KR102604234B1 - 4 wheel drive system - Google Patents

Abstract

The present invention includes a first power transmission device that distributes power received from a transmission to front and rear wheels; a propeller shaft that transmits power distributed from the first power transmission device to the rear wheels; and a second power transmission device coupled to the rear end of the propeller shaft and distributing power received from the propeller shaft to the rear wheels, wherein the first power transmission device and the second power transmission device increase torque. A four-wheel drive system including a first planetary gearset and a second planetary gearset is provided.

Description

Four-wheel drive system {4 WHEEL DRIVE SYSTEM}

The present invention relates to a four-wheel drive system, and more specifically, to a four-wheel drive system capable of switching between a two-wheel drive mode and a four-wheel drive mode.

Generally, a four-wheel drive vehicle based on front-wheel drive implements a four-wheel drive system by distributing part of the power that drives the front wheels to the rear wheels. At this time, a PTU (Power Transfer Unit) is installed to distribute power from the front wheel side to the rear wheel side, and the power transmitted by the PTU is transmitted to the rear wheel side through the propeller shaft.

However, such a four-wheel drive system has the problem that the propeller shaft rotates even in two-wheel drive mode, resulting in energy loss and low fuel efficiency.

The purpose of the present invention is to provide a four-wheel drive system that can increase energy efficiency by blocking unnecessary rotation in a two-wheel drive mode.

Another purpose is to provide a four-wheel drive system driven at high torque.

Another purpose is to provide a four-wheel drive system that can improve rough terrain escape performance.

In order to achieve the above-described object, the present invention includes a first power transmission device that distributes power received from the transmission to the front and rear wheels; a propeller shaft that transmits power distributed from the first power transmission device to the rear wheels; and a second power transmission device coupled to the rear end of the propeller shaft and distributing power received from the propeller shaft to the rear wheels, wherein the first power transmission device and the second power transmission device increase torque. A four-wheel drive system including a first planetary gearset and a second planetary gearset is provided.

Additionally, according to an embodiment of the present invention, the first power transmission device includes a housing; An input shaft that receives power from the transmission; a first gear surrounding the input shaft; a second gear meshed with the first gear to transmit power to the propeller shaft; And it may further include a first sleeve connected between the input shaft and the first gear to transmit or block power.

Additionally, according to an embodiment of the present invention, the first power transmission device may further include a front wheel differential gear that distributes power to the left and right front wheels.

Additionally, according to an embodiment of the present invention, the first planetary gear set includes a sun gear that receives power from the input shaft; a plurality of planetary gears external to the sun gear; and a ring gear in contact with the planetary gear, wherein the first power transmission device includes a second sleeve connecting the ring gear and the housing, and rotation of the ring gear is stopped when the second sleeve is fastened. It is possible to implement a high torque mode in which power is transmitted from the sun gear to the planet gear.

Additionally, according to an embodiment of the present invention, the first power transmission device may include a first actuator that moves the first sleeve and a second actuator that moves the second sleeve.

Additionally, according to an embodiment of the present invention, the second power transmission device includes a housing; An input flange connected to the propeller shaft to transmit power; a third gear disposed coaxially with the input flange; A coupling that transmits or blocks power between the input flange and the third gear; a fourth gear meshed with the third gear; an output shaft penetrating the fourth gear; And it may include a third sleeve connected between the fourth gear and the output shaft to transmit or block power.

Additionally, according to an embodiment of the present invention, the second planetary gear set includes a sun gear that receives power from the output shaft; a plurality of planetary gears external to the sun gear; and a ring gear in contact with the planetary gear, wherein the second power transmission device includes a fourth sleeve connecting the ring gear and the housing, and when the fourth sleeve is fastened, the rotation of the ring gear is stopped. It is possible to implement a high torque mode in which power is transmitted from the sun gear to the planet gear.

Additionally, according to an embodiment of the present invention, the second power transmission device may further include a rear differential gear that distributes power to the left and right rear wheels.

In addition, according to an embodiment of the present invention, the fourth sleeve can be additionally fastened to the rear differential gear, so that the rear differential gear can be changed to a locked state.

Additionally, according to an embodiment of the present invention, the second power transmission device may include a third actuator for moving the third sleeve and a fourth actuator for moving the fourth sleeve.

The four-wheel drive system according to the present invention can increase energy efficiency by blocking unnecessary rotation in two-wheel drive mode.

In addition, it is possible to implement a 4WD-Low mode that operates at low rotation and high torque, and a 4WD-Low-Lock mode that improves rough terrain escape performance, improving driving performance by providing a mode optimized for various driving environments. You can do it.

1 is a diagram briefly showing the power transmission system of a four-wheel drive system according to an embodiment of the present invention;
Figure 2 is a perspective view showing the first power transmission unit (PTU) of a four-wheel drive system according to an embodiment of the present invention;
Figure 3 is a cross-sectional view of Figure 2;
Figure 4 is a cross-sectional view schematically showing the power transmission system of Figure 2;
Figure 5 is a perspective view showing the second power transmission device (RDM) of a four-wheel drive system according to an embodiment of the present invention;
Figure 6 is a cross-sectional view of Figure 5;
Figure 7 is a cross-sectional view schematically showing the power transmission system of Figure 5;
8 is a schematic diagram showing the 2WD mode of a four-wheel drive system according to an embodiment of the present invention;
9 is a schematic diagram showing the 4WD-High mode of a four-wheel drive system according to an embodiment of the present invention;
10 is a schematic diagram showing the 4WD-Low mode of a four-wheel drive system according to an embodiment of the present invention;
11 is a schematic diagram showing the 4WD-Low-Lock mode of a four-wheel drive system according to an embodiment of the present invention;
Figure 12 is a diagram showing hub coupling portions according to the drive mode of a four-wheel drive system according to an embodiment of the present invention.

Hereinafter, a four-wheel drive system according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a diagram briefly showing the power transmission system of a four-wheel drive system according to an embodiment of the present invention. This embodiment is a four-wheel drive system based on front-wheel drive, and the engine 100 is located on the front wheels (400a, 400b) and drives the front wheels (400a, 400b), so it is commonly referred to as the FF system. The power of the engine 100 is transmitted to the transmission 200 to shift gears, and the power of the transmission 200 is transmitted to the first power transmission device 300. The first power transmission device 300 is used in a front-wheel drive-based four-wheel drive system and is also referred to as a PTU (Power Transfer Unit).

The first power transmission device 300 transmits power to the front wheels 400a and 400b, but may selectively send some power to the rear wheels 700a and 700b. This power transmission is achieved by a propeller shaft 500 connected to the first power transmission device 300.

A second power transmission device 600 is provided at the rear end of the propeller shaft 500. The second power transmission device 600 includes a rear differential gear 680 that distributes the power transmitted to the rear wheels 700a and 700b to the left and right. Additionally, the second power transmission device 600 includes a coupling 630 that automatically controls power transmitted to the rear wheels 700a and 700b. The second power transmission device 600 is also referred to as RDM (Rear Differential Module).

The first power transmission device 300 will be described in detail with reference to FIGS. 2 to 4.

Figure 2 is a perspective view showing the first power transmission unit (PTU) of a four-wheel drive system according to an embodiment of the present invention, Figure 3 is a cross-sectional view of Figure 2, and Figure 4 is a cross-sectional view schematically showing the power transmission system of Figure 2. .

The first power transmission device 300 includes a housing 310, an input shaft 322 that receives power from the transmission 200, a first gear 330 surrounding the input shaft 322, and the first gear 330. A second gear 342 that meshes with the gear 330 to transmit power to the propeller shaft 500, and a gear connected between the input shaft 322 and the first gear 330 to transmit or block power. 1 sleeve 332, a first actuator 334 that moves the first sleeve 332, a front wheel differential gear 370 that distributes power to the left and right front wheels 400a and 400b, the input shaft 322 and the A first planetary gearset 360 connecting the front wheel differential gear 370, a second sleeve 362 connecting the ring gear of the first planetary gearset 360 and the housing 310, and the second sleeve It includes a second actuator 364 that moves 362.

The housing 310 accommodates the above-described components in its internal space, and the first actuator 334 and the second actuator 364 may be attached to the outer surface of the housing 310 and may be connected to a control device such as an ECU. It can be connected via CAN communication and controlled electronically.

The input shaft 322 and the first gear 330 rotate together when the first sleeve 332 is fastened, but do not rotate together when the first sleeve 332 is not fastened. When the first gear 330 rotates, the second gear 342 engaged with the first gear 330 rotates. The angle formed by the rotation axes of the first gear 330 and the second gear 342 is 90 degrees. A first pinion shaft 340 extends integrally to the rear end of the second gear 342. An output flange 350 is coupled to the outer peripheral surface of the first pinion shaft 340, and the output flange 350 is coupled to the propeller shaft 500. Accordingly, when the first sleeve 332 is fastened, power is transmitted to the rear wheels 700a and 700b. Conversely, if the first sleeve 332 is not fastened, power is not transmitted to the first gear 330, the second gear 342, and the propeller shaft 500. A two-wheel drive (2WD) mode is implemented by controlling the first actuator 334 to not fasten the first sleeve 332.

The end of the input shaft 322 is coupled to the first planetary gearset 360. The first planetary gearset 360 includes a sun gear that receives power from the input shaft 322, a plurality of planetary gears external to the sun gear, and a ring gear internally in contact with the planetary gear. And a second sleeve 362 connecting the ring gear and the housing 310 is provided.

Here, the planetary gear is also referred to as a pinion gear, and a plurality of the planetary gears may be coupled by a carrier. For convenience of explanation, hereinafter, the planetary gear is defined to mean a configuration including the carrier, and the rotation speed of the planetary gear is defined to mean the rotation speed of the carrier.

As described above, power is input through the sun gear and the sun gear rotates. When the second sleeve 362 is not fastened, both the planet gear and the ring gear may rotate together without being fixed.

On the other hand, when the second sleeve 362 is fastened, the ring gear is fixed and cannot rotate. In this state, as the power of the sun gear is transmitted to the planet gear, the rotation speed is reduced and the torque is increased. A high torque (low rotation) mode is implemented by controlling the second actuator 364 to fasten the second sleeve 362.

The planetary gear is connected to the front wheel differential gear 370. The front wheel differential gear 370 is known as a device that distributes power to the left and right to create a difference in rotation speed. The first intermediate shaft 320 transmits power from the front wheel differential gear 370 to one front wheel 400a. To avoid interference, the first intermediate shaft 320 can be inserted into the hollow of the input shaft 322 and rotates independently of the input shaft 322. A front wheel shaft 380 is provided on the opposite side of the first intermediate shaft 320 centered on the front wheel differential gear 370 to transmit power to the other front wheel 400b.

Figure 4 shows a state in which both the first sleeve 332 and the second sleeve 362 are not fastened. Specifically, the first sleeve 332 can be splined to the A hub formed on the input shaft 322 and the B hub formed on the first gear 330. The fact that the first sleeve 332 is fastened means that the first sleeve 332 moves to the left in the drawing and is coupled to both the A hub and the B hub and the input shaft 322 and the first gear. (330) This means that power is transmitted between. The fact that the first sleeve 332 is not fastened means that the first sleeve 332 moves to the right in the drawing and is coupled only to the B hub between the input shaft 322 and the first gear 330. This means that power transmission is blocked.

The second sleeve 362 can be splined to the C hub formed on the housing 310, the D hub formed on the ring gear, the E hub formed on the planet gear, and the F hub formed on the sun gear. The fact that the second sleeve 362 is fastened means that the second sleeve 362 is moved to the left in the drawing and is coupled to both the C hub and the D hub, thereby preventing the ring gear from rotating. do. The fact that the second sleeve 362 is not fastened means that the second sleeve 362 moves to the right in the drawing and is coupled to the E hub and the F hub so that the ring gear can rotate.

4 shows a two-wheel drive mode, in which power is not transmitted to the rear wheels 700a and 700b, and the rotation speed is not reduced. Other driving modes will be described later.

The second power transmission device 600 will be described in detail with reference to FIGS. 5 to 7 .

Figure 5 is a perspective view showing a second power transmission device (RDM) of a four-wheel drive system according to an embodiment of the present invention, Figure 6 is a cross-sectional view of Figure 5, and Figure 7 is a cross-sectional view schematically showing the power transmission system of Figure 5. .

The second power transmission device 600 includes a housing 610, an input flange 620 that is connected to the propeller shaft 500 and receives power, and a third gear disposed coaxially with the input flange 620 ( 642), a coupling 630 that transmits or blocks power between the input flange 620 and the third gear 642, a fourth gear 650 meshed with the third gear 642, and the third gear 642. An output shaft 660 penetrating the fourth gear 650, a third sleeve 662 connected between the fourth gear 650 and the output shaft 660 to transmit or block power, the third sleeve ( A third actuator 663 that moves 662), a rear differential gear 680 that distributes power to the left and right rear wheels 700a and 700b, and a second connecting the output shaft 660 and the rear differential gear 680. A planetary gearset 670, a fourth sleeve 664 connecting the ring gear of the second planetary gearset 670 and the housing 610, and a fourth actuator 665 that moves the fourth sleeve 664. ) includes.

The housing 610 accommodates the above-described components inside, and the third actuator 663 and the fourth actuator 665 can be attached to the outer surface of the housing 610, and can be connected to a control device such as an ECU by CAN. It can be connected via communication and controlled electronically.

The input flange 620 is coupled to the rear end of the propeller shaft 500 and receives power. A separate shaft may be further provided on the inner peripheral surface of the input flange 620 and rotates together with the input flange 620. The coupling 630 not only transmits or blocks the power of the input flange 620 to the third gear 642, but may also be controlled to transmit only part of the power. The coupling 630 may operate under electronic control. The coupling 630 may include a multi-plate clutch, but other types of clutches may also be provided.

A second pinion shaft 640 extends integrally to the tip of the third gear 642. The second pinion shaft 640 is coupled to the coupling 630. The third gear 642 is meshed with the fourth gear 650. The angle formed by the rotation axes of the third gear 642 and the fourth gear 650 is 90 degrees.

The fourth gear 650 surrounds the output shaft 660. In other words, the output shaft 660 penetrates the fourth gear 650. The fourth gear 650 and the output shaft 660 are not coupled to always rotate together, and power is transmitted when the third sleeve 662 is fastened, and power is transmitted when the third sleeve 662 is not fastened. It is not transmitted and rotates independently.

The end of the output shaft 660 is coupled to the second planetary gearset 670. The second planetary gearset 670 includes a sun gear that receives power from the output shaft 660, a plurality of planetary gears external to the sun gear, and a ring gear internally in contact with the planetary gear. And a fourth sleeve 664 connecting the ring gear and the housing 610 is provided.

The overall principle of the second planetary gearset 670 is the same as that of the first planetary gearset 360. That is, when the fourth sleeve 664 is not fastened, both the planet gear and the ring gear may rotate as one unit without being fixed.

On the other hand, when the fourth sleeve 664 is fastened, the ring gear is fixed and cannot rotate. In this state, as the power of the sun gear is transmitted to the planet gear, the rotation speed is reduced and the torque is increased. A high torque (low rotation) mode is implemented by controlling the fourth actuator 665 to fasten the fourth sleeve 664.

The planetary gear is connected to the rear differential gear 680. The rear differential gear 680 is known as a device that distributes power to the left and right to create a difference in left and right rotation speed. The second intermediate shaft 661 transmits power from the rear wheel differential gear 680 to one rear wheel 700b. To avoid interference, the second intermediate shaft 661 can be inserted into the hollow of the output shaft 660 and rotates independently of the output shaft 660.

Figure 7 shows a state in which both the third sleeve 662 and the fourth sleeve 664 are not fastened. Specifically, the third sleeve 662 can be spline-coupled with the G hub formed on the output shaft 660 and the H hub formed on the fourth gear 650. The fact that the third sleeve 662 is fastened means that the third sleeve 662 moves to the left in the drawing and is coupled to both the G hub and the H hub and the fourth gear 650 and the output shaft. (660) This means that power is transmitted between The fact that the third sleeve 662 is not fastened means that the third sleeve 662 moves to the right in the drawing and is coupled only to the G hub between the fourth gear 650 and the output shaft 660. This means that power transmission is blocked.

The fourth sleeve 664 includes a J hub formed on the housing 610, a K hub formed on the ring gear, an L hub formed on the planetary gear, an M hub formed on the sun gear, and the rear differential gear. Spline connection is possible to the N hub formed at (680). The fact that the fourth sleeve 664 is fastened means that the fourth sleeve 664 moves to the left in the drawing and is coupled to both the J hub and the K hub, thereby preventing the lee gear from rotating. do. The fact that the fourth sleeve 664 is not fastened means that the fourth sleeve 664 moves to the right in the drawing and is coupled to the M hub and the N hub so that the ring gear can rotate.

7 shows a two-wheel drive mode, in which power is not transmitted to the rear wheels 700a and 700b. Note that power is not transmitted, which does not mean that the entire vehicle is stopped. Therefore, when the vehicle is running, the rear differential gear 680, the output shaft 660, and the second wheel are rotated by the rotation of the rear wheels 700a and 700b. The planetary gearset 670, etc. can rotate. However, if rotation due to inertia, etc. is ignored, the third gear 642 and the fourth gear 650 do not rotate.

Hereinafter, driving modes of the four-wheel drive system according to this embodiment will be described with reference to FIGS. 8 to 12.

First, the two-wheel drive (2WD) mode will be described.

Figure 8 is a schematic diagram showing a two-wheel drive (2WD) mode of a four-wheel drive system according to an embodiment of the present invention.

Since this embodiment is a four-wheel drive system based on front-wheel drive, 2WD mode refers to a mode in which power is transmitted to only the two front wheels.

In 2WD mode, both the first sleeve 332 and the second sleeve 362 are not fastened. If the first sleeve 332 is not fastened, the power of the input shaft 322 is not transmitted to the first gear 330. Therefore, power is not transmitted to the second gear 342 engaged with the first gear 330 as well as the propeller shaft 500. Since unnecessary parts do not rotate, energy loss can be reduced.

Since power is not transmitted to the propeller shaft 500, the second power transmission device 600 does not receive power. At this time, the rear wheels (700a, 700b) only rotate while being dragged by the front wheels (400a, 400b).

Next, four-wheel drive (4WD) mode will be described. In this embodiment, the four-wheel drive mode is divided into a high rotation (low torque) mode and a low rotation (high torque) mode. Hereinafter, the low torque (high rotation) mode will be referred to as 4WD-High mode and the high torque (low rotation) mode will be referred to as 4WD-Low mode based on rotation speed.

Figure 9 is a schematic diagram showing the 4WD-High mode of a four-wheel drive system according to an embodiment of the present invention.

In 4WD-High mode, the first sleeve 332 and the third sleeve 662 are fastened. The second sleeve 362 and the fourth sleeve 664 are not fastened. Since the first sleeve 332 is fastened to the first power transmission device 300, a portion of the power of the input shaft 322 is transmitted to the first gear 330. And it is transmitted to the second power transmission device 600 through the propeller shaft 500 through the second gear 342 engaged with the first gear 330 and the output flange 350. Meanwhile, part of the power of the input shaft 322 that is not transmitted to the first gear 330 drives the front wheels 400a and 400b through the first planetary gearset 360 and the front wheel differential gear 370. It is used to order.

In the second power transmission device 600, power is input through the input flange 620, the third gear 642 rotates by the coupling 630, and the third gear 642 and It is transmitted to the fourth gear 650 that engages. Since the third sleeve 662 is fastened, the power of the fourth gear 650 is transmitted to the output shaft 660. The power of the output shaft 660 drives the rear wheels 700a and 700b through the second planetary gearset 670 and the rear wheel differential gear 680.

As described above, in 4WD-High mode, the ring gears of the first planetary gearset 360 and the second planetary gearset 670 are not fixed.

Figure 10 is a schematic diagram showing the 4WD-Low mode of a four-wheel drive system according to an embodiment of the present invention.

In 4WD-Low mode, the first sleeve 332, the second sleeve 362, the third sleeve 662, and the fourth sleeve 664 are all fastened. Among these, as the first sleeve 332 and the third sleeve 662 are fastened, the power from the transmission 200 is transmitted to both the front wheels 400a and 400b and the rear wheels 700a and 700b, as described above. The point is the same.

However, in 4WD-Low mode, as the second sleeve 362 and the fourth sleeve 664 are fastened, the ring gears of the first planetary gearset 360 and the second planetary gearset 670 are It stops and the rotation speed is reduced to increase torque. As a result, in 4WD-Low mode, the torque transmitted to both the front wheels 400a and 400b and the rear wheels 700a and 700b increases.

Figure 11 is a schematic diagram showing the 4WD-Low-Lock mode of a four-wheel drive system according to an embodiment of the present invention.

In 4WD-Low-Lock mode, the first sleeve 332, the second sleeve 362, the third sleeve 662, and the fourth sleeve 664 are all fastened. Accordingly, all hubs combined in the aforementioned 4WD-Low mode are combined. Additionally, the fourth sleeve 664 is coupled to the N hub. That is, the fourth sleeve 664 can move further to the left in the drawing, and is additionally coupled to the N hub while remaining coupled to the J hub and the K hub. As a result, the rear wheel differential gear 680 enters a locked state. When the rear differential gear 680 is locked, the power transmitted to the left and right rear wheels 700a and 700b is always equally distributed. Therefore, the performance of escaping rough terrain, such as when one wheel slips, is improved.

Figure 12 is a diagram showing hub coupling portions according to the drive mode of a four-wheel drive system according to an embodiment of the present invention. The four-wheel drive system according to this embodiment can implement at least four driving modes and can be controlled to select an appropriate mode as needed.

Hereinafter, the operational effects of the four-wheel drive system according to this embodiment will be described.

The four-wheel drive system according to this embodiment can reduce power loss by blocking the rotation of unnecessary parts such as the propeller shaft 500 in 2WD mode. Therefore, fuel efficiency is improved and durability is improved.

In addition, 4WD-Low mode can be implemented, enabling low rotation and high torque driving that cannot be achieved with the transmission 200 alone. Therefore, driving performance is improved on rough terrain or uphill slopes that require high torque.

In addition, 4WD-Low-Lock mode can be implemented, improving rough terrain escape performance. In particular, this can be achieved by forming the N hub and setting the displacement of the fourth sleeve 664 to be large, without adding additional parts.

100: Engine 200: Transmission
300: First power transmission unit (PTU) 310: Housing
320: first intermediate shaft 322: input shaft
330: first gear 332: first sleeve
334: first actuator 340: first pinion shaft
342: second gear 350: output flange
360: first planetary gearset 362: second sleeve
364: second actuator 370: front wheel differential gear
380: Front wheel shaft
400a, 400b: Front wheel 500: Propeller shaft
600: Second power transmission device (RDM) 610: Housing
620: input flange 630: coupling
640: second pinion shaft 642: third gear
650: fourth gear 660: output shaft
661: second intermediate shaft 662: third sleeve
663: Third actuator 664: Fourth sleeve
665: Fourth actuator 670: Second planetary gearset
680: Rear wheel differential gear 700a, 700b: Rear wheel

Claims (10)

A first power transmission device that distributes power received from the transmission to the front and rear wheels;
a propeller shaft that transmits power distributed from the first power transmission device to the rear wheels; and
A second power transmission device coupled to the rear end of the propeller shaft and distributing power received from the propeller shaft to the rear wheels,
The first power transmission device and the second power transmission device include a first planetary gearset and a second planetary gearset that increase torque, respectively,
The first power transmission device includes a housing, an input shaft that receives power from a transmission, a first gear surrounding the input shaft, a second gear that meshes with the first gear to transmit power to the propeller shaft, and the input shaft. It further includes a first sleeve connected between the first gear and transmitting or blocking power,
The first planetary gear set includes a sun gear that receives power from the input shaft, a plurality of planetary gears external to the sun gear, and a ring gear internally in contact with the planetary gear,
The first power transmission device further includes a second sleeve connecting the ring gear and the housing,
A four-wheel drive system that implements a high torque mode in which rotation of the ring gear is stopped by fastening the second sleeve and power is transmitted from the sun gear to the planet gear. delete According to paragraph 1,
The first power transmission device is a four-wheel drive system further including a front wheel differential gear that distributes power to the left and right front wheels. delete According to paragraph 1,
The first power transmission device is a four-wheel drive system including a first actuator that moves the first sleeve and a second actuator that moves the second sleeve. A first power transmission device that distributes power received from the transmission to the front and rear wheels;
a propeller shaft that transmits power distributed from the first power transmission device to the rear wheels; and
A second power transmission device coupled to the rear end of the propeller shaft and distributing power received from the propeller shaft to the rear wheels,
The first power transmission device and the second power transmission device include a first planetary gearset and a second planetary gearset that increase torque, respectively,
The second power transmission device includes a housing, an input flange connected to the propeller shaft to receive power, a third gear disposed coaxially with the input flange, and a gear that transmits or blocks power between the input flange and the third gear. It further includes a coupling, a fourth gear engaged with the third gear, an output shaft penetrating the fourth gear, and a third sleeve connected between the fourth gear and the output shaft to transmit or block power,
The second planetary gear set includes a sun gear that receives power from the output shaft, a plurality of planet gears external to the sun gear, and a ring gear internal to the planet gear,
The second power transmission device further includes a fourth sleeve connecting the ring gear and the housing,
A four-wheel drive system that implements a high torque mode in which rotation of the ring gear is stopped by fastening the fourth sleeve and power is transmitted from the sun gear to the planet gear. delete According to clause 6,
The second power transmission device is a four-wheel drive system further including a rear differential gear that distributes power to the left and right rear wheels. According to clause 8,
The fourth sleeve can be additionally fastened to the rear differential gear to change the rear differential gear to a locked state. According to clause 6,
The second power transmission device is a four-wheel drive system including a third actuator for moving the third sleeve and a fourth actuator for moving the fourth sleeve.