A second pinion gear P2 gear-coupled to the second sun gear S2 and the second ring gear R2 is connected to the second planet carrier PC2 to rotate.

The third planetary gear set PG3 is a double pinion planetary gear set including a third sun gear S3, a third ring gear R3, and a third planet carrier PC3 as its operating member. The third planet carrier PC3 is connected to and rotates with a third pinion gear P3 gear-coupled with the third sun gear S3 and the third ring gear R3.

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

The fourth operating member N4 is fixedly connected to the input shaft 10 to act as an input member at all times. The third operating member (N3) is fixedly connected to the output shaft 20 to always act as an output member. The first operating member (N1) is fixedly connected to the transmission case (30) acts as a stop member at all times.

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

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

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

More specifically, the first clutch C1 selectively connects the input shaft 10 and the second planet carrier PC2. The second clutch C2 selectively connects the first planet carrier PC1 and the second planet carrier PC2. The third clutch C3 selectively connects the third ring gear R3 and the third planet carrier PC3. The fourth clutch C4 selectively connects the second planet carrier PC2 and the third sun gear S3. The first brake B1 selectively connects the third planet 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 8 forward speeds and 1 reverse speed, and two friction members operate at each shift stage.

That is, the fourth clutch C4 and the first brake B1 operate at the first forward speed D1. In the second forward speed D2, the second clutch C2 and the first brake B1 operate. In the third forward speed D3, the second clutch C2 and the fourth clutch C4 operate. In the fourth forward speed D4, the second clutch C2 and the third clutch C3 operate. In the fifth forward speed D5, the second clutch C2 and the second brake B2 operate. At the sixth forward speed D6, the first clutch C1 and the second clutch C2 operate. At the seventh forward speed D7, the first clutch C1 and the second brake B2 operate. At the eighth forward speed D8, the first and third clutches C1 and C3 or the first and fourth clutches C1 and C4 operate. That is, when the first clutch C1 and the third clutch C3 operate and when the first clutch C1 and the fourth clutch C4 operate, the same forward eighth speed D8 is implemented. In the reverse first speed Rev1, the fourth clutch C4 and the second brake B2 operate.

Hereinafter, the formation of eight forward speeds and one reverse speed in the power train of the automatic transmission according to an embodiment of the present invention will be described in detail.

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

Since the second operating member N2 and the eighth operating member N8 are fixedly connected to each other, they are always rotated at the same speed, and the sixth operating member N6 and the ninth operating member N9 are fixed to each other. It always rotates at the same speed.

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

[1st speed forward]

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

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

Since the fourth clutch C4 operates, the seventh operating member N7 rotates at the same speed as the fifth operating member N5 of the second planetary gear set PG2. Therefore, the velocity diagram of the third planetary gear set PG3 is formed as shown in FIG.

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

[2 speed forward]

In the second forward speed D2, the second clutch C2 and the first brake B1 operate.

Since the first brake B1 is operated, the ninth operating member N9 and the sixth operating member N6 fixedly connected thereto are stopped. Since the fourth operating member N4 rotates at the same speed as the input shaft 10 and the sixth operating member N6 stops, the speed diagram of the second planetary gear set PG2 is formed as shown in FIG. 4. .

Since the second clutch C2 operates, the third operating member N3 rotates at the same speed as the fifth operating member N5.

Accordingly, the speed diagram of the first planetary gear set PG1 is formed as shown in FIG. 4, and the second forward speed D2 is output through the third operating member N3, which is an output member.

[3 speed forward]

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

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

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

Under these conditions, the speed diagrams of the first, second and third planetary gear sets PG1, PG2 and PG3 by the interaction of the first, second and third planetary gear sets PG1, PG2 and PG3 are shown in FIG. It is formed as described above, and the third forward speed D3 is output through the third operating member (N3) that is the output member.

[4 forward speed]

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

Since the third clutch C3 is operated, the eighth operating member N8 and the ninth operating member N9 of the third planetary gear set PG3 rotate at the same speed, so that the third planetary gear set PG3 is Rotate integrally

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

Since the second clutch C2 operates, the third operating member N3 rotates at the same speed as the fifth operating member N5.

Under these conditions, the speed diagrams of the first, second and third planetary gear sets PG1, PG2 and PG3 by the interaction of the first, second and third planetary gear sets PG1, PG2 and PG3 are shown in FIG. As described above, the fourth forward speed D4 is output through the third operating member N3 which is an output member.

[5th forward]

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

Since the second brake B2 operates, the seventh operating member N7 stops. Since the second clutch operates, the third operating member N3 rotates at the same speed as the fifth operating member N5.

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

Under these conditions, the velocity diagrams of the first, second and third planetary gear sets PG1, PG2 and PG3 by the interaction of the first, second and third planetary gear sets PG1, PG2 and PG3 are shown in FIG. It is formed as described above, the fifth forward speed (D5) is output through the third operating member (N3) output member.

[6th forward]

At the sixth forward speed D6, the first clutch C1 and the second clutch C2 operate.

Since the first clutch C1 operates, 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 at the rotational speed of the input shaft 10.

Since the second clutch C2 operates, the third operating member N3 rotates at the same speed as the fifth operating member N5. That is, the sixth forward speed D6 is output while the third operation member N3, which is an output member, rotates at the rotational speed of the input shaft 10.

[7th forward]

At the seventh forward speed D7, the first clutch C1 and the second brake B2 operate.

Since the first clutch C1 operates, 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 at the rotational speed of the input shaft 10.

Since the second brake B2 operates, the seventh operating member N7 stops. Since the ninth operating member N9 is fixedly connected to the sixth operating member N6, the ninth operating member N9 rotates at the rotational speed of the input shaft 10. Thus, the velocity diagram of the third planetary gear set PG3 is formed as shown in FIG.

Since the first operating member N1 is stopped and the second operating member N2 rotates at the same speed as the eighth operating member N8, the speed diagram of the first planetary gear set PG1 is shown in FIG. As formed.

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

[8th forward]

At the eighth forward speed D8, the first and third clutches C1 and C3 or the first and fourth clutches C1 and C4 operate. That is, when the first clutch C1 and the third clutch C3 operate and when the first clutch C1 and the fourth clutch C4 operate, the same forward eighth speed D8 is implemented.

First, the case where the first clutch C1 and the fourth clutch C4 operate will be described.

Since the first clutch C1 operates, 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 at the rotational speed of the input shaft 10.

Since the fourth clutch C4 operates, the seventh operating member N7 rotates at the speed of the input shaft 10, and the ninth operating member N9 fixedly connected to the sixth operating member N6 is also input shaft 10. Rotate at speed. Therefore, the third planetary gear set PG3 rotates integrally at the rotational speed of the input shaft 10.

Accordingly, since the second operating member N2 rotates at the rotational speed of the input shaft 10 and the first operating member N1 is stopped, the speed diagram of the first planetary gear set PG1 is shown in FIG. 10. As described above, the eighth forward speed D8 is output through the third operating member N3 which is an output member.

Next, the case where the first clutch C1 and the third clutch C3 operate will be described.

Since the first clutch C1 operates, 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 at the rotational speed of the input shaft 10. At this time, the ninth operating member N9 fixedly connected to the sixth operating member N6 also rotates at the rotational speed of the input shaft 10.

Since the third clutch C3 operates, the eighth operating member N8 and the ninth operating member N9 rotate at the same speed, and the third planetary gear set PG3 is integrated at the rotational speed of the input shaft 10. Rotate to

Accordingly, since the second operating member N2 rotates at the rotational speed of the input shaft 10 and the first operating member N1 is stopped, the speed diagram of the first planetary gear set PG1 is shown in FIG. 10. As described above, the eighth forward speed D8 is output through the third operating member N3 which is an output member.

That is, the second planetary gear set PG2 is integrally rotated at the rotational speed of the input shaft 10 by the operation of the first clutch C1. Accordingly, the ninth operating member N9 also rotates the input shaft 10. At this time, the third clutch C3 operates, the fourth clutch C4 operates, or the third planetary gear set PG3 rotates integrally at the rotational speed of the input shaft 10. It will show the speed diagram.

[1 speed reverse]

In the reverse first speed Rev1, the fourth clutch C4 and the second brake B2 operate.

Since the second brake B2 operates, the seventh operating member N7 stops. Since the fourth clutch C4 operates, the fifth operating member N5 also stops. Thus, the velocity diagram of the second planetary gear set PG2 is formed as shown in FIG.

Since the seventh operating member N7 is stopped and the ninth operating member N9 rotates at the same speed as the sixth operating member N6, the speed diagram of the third planetary gear set PG3 is shown in FIG. Is formed.

Since the first operating member N1 is always stopped and the second operating member N2 rotates at the same speed as the eighth operating member N8, the speed diagram of the first planetary gear set PG1 is shown in FIG. As formed.

Therefore, the reverse 1 speed Rev1 is output through the third operating member N3 which is the output member.

In FIG. 2, an example of the speed ratio which is possible with respect to 8 forward speeds and 1 reverse speed is described. For example, the number of sun gear / ring gear teeth of the first planetary gear set PG1 is 10 and 22, the number of sun gear / ring gear teeth of the second planetary gear set PG2 is 10 and 23, respectively, and the third planetary gear The number of sun gear / ring gear teeth of the set PG3 is 10 and 26, respectively.

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

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and easily changed and equalized by those skilled in the art from the embodiments of the present invention. It includes all changes to the extent deemed acceptable.

1 is a block diagram of a power train of an automatic transmission according to a first embodiment of the present invention.

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

3 is a speed diagram showing the rotational speed of each operating member at the forward 1 speed of the power train of the automatic transmission according to the embodiments of the present invention.

Figure 4 is a speed diagram showing the rotational speed of each operating member at the second forward speed of the power train of the automatic transmission according to an embodiment of the present invention.

Figure 5 is a speed diagram showing the rotational speed of each operating member at the third forward speed of the power train of the automatic transmission according to an embodiment of the present invention.

Figure 6 is a speed diagram showing the rotational speed of each operating member at the fourth forward speed of the power train of the automatic transmission according to an embodiment of the present invention.

Figure 7 is a speed diagram showing the rotational speed of each operating member at 5 forward speeds of the power train of the automatic transmission according to the embodiment of the present invention.

8 is a speed diagram showing the rotational speed of each operating member at sixth forward speed of the power train of the automatic transmission according to the embodiment of the present invention.

Figure 9 is a speed diagram showing the rotational speed of each operating member at seven forward speeds of the power train of the automatic transmission according to the embodiment of the present invention.

Figure 10 is a speed diagram showing the rotational speed of each operating member at eight forward speeds of the power train of the automatic transmission according to the embodiment of the present invention.

11 is a speed diagram showing the rotational speed of each operating member at the reverse speed 1 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 operating member selectively connected to the transmission case and selectively connected to the fifth operating member, an eighth operating member fixedly connected to the second operating member, and fixedly connected to the sixth operating member and A third planetary gear set including a ninth operating member selectively connected to an eight 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; A power train of an automatic transmission comprising a. The method of claim 1, The plurality of friction members, A first clutch for 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 for selectively connecting 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 for selectively connecting the ninth operating member and the transmission case; And A first brake for selectively connecting the seventh operation member and the transmission case; A power train of an automatic transmission comprising a. The method of claim 1, The first planetary gear set is a double pinion planetary gear set including a first sun gear, a first ring gear, and a first planet carrier as its operating member. The first sun gear acts as a first actuating member, the first ring gear acts as a second actuating member, and the first planet carrier acts as a third actuating member. . The method of claim 1, The second planetary gear set is a single pinion planetary gear set including a second sun gear, a second planet carrier, and a second ring gear as its operating member, The second sun gear acts as a fourth actuating member, the second planet carrier acts as a fifth actuating member, and the second ring gear acts as a sixth actuating member. . The method of 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 planet carrier as its operating member, The third sun gear acts as a seventh actuating member, the third ring gear acts as an eighth actuating member, and the third planetary carrier acts as a ninth actuating member. . The method of claim 2, 4th clutch and 1st brake operate at forward 1 speed, At the 2nd forward speed, the second clutch and the first brake operate, At the 3rd forward speed, the second clutch and the fourth clutch operate. At the 4th forward speed, the second clutch and the third clutch operate At the 5th forward speed, the second clutch and the second brake operate, At the 6th forward speed, the first clutch and the second clutch operate At the 7th forward, the first clutch and the second brake actuate, At 8th forward speed, the first and third clutches or the first and fourth clutches operate, A power train of an automatic transmission, characterized in that the fourth clutch and the second brake operate in reverse 1 speed. The method of claim 1, The first planetary gear set is a double pinion planetary gear set including a first sun gear, a first ring gear, and a first planet carrier as its operating member, wherein the first sun gear acts as a first actuating member. The first ring gear acts as a second actuating member, and the first planet carrier acts as a third actuating member; The second planetary gear set is a single pinion planetary gear set including a second sun gear, a second planet carrier, and a second ring gear as its operating member, wherein the second sun gear acts as a fourth operating member. The planetary carrier acts as the fifth actuating member, and the second ring gear acts as the sixth actuating member; The third planetary gear set is a double pinion planetary gear set including a third sun gear, a third ring gear, and a third planet carrier as its operating member, wherein the third sun gear acts as a seventh operating member. And a third ring gear acts as an eighth actuating member, and the third planet carrier acts as a ninth actuating member. The method of claim 7, wherein The plurality of friction members, A first clutch selectively connecting the input shaft and the second planet carrier; A second clutch for selectively connecting the first planetary carrier and the second planetary carrier; A third clutch for selectively connecting the third ring gear and the third planet carrier; A fourth clutch for selectively connecting the second planetary carrier and the third sun gear; A first brake for selectively connecting the third planetary carrier and the transmission case; And A first brake for selectively connecting the third sun gear and the transmission case; A power train of an automatic transmission comprising a. The method of claim 8, 4th clutch and 1st brake operate at forward 1 speed, At the 2nd forward speed, the second clutch and the first brake operate, At the 3rd forward speed, the second clutch and the fourth clutch operate. At the 4th forward speed, the second clutch and the third clutch operate At the 5th forward speed, the second clutch and the second brake operate, At the 6th forward speed, the first clutch and the second clutch operate At the 7th forward, the first clutch and the second brake actuate, At 8th forward speed, the first and third clutches or the first and fourth clutches operate, A power train of an automatic transmission, characterized in that the fourth clutch and the second brake operate in reverse 1 speed.

Images